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AGING AIRCRAFT
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YOURTCFG(at)aol.com
Guest

Posted: Sun Mar 12, 2006 7:19 pm Post subject: AGING AIRCRAFT

HI KIDS.

 

        Later this month I will be  attending the FAA meeting on aging 

aircraft to be held in Kansas City.   With me will be Mr. Gary Rankin, the pres. of 

the Navion Society.  Many  other type groups will be represented as well as 

type certificate holders.   The FAA is seeking guidance for proposals that will 

effect the long term life of  our airframes.  

    I am told on good authority that the FAA has no  hidden agenda here but 

is sincerely looking for help from the industry regarding  this issue.  The 

recent wing failure of the Chauks Airline Grumman Mallard  precipitated this 

meeting.

    There are a few sugestions already making there way  to the surface.  

One, sponsored by the EAA, would allow all aircraft  certificate under the old 

CAR-3 standards to "opt out" of the normal category  and be placed in a new 

category allowing for much more flexibility in the use of  parts and 

modifications.  Although I have not seen a hard draft of  this proposal, it appears it 

would be similar to the Canadian "owner maintained"  category, we shall see.  

While I don't see this as a bad proposal, and  support the concept, it doesn't 

seem to address the FAAs real  concern.  The airframes would soldier on, albeit 

with new parts etc, with  no regard to the main issue, old airframes. 

    Another idea is that type certificate holders and  type groups join 

forces and create a "super annual" inspection.  This would  be done at a 

predetermined time, ether years of flight hours or both.   It could only be done by an 

approved (special training) facility.  It may  or may not be reoccurring.

    I have spoken to the new owner of Twin Commander,  Jim Mathison.  There 

will be a representative from Twin, there and we  plan to meet.

    This may be one of the most significant meetings  with the FAA to happen 

in years, maybe ever.  Input there will help guide  the decision making 

process for many years to come.

    What are your thoughts??  Do you have any  input you would like me to 

carry tot he floor from you??   jb

WINGFLYER1(at)aol.com
Guest

Posted: Sun Mar 12, 2006 8:01 pm Post subject: AGING AIRCRAFT

I would like to know if a study has been done on aircraft that were built  

during the fifties as far as in-flight break up or wing seperations measure up.  

And how long will the airframes/wings last under normal flying conditions. 

What  is the projected life/safety of my 680. Gil Walker

john(at)vormbaum.com
Guest

Posted: Sun Mar 12, 2006 9:53 pm Post subject: AGING AIRCRAFT

Captain Jimbob,



I would especially like to see the really high time airframes of the 

Commander world championed, like John Towner's 23,000-hr.+ airframe and my 

own 18,000-hr. airframe. I think showing well maintained older, high time 

airframes in excellent running condition as evidence of their durability 

would go a long way towards setting reasonable standards were the FAA to 

implement inspection timeframes.



I would also like some methods of airframe life extension addressed, like 

new spar caps etc. You might want to dig for the Australian CAA document 

that, after research, recommended a lifespan for Aero Commander 500B's to be 

35,000 hours, at which time a spar cap replacement is mandated. The document 

further states that after spar cap replacement, the airframe would be good 

for another 35,000 hours.



We have the benefit of flying an airplane that is exceptionally well built 

and designed to be rugged far beyond the limits for which it is approved. 

Since building new Commanders is out of the question (regardless of type 

certificate ownership, tooling, and cost), we need to be very creative in 

ensuring that these airplanes will fly for years to come.



Good luck,



/John



PS: I need about 50 more years out of my airframe (if I decide to quit 

flying at 87, that is).

---

YOURTCFG(at)aol.com
Guest

Posted: Sun Mar 12, 2006 10:01 pm Post subject: AGING AIRCRAFT

In a message dated 3/12/2006 9:54:45 PM Pacific Standard Time,  

john(at)vormbaum.com writes:



John  Towner's 23,000-hr.+ airframe and my 

own 18,000-hr.  airframe.

