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Is EFIS vulnerable at engine start?
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smineart(at)mahaska.org
Guest

Posted: Wed Aug 30, 2006 3:59 am Post subject: Is EFIS vulnerable at engine start?

The obsolescence of the avionics switch and bus has been well-discussed, 

but: is a Dynon EFIS on the E-bus vulnerable to current fluctuations during 

engine startup?  My ignition and starter will be powered from the always-hot 

battery bus, so I could wait to switch on the master until immediately after 

starting- would this be advisable?  Does the display need its own switch?

Steve Mineart

CH-601/Corvair

Do not archive

FLYaDIVE(at)aol.com
Guest

Posted: Wed Aug 30, 2006 4:42 am Post subject: Is EFIS vulnerable at engine start?

In a message dated 8/30/2006 8:06:57 AM Eastern Standard Time, smineart(at)mahaska.org writes:

  	  Quote: 	
		  The obsolescence of the avionics switch and bus has been well-discussed, 

but: is a Dynon EFIS on the E-bus vulnerable to current fluctuations during 

engine startup?  My ignition and starter will be powered from the always-hot 

battery bus, so I could wait to switch on the master until immediately after 

starting- would this be advisable?  Does the display need its own switch?

Steve Mineart

CH-601/Corvair

Do not archive 	


 ===========================================

 Steve:

  

  

 I spoke with Blue Mountain and they said to keep the EFIS off until after start up.  I also shut the EFIS down before shutting down the engine.  I installed a Pull CB to act as a switch.

  

  

 Barry

"Chop'd Liver"



"Show them the first time, correct them the second time, kick them the third 

time." 

Yamashiada

Bill Denton

Joined: 10 Jan 2006
Posts: 97
Location: Chicago, IL USA

Posted: Wed Aug 30, 2006 4:56 am Post subject: Is EFIS vulnerable at engine start?

Dynon disagrees...

  

 The  following exchange came from Dynon's message board:

  

 Question: "I've just installed my D10A and as advised in the  instructions wired it through a 2 amp fuse.  Since I didn't order the  internal battery, I did not connect the "stay alive" wire and also did not  install a separate power switch.  The unit comes on when I turn on the  master switch without my pressing the unit's power button.  I assume this  in normal, but can I have problems with power spikes during engine start?   Should I install a separate power switch in the Dynon circuit?  If not,  should I turn off the EFIS before engine start?" 

  

  

 Answer, from Dynon Support:

 

"The EFIS is indeed designed to come alive when  power is applied. 

 

Many customers install the EFIS in exactly the  same electrical configuration you have set up. The unit will not be damaged by  having it on during engine start, but it may reboot if the voltage momentarily  drops below 10V. 

 

Also, since you did not purchase the internal  battery, you may want to connect the keep alive wire to power the clock when  your master switch is off. Otherwise it will reset after every power cycle." 

  

 I  hope this is useful...

  

  

  

  

  

  

  

  

  

  

  

 --

planepubs(at)ev1.net
Guest

Posted: Wed Aug 30, 2006 5:52 am Post subject: Is EFIS vulnerable at engine start?

And I think that I would spring for a $10 switch as  just a tiny bit more protection on my $3000 instrument.  

   

 Spikes Happen



  

 Al

 General Aviation - Pricing People Out  Daily

  

  

  

On 08/30/2006 7:56:01 AM, Bill Denton (bdenton(at)bdenton.com (bdenton(at)bdenton.com)) wrote:

[quote] Dynon  disagrees...

 

 The following exchange came from

 Dynon's  message board:

 

 Question: "I've just installed my D10A and  as

 advised in the instructions wired it through a 2 amp fuse. Since  I

 didn't order the internal battery, I did not connect the "stay alive"  wire and also did not install a separate power switch. The unit comes on when I  turn on the master switch without my pressing the unit's

 power button. I  assume this in normal, but can I have problems with power

 spikes during  engine start? Should I install a separate power switch in

 the Dynon  circuit? If not, should I turn off the EFIS before engine

  start?"

