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wlannon(at)shaw.ca
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 Posted: Sun Jul 16, 2017 10:40 am Post subject: [Non-DoD Source] Engine mount rubbers - YAK-50 |
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This has been an area of concern since my first CJ6/Huosai experience in 1993.
Gord: Could you please explain what you mean by “sleeve”. It would appear you are referring to the damper support washers.
The reason for my confusion is years of experience with this type of damper installation on other aircraft using the small P&W radials (R1340 & R985). In particular the Harvard and T6.
Kind of blew my mind to find a rubber vibration damper with no internal steel bushing (sleeve?) to control the compression of the rubber. Eventually got used to guessing at the torque and forgot about it.
In the P&W case (and probably most, if not all, engine manufacturers) this is not an engine component. It was usually left to the determinations of the airframe manufacturer.
Question for Yak 50, 52, 55, 18T, Sukhoi, etc. owners: Does your M14P installation use internal bushings to establish damper compression? If so could someone measure the exact bushing length?
Walt
F rom: Gordon Price (gord(at)thedampub.ca)
Sent: Sunday, July 16, 2017 6:50 AM
To: yak-list(at)matronics.com (yak-list(at)matronics.com)
Subject: Re: [Non-DoD Source] Engine mount rubbers - YAK-50
Thanks Doc
That is a big difference!
Here is the drawing George Coy sent to me.
Do you know if the rubber is bonded to the sleeve and are there sleeves on both the front and back rubbers?
We will know more once we get the engine off the mount on Wednesday.
Gord
| Quote: | On Jul 16, 2017, at 9:19 AM, Roger Kemp <f16viperdoc(at)me.com (f16viperdoc(at)me.com)> wrote:
Gord,
The instructions I got were to compress to 44.5 mm.
Doc
Sent from my iPad
On Jul 14, 2017, at 11:31 AM, Gordon Price <gord(at)thedampub.ca (gord(at)thedampub.ca)> wrote:
| Quote: |
Good point Doug and thank you for that. There is a measurement of 34.5 mm on the plans sent to me by George Coy. At that point should the metal sleeves inside touch?
Does anyone have method of torquing that would be helpful or sod you just compress to 34.5 mm.
Could not enough torque could cause this problem? Could too much torque cause the problem? We don’t know so if someone has experience please let us know.
We have yet to remove the engine since work is backed up in the shop however I am told that the forward rubber mounts that are installed did not have the washer with a sleeve. Only a washer..no sleeve.
Also, which mounts do you sell Doug? With or without the sleeve?
Thanks
Gord
| Quote: | On Jul 14, 2017, at 11:54 AM, doug sapp <dougsappllc(at)gmail.com (dougsappllc(at)gmail.com)> wrote:
Gents, Addressing the "mount rubber" issue only.
Are we 100% sure that the bonding or the failure of bonding to the washer or to the bushing is the problem here? I suspect that it is not. I suspect that the mount rubber were incorrectly installed. Since there is no actual torque value stated in anything I have read it seems that there exists a large opportunity to install them without enough torque, meaning not tight enough. In a "normal situation" (gentleman's acro) I would think that proper installation would not be as critical as is would be in this rather unusual high g loading situation. This would help explain why this problem/situation has not been seen much in the past.
Just a WAG on my part, YMMV.
Doug
On Fri, Jul 14, 2017 at 5:32 AM, Gordon Price <gord(at)thedampub.ca (gord(at)thedampub.ca)> wrote:
| Quote: | As I recall Richard you did say that the YAK 50 could be flown forever at +5 and -3.
As I said SOMETIMES I see +8 and -5 G. Just being honest. A normal airshow routine is +6 and -4 and yes the airplane has all the mods and lightweight equipment. As for the pilot weight… I am always working on that.
You are right . The engine is spectacular and increased power has changed the flying characteristics of the airplane which I am still getting used to. I should be fully up to speed by the end of August when I fly the CNE Canadian International Air Show in Toronto.
Back to the subject I have been to introduce for discussion………..
Attached is a picture of the different engine mount rubbers.
On the left 2 new ones with the rubber bonded to the steel insert and on the right one of the damaged mounts where the steel insert is not bonded and can turn and cut the rubber.
<rubber.jpeg>
| Quote: | On Jul 14, 2017, at 2:20 AM, That's looking at his note <richard2835492219526631817Apple-interchange-newline"> (richard.goode(at)russianaeros.com) Firstly I would like to make it clear that we supplied the engine together with the engine mount rubbers to Gordon Price. But we have used exactly the same rubbers on around 300 engines that we have supplied to a wide variety of aircraft, including competition Sukhois and have never had this problem before. But we will sort it out, and we know from Gordon that the engine is performing spectacularly well.
But it raises an issue which I think is far more important, and that is flying a Yak 50 to its design limits of plus 9G and minus 6G. I have done a lot of research on this topic, and the 50 was unfortunate in that it was introduced at a time that aerobatics changing from being big graceful manoeuvres to sharp angles. The Russian team was well funded and incredibly well motivated, and they were flying them beyond these limits, and had four fatal accidents to team members. During this period Yakovlev issued a series of service bulletins to reinforce the last bit of the aircraft that had broken, culminating in bulletin 79 – a 4.5 mm steel plate on top and bottom of the centre section.
But firstly, remember that the Russian pilots were all relatively light; the aeroplane was flown only with one fuel tank; no generator; air compressor; a light battery. Then, the TOTAL service life of a team aircraft was 47 hours. After that it was scrapped. And for any other aircraft, the total service life was 300 hours, and then it was scrapped!
I have a serious concern that many pilots today are flying aircraft that have done far more hours than this; are ignorant of these issues, and yet feel that they still have a plus 9G aircraft, with a heavy Western pilot; smoke system; both fuel tanks et cetera!
I prepared a detailed paper some years ago following discussions with Yakovlev describing the individual failures and then the subsequent service bulletins. I will send this to anyone who is interested.
Richard Goode Aerobatics
Rhodds Farm
Lyonshall
Hereford
HR5 3LW
Tel: (richard.goode(at)russianaeros.com)[url=tel:+44%201544%20340120]+44 (0) 1544 340120[/url]
Fax: [url=tel:+44%201544%20340129]+44 (0) 1544 340129[/url]
www.russianaeros.com
From: owner-yak-list-server(at)matronics.com (owner-yak-list-server(at)matronics.com) [mailto:owner-yak-list-server(at)matronics.com (owner-yak-list-server(at)matronics.com)] On Behalf Of Gordon Price
Sent: 13 July 2017 19:31
To: yak-list(at)matronics.com (yak-list(at)matronics.com)
Subject: Re: [Non-DoD Source] Engine mount rubbers - YAK-50
Thanks for the advice Frank however it would be nice on this forum if we could just stick to the topic at hand.
In this case… the topic it is a problem with engine mount rubbers and the fact that the ones supplied did not have the sleeve bonded to the rubber.
Has anyone ever experienced this?
| Quote: | On Jul 13, 2017, at 1:44 PM, Frank Stelwagon <pfstelwagon(at)earthlink.net (pfstelwagon(at)earthlink.net)> wrote:
Mark wasn’t lecturing you! He was telling you what he knows from experience (lots of it). It might be safer to listen.
From:owner-yak-list-server(at)matronics.com (owner-yak-list-server(at)matronics.com) [mailto:owner-yak-list-server(at)matronics.com (owner-yak-list-server(at)matronics.com)] On Behalf Of Gord Price
Sent: Thursday, July 13, 2017 10:22 AM
To: yak-list(at)matronics.com (yak-list(at)matronics.com)
Subject: Re: [Non-DoD Source] Engine mount rubbers - YAK-50
Mark. I asked for help .....not a lecture on a subject that I am well versed in nor assumptions that are incorrect
I have solved the problem and I am surprised you did not offer the advice that the sleeve does not require bonding....if it is the correct mounting rubber.
The rubbers that were supplied and installed by my mechanic do not have the sleeve bonded. In fact the front rubbers do not even have a sleeve. No wonder they were coming apart.
A new 'proper' set is being installed this weekend. I never had this problem with the old engine because it had the correct rubber mounts which were sold with the engine.
I believe this will solve the problem and I will carry on flying a very aggressive and dynamic AIRSHOW routine that is well within the limits of my airplane which is constantly being inspected.
It is not the type of flying that most YAK owners engage in however I am quite at ease flying it this way. I first flew Victor Smolin's YAK 50 in 1982 and I was taught the Lomcevak by its inventor Ladislav Bezak in 1980. [url=tel:331%20826%209942]331 826 9942[/url]. Gord cell Mexico
[url=tel:333%20495%205044]333 495 5044[/url] Sandy cell Mexico
[url=tel:519%20375%206233]519 375 6233[/url] Gord cell Canada
[url=tel:519%20378%206800]519 378 6800[/url] Sandy cell Canada
[url=tel:519%20538%202868]519 538 2868[/url] House Canada
[url=tel:226%20777%204383]226 777 4383[/url] Email voice message anywhere
Sent from my iPhone
On Jul 13, 2017, at 12:00 PM, Bitterlich, Mark G CIV NAVAIR, WD <mark.bitterlich(at)navy.mil (mark.bitterlich(at)navy.mil)> wrote:
| Quote: |
--> Yak-List message posted by: "Bitterlich, Mark G CIV NAVAIR, WD" <mark.bitterlich(at)navy.mil (mark.bitterlich(at)navy.mil)>
Typically, the rubber used in these engine mounts deteriorates with age. Personally what I would try to do under your circumstance is to measure a new one with a durometer, and then have a mold constructed and replace them with a polyurethane equivalent.
You did not ask this, and I am sorry for sticking my nose into the topic and changing the subject somewhat, but I would suggest that you also make sure you have the Russian recording accelerometer installed in your 50, (or a suitable replacement) and are keeping track of the cycles. The 50 is indeed rated to +9/-6 assuming all the mods are incorporated. However that was not an unlimited qualification. Meaning that after so many "cycles" (as documented on the recording accelerometer), it was a requirement to replace the wings. Considering most 50's that were flown in unlimited events were usually retired under 100 hours of flight time, it might be worth keeping in mind.
The kind of damage to engine mount rubbers that you are describing is something commonly seen on Sukhoi's flying Unlimited level aerobatic competition, usually with engines just like yours and MTV9-260 props, thus I suspect you are approaching that kind of G loading. That said, the Suke construction otherwise is much stronger than the 50. Another thing that generates this kind of stress is gyroscopic maneuvers usually accompanied by prop shaft seal damage.
