Subaru engine failure

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yukon
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Subaru engine failure

Post by yukon »

Does anybody have any information on the Egg RV-7a that landed off-field in Arizona today?

John
RV-9

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cjensen
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Post by cjensen »

I got a call around 2:30pm central time to make me aware of it.

Roger Everson's airplane. The only thing I know (second or third hand info here...) is that for some reason the MP went to 40", which is overboosted, he got a light, and shut it down, tried to land and ended up on it's back. Substantial damage to airframe and engine-no injuries.

He had JUST finished the 40 hour fly off.

Egg H4 supercharged 2.5L

:(
Chad Jensen
Missing my RV-7...
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JohnR
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Post by JohnR »

I sure hate to hear that. I hope the pilot is okay.
JohnR
RV-7A - Fuselage - SOLD, just not supposed to be
Numbers 6:24 - The LORD bless thee, and keep thee

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cjensen
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Post by cjensen »

Pilot is okay from what I hear. He was able to climb out on his own.

Also, from what I hear...the next flight was to be his first with his wife...
Chad Jensen
Missing my RV-7...
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yukon
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Post by yukon »

Glad he's OK. Sorry about the plane.

John
RV-9

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JohnR
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Post by JohnR »

If it had to happen, better it happened when he was by himself. Glad to hear he is okay. I really feel for him but at least airplanes can be replaced.

Our chapter was flying Young Eagles Thursday and had a bad situation develop. I was not there but one of the planes flying, a Glasair, had the fuel pump quit and ended up upside down in a bean field just short of the airport. Article hear:

http://www.kcrg.com/news/local/8237117.html

Pretty lousy reporting. The pilot did a great job and got the plane on the ground without stalling and spinning it in. Once on the ground it flipped over in the bean field. The report makes it sound liae they just fell out of the sky when the engine quit. :roll:

Just glad both of them were not injured worse than they were. A young Eagles event is one place you really don't want problems.
JohnR
RV-7A - Fuselage - SOLD, just not supposed to be
Numbers 6:24 - The LORD bless thee, and keep thee

Spike
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Post by Spike »

Im very glad nobody was injured on both accounts. Staying healthy is the number one priority. Aluminum can be replaced.

Pass along our well wishes from the board if you guys can.

John
http://www.rivetbangers.com - Now integrating web and mail!
Current Build: 2 years into a beautiful little girl

tmbg
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Post by tmbg »

very happy noone was hurt...

I have a question though, not to second guess the pilot, but was shutting down the correct option in this case? Seems like an overboost condition could be fixed just by pulling the power back...
Ian
RV-7 SB, chugging toward final assembly
IO-360-C1C 200hp obtained.
Hartzell BA prop received.
James Cowl ordered.
N773WW reserved!

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cjensen
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Post by cjensen »

Ross can explain this better than I...

I may have been mis-informed as well, since I had third hand info. He may not have shut it down...as in, it quit on it's own.

Ross knows the system in and out, so I'm sure he can fill us in on why it quit when it did.

If Roger gives a post on the Subie Yahoo group, I'll copy and paste it here.
Chad Jensen
Missing my RV-7...
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rv6ejguy
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Post by rv6ejguy »

I certainly don't know why Roger's STI quit but if the comment about spiking boost is correct, that can only be caused by the electric throttle closing based on other ECU commands or a problem with the supercharger bleed valve closing without pilot command. Don't know if Roger had an electronic or cable actuated bleed valve.

The OE ECUs frankly scare me on these engines as applied to aircraft. Read the latest CONTACT! for some unfortunate case studies.

I have an STI powered jet boat in my shop now, rewiring to take an SDS unit now because nobody could figure out the wiring for the OE unit. I was looking at the schematics for the ECU and it is a nightmare like the wiring. There are no less than 24 other devices and control modules hooked to the ECU, many delivering feedback signals. With all these and the unknown responses outputted as a result of out of range operation... well you get the picture.

OE ECUs protect the engine from damage first by possibly closing the throttle, doing a fuel cut or turning off the pump or second, limp you home (no use in an airplane either).

Just beware. These are very complicated and can bite you, even after 40 hours of flight time. The only people who understand all the control and software logic on these ECUs are the designers.
Ross Farnham

Flying RV6A turbo Subie
Building RV10 twin turbo Subie

tmbg
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Post by tmbg »

I have to wonder if anyone's playing with alternate forms of engine management, such as Megasquirt. I'm running Megasquirt on a project turbo car of mine, and it gives me a heck of a lot of flexibility. Maybe that's the solution to the subaru debacle?
Ian
RV-7 SB, chugging toward final assembly
IO-360-C1C 200hp obtained.
Hartzell BA prop received.
James Cowl ordered.
N773WW reserved!