 

 

 Answer, from Dynon Support:

 

  "The EFIS is indeed

 designed to come alive when power is  applied.

 

 Many customers install the EFIS in exactly the same  electrical

 configuration you have set up. The unit will not be damaged  by having it

 on during engine start, but it may reboot if the voltage  momentarily drops

 below 10V.

 

 Also, since you did not  purchase the internal battery, you may want to

 connect the keep alive  wire to power the clock when your master switch is

 off. Otherwise it  will reset after every power   [quote][b]

denis.walsh(at)comcast.ne
Guest

Posted: Wed Aug 30, 2006 6:01 am Post subject: Is EFIS vulnerable at engine start?

I can add a bit to this.

Mine is a D-100 but essentially the same.  



It has never blinked on engine start.  This may very well be because I have an internal battery.   However, The good news is that if it does require a reboot, it comes up with a useable attitude and airspeed in a few seconds (three to five).  The altitude tape takes another while.  This rapid erection is so fast and has seemed so reliable that I have checked it in flight several times when the system  has become addled after multiple gyrations caused by continuous loops, cloverleafs and whifferdills.  In each case it comes up, in level flight, in the same five seconds.  If left on its own, it can take almost a minute to get straight after a good thrashing.



I should hasten to add that this does not happen very often, although I do the multiple aerobatic quite often.



I really like the unit, especially since the new horizontal compass card is available as a split screen option.

 

Denis Walsh  



On Aug 30, 2006, at 07:56 249610008, Bill Denton wrote:

[quote]  Dynon disagrees...

  

 The following exchange came from Dynon's message board:

  

 Question: "I've just installed my D10A and as advised in the instructions wired it through a 2 amp fuse.  Since I didn't order the internal battery, I did not connect the "stay alive" wire and also did not install a separate power switch.  The unit comes on when I turn on the master switch without my pressing the unit's power button.  I assume this in normal, but can I have problems with power spikes during engine start?  Should I install a separate power switch in the Dynon circuit?  If not, should I turn off the EFIS before engine start?" 

  

  

 Answer, from Dynon Support:

 

"The EFIS is indeed designed to come alive when power is applied. 

 

Many customers install the EFIS in exactly the same electrical configuration you have set up. The unit will not be damaged by having it on during engine start, but it may reboot if the voltage momentarily drops below 10V. 

 

Also, since you did not purchase the internal battery, you may want to connect the keep alive wire to power the clock when your master switch is off. Otherwise it will reset after every power cycle." 

  

 I hope this is useful...

  

  

  

  

  

  

  

  

  

  

  

 --

nuckollsr(at)cox.net
Guest

Posted: Wed Aug 30, 2006 6:01 am Post subject: Is EFIS vulnerable at engine start?

At 08:41 AM 8/30/2006 -0400, you wrote:



 	  Quote: 	
		  In a message dated 8/30/2006 8:06:57 AM Eastern Standard Time, 

smineart(at)mahaska.org writes:

The obsolescence of the avionics switch and bus has been well-discussed,

but: is a Dynon EFIS on the E-bus vulnerable to current fluctuations during

engine startup?  My ignition and starter will be powered from the always-hot

battery bus, so I could wait to switch on the master until immediately after

starting- would this be advisable?  Does the display need its own switch?

Steve Mineart

CH-601/Corvair

Do not archive



===========================================

Steve:

I spoke with Blue Mountain and they said to keep the EFIS off until after 

start up.  I also shut the EFIS down before shutting down the engine.  I 

installed a Pull CB to act as a switch.


	


     I believe the question was about a Dynon system, not

     Blue Mountain. Hopefully, the folks at Dynon are a bit

     more agile in their management of input power

     perturbations than Blue Mountain . . . the very

     best source of lucid answer is from Dynon. Let us

     know what they say.



     A side note: I'll suggest that your ignition system

     operate from the always hot bus as you've described

     but the starter control should power from the main

     bus so that it's disabled when the master switch

     is OFF.



     Bob . . .