Good luck.
Mark
-----Original Message-----
From: owner-yak-list-server(at)matronics.com (owner-yak-list-server(at)matronics.com) [mailto:owner-yak-list-server(at)matronics.com (owner-yak-list-server(at)matronics.com)] On Behalf Of Gordon Price yak-list(at)matronics.com (yak-list(at)matronics.com)
Subject: [Non-DoD Source] Engine mount rubbers - YAK-50
--> Yak-List message posted by: Gordon Price <gord(at)thedampub.ca (gord(at)thedampub.ca)>
We just installed a zero’d M-13PF with Barrett Pistons which dyno'd at 435 HP on my YAK 50. Performance is much enhanced however we have just found some engine mount rubbers are being torn up because the metal sleeve is moving and cutting the rubber. The airplane is being flown under the G limits however during the air show sequence I am sometimes seeing +8 and -5 G. We never had this problem with the old 360 HP engine. We have a new set being installed in the next few days which should yield more information. Does anyone have experience in this area? Thinking of bonding the sleeve to the rubber to prevent the sleeve movement. Thanks in advance. Gord
http://www.matronics.com/Navigator?Yak-List
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Thanks Doc
That is a big difference!
Here is the drawing George Coy sent to me.
Do you know if the rubber is bonded to the sleeve and are there sleeves on both the front and back rubbers?
We will know more once we get the engine off the mount on Wednesday.
Gord
| Quote: | On Jul 16, 2017, at 9:19 AM, Roger Kemp <f16viperdoc(at)me.com> wrote:
Gord,
The instructions I got were to compress to 44.5 mm.
Doc
Sent from my iPad
On Jul 14, 2017, at 11:31 AM, Gordon Price <gord(at)thedampub.ca <mailto:gord(at)thedampub.ca>> wrote:
>
> Good point Doug and thank you for that. There is a measurement of 34.5 mm on the plans sent to me by George Coy. At that point should the metal sleeves inside touch?
>
> Does anyone have method of torquing that would be helpful or sod you just compress to 34.5 mm.
>
> Could not enough torque could cause this problem? Could too much torque cause the problem? We don’t know so if someone has experience please let us know.
>
> We have yet to remove the engine since work is backed up in the shop however I am told that the forward rubber mounts that are installed did not have the washer with a sleeve. Only a washer..no sleeve.
>
> Also, which mounts do you sell Doug? With or without the sleeve?
>
> Thanks
>
> Gord
>
>> On Jul 14, 2017, at 11:54 AM, doug sapp <dougsappllc(at)gmail.com <mailto:dougsappllc(at)gmail.com>> wrote:
>>
>> Gents,
>> Addressing the "mount rubber" issue only.
>> Are we 100% sure that the bonding or the failure of bonding to the washer or to the bushing is the problem here? I suspect that it is not. I suspect that the mount rubber were incorrectly installed. Since there is no actual torque value stated in anything I have read it seems that there exists a large opportunity to install them without enough torque, meaning not tight enough. In a "normal situation" (gentleman's acro) I would think that proper installation would not be as critical as is would be in this rather unusual high g loading situation. This would help explain why this problem/situation has not been seen much in the past.
>>
>> Just a WAG on my part, YMMV.
>>
>> Doug
>>
>> On Fri, Jul 14, 2017 at 5:32 AM, Gordon Price <gord(at)thedampub.ca <mailto:gord(at)thedampub.ca>> wrote:
>> As I recall Richard you did say that the YAK 50 could be flown forever at +5 and -3.
>>
>> As I said SOMETIMES I see +8 and -5 G. Just being honest. A normal airshow routine is +6 and -4 and yes the airplane has all the mods and lightweight equipment. As for the pilot weight… I am always working on that.
>>
>> You are right . The engine is spectacular and increased power has changed the flying characteristics of the airplane which I am still getting used to. I should be fully up to speed by the end of August when I fly the CNE Canadian International Air Show in Toronto.
>>
>>
>> Back to the subject I have been to introduce for discussion………..
>>
>>
>> Attached is a picture of the different engine mount rubbers.
>>
>> On the left 2 new ones with the rubber bonded to the steel insert and on the right one of the damaged mounts where the steel insert is not bonded and can turn and cut the rubber.
>>
>> <rubber.jpeg>
>>
>>
>>
>>> On Jul 14, 2017, at 2:20 AM, That's looking at his note <richard2835492219526631817Apple-interchange-newline"> <mailto:richard.goode(at)russianaeros.com>
>>> <mailto:richard.goode(at)russianaeros.com>Firstly I would like to make it clear that we supplied the engine together with the engine mount rubbers to Gordon Price. But we have used exactly the same rubbers on around 300 engines that we have supplied to a wide variety of aircraft, including competition Sukhois and have never had this problem before. But we will sort it out, and we know from Gordon that the engine is performing spectacularly well.
>>>
>>> But it raises an issue which I think is far more important, and that is flying a Yak 50 to its design limits of plus 9G and minus 6G. I have done a lot of research on this topic, and the 50 was unfortunate in that it was introduced at a time that aerobatics changing from being big graceful manoeuvres to sharp angles. The Russian team was well funded and incredibly well motivated, and they were flying them beyond these limits, and had four fatal accidents to team members. During this period Yakovlev issued a series of service bulletins to reinforce the last bit of the aircraft that had broken, culminating in bulletin 79 – a 4.5 mm steel plate on top and bottom of the centre section.
>>>
>>> But firstly, remember that the Russian pilots were all relatively light; the aeroplane was flown only with one fuel tank; no generator; air compressor; a light battery. Then, the TOTAL service life of a team aircraft was 47 hours. After that it was scrapped. And for any other aircraft, the total service life was 300 hours, and then it was scrapped!
>>>
>>> I have a serious concern that many pilots today are flying aircraft that have done far more hours than this; are ignorant of these issues, and yet feel that they still have a plus 9G aircraft, with a heavy Western pilot; smoke system; both fuel tanks et cetera!
>>>
>>> I prepared a detailed paper some years ago following discussions with Yakovlev describing the individual failures and then the subsequent service bulletins. I will send this to anyone who is interested.
>>>
>>> <mailto:richard.goode(at)russianaeros.com>Richard Goode Aerobatics
>>> Rhodds Farm
>>> Lyonshall
>>> Hereford
>>> HR5 3LW
>>>
>>> <mailto:richard.goode(at)russianaeros.com>Tel: <mailto:richard.goode(at)russianaeros.com>+44 (0) 1544 340120 <tel:+44%201544%20340120>
>>> Fax: +44 (0) 1544 340129 <tel:+44%201544%20340129>
>>> www.russianaeros.com <http://www.russianaeros.com/>
>>>
>>> From: owner-yak-list-server(at)matronics.com <mailto:owner-yak-list-server(at)matronics.com> [mailto:owner-yak-list-server(at)matronics.com <mailto:owner-yak-list-server(at)matronics.com>] On Behalf Of Gordon Price
>>> Sent: 13 July 2017 19:31
>>> To: yak-list(at)matronics.com <mailto:yak-list(at)matronics.com>
>>> Subject: Re: [Non-DoD Source] Engine mount rubbers - YAK-50
>>>
>>> Thanks for the advice Frank however it would be nice on this forum if we could just stick to the topic at hand.
>>>
>>> In this case… the topic it is a problem with engine mount rubbers and the fact that the ones supplied did not have the sleeve bonded to the rubber.
>>>
>>> Has anyone ever experienced this?
>>>
>>>> On Jul 13, 2017, at 1:44 PM, Frank Stelwagon <pfstelwagon(at)earthlink.net <mailto:pfstelwagon(at)earthlink.net>> wrote:
>>>>
>>>> Mark wasn’t lecturing you! He was telling you what he knows from experience (lots of it). It might be safer to listen.
>>>>
>>>> From: owner-yak-list-server(at)matronics.com <mailto:owner-yak-list-server(at)matronics.com> [mailto:owner-yak-list-server(at)matronics.com <mailto:owner-yak-list-server(at)matronics.com>] On Behalf Of Gord Price
>>>> Sent: Thursday, July 13, 2017 10:22 AM
>>>> To: yak-list(at)matronics.com <mailto:yak-list(at)matronics.com>
>>>> Subject: Re: [Non-DoD Source] Engine mount rubbers - YAK-50
>>>>
>>>> Mark. I asked for help .....not a lecture on a subject that I am well versed in nor assumptions that are incorrect
>>>>
>>>> I have solved the problem and I am surprised you did not offer the advice that the sleeve does not require bonding....if it is the correct mounting rubber.
>>>>
>>>> The rubbers that were supplied and installed by my mechanic do not have the sleeve bonded. In fact the front rubbers do not even have a sleeve. No wonder they were coming apart.
>>>>
>>>> A new 'proper' set is being installed this weekend. I never had this problem with the old engine because it had the correct rubber mounts which were sold with the engine.
>>>>
>>>> I believe this will solve the problem and I will carry on flying a very aggressive and dynamic AIRSHOW routine that is well within the limits of my airplane which is constantly being inspected.
>>>>
>>>> It is not the type of flying that most YAK owners engage in however I am quite at ease flying it this way. I first flew Victor Smolin's YAK 50 in 1982 and I was taught the Lomcevak by its inventor Ladislav Bezak in 1980.
>>>>
>>>> 331 826 9942 <tel:331%20826%209942>. Gord cell Mexico
>>>> 333 495 5044 <tel:333%20495%205044> Sandy cell Mexico
>>>> 519 375 6233 <tel:519%20375%206233> Gord cell Canada
>>>> 519 378 6800 <tel:519%20378%206800> Sandy cell Canada
>>>> 519 538 2868 <tel:519%20538%202868> House Canada
>>>> 226 777 4383 <tel:226%20777%204383> Email voice message anywhere
>>>> Sent from my iPhone
>>>>
>>>>
>>>> On Jul 13, 2017, at 12:00 PM, Bitterlich, Mark G CIV NAVAIR, WD <mark.bitterlich(at)navy.mil <mailto:mark.bitterlich(at)navy.mil>> wrote:
>>>>
>>>>> --> Yak-List message posted by: "Bitterlich, Mark G CIV NAVAIR, WD" <mark.bitterlich(at)navy.mil <mailto:mark.bitterlich(at)navy.mil>>
>>>>>
>>>>> Typically, the rubber used in these engine mounts deteriorates with age. Personally what I would try to do under your circumstance is to measure a new one with a durometer, and then have a mold constructed and replace them with a polyurethane equivalent.