I have spoken to Andy Towner and he or John will be at this meeting.   You 

comments are well taken.  There are also stories of very high time  Cessna and 

Beech products.  What we need to do is create an affordable  inspection program 

that will insure that every airframe can be maintained in a  way that will 

mimic the high time airframes we know are out there.  What is  different about 

them that has allowed them to stand that test of time?  We  also need to fine 

the trouble areas and inspect?repair?modify these areas.  

    Thanks John.  jb

YOURTCFG(at)aol.com
Guest

Posted: Sun Mar 12, 2006 10:13 pm Post subject: AGING AIRCRAFT

In a message dated 3/12/2006 8:02:24 PM Pacific Standard Time,  

WINGFLYER1(at)aol.com writes:



I would  like to know if a study has been done on aircraft that were built   

during the fifties as far as in-flight break up or wing  seperations

I don't know of any studies.  The FAA has so far been reactionary to  this 

growing concern.  Several airframes have, over the last decade, ether  failed 

catastrophically (Beech model 18, Beech T-34, Cessna 400 series and the  recent 

Mallard) of been found to have serious defects.  In some cases there  were 

extenuating circumstance (aerobatic trining?dodfighting)  But in many  others, 

simply fatigue and age appear to be the culprit.  

    I think the Commander is one of the best built  airframes ever, but there 

are areas that are showing signs of  deterioration.  Landing gear trusses in 

your 680 are all showing some  degree of corrosion.  I have looked at many of 

these airframes and have  never seen one with no corrosion present.  The wings 

will probably not be  the most problematic area for an older Commander, but 

the replacement of  the gear trusses would be a huge burden for an owner.  

   As a type group, we need to address this and other issues  that will make 

cretin our airplane fly on another fifty years.  Thanks  Gill  jb

nico(at)cybersuperstore.c
Guest

Posted: Sun Mar 12, 2006 10:24 pm Post subject: AGING AIRCRAFT

Interesting comment, John. If one owns the type certification and the

tooling, surely if cost is not a factor, one can build new Commanders, or am

I missing something. I would opt for a new power plant, of course, perhaps

something like a new generation diesel engine.



Nico

---

john(at)vormbaum.com
Guest

Posted: Sun Mar 12, 2006 11:47 pm Post subject: AGING AIRCRAFT

Great points, Jim. I knew you had all this stuff well in hand, but I thought 

I'd point out some of the obvious things anyway .



/J

---

john(at)vormbaum.com
Guest

Posted: Sun Mar 12, 2006 11:47 pm Post subject: AGING AIRCRAFT

Nico,



Funny enough, at some point in the near future I'm going to Arizona to take 

a look at a (certified, I think) 350hp turbodiesel that would hang nicely on 

a Commander wing.



There are a few things that make building a "new" Commander extremely 

unlikely:



1) Twin Commander Corp. owns the tooling & type certificate for the piston 

airplanes and has no interest in supporting them

2) From what I've heard, the tooling/jigs for the pistons are very worn out, 

and if new ones were to be built, any mfr. would have to re-tool....at great 

cost.



The real clincher is the parts count in Commanders (Sir Barry, do you have a 

number?). Just the nacelle alone has an extraordinary number of parts if I 

recall correctly. To build a new airplane in an even remotely cost-effective 

method, the airplane would have to be re-engineered. You could probably 

redesign the nacelles and the rest of the fuselage with far fewer parts, 

maybe even mix in some composites, but the man-hours required would still be 

a killer. I don't think there's a way you could build them and sell them at 

a profit for under $1M, which is quite steep for a piston twin (see many new 

2005 Barons flying around? I bet they only built 20 of them last year). The 

man-hours were such a problem, they even stopped flat-riveting the lower 

fuselages on Shrikes to cut corners. It didn't help keep the line alive.



Even if you could clean-sheet the design, preserving the original 

aerodynamics & appearance, it would still take a HUGE amount of capital to 

build something that wouldn't be too competitive in today's market. For the 

price you'd have to sell them, you could probably step into a turbine 

utility aircraft or even a VLJ.