      ---------------------------------------------------------

      < What is so wonderful about scientific truth...is that >

      < the authority which determines whether there can be   >

      < debate or not does not reside in some fraternity of   >

      < scientists; nor is it divine. The authority rests     >

      < with experiment.                                      >

      <                            --Lawrence M. Krauss       >

      ---------------------------------------------------------

nuckollsr(at)cox.net
Guest

Posted: Wed Aug 30, 2006 6:08 am Post subject: Is EFIS vulnerable at engine start?

At 07:56 AM 8/30/2006 -0500, you wrote:



 	  Quote: 	
		  Dynon disagrees...



The following exchange came from Dynon's message board:



Question: "I've just installed my D10A and as advised in the instructions 

wired it through a 2 amp fuse.  Since I didn't order the internal battery, 

I did not connect the "stay alive" wire and also did not install a 

separate power switch.  The unit comes on when I turn on the master switch 

without my pressing the unit's power button.  I assume this in normal, but 

can I have problems with power spikes during engine start?  Should I 

install a separate power switch in the Dynon circuit?  If not, should I 

turn off the EFIS before engine start?"

Answer, from Dynon Support:



"The EFIS is indeed designed to come alive when power is applied.



Many customers install the EFIS in exactly the same electrical 

configuration you have set up. The unit will not be damaged by having it 

on during engine start, but it may reboot if the voltage momentarily drops 

below 10V.



Also, since you did not purchase the internal battery, you may want to 

connect the keep alive wire to power the clock when your master switch is 

off. Otherwise it will reset after every power cycle."



I hope this is useful...


	


   Aha! thank you sir for doing this research

   and offering the resulting data.



   If I'm interpreting their reply correctly, it

   is useful to run their keep-alive wire to

   the always hot battery bus to support the internal

   clock.



   I note that Dynon has published their installation

   manuals at:



http://www.dynonavionics.com/docs/support_documentation.html



   I've not read them in detail but what I had time

   to look at seems lucid and complete . . . including

   descriptions of the connector pin-outs.



   Bob . . .

Terry Watson

Joined: 09 Jan 2006
Posts: 290
Location: Seattle, WA USA

Posted: Wed Aug 30, 2006 7:47 am Post subject: Is EFIS vulnerable at engine start?

Blue Mountain’s EFIS/one was designed by someone who thinks all airplanes should have a 28 volt electrical system, so it can’t handle the drop in voltage during engine start. But, it also has all of my engine gauges, so I had to install a second battery to keep the engine and starter on separate busses during start-up. Maybe I should have just relied on a low oil pressure light to tell me what I really need to know about the engine during start-up.  

   

Terry  

RV-8A still finishing  

Seattle    

   

    

   

    

I spoke with Blue  Mountain and they said to keep the EFIS off until after start up.  I also shut the EFIS down before shutting down the engine.  I installed a Pull CB to act as a switch.  

    

   

    

   

    

Barry

 "Chop'd Liver"

 

 

   

  

    [quote]



matronics.com/Navigator?AeroElectric-List



[b]

FLYaDIVE(at)aol.com
Guest

Posted: Wed Aug 30, 2006 8:06 am Post subject: Is EFIS vulnerable at engine start?

Terry: 

I also have the Grand Rapids EIS in the same plane and their instructions are to leave it on all the time.   

Go Figure! 

  

Barry 

=================== 

Blue Mountainâ€™s EFIS/one was designed by someone who thinks all airplanes should have a 28 volt electrical system, so it canâ€™t handle the drop in voltage during engine start. But, it also has all of my engine gauges, so I had to install a second battery to keep the engine and starter on separate busses during start-up. Maybe I should have just relied on a low oil pressure light to tell me what I really need to know about the engine during start-up. 

  

Terry 

RV-8A still finishing 

Seattle  

 

  

 

  

I spoke with Blue Mountain and they said to keep the EFIS off until after start up.  I also shut the EFIS down before shutting down the engine.  I installed a Pull CB to act as a switch.