>>>>>
>>>>> You did not ask this, and I am sorry for sticking my nose into the topic and changing the subject somewhat, but I would suggest that you also make sure you have the Russian recording accelerometer installed in your 50, (or a suitable replacement) and are keeping track of the cycles. The 50 is indeed rated to +9/-6 assuming all the mods are incorporated. However that was not an unlimited qualification. Meaning that after so many "cycles" (as documented on the recording accelerometer), it was a requirement to replace the wings. Considering most 50's that were flown in unlimited events were usually retired under 100 hours of flight time, it might be worth keeping in mind.
>>>>>
>>>>> The kind of damage to engine mount rubbers that you are describing is something commonly seen on Sukhoi's flying Unlimited level aerobatic competition, usually with engines just like yours and MTV9-260 props, thus I suspect you are approaching that kind of G loading. That said, the Suke construction otherwise is much stronger than the 50. Another thing that generates this kind of stress is gyroscopic maneuvers usually accompanied by prop shaft seal damage.
>>>>>
>>>>> Good luck.
>>>>>
>>>>> Mark
>>>>>
>>>>>
>>>>> -----Original Message-----
>>>>> From: owner-yak-list-server(at)matronics.com <mailto:owner-yak-list-server(at)matronics.com> [mailto:owner-yak-list-server(at)matronics.com <mailto:owner-yak-list-server(at)matronics.com>] On Behalf Of Gordon Price
>>>>> yak-list(at)matronics.com <mailto:yak-list(at)matronics.com>
>>>>> Subject: [Non-DoD Source] Engine mount rubbers - YAK-50
>>>>>
>>>>> --> Yak-List message posted by: Gordon Price <gord(at)thedampub.ca <mailto:gord(at)thedampub.ca>>
>>>>>
>>>>>
>>>>> We just installed a zero’d M-13PF with Barrett Pistons which dyno'd at 435 HP on my YAK 50. Performance is much enhanced however we have just found some engine mount rubbers are being torn up because the metal sleeve is moving and cutting the rubber. The airplane is being flown under the G limits however during the air show sequence I am sometimes seeing +8 and -5 G. We never had this problem with the old 360 HP engine. We have a new set being installed in the next few days which should yield more information. Does anyone have experience in this area? Thinking of bonding the sleeve to the rubber to prevent the sleeve movement. Thanks in advance. Gord
>>>>>
>>>>>
>>>>>
>>>>> http://www.matronics.com/Navigator?Yak-List <http://www.matronics.com/Navigator?Yak-List>
>>>>> <========================== &nb --> MailScanner has detected a possible fraud attempt from "forums.matronics.com" claiming to behttp://forums.ma===========================; --> <http://forums.matronics.com/>MailScanner has detected a possible fraud attempt from "wiki.matronics.com" claiming to behttp://wiki.matronics.co==========================; - List Conbsp; -Matt Dralle, List Ads.com/contribution">http://www.matronics.com/contribution <http://wiki.matronics.com/>
>>>>>
>>>>>
>>>>>
>>>>>
>>>
>>>
>>>
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>>> dangerous content by MailScanner <http://www.mailscanner.info/>, and is
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gord(at)thedampub.ca
Guest
|
| Posted: Sun Jul 16, 2017 12:02 pm Post subject: [Non-DoD Source] Engine mount rubbers - YAK-50 |
|
|
Hi Walt.
Hopefully these pictures will help explain the dilemma.
After 20 hrs on the engine.
[img]cid:981E4BF5-D4B4-49B2-AA7C-F3CCD151A0EA[/img] This shows a new mount on top. The old sleeve/washer is sitting on top of the new mount. It is smaller
[img]cid:602B1E73-62CE-4EF5-B325-B5D4CD36F0E8[/img] This is the old rear rubber mount. The sleeve/washer has cut the rubber
[img]cid:FE878353-3735-4492-B3E7-02C1308F4C91[/img] This is the old mount and sleeve/washer another view
[img]cid:B1BC1E63-09E2-4411-A45A-0263CB9DF639[/img] another view of the old sleeve/washer and rubber mount
I was in Mexico when the engine was put on the airplane last winter. I was told that there is no washer/sleeve on the front rubber, only a washer. We won’t know until we get the engine off on Wednesday what exactly is there.
The new rubber mounts I have purchased have the metal bonded to the rubber, both front and back rubbers.
I agree. I too, am confused with no internal bushing in the mounts. I have been told that the measurement between the washers is to be 34.5 mm.
Gord
[quote]On Jul 16, 2017, at 2:36 PM, Walter Lannon <wlannon(at)shaw.ca (wlannon(at)shaw.ca)> wrote:
This has been an area of concern since my first CJ6/Huosai experience in 1993.
Gord: Could you please explain what you mean by “sleeve”. It would appear you are referring to the damper support washers.
The reason for my confusion is years of experience with this type of damper installation on other aircraft using the small P&W radials (R1340 & R985). In particular the Harvard and T6.
Kind of blew my mind to find a rubber vibration damper with no internal steel bushing (sleeve?) to control the compression of the rubber. Eventually got used to guessing at the torque and forgot about it.
In the P&W case (and probably most, if not all, engine manufacturers) this is not an engine component. It was usually left to the determinations of the airframe manufacturer.
Question for Yak 50, 52, 55, 18T, Sukhoi, etc. owners: Does your M14P installation use internal bushings to establish damper compression? If so could someone measure the exact bushing length?
Walt
F rom: Gordon Price (gord(at)thedampub.ca)
Sent: Sunday, July 16, 2017 6:50 AM
To: yak-list(at)matronics.com (yak-list(at)matronics.com)
Subject: Re: [Non-DoD Source] Engine mount rubbers - YAK-50
Thanks Doc
That is a big difference!
Here is the drawing George Coy sent to me.
Do you know if the rubber is bonded to the sleeve and are there sleeves on both the front and back rubbers?
We will know more once we get the engine off the mount on Wednesday.
Gord
[quote]On Jul 16, 2017, at 9:19 AM, Roger Kemp <f16viperdoc(at)me.com (f16viperdoc(at)me.com)> wrote:
Gord,
The instructions I got were to compress to 44.5 mm.
DocSent from my iPad
On Jul 14, 2017, at 11:31 AM, Gordon Price <gord(at)thedampub.ca (gord(at)thedampub.ca)> wrote:
[quote]
Good point Doug and thank you for that. There is a measurement of 34.5 mm on the plans sent to me by George Coy. At that point should the metal sleeves inside touch?
Does anyone have method of torquing that would be helpful or sod you just compress to 34.5 mm.
Could not enough torque could cause this problem? Could too much torque cause the problem? We don’t know so if someone has experience please let us know.
We have yet to remove the engine since work is backed up in the shop however I am told that the forward rubber mounts that are installed did not have the washer with a sleeve. Only a washer..no sleeve.
Also, which mounts do you sell Doug? With or without the sleeve?
Thanks
Gord
[quote]On Jul 14, 2017, at 11:54 AM, doug sapp <dougsappllc(at)gmail.com (dougsappllc(at)gmail.com)> wrote:
Gents,Addressing the "mount rubber" issue only.
Are we 100% sure that the bonding or the failure of bonding to the washer or to the bushing is the problem here? I suspect that it is not. I suspect that the mount rubber were incorrectly installed. Since there is no actual torque value stated in anything I have read it seems that there exists a large opportunity to install them without enough torque, meaning not tight enough. In a "normal situation" (gentleman's acro) I would think that proper installation would not be as critical as is would be in this rather unusual high g loading situation. This would help explain why this problem/situation has not been seen much in the past.
Just a WAG on my part, YMMV.
Doug
On Fri, Jul 14, 2017 at 5:32 AM, Gordon Price <gord(at)thedampub.ca (gord(at)thedampub.ca)> wrote:[quote]As I recall Richard you did say that the YAK 50 could be flown forever at +5 and -3.
As I said SOMETIMES I see +8 and -5 G. Just being honest. A normal airshow routine is +6 and -4 and yes the airplane has all the mods and lightweight equipment. As for the pilot weight… I am always working on that.
You are right . The engine is spectacular and increased power has changed the flying characteristics of the airplane which I am still getting used to. I should be fully up to speed by the end of August when I fly the CNE Canadian International Air Show in Toronto.
Back to the subject I have been to introduce for discussion………..
Attached is a picture of the different engine mount rubbers.
On the left 2 new ones with the rubber bonded to the steel insert and on the right one of the damaged mounts where the steel insert is not bonded and can turn and cut the rubber.
<rubber.jpeg>
[quote]On Jul 14, 2017, at 2:20 AM, That's looking at his note <richard2835492219526631817Apple-interchange-newline"> (richard.goode(at)russianaeros.com)Firstly I would like to make it clear that we supplied the engine together with the engine mount rubbers to Gordon Price. But we have used exactly the same rubbers on around 300 engines that we have supplied to a wide variety of aircraft, including competition Sukhois and have never had this problem before. But we will sort it out, and we know from Gordon that the engine is performing spectacularly well.
But it raises an issue which I think is far more important, and that is flying a Yak 50 to its design limits of plus 9G and minus 6G. I have done a lot of research on this topic, and the 50 was unfortunate in that it was introduced at a time that aerobatics changing from being big graceful manoeuvres to sharp angles. The Russian team was well funded and incredibly well motivated, and they were flying them beyond these limits, and had four fatal accidents to team members. During this period Yakovlev issued a series of service bulletins to reinforce the last bit of the aircraft that had broken, culminating in bulletin 79 – a 4.5 mm steel plate on top and bottom of the centre section.
But firstly, remember that the Russian pilots were all relatively light; the aeroplane was flown only with one fuel tank; no generator; air compressor; a light battery. Then, the TOTAL service life of a team aircraft was 47 hours. After that it was scrapped. And for any other aircraft, the total service life was 300 hours, and then it was scrapped!
I have a serious concern that many pilots today are flying aircraft that have done far more hours than this; are ignorant of these issues, and yet feel that they still have a plus 9G aircraft, with a heavy Western pilot; smoke system; both fuel tanks et cetera!
I prepared a detailed paper some years ago following discussions with Yakovlev describing the individual failures and then the subsequent service bulletins. I will send this to anyone who is interested.