I personally have a fantasy that some lottery winning aviation fool *will* 

resurrect the design, maybe even the turbines too, with a fair bit of 

composite structure, wet wings instead of bladders, none of the AD's, and 

all modern accoutrements, but I just don't see it happening.



Cheers,



/John



---

barry.collman(at)air-brit
Guest

Posted: Mon Mar 13, 2006 4:28 am Post subject: AGING AIRCRAFT

Hi John,



Nope, I'm sorry, but I don't have the parts count for a Commander.



But, if you bring yours to the next Fly-In, we could strip it down and find out!



Maybe 'down-under' Richard has an 'ball-park' figure after his extensive 

restoration of a 680E?



Best Regards,

Barry



---

BobsV35B(at)aol.com
Guest

Posted: Mon Mar 13, 2006 5:45 am Post subject: AGING AIRCRAFT

Good Morning Gil,  



I agree with the intent of your message, but I question your inclusion of  

the Beech 18. I have heard of NO instances of catastrophic failure in a Twin  

Beech airframe over the last decade.

 

Fact is, I know of no such failure in the history of the aircraft, though  

there may well have been a few. The currently required spar strap was mandated  

after inspections showed corrosion and few cracks.

 

I agree that inspections are needed and there are problems, but if you know  

of specific Twin Beech difficulties, I would appreciate your letting me know  

what they were.

 

Happy  Skies,



Old Bob

AKA

Bob Siegfried

Ancient Aviator

Stearman  N3977A

Brookeridge Air Park LL22

Downers Grove, IL 60516

630  985-8503



 

In a message dated 3/13/2006 12:14:10 A.M. Central Standard Time,  

YOURTCFG(at)aol.com writes:



I don't  know of any studies.  The FAA has so far been reactionary to  this  

growing concern.  Several airframes have, over the last decade,  ether  

failed 

catastrophically (Beech model 18, Beech T-34, Cessna  400 series and the  

recent 

Mallard) of been found to have serious  defects.  In some cases there  were 

extenuating circumstance  (aerobatic trining?dodfighting)  But in many  

others, 

simply  fatigue and age appear to be the culprit.

n395v

Joined: 10 Jan 2006
Posts: 450

Posted: Mon Mar 13, 2006 5:54 am Post subject: Re: AGING AIRCRAFT

 	  Quote: 	
		  I would like to know if a study has been done 	




Cessna did a government funded joint study on their 400 series Twins looking mainly at wing spars. This was a result of 2 High time (20,000 hrs plus) wing spar failures on 401/402s. Both were in air taxi service (heavy pax load, light fuel lots of TO and LDGS) Both failures involved either a manufactuuring defect or faulty structural repairs at the point of failure.



Twin Cessnas with tip tanks oddly enough suffer less spar fatigue with high fuel loads and low pax loads (the condition most owner operators fly)

As a result the FAA ultimately issued an AD  (approx $60,000) requiring a spar strap kit at relatively conservative number of hours. The hours were based on the Cessna study funded by the FAA. Cesna refuses to make the data public because it contains "proprietary information" and apparently proprietary info is excluded from discovery under the freedom of info act. My guess is that Cessna would not be unhappy if the entire piston Twin Fleet was grounded.



The numbers of aircraft involved were so large that it was estimated it would take 6-8 years to manufacture all the kits and train enough shops to do the fix. As such the FAA at a public meeting relented and came up with a schedule that fixed 121 operators first and at lower times. Part 91 later at higher times.



Jim Bob.........



Talk to John Frank or Mike Busch at CPA Cessna Pilot's assoc. They spent a lot of time with the FAA small airplane directorate on this and accomplished a lot. I am certain both will be at the meeting. I would also imagine teaming up with Dick Ward and the Twin Bonanza society might be a good idea.



John V.....



At one time I thought "Mr. RPM had a maint Facility in Costa Rica doing Twin Commander wing spar caps at a bargain price (relatively speaking).