  

 

  

 

  

Barry

"Chop'd Liver"



  [quote][b]

bicyclop(at)pacbell.net
Guest

Posted: Wed Aug 30, 2006 8:21 am Post subject: Is EFIS vulnerable at engine start?

We’ve got a D-10 without internal battery in our RV, on the E-bus. When the master and/or E-bus switches are turned on before start, the EFIS comes on. Starting the engine browns it out. Sometimes it comes back up, sometimes it doesn’t and must be disconnected by momentarily pulling the breaker before it will re-boot. Thus, we have written into the checklist to verify breaker pulled before start and at shutdown.  

   

Incidentally, we have a LSE Plasma 1 ignition on one side and it starts reliably with never a kickback even though we are (apparently) dropping the bus voltage below 10v.  

   

Pax,  

   

Ed Holyoke  

   

--

N6030X(at)DaveMorris.com
Guest

Posted: Wed Aug 30, 2006 8:31 am Post subject: Is EFIS vulnerable at engine start?

You could stick something like this in between your electrical system 

and your EFIS:

http://store.mp3car.com/ProductDetails.asp?ProductCode=PWR-012



This will handle short complete outages of power and is designed to 

keep a PC running in a car even during cranking.

There's a whole crop of "carputer" devices that are showing up now, 

that may be interesting for aviation.



Dave Morris



At 10:46 AM 8/30/2006, you wrote:

 	  Quote: 	
		  Blue Mountain's EFIS/one was designed by someone who thinks all 

airplanes should have a 28 volt electrical system, so it can't 

handle the drop in voltage during engine start. But, it also has all 

of my engine gauges, so I had to install a second battery to keep 

the engine and starter on separate busses during start-up. Maybe I 

should have just relied on a low oil pressure light to tell me what 

I really need to know about the engine during start-up.



Terry

RV-8A still finishing

Seattle

I spoke with Blue Mountain and they said to keep the EFIS off until 

after start up.  I also shut the EFIS down before shutting down the 

engine.  I installed a Pull CB to act as a switch.

Barry

"Chop'd Liver"



<http://www.matronics.com/Navigator?AeroElectric-List>http://www.matronics.com/Navigator?AeroElectric-List

<http://www.matronics.com/contribution>http://www.matronics.com/contribution

nuckollsr(at)cox.net
Guest

Posted: Wed Aug 30, 2006 8:35 am Post subject: Is EFIS vulnerable at engine start?

At 12:05 PM 8/30/2006 -0400, you wrote:

 	  Quote: 	
		  I also have the Grand Rapids EIS in the same plane and their instructions 

are to leave it on all the time.

Go Figure!

===================


	




 	  Quote: 	
		  Blue Mountain's EFIS/one was designed by someone who thinks all airplanes 

should have a 28 volt electrical system, so it can't handle the drop in 

voltage during engine start. But, it also has all of my engine gauges, so 

I had to install a second battery to keep the engine and starter on 

separate busses during start-up. Maybe I should have just relied on a low 

oil pressure light to tell me what I really need to know about the engine 

during start-up.

===================


	




 	  Quote: 	
		  I spoke with Blue Mountain and they said to keep the EFIS off until after 

start up.  I also shut the EFIS down before shutting down the engine.  I 

installed a Pull CB to act as a switch.


	




     DO-160 design philosophies have been with us for

     decades. It's unfortunate that some otherwise

     capable individuals do not take advantage of

     recipes for success that are free for the taking.



     Bob . . .

      ---------------------------------------------------------

      < What is so wonderful about scientific truth...is that >

      < the authority which determines whether there can be   >

      < debate or not does not reside in some fraternity of   >

      < scientists; nor is it divine. The authority rests     >

      < with experiment.                                      >

      <                            --Lawrence M. Krauss       >

      ---------------------------------------------------------

brian-av(at)lloyd.com
Guest

Posted: Wed Aug 30, 2006 9:00 am Post subject: Is EFIS vulnerable at engine start?