Richard Goode Aerobatics
Rhodds Farm
Lyonshall
Hereford
HR5 3LW
Tel: (richard.goode(at)russianaeros.com)[url=tel:+44%201544%20340120]+44 (0) 1544 340120[/url]
Fax: [url=tel:+44%201544%20340129]+44 (0) 1544 340129[/url]
www.russianaeros.com
From: owner-yak-list-server(at)matronics.com (owner-yak-list-server(at)matronics.com) [mailto:owner-yak-list-server(at)matronics.com (owner-yak-list-server(at)matronics.com)] On Behalf Of Gordon PriceSent: 13 July 2017 19:31To: yak-list(at)matronics.com (yak-list(at)matronics.com)Subject: Re: [Non-DoD Source] Engine mount rubbers - YAK-50
Thanks for the advice Frank however it would be nice on this forum if we could just stick to the topic at hand.
In this case… the topic it is a problem with engine mount rubbers and the fact that the ones supplied did not have the sleeve bonded to the rubber.
Has anyone ever experienced this?
[quote]On Jul 13, 2017, at 1:44 PM, Frank Stelwagon <pfstelwagon(at)earthlink.net (pfstelwagon(at)earthlink.net)> wrote:
Mark wasn’t lecturing you! He was telling you what he knows from experience (lots of it). It might be safer to listen.
From: owner-yak-list-server(at)matronics.com (owner-yak-list-server(at)matronics.com) [mailto:owner-yak-list-server(at)matronics.com (owner-yak-list-server(at)matronics.com)] On Behalf Of Gord PriceSent: Thursday, July 13, 2017 10:22 AMTo: yak-list(at)matronics.com (yak-list(at)matronics.com)Subject: Re: [Non-DoD Source] Engine mount rubbers - YAK-50
Mark. I asked for help .....not a lecture on a subject that I am well versed in nor assumptions that are incorrect
I have solved the problem and I am surprised you did not offer the advice that the sleeve does not require bonding....if it is the correct mounting rubber.
The rubbers that were supplied and installed by my mechanic do not have the sleeve bonded. In fact the front rubbers do not even have a sleeve. No wonder they were coming apart.
A new 'proper' set is being installed this weekend. I never had this problem with the old engine because it had the correct rubber mounts which were sold with the engine.
I believe this will solve the problem and I will carry on flying a very aggressive and dynamic AIRSHOW routine that is well within the limits of my airplane which is constantly being inspected.
It is not the type of flying that most YAK owners engage in however I am quite at ease flying it this way. I first flew Victor Smolin's YAK 50 in 1982 and I was taught the Lomcevak by its inventor Ladislav Bezak in 1980.[url=tel:331%20826%209942]331 826 9942[/url]. Gord cell Mexico
[url=tel:333%20495%205044]333 495 5044[/url] Sandy cell Mexico
[url=tel:519%20375%206233]519 375 6233[/url] Gord cell Canada
[url=tel:519%20378%206800]519 378 6800[/url] Sandy cell Canada
[url=tel:519%20538%202868]519 538 2868[/url] House Canada
[url=tel:226%20777%204383]226 777 4383[/url] Email voice message anywhere
Sent from my iPhone
On Jul 13, 2017, at 12:00 PM, Bitterlich, Mark G CIV NAVAIR, WD <mark.bitterlich(at)navy.mil (mark.bitterlich(at)navy.mil)> wrote:
[quote]
--> Yak-List message posted by: "Bitterlich, Mark G CIV NAVAIR, WD" <mark.bitterlich(at)navy.mil (mark.bitterlich(at)navy.mil)>Typically, the rubber used in these engine mounts deteriorates with age. Personally what I would try to do under your circumstance is to measure a new one with a durometer, and then have a mold constructed and replace them with a polyurethane equivalent. You did not ask this, and I am sorry for sticking my nose into the topic and changing the subject somewhat, but I would suggest that you also make sure you have the Russian recording accelerometer installed in your 50, (or a suitable replacement) and are keeping track of the cycles. The 50 is indeed rated to +9/-6 assuming all the mods are incorporated. However that was not an unlimited qualification. Meaning that after so many "cycles" (as documented on the recording accelerometer), it was a requirement to replace the wings. Considering most 50's that were flown in unlimited events were usually retired under 100 hours of flight time, it might be worth keeping in mind. The kind of damage to engine mount rubbers that you are describing is something commonly seen on Sukhoi's flying Unlimited level aerobatic competition, usually with engines just like yours and MTV9-260 props, thus I suspect you are approaching that kind of G loading. That said, the Suke construction otherwise is much stronger than the 50. Another thing that generates this kind of stress is gyroscopic maneuvers usually accompanied by prop shaft seal damage. Good luck. Mark--
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Viperdoc
Joined: 19 Apr 2014
Posts: 484
Location: 08A
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| Posted: Sun Jul 16, 2017 1:27 pm Post subject: [Non-DoD Source] Engine mount rubbers - YAK-50 |
|
|
Gordon,
Not at hanger today. Will look in my spares. I have a set of new motor mounts from Aerostar.
Doc
Sent from my iPad
On Jul 16, 2017, at 8:50 AM, Gordon Price <gord(at)thedampub.ca (gord(at)thedampub.ca)> wrote:
[quote]Thanks Doc
That is a big difference!
Here is the drawing George Coy sent to me.
Do you know if the rubber is bonded to the sleeve and are there sleeves on both the front and back rubbers?
We will know more once we get the engine off the mount on Wednesday.
Gord
<DAMPERS INSTALL ING Model (1).pdf>
[quote]On Jul 16, 2017, at 9:19 AM, Roger Kemp <f16viperdoc(at)me.com (f16viperdoc(at)me.com)> wrote:
Gord,
The instructions I got were to compress to 44.5 mm.
DocSent from my iPad
On Jul 14, 2017, at 11:31 AM, Gordon Price <gord(at)thedampub.ca (gord(at)thedampub.ca)> wrote:
[quote]Good point Doug and thank you for that. There is a measurement of 34.5 mm on the plans sent to me by George Coy. At that point should the metal sleeves inside touch?
Does anyone have method of torquing that would be helpful or sod you just compress to 34.5 mm.
Could not enough torque could cause this problem? Could too much torque cause the problem? We don’t know so if someone has experience please let us know.
We have yet to remove the engine since work is backed up in the shop however I am told that the forward rubber mounts that are installed did not have the washer with a sleeve. Only a washer..no sleeve.
Also, which mounts do you sell Doug? With or without the sleeve?
Thanks
Gord
[quote]On Jul 14, 2017, at 11:54 AM, doug sapp <dougsappllc(at)gmail.com (dougsappllc(at)gmail.com)> wrote:
Gents,Addressing the "mount rubber" issue only.
Are we 100% sure that the bonding or the failure of bonding to the washer or to the bushing is the problem here? I suspect that it is not. I suspect that the mount rubber were incorrectly installed. Since there is no actual torque value stated in anything I have read it seems that there exists a large opportunity to install them without enough torque, meaning not tight enough. In a "normal situation" (gentleman's acro) I would think that proper installation would not be as critical as is would be in this rather unusual high g loading situation. This would help explain why this problem/situation has not been seen much in the past.
Just a WAG on my part, YMMV.
Doug
On Fri, Jul 14, 2017 at 5:32 AM, Gordon Price <gord(at)thedampub.ca (gord(at)thedampub.ca)> wrote:[quote]As I recall Richard you did say that the YAK 50 could be flown forever at +5 and -3.
As I said SOMETIMES I see +8 and -5 G. Just being honest. A normal airshow routine is +6 and -4 and yes the airplane has all the mods and lightweight equipment. As for the pilot weight… I am always working on that.
You are right . The engine is spectacular and increased power has changed the flying characteristics of the airplane which I am still getting used to. I should be fully up to speed by the end of August when I fly the CNE Canadian International Air Show in Toronto.
Back to the subject I have been to introduce for discussion………..
Attached is a picture of the different engine mount rubbers.
On the left 2 new ones with the rubber bonded to the steel insert and on the right one of the damaged mounts where the steel insert is not bonded and can turn and cut the rubber.
<rubber.jpeg>
[quote]On Jul 14, 2017, at 2:20 AM, That's looking at his note <richard2835492219526631817Apple-interchange-newline"> (richard.goode(at)russianaeros.com) (richard.goode(at)russianaeros.com)Firstly I would like to make it clear that we supplied the engine together with the engine mount rubbers to Gordon Price. But we have used exactly the same rubbers on around 300 engines that we have supplied to a wide variety of aircraft, including competition Sukhois and have never had this problem before. But we will sort it out, and we know from Gordon that the engine is performing spectacularly well.
But it raises an issue which I think is far more important, and that is flying a Yak 50 to its design limits of plus 9G and minus 6G. I have done a lot of research on this topic, and the 50 was unfortunate in that it was introduced at a time that aerobatics changing from being big graceful manoeuvres to sharp angles. The Russian team was well funded and incredibly well motivated, and they were flying them beyond these limits, and had four fatal accidents to team members. During this period Yakovlev issued a series of service bulletins to reinforce the last bit of the aircraft that had broken, culminating in bulletin 79 – a 4.5 mm steel plate on top and bottom of the centre section.
But firstly, remember that the Russian pilots were all relatively light; the aeroplane was flown only with one fuel tank; no generator; air compressor; a light battery. Then, the TOTAL service life of a team aircraft was 47 hours. After that it was scrapped. And for any other aircraft, the total service life was 300 hours, and then it was scrapped!
I have a serious concern that many pilots today are flying aircraft that have done far more hours than this; are ignorant of these issues, and yet feel that they still have a plus 9G aircraft, with a heavy Western pilot; smoke system; both fuel tanks et cetera!
I prepared a detailed paper some years ago following discussions with Yakovlev describing the individual failures and then the subsequent service bulletins. I will send this to anyone who is interested.
Richard Goode Aerobatics
Rhodds Farm
Lyonshall
Hereford
HR5 3LW
Tel: (richard.goode(at)russianaeros.com)[url=tel:+44%201544%20340120]+44 (0) 1544 340120[/url]
Fax: [url=tel:+44%201544%20340129]+44 (0) 1544 340129[/url]
www.russianaeros.com
From: owner-yak-list-server(at)matronics.com (owner-yak-list-server(at)matronics.com) [mailto:owner-yak-list-server(at)matronics.com (owner-yak-list-server(at)matronics.com)] On Behalf Of Gordon PriceSent: 13 July 2017 19:31To: yak-list(at)matronics.com (yak-list(at)matronics.com)Subject: Re: [Non-DoD Source] Engine mount rubbers - YAK-50
Thanks for the advice Frank however it would be nice on this forum if we could just stick to the topic at hand.