I think clearly the spar cap and engine mount trusses are going to be the issues on the Twin Commanders. It saddened me to see my old 560 (SN#54) go on e bay because of intragranular wing spar corrosion. (Corrosion in the web not the cap)

_________________
Milt

nico(at)cybersuperstore.c
Guest

Posted: Mon Mar 13, 2006 6:38 am Post subject: AGING AIRCRAFT

Funny enough, I, too, have toyed with the lottery-winning-fool idea. It just

hasn't happened yet. And as soon as it does, if it does, one would probably

be swayed by the logic of the investment and not do it. Pity, though.

Nico

---

steve2(at)sover.net
Guest

Posted: Mon Mar 13, 2006 7:19 am Post subject: AGING AIRCRAFT

Ever since the CASA did a hatchet job on running lean of peak (by blaming a 

Navajo accident on it) I've been suspicious of their conclusions. The 

following links make interesting reading, but I don't take this fellow's 

writings as the last word. From what I've read and learned, the way in which 

an aircraft is flown and loaded (aerodynamically and weighted) over its life 

has more to do with fatigue than the number of hours.



With that being said, it seems there were a couple of bad design decisions 

in the spar. Be interested in if any of you folks have better insight.



http://www.casa.gov.au/airworth/papers/AeroCommander.pdf



http://www.casa.gov.au/airworth/papers/littleairliners.pdf



Steve

---

barry.collman(at)air-brit
Guest

Posted: Mon Mar 13, 2006 8:02 am Post subject: AGING AIRCRAFT

Hi Steve,



That's an interesting document 

(http://www.casa.gov.au/airworth/papers/AeroCommander.pdf).



It mentions on page 17, an accident to ZK-BWA. This was a Model 680, s/n 

437-109.



I have a copy of the Accident Report (No. 25/3/1192). This showed a catalogue of 

incidents which eventually gave rise to the wing failure:



"At some time after the aircraft was purchased by Bay of Plenty Airways it was 

involved in an accident which resulted in complete fracture of the rear spar 

lower cap and partial fracture of the rear spar upper cap of the starboard 

wing."

(The aircraft did have a hard landing in the US while a Bay of Plenty Airways 

pilot was familiarising himself with the aircraft. Structural repairs were 

necessary before the aircraft could be flown again).



"For a considerable time before the last flight those defects permitted a 

transference of load from the rear spar structure to the front spar structure 

and a fatigue crack developed in the lower cap of the front spar".



"A number of incidents which occurred during the operation of the aircraft in 

New Zealand had a cumulatively adverse effect on a structure weakened by the 

spar cap defects referred to".



"The pilot flew across the summit of Mount Ruapehu at a height which contravened 

regulation 38 of the Civil Aviation Regulations in respect of minimum safe 

heights".



"In the summit area, turbulence, or some manoeuvre involving the pilot's 

judgment, caused the starboard propeller, and possibly an adjacent portion of 

the bottom of the fuselage, to strike a part of the mountain".



"Vibration induced by the damaged propeller coupled with turbulence of a violent 

character caused the fatigue crack in the front spar lower cap to propoagate 

very rapidly to complete failure, with consequent separation of the starboard 

wing from the rest of the structure".



"The turbulence encountered by the aircraft on its last flight would no, by 

itself, have caused separation of the wing from the rest of the of the 

structure, despite the existence of the defects referred to. Nor would the 

propeller strike in similar isolation".



"As a result of this investigation the structural integrity of the Aero 

Commander 680S aircraft as a type is unquestioned".



I just thought I'd pass that detail on.



Best Regards,

Barry



---

YOURTCFG(at)aol.com
Guest

Posted: Mon Mar 13, 2006 8:15 am Post subject: AGING AIRCRAFT

In a message dated 3/12/2006 10:24:47 PM Pacific Standard Time,  

nico(at)cybersuperstore.com writes:



If one  owns the type certification and the

tooling, 

Unfortunately, not all of the tooling exists.  When the Commander line  was 

abandoned by Gulfstream, much of the tooling was simply left outside to  rust.  