On Aug 30, 2006, at 6:51 AM, A DeMarzo wrote:



 	  Quote: 	
		   And I think that I would spring for a $10 switch as just a tiny bit  

 more protection on my $3000 instrument.



 Spikes Happen


	


This is an old wives' tale. I am amazed at how long this one has  

persisted. The only "spike" are you going to have to deal with in  

your airplane is load-dump from the alternator after turning off a  

big load. And that will be absorbed by the battery. The "spike" that  

happens during start is just the voltage sag due to the huge load  

presented by the starter. If you don't believe me, put a 'scope on  

your bus and watch it while starting the engine. No "spike".



Hasn't this one been beaten to death?



And as for Blue Mountain telling you to turn off your EFIS during  

start, that is only a problem with 14V electrical systems where the  

starter can draw the bus down to a voltage below which the BM-EFIS'  

power supply will work. That is why Greg at BM likes 28V electrical  

systems. His equipment does not reboot during start with a 28V  

electrical system. It makes sense to me too.



Brian Lloyd                         361 Catterline Way

brian HYPHEN av AT lloyd DOT com    Folsom, CA 95630

+1.916.367.2131 (voice)             +1.270.912.0788 (fax)



I fly because it releases my mind from the tyranny of petty things . . .

— Antoine de Saint-Exupéry

Terry Watson

Joined: 09 Jan 2006
Posts: 290
Location: Seattle, WA USA

Posted: Wed Aug 30, 2006 10:18 am Post subject: Is EFIS vulnerable at engine start?

Let's see: Bluemountain designed their EFIS for experimental aircraft. The

biggest single segment of experimental aircraft are RV's. There must be some

but I have never heard of 28 volt RV. Every one I have ever seen was a 14

volt design. Most other experimental aircraft that I am aware of are also 14

volt designs.



Either Greg made a serious mistake in accessing the needs of his potential

market, or I have a serious case of tunnel vision. Nothing in his sales

literature says anything about it not working with a 14 volt system. 



But maybe I'm just in a crappy mood about BMA at the moment. I tried to

install the latest update to the software in my BMA EFIS/one last night and

it locked up on me -- again. The last time this happened I had to ship it

back to Tennessee, which cost $85 just for shipping. (But they didn't charge

for the repair and updating some of the internal hardware and software.) I

am now waiting for their support to answer my email or return my phone call.



Terry


<snip>



And as for Blue Mountain telling you to turn off your EFIS during  

start, that is only a problem with 14V electrical systems where the  

starter can draw the bus down to a voltage below which the BM-EFIS'  

power supply will work. That is why Greg at BM likes 28V electrical  

systems. His equipment does not reboot during start with a 28V  

electrical system. It makes sense to me too.



Brian Lloyd                         361 Catterline Way

brian HYPHEN av AT lloyd DOT com    Folsom, CA 95630

+1.916.367.2131 (voice)             +1.270.912.0788 (fax)



I fly because it releases my mind from the tyranny of petty things . . .

— Antoine de Saint-Exupéry

FLYaDIVE(at)aol.com
Guest

Posted: Wed Aug 30, 2006 11:45 am Post subject: Is EFIS vulnerable at engine start?

In a message dated 8/30/06 2:22:29 PM Eastern Daylight Time, 

terry(at)tcwatson.com writes:



 	  Quote: 	
		   But maybe I'm just in a crappy mood about BMA at the moment. I tried to

  install the latest update to the software in my BMA EFIS/one last night and

  it locked up on me -- again. The last time this happened I had to ship it

  back to Tennessee, which cost $85 just for shipping. (But they didn't 

charge
	


 	  Quote: 	
		    for the repair and updating some of the internal hardware and software.) I

  am now waiting for their support to answer my email or return my phone 

call.
	


 	  Quote: 	
		    

  Terry

======================
	


Terry:



I can't blame you ... My NEW unit FAILED the first time I installed it.  I 

knew what was wrong (bad accelerometer) but after calling them the tech dept. 

wanted me to upgrade the software.  $35 for a connection cable (50 ft long  - no 

short ones available) and two hours of trying to down load and configure ...  