In this case… the topic it is a problem with engine mount rubbers and the fact that the ones supplied did not have the sleeve bonded to the rubber.
Has anyone ever experienced this?
[quote]On Jul 13, 2017, at 1:44 PM, Frank Stelwagon <pfstelwagon(at)earthlink.net (pfstelwagon(at)earthlink.net)> wrote:
Mark wasn’t lecturing you! He was telling you what he knows from experience (lots of it). It might be safer to listen.
From: owner-yak-list-server(at)matronics.com (owner-yak-list-server(at)matronics.com) [mailto:owner-yak-list-server(at)matronics.com (owner-yak-list-server(at)matronics.com)] On Behalf Of Gord PriceSent:Thursday, July 13, 2017 10:22 AMTo: yak-list(at)matronics.com (yak-list(at)matronics.com)Subject:Re: [Non-DoD Source] Engine mount rubbers - YAK-50
Mark. I asked for help .....not a lecture on a subject that I am well versed in nor assumptions that are incorrect
I have solved the problem and I am surprised you did not offer the advice that the sleeve does not require bonding....if it is the correct mounting rubber.
The rubbers that were supplied and installed by my mechanic do not have the sleeve bonded. In fact the front rubbers do not even have a sleeve. No wonder they were coming apart.
A new 'proper' set is being installed this weekend. I never had this problem with the old engine because it had the correct rubber mounts which were sold with the engine.
I believe this will solve the problem and I will carry on flying a very aggressive and dynamic AIRSHOW routine that is well within the limits of my airplane which is constantly being inspected.
It is not the type of flying that most YAK owners engage in however I am quite at ease flying it this way. I first flew Victor Smolin's YAK 50 in 1982 and I was taught the Lomcevak by its inventor Ladislav Bezak in 1980.[url=tel:331%20826%209942]331 826 9942[/url]. Gord cell Mexico
[url=tel:333%20495%205044]333 495 5044[/url] Sandy cell Mexico
[url=tel:519%20375%206233]519 375 6233[/url] Gord cell Canada
[url=tel:519%20378%206800]519 378 6800[/url] Sandy cell Canada
[url=tel:519%20538%202868]519 538 2868[/url] House Canada
[url=tel:226%20777%204383]226 777 4383[/url] Email voice message anywhere
Sent from my iPhone
On Jul 13, 2017, at 12:00 PM, Bitterlich, Mark G CIV NAVAIR, WD <mark.bitterlich(at)navy.mil (mark.bitterlich(at)navy.mil)> wrote:
[quote]
--> Yak-List message posted by: "Bitterlich, Mark G CIV NAVAIR, WD" <mark.bitterlich(at)navy.mil (mark.bitterlich(at)navy.mil)>Typically, the rubber used in these engine mounts deteriorates with age. Personally what I would try to do under your circumstance is to measure a new one with a durometer, and then have a mold constructed and replace them with a polyurethane equivalent. You did not ask this, and I am sorry for sticking my nose into the topic and changing the subject somewhat, but I would suggest that you also make sure you have the Russian recording accelerometer installed in your 50, (or a suitable replacement) and are keeping track of the cycles. The 50 is indeed rated to +9/-6 assuming all the mods are incorporated. However that was not an unlimited qualification. Meaning that after so many "cycles" (as documented on the recording accelerometer), it was a requirement to replace the wings. Considering most 50's that were flown in unlimited events were usually retired under 100 hours of flight time, it might be worth keeping in mind. The kind of damage to engine mount rubbers that you are describing is something commonly seen on Sukhoi's flying Unlimited level aerobatic competition, usually with engines just like yours and MTV9-260 props, thus I suspect you are approaching that kind of G loading. That said, the Suke construction otherwise is much stronger than the 50. Another thing that generates this kind of stress is gyroscopic maneuvers usually accompanied by prop shaft seal damage. Good luck. Mark--
| | - The Matronics Yak-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Yak-List |
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Viperdoc |
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dsavarese0812(at)bellsout
Guest
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| Posted: Sun Jul 16, 2017 1:39 pm Post subject: [Non-DoD Source] Engine mount rubbers - YAK-50 |
|
|
A comment regarding the two dimension mentioned in this thread: 44.5 mm vs.34.5 mm. The 34.5 mm compression dimension comes directly from an Aeromotors document/diagram 14-000-40DMFI. If one were to use the 44.5 mm compression dimension, that would be 10mm (or about 3/8") LESS compression on the engine mount rubbers. I seriously doubt one could decrease the compression dimension by 3/8" and still get the cotter pins into the castellated nuts on the end of the mounting thru-bolt. I've attached a copy of the Aeromotors document/diagram for reference.
Dennis
From: Gordon Price <gord(at)thedampub.ca>
To: yak-list(at)matronics.com
Sent: Sunday, July 16, 2017 4:04 PM
Subject: Re: [Non-DoD Source] Engine mount rubbers - YAK-50
Hi Walt.
Hopefully these pictures will help explain the dilemma.
After 20 hrs on the engine.
[img]cid:3Ft0uhnq9noEQiJeDUHW[/img] This shows a new mount on top. The old sleeve/washer is sitting on top of the new mount. It is smaller
[img]cid:LOCtWdB6ZHyXMIi56xAr[/img] This is the old rear rubber mount. The sleeve/washer has cut the rubber
[img]cid:HHCX4i6GxaPGzMoZojNk[/img] This is the old mount and sleeve/washer another view
[img]cid:a6iX6UNs04Tv0lvvH0Ah[/img] another view of the old sleeve/washer and rubber mount
I was in Mexico when the engine was put on the airplane last winter. I was told that there is no washer/sleeve on the front rubber, only a washer. We won’t know until we get the engine off on Wednesday what exactly is there.
The new rubber mounts I have purchased have the metal bonded to the rubber, both front and back rubbers.
I agree. I too, am confused with no internal bushing in the mounts. I have been told that the measurement between the washers is to be 34.5 mm.
Gord
[quote]On Jul 16, 2017, at 2:36 PM, Walter Lannon <wlannon(at)shaw.ca (wlannon(at)shaw.ca)> wrote:
This has been an area of concern since my first CJ6/Huosai experience in 1993.
Gord: Could you please explain what you mean by “sleeve”. It would appear you are referring to the damper support washers.
The reason for my confusion is years of experience with this type of damper installation on other aircraft using the small P&W radials (R1340 & R985). In particular the Harvard and T6.
Kind of blew my mind to find a rubber vibration damper with no internal steel bushing (sleeve?) to control the compression of the rubber. Eventually got used to guessing at the torque and forgot about it.
In the P&W case (and probably most, if not all, engine manufacturers) this is not an engine component. It was usually left to the determinations of the airframe manufacturer.
Question for Yak 50, 52, 55, 18T, Sukhoi, etc. owners: Does your M14P installation use internal bushings to establish damper compression? If so could someone measure the exact bushing length?
Walt
From: Gordon Price (gord(at)thedampub.ca)
Sent: Sunday, July 16, 2017 6:50 AM
To: yak-list(at)matronics.com (yak-list(at)matronics.com)
Subject: Re: [Non-DoD Source] Engine mount rubbers - YAK-50
Thanks Doc
That is a big difference!
Here is the drawing George Coy sent to me.
Do you know if the rubber is bonded to the sleeve and are there sleeves on both the front and back rubbers?
We will know more once we get the engine off the mount on Wednesday.
Gord
[quote]On Jul 16, 2017, at 9:19 AM, Roger Kemp <f16viperdoc(at)me.com (f16viperdoc(at)me.com)> wrote:
Gord,
The instructions I got were to compress to 44.5 mm.
DocSent from my iPad
On Jul 14, 2017, at 11:31 AM, Gordon Price <gord(at)thedampub.ca (gord(at)thedampub.ca)> wrote:
[quote]
Good point Doug and thank you for that. There is a measurement of 34.5 mm on the plans sent to me by George Coy. At that point should the metal sleeves inside touch?
Does anyone have method of torquing that would be helpful or sod you just compress to 34.5 mm.
Could not enough torque could cause this problem? Could too much torque cause the problem? We don’t know so if someone has experience please let us know.
We have yet to remove the engine since work is backed up in the shop however I am told that the forward rubber mounts that are installed did not have the washer with a sleeve. Only a washer..no sleeve.
Also, which mounts do you sell Doug? With or without the sleeve?
Thanks
Gord
[quote]On Jul 14, 2017, at 11:54 AM, doug sapp <dougsappllc(at)gmail.com (dougsappllc(at)gmail.com)> wrote:
Gents,Addressing the "mount rubber" issue only.
Are we 100% sure that the bonding or the failure of bonding to the washer or to the bushing is the problem here? I suspect that it is not. I suspect that the mount rubber were incorrectly installed. Since there is no actual torque value stated in anything I have read it seems that there exists a large opportunity to install them without enough torque, meaning not tight enough. In a "normal situation" (gentleman's acro) I would think that proper installation would not be as critical as is would be in this rather unusual high g loading situation. This would help explain why this problem/situation has not been seen much in the past.
Just a WAG on my part, YMMV.
Doug
On Fri, Jul 14, 2017 at 5:32 AM, Gordon Price <gord(at)thedampub.ca (gord(at)thedampub.ca)> wrote:[quote]As I recall Richard you did say that the YAK 50 could be flown forever at +5 and -3.
As I said SOMETIMES I see +8 and -5 G. Just being honest. A normal airshow routine is +6 and -4 and yes the airplane has all the mods and lightweight equipment. As for the pilot weight… I am always working on that.
You are right . The engine is spectacular and increased power has changed the flying characteristics of the airplane which I am still getting used to. I should be fully up to speed by the end of August when I fly the CNE Canadian International Air Show in Toronto.
Back to the subject I have been to introduce for discussion………..
Attached is a picture of the different engine mount rubbers.
On the left 2 new ones with the rubber bonded to the steel insert and on the right one of the damaged mounts where the steel insert is not bonded and can turn and cut the rubber.
<rubber.jpeg>
[quote]On Jul 14, 2017, at 2:20 AM, That's looking at his note <richard2835492219526631817Apple-interchange-newline"> (richard.goode(at)russianaeros.com)Firstly I would like to make it clear that we supplied the engine together with the engine mount rubbers to Gordon Price. But we have used exactly the same rubbers on around 300 engines that we have supplied to a wide variety of aircraft, including competition Sukhois and have never had this problem before. But we will sort it out, and we know from Gordon that the engine is performing spectacularly well.