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rv6ejguy
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Post by rv6ejguy »

People are using many different aftermarket ECUs for aviation. Probably a better bet than many OE ones. We've been doing it for 13 years now: http://www.sdsefi.com/aircraft.html
Ross Farnham

Flying RV6A turbo Subie
Building RV10 twin turbo Subie

Hadley
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updates

Post by Hadley »

does anyone have more details on this accident?

i have a 2.5L STI i am installing in my 7a and the more info i can gather on this topic BEFORE my flight testing the better.

thanks,

rvhad 8)

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cjensen
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Post by cjensen »

Here's the latest thread from the Subie Yahoo group.

It reads from BOTTOM TO TOP-the top response is Roger's from today, and it's his first post since the accident.
I had one prior instance where two fuses blew due to the butterfly valve going over-center in the 'open' position, which provided atmospheric pressure (unboosted) to the engine. I checked carefully and found that it was not physically possible for the linkage to go over-center in the 'closed' or boosted position. I had flown numerous times after this instance without any problems.

I checked manifold pressure this time and every time prior to takeoff. All was normal during the runup of the last flight--pressure went up to 33-34" with increased engine rpm, and down again with the engine at idle.

Knowing what I do now, I'd want to install a second butterfly valve/wastegate mechanism on the boost tube with a manual cable to pull open as an emergency bypass. In hindsight, after having those blown fuses, I should have replaced that servo motor. But it worked fine, and I thought the fuses had protected it.

It was just a vehicle, but the building process is so long, and the airplane flew so well that I'm feeling a real sense of loss. Don't know what I'll do next. Hope to see you at OSH.
Roger Evenson, with RV-9A salvage.



----- Original Message ----
From: "eaainc@aol.com" <eaainc@aol.com>
To: subaruaircraft@yahoogroups.com
Sent: Sunday, July 8, 2007 6:23:19 AM
Subject: Re: [subaruaircraft] Re: Supercharged 7A down in AZ?


Thanks,
Mickey
Not all details clear yet but we do know the supercharger boost control valve was adjusted 2 times due to blowing fuses. The load on the servo, from pushing against an over-center butterfly valve, blowing the fuse 2 times, was likely enough to damage the servo. 2A is a lot of power for a servo. The servo, when free to move, only has to push against a very light valve, lets just say a one lb requirement. It's capability is 40 lb when in ambient temperature and 20lb when in the engine compartment.

On a later takeoff, the vale was partially closed, due to a damaged servo, and it forced all the high pressure air into the engine, taking out at least one cylinder. The warning system worked by flashing the EIS warning and also the ECM trouble light turned on. I am not sure if a ru-up was done prior to takeoff.

In any case, this is a very careful builder and he did try to correct the servo adjustment, the unknown was that the servo had already sustained internal damage from running up against a mechanical stop 2 times before, blowing the fuse each time.

I have not been at the airplane so some of this is speculation, but seems what happened from the information we have.

Jan


-----Original Message-----
From: rv8ch <mc@rv8.ch>
To: subaruaircraft@ yahoogroups. com
Sent: Sat, 7 Jul 2007 3:14 am
Subject: [subaruaircraft] Re: Supercharged 7A down in AZ?


> Off airport landing with a supercharged 4 cylinder. Somehow the MP
went to
> at least 40" and boost warning lights came on. (We will try to
find out why)

Any further news about what happened here? As a builder with a 4
cylinder supercharged engine, I'd like to know if there is something I
can do to ensure that this does not happen to mine.

Thanks,
Mickey
Chad Jensen
Missing my RV-7...
Vertical Power support
920.216.3699
http://verticalpower.com

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rv6ejguy
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Post by rv6ejguy »

It is interesting that Roger states that it was not possible for the relief valve to go fully closed from a servo malfunction if I read this right. Even if the valve does not fully close, it the supercharger mass flow greatly exceeds the flow rate of the relief valve in the partially open condition, boost will rise.

We may never know what actually caused the spike or the consequent ECU response to it. Very high boost spikes put tremendous loads on the supercharger and drive system with positive displacement blowers. This condition must be avoided at all costs. A cable activated relief valve which is always opened before closing the throttle might be the safest bet. You just always have to remember. A spring loaded blow off valve should prevent this from causing damage. I think these are fitted the the Egg STI packages so the whole matter remains something of a mystery.

I feel Roger's pain. All that work... Argghh. :(
Ross Farnham

Flying RV6A turbo Subie
Building RV10 twin turbo Subie

Hadley
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the most current wastegate info

Post by Hadley »

gentlemen,

when i took my trip to egg in may, jan told me to use a cable system that would pull the wastegate open when the electronic throttle is closed. i am using a dual throttle quadrant with a bolt running through the throttle. this bolt will pickup the wastegate controller and pull it open when the throttle is closed, MECHANICALLY.

the pilot can NOT screw up and it will eliminate the chance of ruining your expensive engine because of a servo failure.

i am building my system accordingly.

happy landings,

had

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