I called them back .. This time I was lucky and talked to the BOSS.  In 

seconds he confirmed that it was the accelerometer and told me to ship it back.  

They did the software upgrade and the unit is in and working.  All at no charge. 

 But, WHY did it fail ... A brand new unit?  I can't blame BMA for an 

accelerometer problem, they did not make it.  But, now I am always wondering if it is 

going to fail, especially when I would need it the most.



Barry

"Chop'd Liver"



"Show them the first time, correct them the second time, kick them the third 

time." 

Yamashiada

FLYaDIVE(at)aol.com
Guest

Posted: Wed Aug 30, 2006 12:34 pm Post subject: Is EFIS vulnerable at engine start?

In a message dated 8/30/06 12:39:51 PM Eastern Daylight Time, 

nuckollsr(at)cox.net writes:



 	  Quote: 	
		    DO-160 design philosophies have been with us for

       decades. It's unfortunate that some otherwise

       capable individuals do not take advantage of

       recipes for success that are free for the taking.

  

       Bob . . .

  

========================
	


Bob:



What individuals?  I did not design the EFIS, guess you are referring to BMA. 

 I wish I would have been consulted on functions and layout, but what do I 

know?  I only have install it and use it!

I'm not impressed with the GPS screens or the mounting method, or how they 

didn't hook up the magnetometer.  And I'm still trying to get the bugs out with 

the Pitot - Static System and its readings (I have a DUAL system - EFIS and 

Steam gages).



Barry

"Chop'd Liver"



"Show them the first time, correct them the second time, kick them the third 

time." 

Yamashiada

nuckollsr(at)cox.net
Guest

Posted: Wed Aug 30, 2006 4:06 pm Post subject: Is EFIS vulnerable at engine start?

At 04:33 PM 8/30/2006 -0400, you wrote:



 	  Quote: 	
		  



In a message dated 8/30/06 12:39:51 PM Eastern Daylight Time,

nuckollsr(at)cox.net writes:



 >  DO-160 design philosophies have been with us for

 >       decades. It's unfortunate that some otherwise

 >       capable individuals do not take advantage of

 >       recipes for success that are free for the taking.

 >

 >       Bob . . .

 >

========================

Bob:



What individuals?  I did not design the EFIS, guess you are referring to BMA.

  I wish I would have been consulted on functions and layout, but what do I

know?  I only have install it and use it!


	


    All individuals. Many who do not have a background in

    TC aircraft are not cognizant of the dragons already slain

    in decades of effort by those who have gone before us.

    Virtually every individual I've met who had an idea and

    starry-eyed dream (Including Greg) was offered no-charge,

    design  assistance with packaging, power conditioning and I/O

    configurations that are proven ingredients in the recipe

    for success. Only a tiny fraction have accepted the offer.



 	  Quote: 	
		  I'm not impressed with the GPS screens or the mounting method, or how they

didn't hook up the magnetometer.  And I'm still trying to get the bugs out 

with

the Pitot - Static System and its readings (I have a DUAL system - EFIS and

Steam gages).


	


    And all those are performance and systems integration issues.

    Let us all hope that once those snakes are sacked and tied

    that environmental worms don't spill out. Those issues

    are generally beyond the ability of the installer

    to deal with and are the responsibility of the manufacturer.



    Bob . . .

gert.v(at)sbcglobal.net
Guest

Posted: Wed Aug 30, 2006 5:12 pm Post subject: Is EFIS vulnerable at engine start?

begs the question, what about the current crop of electronic engine 

instruments, ya all keep them off till u engine is running.

What good are they if u can't have them on during engine start  

so u wait till the engine is running, switch u electronic instruments on 

to discover u have no oil pressure, oops....somehow i don't think i want 

Blue Mountain to check my oil pressure if i have to have their system 

off during engine start.



A DeMarzo wrote:

 	  Quote: 	
		   And I think that I would spring for a $10 switch as just a tiny bit 

 more protection on my $3000 instrument. 