But it raises an issue which I think is far more important, and that is flying a Yak 50 to its design limits of plus 9G and minus 6G. I have done a lot of research on this topic, and the 50 was unfortunate in that it was introduced at a time that aerobatics changing from being big graceful manoeuvres to sharp angles. The Russian team was well funded and incredibly well motivated, and they were flying them beyond these limits, and had four fatal accidents to team members. During this period Yakovlev issued a series of service bulletins to reinforce the last bit of the aircraft that had broken, culminating in bulletin 79 – a 4.5 mm steel plate on top and bottom of the centre section.
But firstly, remember that the Russian pilots were all relatively light; the aeroplane was flown only with one fuel tank; no generator; air compressor; a light battery. Then, the TOTAL service life of a team aircraft was 47 hours. After that it was scrapped. And for any other aircraft, the total service life was 300 hours, and then it was scrapped!
I have a serious concern that many pilots today are flying aircraft that have done far more hours than this; are ignorant of these issues, and yet feel that they still have a plus 9G aircraft, with a heavy Western pilot; smoke system; both fuel tanks et cetera!
I prepared a detailed paper some years ago following discussions with Yakovlev describing the individual failures and then the subsequent service bulletins. I will send this to anyone who is interested.
Richard Goode Aerobatics
Rhodds Farm
Lyonshall
Hereford
HR5 3LW
Tel: (richard.goode(at)russianaeros.com)[url=]+44 (0) 1544 340120[/url]
Fax: [url=]+44 (0) 1544 340129[/url]
www.russianaeros.com
From: owner-yak-list-server(at) matronics.com (owner-yak-list-server(at)matronics.com) [mailto:owner- yak-list-server(at)matronics.com (owner-yak-list-server(at)matronics.com)] On Behalf Of Gordon PriceSent: 13 July 2017 19:31To: yak-list(at)matronics.com (yak-list(at)matronics.com)Subject: Re: [Non-DoD Source] Engine mount rubbers - YAK-50
Thanks for the advice Frank however it would be nice on this forum if we could just stick to the topic at hand.
In this case… the topic it is a problem with engine mount rubbers and the fact that the ones supplied did not have the sleeve bonded to the rubber.
Has anyone ever experienced this?
[quote]On Jul 13, 2017, at 1:44 PM, Frank Stelwagon <pfstelwagon(at)earthlink.net (pfstelwagon(at)earthlink.net)> wrote:
Mark wasn’t lecturing you! He was telling you what he knows from experience (lots of it). It might be safer to listen.
From: owner-yak-list-server(at) matronics.com (owner-yak-list-server(at)matronics.com) [mailto:owner- yak-list-server(at)matronics.com (owner-yak-list-server(at)matronics.com)] On Behalf Of Gord PriceSent: Thursday, July 13, 2017 10:22 AMTo: yak-list(at)matronics.com (yak-list(at)matronics.com)Subject: Re: [Non-DoD Source] Engine mount rubbers - YAK-50
Mark. I asked for help .....not a lecture on a subject that I am well versed in nor assumptions that are incorrect
I have solved the problem and I am surprised you did not offer the advice that the sleeve does not require bonding....if it is the correct mounting rubber.
The rubbers that were supplied and installed by my mechanic do not have the sleeve bonded. In fact the front rubbers do not even have a sleeve. No wonder they were coming apart.
A new 'proper' set is being installed this weekend. I never had this problem with the old engine because it had the correct rubber mounts which were sold with the engine.
I believe this will solve the problem and I will carry on flying a very aggressive and dynamic AIRSHOW routine that is well within the limits of my airplane which is constantly being inspected.
It is not the type of flying that most YAK owners engage in however I am quite at ease flying it this way. I first flew Victor Smolin's YAK 50 in 1982 and I was taught the Lomcevak by its inventor Ladislav Bezak in 1980.
[url=]331 826 9942[/url]. Gord cell Mexico
[url=]333 495 5044[/url] Sandy cell Mexico
[url=]519 375 6233[/url] Gord cell Canada
[url=]519 378 6800[/url] Sandy cell Canada
[url=]519 538 2868[/url] House Canada
[url=]226 777 4383[/url] Email voice message anywhere
Sent from my iPhone
On Jul 13, 2017, at 12:00 PM, Bitterlich, Mark G CIV NAVAIR, WD <mark.bitterlich(at)navy.mil (mark.bitterlich(at)navy.mil)> wrote:
[quote]--> Yak-List message posted by: "Bitterlich, Mark G CIV NAVAIR, WD" <mark.bitterlich(at)navy.mil (mark.bitterlich(at)navy.mil)>Typically, the rubber used in these engine mounts deteriorates with age. Personally what I would try to do under your circumstance is to measure a new one with a durometer, and then have a mold constructed and replace them with a polyurethane equivalent. You did not ask this, and I am sorry for sticking my nose into the topic and changing the subject somewhat, but I would suggest that you also make sure you have the Russian recording accelerometer installed in your 50, (or a suitable replacement) and are keeping track of the cycles. The 50 is indeed rated to +9/-6 assuming all the mods are incorporated. However that was not an unlimited qualification. Meaning that after so many "cycles" (as documented on the recording accelerometer), it was a requirement to replace the wings. Considering most 50's that were flown in unlimited events were usually retired under 100 hours of flight time, it might be worth keeping in mind. The kind of damage to engine mount rubbers that you are describing is something commonly seen on Sukhoi's flying Unlimited level aerobatic competition, usually with engines just like yours and MTV9-260 props, thus I suspect you are approaching that kind of G loading. That said, the Suke construction otherwise is much stronger than the 50. Another thing that generates this kind of stress is gyroscopic maneuvers usually accompanied by prop shaft seal damage. Good luck. Mark--
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wlannon(at)shaw.ca
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| Posted: Sun Jul 16, 2017 4:37 pm Post subject: [Non-DoD Source] Engine mount rubbers - YAK-50 |
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Thanks Gord;
Explains a whole bunch. The corresponding part for the Huosai is a simple washer, same shape but no sleeve.
I will call the M14 version a sleeved washer. Noted on the Motorstar drawing that the two sleeves cannot touch each other so not sure of advantage though possibly improved torque load resistance.
One wonders how many M14 powered CJ’s around with Huosai dampers.
Walt
From: Gordon Price (gord(at)thedampub.ca)
Sent: Sunday, July 16, 2017 12:53 PM
To: yak-list(at)matronics.com (yak-list(at)matronics.com)
Subject: Re: [Non-DoD Source] Engine mount rubbers - YAK-50
Hi Walt.
Hopefully these pictures will help explain the dilemma.
After 20 hrs on the engine.
[img]cid:1D10E792167948718CF32B8C8E8D9E9B(at)WalterHP[/img] This shows a new mount on top. The old sleeve/washer is sitting on top of the new mount. It is smaller
[img]cid:EDF80EB162CC4CB2BB40B2B853570C1F(at)WalterHP[/img] This is the old rear rubber mount. The sleeve/washer has cut the rubber
[img]cid:6F509882051941C9B93F4B5D9FED7F6E(at)WalterHP[/img] This is the old mount and sleeve/washer another view
[img]cid:5E43EBEDD9724650A33E326EAD169D71(at)WalterHP[/img] another view of the old sleeve/washer and rubber mount
I was in Mexico when the engine was put on the airplane last winter. I was told that there is no washer/sleeve on the front rubber, only a washer. We won’t know until we get the engine off on Wednesday what exactly is there.
The new rubber mounts I have purchased have the metal bonded to the rubber, both front and back rubbers.
I agree. I too, am confused with no internal bushing in the mounts. I have been told that the measurement between the washers is to be 34.5 mm.
Gord
[quote] On Jul 16, 2017, at 2:36 PM, Walter Lannon <wlannon(at)shaw.ca (wlannon(at)shaw.ca)> wrote:
This has been an area of concern since my first CJ6/Huosai experience in 1993.
Gord: Could you please explain what you mean by “sleeve”. It would appear you are referring to the damper support washers.
The reason for my confusion is years of experience with this type of damper installation on other aircraft using the small P&W radials (R1340 & R985). In particular the Harvard and T6.
Kind of blew my mind to find a rubber vibration damper with no internal steel bushing (sleeve?) to control the compression of the rubber. Eventually got used to guessing at the torque and forgot about it.
In the P&W case (and probably most, if not all, engine manufacturers) this is not an engine component. It was usually left to the determinations of the airframe manufacturer.
Question for Yak 50, 52, 55, 18T, Sukhoi, etc. owners: Does your M14P installation use internal bushings to establish damper compression? If so could someone measure the exact bushing length?
Walt
F rom: Gordon Price (gord(at)thedampub.ca)
Sent: Sunday, July 16, 2017 6:50 AM
To: yak-list(at)matronics.com (yak-list(at)matronics.com)
Subject: Re: [Non-DoD Source] Engine mount rubbers - YAK-50
Thanks Doc
That is a big difference!
Here is the drawing George Coy sent to me.
Do you know if the rubber is bonded to the sleeve and are there sleeves on both the front and back rubbers?
We will know more once we get the engine off the mount on Wednesday.
Gord
| Quote: | On Jul 16, 2017, at 9:19 AM, Roger Kemp <f16viperdoc(at)me.com (f16viperdoc(at)me.com)> wrote:
Gord,
The instructions I got were to compress to 44.5 mm.
Doc
Sent from my iPad
On Jul 14, 2017, at 11:31 AM, Gordon Price <gord(at)thedampub.ca (gord(at)thedampub.ca)> wrote:
| Quote: |
Good point Doug and thank you for that. There is a measurement of 34.5 mm on the plans sent to me by George Coy. At that point should the metal sleeves inside touch?
Does anyone have method of torquing that would be helpful or sod you just compress to 34.5 mm.
Could not enough torque could cause this problem? Could too much torque cause the problem? We don’t know so if someone has experience please let us know.
We have yet to remove the engine since work is backed up in the shop however I am told that the forward rubber mounts that are installed did not have the washer with a sleeve. Only a washer..no sleeve.
Also, which mounts do you sell Doug? With or without the sleeve?
Thanks
Gord
| Quote: | On Jul 14, 2017, at 11:54 AM, doug sapp <dougsappllc(at)gmail.com (dougsappllc(at)gmail.com)> wrote:
Gents, Addressing the "mount rubber" issue only.