Some had lead involved in tit's construction.  There was an  environmental 

concern and the tooling was scraped.   jb

CloudCraft(at)aol.com
Guest

Posted: Mon Mar 13, 2006 8:31 am Post subject: AGING AIRCRAFT

In a message dated 13-Mar-06 07:19:39 Pacific Standard Time, steve2(at)sover.net 

writes:

http://www.casa.gov.au/airworth/papers/AeroCommander.pdf



http://www.casa.gov.au/airworth/papers/littleairliners.pdf

<><><><><><>



Steve, 



Thank you for those links.  They make for interesting reading -- and I'll 

devote some time to that this week.



Capt. JimBob,



What ever the outcome, I want to thank you for making the journey to meet 

with the FAA.  I know what these meetings are like: they're not at all fun but 

very necessary.  (I've been on teleconferences with the Small Airplane 

Directorate and that was bad enough.)



Taking your personal time to represent the fleet is above and beyond.



Wing Commander Gordon

Life is not simple anywhere. Probably less so elsewhere.

CloudCraft(at)aol.com
Guest

Posted: Mon Mar 13, 2006 8:33 am Post subject: AGING AIRCRAFT

In a message dated 13-Mar-06 08:06:17 Pacific Standard Time, 

barry.collman(at)air-britain.co.uk writes:

"The pilot flew across the summit of Mount Ruapehu at a height which 

contravened 

regulation 38 of the Civil Aviation Regulations in respect of minimum safe 

heights".... caused the starboard propeller, and possibly an adjacent portion 

of 

the bottom of the fuselage, to strike a part of the mountain".

Hey!  That's a good idea!  We need to get ourselves one of those laws!



Wing Commander Gordon



Life is not simple anywhere. Probably less so elsewhere.

CloudCraft(at)aol.com
Guest

Posted: Mon Mar 13, 2006 8:37 am Post subject: AGING AIRCRAFT

In a message dated 13-Mar-06 08:16:18 Pacific Standard Time, YOURTCFG(at)aol.com 

writes:

Some had lead involved in tit's construction.  There was an  environmental 

concern and the tooling was scraped. 

<><><><><>



Some of those girls worked in Las Vegas.  Most use silicone for tits 

construction now.



Wing Commander Gordon



Life is not simple anywhere. Probably less so elsewhere.

steve2(at)sover.net
Guest

Posted: Mon Mar 13, 2006 8:54 am Post subject: AGING AIRCRAFT

Lead hasn't been used for bodywork for some time now.



---

cschuerm(at)cox.net
Guest

Posted: Mon Mar 13, 2006 9:39 am Post subject: AGING AIRCRAFT

YOURTCFG(at)aol.com wrote:

 	  Quote: 	
		       What are your thoughts?? 


	


What a wonderful opportunity Jim!

I think Commanders are a little unique from an "Aging Aircraft" 

perspective.  It's fairly well proven that Commanders are so well built 

that they don't suffer as much from fatigue as many other models.  They 

do have a few environmental weakness that are unique though.  Many 

Commanders have seen a lot of heavy use (because they are so good at it) 

and also many spend most of their lives outside due to lack of large 

enough hangars.  They also have an unusual number of various alloy 

extrusions throughout the airframe.  Due to these items, I think that 

corrosion is far more an issue than either age or hours.  As we know, 

corrosion in many aluminum alloys is greatly accelerated by stress - 

especially in the presence of water.  The nacelle trusses are a prime 

example of the results of a hard alloy which is under significan stress 

and often is exposed to an electrolyte.  I can say that every bathtub 

commander I've seen in the last 10 years has significant exfoliating 

corrosion on the little extrusion where the sway brace attaches to the 

spar cap on the outboard side of the nacelle.

For my two cents worth, I think that an inventory of extruded parts 

which are both under stress AND are subject to exposure to water would 

be an excellent starting point for your "super annual" concept.  There 

are several hidden parts which I believe should be uncovered and 

inspected every decade or so.  The vertical hangars behind the firewall 

on the front of the spar - for example - have probably never been looked 

at on most Commanders.  They're a prime candidate for failure at some point.

This is a great opportunity to eliminate the possibility of an in-flight 

failure of a Commander with the resulting knee-jerk reaction of the FAA.



cheers

Chris

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