  

 Spikes Happen

  

 Al

 General Aviation - Pricing People Out Daily

  

  

  

 On 08/30/2006 7:56:01 AM, Bill Denton (bdenton(at)bdenton.com 

 <mailto:bdenton(at)bdenton.com>) wrote:

 > Dynon disagrees...

 >

 > The following exchange came from

 > Dynon's message board:

 >

 > Question: "I've just installed my D10A and as

 > advised in the instructions wired it through a 2 amp fuse. Since I

 > didn't order the internal battery, I did not connect the "stay 

 alive" wire and also did not install a separate power switch. The unit 

 comes on when I turn on the master switch without my pressing the unit's

 > power button. I assume this in normal, but can I have problems with 

 power

 > spikes during engine start? Should I install a separate power switch in

 > the Dynon circuit? If not, should I turn off the EFIS before engine

 > start?"

 >

 >

 > Answer, from Dynon Support:

 >

 > "The EFIS is indeed

 > designed to come alive when power is applied.

 >

 > Many customers install the EFIS in exactly the same electrical

 > configuration you have set up. The unit will not be damaged by having it

 > on during engine start, but it may reboot if the voltage momentarily 

 drops

 > below 10V.

 >

 > Also, since you did not purchase the internal battery, you may want to

 > connect the keep alive wire to power the clock when your master 

 switch is

 > off. Otherwise it will reset after every power

 *

 *


	


-- 



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nuckollsr(at)cox.net
Guest

Posted: Wed Aug 30, 2006 5:52 pm Post subject: Is EFIS vulnerable at engine start?

At 08:10 PM 8/30/2006 -0500, you wrote:



 	  Quote: 	
		  



begs the question, what about the current crop of electronic engine 

instruments, ya all keep them off till u engine is running.

What good are they if u can't have them on during engine start  

so u wait till the engine is running, switch u electronic instruments on 

to discover u have no oil pressure, oops....somehow i don't think i want 

Blue Mountain to check my oil pressure if i have to have their system off 

during engine start.


	


     The risks are exceedingly low. I suppose there are

     folks who tell tales of having lost an engine when a pump

     shaft sheared on startup . . . but think about it. Just

     how highly stressed are the oil pump parts?  If one is

     really worried about a bullet proof oil pressure indication

     at startup, perhaps a pressure switch and "OIL P WARN" light

     in the annunciator panel is called for.



     I wouldn't put engine instrumentation on the e-bus. 99.999% of

     the time, engine instruments show the same things they said

     the last time you looked at them. Loss of some engine functionality

     in addition to loss of alternator on same tank of fuel is exceedingly

     remote. Or, one could install an SD-8 for unlimited endurance on

     an 8 Amp e-bus and flip the instrumentation on from time to time.



     Bob . . .

FLYaDIVE(at)aol.com
Guest

Posted: Thu Aug 31, 2006 3:14 am Post subject: Is EFIS vulnerable at engine start?

In a message dated 8/30/06 9:15:25 PM Eastern Daylight Time, 

gert.v(at)sbcglobal.net writes:



 	  Quote: 	
		   begs the question, what about the current crop of electronic engine 

  instruments, ya all keep them off till u engine is running.

  What good are they if u can't have them on during engine start  

  so u wait till the engine is running, switch u electronic instruments on 

  to discover u have no oil pressure, oops....somehow i don't think i want 

  Blue Mountain to check my oil pressure if i have to have their system 

  off during engine start.

======================
	


I do not know if Blue Mountain (BMA) has an EIS.  What I was mentioning was 

the EFIS system.  There is also a huge difference between the electronics of an 

EFIS or Com radio and a simple sending unit and gage used for fuel quantity, 

oil temp & pressure and the like.

Now, Grand Rapids states KEEP THE UNIT ON.  So there is a difference in 

electrical design between the two or at least their thinking!



Barry

"Chop'd Liver"



"Show them the first time, correct them the second time, kick them the third 

time." 

Yamashiada

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