Are we 100% sure that the bonding or the failure of bonding to the washer or to the bushing is the problem here? I suspect that it is not. I suspect that the mount rubber were incorrectly installed. Since there is no actual torque value stated in anything I have read it seems that there exists a large opportunity to install them without enough torque, meaning not tight enough. In a "normal situation" (gentleman's acro) I would think that proper installation would not be as critical as is would be in this rather unusual high g loading situation. This would help explain why this problem/situation has not been seen much in the past.
Just a WAG on my part, YMMV.
Doug
On Fri, Jul 14, 2017 at 5:32 AM, Gordon Price <gord(at)thedampub.ca (gord(at)thedampub.ca)> wrote:
| Quote: | As I recall Richard you did say that the YAK 50 could be flown forever at +5 and -3.
As I said SOMETIMES I see +8 and -5 G. Just being honest. A normal airshow routine is +6 and -4 and yes the airplane has all the mods and lightweight equipment. As for the pilot weight… I am always working on that.
You are right . The engine is spectacular and increased power has changed the flying characteristics of the airplane which I am still getting used to. I should be fully up to speed by the end of August when I fly the CNE Canadian International Air Show in Toronto.
Back to the subject I have been to introduce for discussion………..
Attached is a picture of the different engine mount rubbers.
On the left 2 new ones with the rubber bonded to the steel insert and on the right one of the damaged mounts where the steel insert is not bonded and can turn and cut the rubber.
<rubber.jpeg>
| Quote: | On Jul 14, 2017, at 2:20 AM, That's looking at his note <richard2835492219526631817Apple-interchange-newline"> (richard.goode(at)russianaeros.com) Firstly I would like to make it clear that we supplied the engine together with the engine mount rubbers to Gordon Price. But we have used exactly the same rubbers on around 300 engines that we have supplied to a wide variety of aircraft, including competition Sukhois and have never had this problem before. But we will sort it out, and we know from Gordon that the engine is performing spectacularly well.
But it raises an issue which I think is far more important, and that is flying a Yak 50 to its design limits of plus 9G and minus 6G. I have done a lot of research on this topic, and the 50 was unfortunate in that it was introduced at a time that aerobatics changing from being big graceful manoeuvres to sharp angles. The Russian team was well funded and incredibly well motivated, and they were flying them beyond these limits, and had four fatal accidents to team members. During this period Yakovlev issued a series of service bulletins to reinforce the last bit of the aircraft that had broken, culminating in bulletin 79 – a 4.5 mm steel plate on top and bottom of the centre section.
But firstly, remember that the Russian pilots were all relatively light; the aeroplane was flown only with one fuel tank; no generator; air compressor; a light battery. Then, the TOTAL service life of a team aircraft was 47 hours. After that it was scrapped. And for any other aircraft, the total service life was 300 hours, and then it was scrapped!
I have a serious concern that many pilots today are flying aircraft that have done far more hours than this; are ignorant of these issues, and yet feel that they still have a plus 9G aircraft, with a heavy Western pilot; smoke system; both fuel tanks et cetera!
I prepared a detailed paper some years ago following discussions with Yakovlev describing the individual failures and then the subsequent service bulletins. I will send this to anyone who is interested.
Richard Goode Aerobatics
Rhodds Farm
Lyonshall
Hereford
HR5 3LW
Tel: (richard.goode(at)russianaeros.com)[url=tel:+44%201544%20340120]+44 (0) 1544 340120[/url]
Fax: [url=tel:+44%201544%20340129]+44 (0) 1544 340129[/url]
www.russianaeros.com
From: owner-yak-list-server(at)matronics.com (owner-yak-list-server(at)matronics.com) [mailto:owner-yak-list-server(at)matronics.com (owner-yak-list-server(at)matronics.com)] On Behalf Of Gordon Price
Sent: 13 July 2017 19:31
To: yak-list(at)matronics.com (yak-list(at)matronics.com)
Subject: Re: [Non-DoD Source] Engine mount rubbers - YAK-50
Thanks for the advice Frank however it would be nice on this forum if we could just stick to the topic at hand.
In this case… the topic it is a problem with engine mount rubbers and the fact that the ones supplied did not have the sleeve bonded to the rubber.
Has anyone ever experienced this?
| Quote: | On Jul 13, 2017, at 1:44 PM, Frank Stelwagon <pfstelwagon(at)earthlink.net (pfstelwagon(at)earthlink.net)> wrote:
Mark wasn’t lecturing you! He was telling you what he knows from experience (lots of it). It might be safer to listen.
From: owner-yak-list-server(at)matronics.com (owner-yak-list-server(at)matronics.com) [mailto:owner-yak-list-server(at)matronics.com (owner-yak-list-server(at)matronics.com)] On Behalf Of Gord Price
Sent: Thursday, July 13, 2017 10:22 AM
To: yak-list(at)matronics.com (yak-list(at)matronics.com)
Subject: Re: [Non-DoD Source] Engine mount rubbers - YAK-50
Mark. I asked for help .....not a lecture on a subject that I am well versed in nor assumptions that are incorrect
I have solved the problem and I am surprised you did not offer the advice that the sleeve does not require bonding....if it is the correct mounting rubber.
The rubbers that were supplied and installed by my mechanic do not have the sleeve bonded. In fact the front rubbers do not even have a sleeve. No wonder they were coming apart.
A new 'proper' set is being installed this weekend. I never had this problem with the old engine because it had the correct rubber mounts which were sold with the engine.
I believe this will solve the problem and I will carry on flying a very aggressive and dynamic AIRSHOW routine that is well within the limits of my airplane which is constantly being inspected.
It is not the type of flying that most YAK owners engage in however I am quite at ease flying it this way. I first flew Victor Smolin's YAK 50 in 1982 and I was taught the Lomcevak by its inventor Ladislav Bezak in 1980. [url=tel:331%20826%209942]331 826 9942[/url]. Gord cell Mexico
[url=tel:333%20495%205044]333 495 5044[/url] Sandy cell Mexico
[url=tel:519%20375%206233]519 375 6233[/url] Gord cell Canada
[url=tel:519%20378%206800]519 378 6800[/url] Sandy cell Canada
[url=tel:519%20538%202868]519 538 2868[/url] House Canada
[url=tel:226%20777%204383]226 777 4383[/url] Email voice message anywhere
Sent from my iPhone
On Jul 13, 2017, at 12:00 PM, Bitterlich, Mark G CIV NAVAIR, WD <mark.bitterlich(at)navy.mil (mark.bitterlich(at)navy.mil)> wrote:
| Quote: |
--> Yak-List message posted by: "Bitterlich, Mark G CIV NAVAIR, WD" <mark.bitterlich(at)navy.mil (mark.bitterlich(at)navy.mil)>
Typically, the rubber used in these engine mounts deteriorates with age. Personally what I would try to do under your circumstance is to measure a new one with a durometer, and then have a mold constructed and replace them with a polyurethane equivalent.
You did not ask this, and I am sorry for sticking my nose into the topic and changing the subject somewhat, but I would suggest that you also make sure you have the Russian recording accelerometer installed in your 50, (or a suitable replacement) and are keeping track of the cycles. The 50 is indeed rated to +9/-6 assuming all the mods are incorporated. However that was not an unlimited qualification. Meaning that after so many "cycles" (as documented on the recording accelerometer), it was a requirement to replace the wings. Considering most 50's that were flown in unlimited events were usually retired under 100 hours of flight time, it might be worth keeping in mind.
The kind of damage to engine mount rubbers that you are describing is something commonly seen on Sukhoi's flying Unlimited level aerobatic competition, usually with engines just like yours and MTV9-260 props, thus I suspect you are approaching that kind of G loading. That said, the Suke construction otherwise is much stronger than the 50. Another thing that generates this kind of stress is gyroscopic maneuvers usually accompanied by prop shaft seal damage.
Good luck.
Mark
-----Original Message-----
From: owner-yak-list-server(at)matronics.com (owner-yak-list-server(at)matronics.com) [mailto:owner-yak-list-server(at)matronics.com (owner-yak-list-server(at)matronics.com)] On Behalf Of Gordon Price yak-list(at)matronics.com (yak-list(at)matronics.com)
Subject: [Non-DoD Source] Engine mount rubbers - YAK-50
--> Yak-List message posted by: Gordon Price <gord(at)thedampub.ca (gord(at)thedampub.ca)>
We just installed a zero’d M-13PF with Barrett Pistons which dyno'd at 435 HP on my YAK 50. Performance is much enhanced however we have just found some engine mount rubbers are being torn up because the metal sleeve is moving and cutting the rubber. The airplane is being flown under the G limits however during the air show sequence I am sometimes seeing +8 and -5 G. We never had this problem with the old 360 HP engine. We have a new set being installed in the next few days which should yield more information. Does anyone have experience in this area? Thinking of bonding the sleeve to the rubber to prevent the sleeve movement. Thanks in advance. Gord
http://www.matronics.com/Navigator?Yak-List
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Thanks Doc
That is a big difference!
Here is the drawing George Coy sent to me.
Do you know if the rubber is bonded to the sleeve and are there sleeves on both the front and back rubbers?
We will know more once we get the engine off the mount on Wednesday.
Gord
[quote] On Jul 16, 2017, at 9:19 AM, Roger Kemp <f16viperdoc(at)me.com (f16viperdoc(at)me.com)> wrote:
Gord,
The instructions I got were to compress to 44.5 mm.
Doc
Sent from my iPad
On Jul 14, 2017, at 11:31 AM, Gordon Price <gord(at)thedampub.ca (gord(at)thedampub.ca) <mailto:gord(at)thedampub.ca (gord(at)thedampub.ca)>> wrote:
>
> Good point Doug and thank you for that. There is a measurement of 34.5 mm on the plans sent to me by George Coy. At that point should the metal sleeves inside touch?
>
> Does anyone have method of torquing that would be helpful or sod you just compress to 34.5 mm.
>
> Could not enough torque could cause this problem? Could too much torque cause the problem? We don’t know so if someone has experience please let us know.
>
> We have yet to remove the engine since work is backed up in the shop however I am told that the forward rubber mounts that are installed did not have the washer with a sleeve. Only a washer..no sleeve.
>
> Also, which mounts do you sell Doug? With or without the sleeve?
>
> Thanks
>
> Gord
>
>> On Jul 14, 2017, at 11:54 AM, doug sapp <dougsappllc(at)gmail.com (dougsappllc(at)gmail.com) <mailto:dougsappllc(at)gmail.com (dougsappllc(at)gmail.com)>> wrote:
>>
>> Gents,
>> Addressing the "mount rubber" issue only.
>> Are we 100% sure that the bonding or the failure of bonding to the washer or to the bushing is the problem here? I suspect that it is not. I suspect that the mount rubber were incorrectly installed. Since there is no actual torque value stated in anything I have read it seems that there exists a large opportunity to install them without enough torque, meaning not tight enough. In a "normal situation" (gentleman's acro) I would think that proper installation would not be as critical as is would be in this rather unusual high g loading situation. This would help explain why this problem/situation has not been seen much in the past.
>>
>> Just a WAG on my part, YMMV.
>>
>> Doug
>>
>> On Fri, Jul 14, 2017 at 5:32 AM, Gordon Price <gord(at)thedampub.ca (gord(at)thedampub.ca) <mailto:gord(at)thedampub.ca (gord(at)thedampub.ca)>> wrote:
>> As I recall Richard you did say that the YAK 50 could be flown forever at +5 and -3.
>>
>> As I said SOMETIMES I see +8 and -5 G. Just being honest. A normal airshow routine is +6 and -4 and yes the airplane has all the mods and lightweight equipment. As for the pilot weight… I am always working on that.
>>
>> You are right . The engine is spectacular and increased power has changed the flying characteristics of the airplane which I am still getting used to. I should be fully up to speed by the end of August when I fly the CNE Canadian International Air Show in Toronto.
>>
>>
>> Back to the subject I have been to introduce for discussion………..
>>
>>
>> Attached is a picture of the different engine mount rubbers.
>>
>> On the left 2 new ones with the rubber bonded to the steel insert and on the right one of the damaged mounts where the steel insert is not bonded and can turn and cut the rubber.
>>
>> <rubber.jpeg>
>>
>>
>>
>>> On Jul 14, 2017, at 2:20 AM, That's looking at his note <richard2835492219526631817Apple-interchange-newline"> <mailto:richard.goode(at)russianaeros.com (richard.goode(at)russianaeros.com)>
>>> <mailto:richard.goode(at)russianaeros.com (richard.goode(at)russianaeros.com)>Firstly I would like to make it clear that we supplied the engine together with the engine mount rubbers to Gordon Price. But we have used exactly the same rubbers on around 300 engines that we have supplied to a wide variety of aircraft, including competition Sukhois and have never had this problem before. But we will sort it out, and we know from Gordon that the engine is performing spectacularly well.
>>>
>>> But it raises an issue which I think is far more important, and that is flying a Yak 50 to its design limits of plus 9G and minus 6G. I have done a lot of research on this topic, and the 50 was unfortunate in that it was introduced at a time that aerobatics changing from being big graceful manoeuvres to sharp angles. The Russian team was well funded and incredibly well motivated, and they were flying them beyond these limits, and had four fatal accidents to team members. During this period Yakovlev issued a series of service bulletins to reinforce the last bit of the aircraft that had broken, culminating in bulletin 79 – a 4.5 mm steel plate on top and bottom of the centre section.
>>>
>>> But firstly, remember that the Russian pilots were all relatively light; the aeroplane was flown only with one fuel tank; no generator; air compressor; a light battery. Then, the TOTAL service life of a team aircraft was 47 hours. After that it was scrapped. And for any other aircraft, the total service life was 300 hours, and then it was scrapped!
>>>
>>> I have a serious concern that many pilots today are flying aircraft that have done far more hours than this; are ignorant of these issues, and yet feel that they still have a plus 9G aircraft, with a heavy Western pilot; smoke system; both fuel tanks et cetera!
>>>
>>> I prepared a detailed paper some years ago following discussions with Yakovlev describing the individual failures and then the subsequent service bulletins. I will send this to anyone who is interested.
>>>
>>> <mailto:richard.goode(at)russianaeros.com (richard.goode(at)russianaeros.com)>Richard Goode Aerobatics
>>> Rhodds Farm
>>> Lyonshall
>>> Hereford
>>> HR5 3LW
>>>
>>> <mailto:richard.goode(at)russianaeros.com (richard.goode(at)russianaeros.com)>Tel: <mailto:richard.goode(at)russianaeros.com (richard.goode(at)russianaeros.com)>+44 (0) 1544 340120 <[url=tel:+44%201544%20340120]tel:+44%201544%20340120[/url]>
>>> Fax: +44 (0) 1544 340129 <[url=tel:+44%201544%20340129]tel:+44%201544%20340129[/url]>
>>> www.russianaeros.com <http://www.russianaeros.com/>
>>>
>>> From: owner-yak-list-server(at)matronics.com (owner-yak-list-server(at)matronics.com) <mailto:owner-yak-list-server(at)matronics.com (owner-yak-list-server(at)matronics.com)> [mailto:owner-yak-list-server(at)matronics.com (owner-yak-list-server(at)matronics.com) <mailto:owner-yak-list-server(at)matronics.com (owner-yak-list-server(at)matronics.com)>] On Behalf Of Gordon Price
>>> Sent: 13 July 2017 19:31
>>> To: yak-list(at)matronics.com (yak-list(at)matronics.com) <mailto:yak-list(at)matronics.com (yak-list(at)matronics.com)>
>>> Subject: Re: [Non-DoD Source] Engine mount rubbers - YAK-50
>>>
>>> Thanks for the advice Frank however it would be nice on this forum if we could just stick to the topic at hand.
>>>
>>> In this case… the topic it is a problem with engine mount rubbers and the fact that the ones supplied did not have the sleeve bonded to the rubber.
>>>
>>> Has anyone ever experienced this?
>>>
>>>> On Jul 13, 2017, at 1:44 PM, Frank Stelwagon <pfstelwagon(at)earthlink.net (pfstelwagon(at)earthlink.net) <mailto:pfstelwagon(at)earthlink.net (pfstelwagon(at)earthlink.net)>> wrote:
>>>>
>>>> Mark wasn’t lecturing you! He was telling you what he knows from experience (lots of it). It might be safer to listen.
>>>>
>>>> From: owner-yak-list-server(at)matronics.com (owner-yak-list-server(at)matronics.com) <mailto:owner-yak-list-server(at)matronics.com (owner-yak-list-server(at)matronics.com)> [mailto:owner-yak-list-server(at)matronics.com (owner-yak-list-server(at)matronics.com) <mailto:owner-yak-list-server(at)matronics.com (owner-yak-list-server(at)matronics.com)>] On Behalf Of Gord Price
>>>> Sent: Thursday, July 13, 2017 10:22 AM
>>>> To: yak-list(at)matronics.com (yak-list(at)matronics.com) <mailto:yak-list(at)matronics.com (yak-list(at)matronics.com)>
>>>> Subject: Re: [Non-DoD Source] Engine mount rubbers - YAK-50
>>>>
>>>> Mark. I asked for help .....not a lecture on a subject that I am well versed in nor assumptions that are incorrect
>>>>
>>>> I have solved the problem and I am surprised you did not offer the advice that the sleeve does not require bonding....if it is the correct mounting rubber.
>>>>
>>>> The rubbers that were supplied and installed by my mechanic do not have the sleeve bonded. In fact the front rubbers do not even have a sleeve. No wonder they were coming apart.
>>>>
>>>> A new 'proper' set is being installed this weekend. I never had this problem with the old engine because it had the correct rubber mounts which were sold with the engine.
>>>>
>>>> I believe this will solve the problem and I will carry on flying a very aggressive and dynamic AIRSHOW routine that is well within the limits of my airplane which is constantly being inspected.
>>>>
>>>> It is not the type of flying that most YAK owners engage in however I am quite at ease flying it this way. I first flew Victor Smolin's YAK 50 in 1982 and I was taught the Lomcevak by its inventor Ladislav Bezak in 1980.
>>>>
>>>> 331 826 9942 <[url=tel:331%20826%209942]tel:331%20826%209942[/url]>. Gord cell Mexico
>>>> 333 495 5044 <[url=tel:333%20495%205044]tel:333%20495%205044[/url]> Sandy cell Mexico
>>>> 519 375 6233 <[url=tel:519%20375%206233]tel:519%20375%206233[/url]> Gord cell Canada
>>>> 519 378 6800 <[url=tel:519%20378%206800]tel:519%20378%206800[/url]> Sandy cell Canada
>>>> 519 538 2868 <[url=tel:519%20538%202868]tel:519%20538%202868[/url]> House Canada
>>>> 226 777 4383 <[url=tel:226%20777%204383]tel:226%20777%204383[/url]> Email voice message anywhere
>>>> Sent from my iPhone
>>>>
>>>>
>>>> On Jul 13, 2017, at 12:00 PM, Bitterlich, Mark G CIV NAVAIR, WD <mark.bitterlich(at)navy.mil (mark.bitterlich(at)navy.mil) <mailto:mark.bitterlich(at)navy.mil (mark.bitterlich(at)navy.mil)>> wrote:
>>>>
>>>>> --> Yak-List message posted by: "Bitterlich, Mark G CIV NAVAIR, WD" <mark.bitterlich(at)navy.mil (mark.bitterlich(at)navy.mil) <mailto:mark.bitterlich(at)navy.mil (mark.bitterlich(at)navy.mil)>>
>>>>>
>>>>> Typically, the rubber used in these engine mounts deteriorates with age. Personally what I would try to do under your circumstance is to measure a new one with a durometer, and then have a mold constructed and replace them with a polyurethane equivalent.
>>>>>
>>>>> You did not ask this, and I am sorry for sticking my nose into the topic and changing the subject somewhat, but I would suggest that you also make sure you have the Russian recording accelerometer installed in your 50, (or a suitable replacement) and are keeping track of the cycles. The 50 is indeed rated to +9/-6 assuming all the mods are incorporated. However that was not an unlimited qualification. Meaning that after so many "cycles" (as documented on the recording accelerometer), it was a requirement to replace the wings. Considering most 50's that were flown in unlimited events were usually retired under 100 hours of flight time, it might be worth keeping in mind.
>>>>>
>>>>> The kind of damage to engine mount rubbers that you are describing is something commonly seen on Sukhoi's flying Unlimited level aerobatic competition, usually with engines just like yours and MTV9-260 props, thus I suspect you are approaching that kind of G loading. That said, the Suke construction otherwise is much stronger than the 50. Another thing that generates this kind of stress is gyroscopic maneuvers usually accompanied by prop shaft seal damage.
>>>>>
>>>>> Good luck.
>>>>>
>>>>> Mark
>>>>>
>>>>>
>>>>> --
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