What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

RV-10 Gear Collapse

I don't know any further details, but there are some closeups of the gear, and an interview with the owner, here.
 
ECM?

I don't know about you folks... but having an ECM decided when it wants to let me have full power or not really makes me nervous... I need to be the authority on having the engine make full power or not... I still don't get a good warm and fuzzy about having a car engine in an airplane.... one guy tried 10 or so subes in his rv-4 until he got a lycoming, another local guy had the bottom end fail on him and landed safe thankfully, another guy we discussed not too long ago on the forum (his NTSB report) purchased the farm in an RV-10... Now this guy has an engine failure of some sort... I know that there are a lot of guys championing the car engines.... but I still don't get the warm and fuzzy.... :( Is there anywhere that compiles statistics on car engines installed on airplanes? (no flame wars allowed!) (not that I will ever ever ever have a car engine in my airplane)
Best
Brian Wallis
 
Last edited:
Yes, there are some figures...

...Brian. Jess Meyers at www.beltedair.com has a lot of Chevy V-6 and V-8 engines flying in RV's IIRC. He does away with the computer completely and has a simple belt drive and a carburetor, electronic ignition. Quite successful actually.

Regards,
 
From an engineering standpoint I would think that an ECM isn't the problem, per se, but an ECM that is programmed for an automotive application. I don't know anything about what modifications, if any, are done to the stock Chevy ECM in this case but it would seem that, unless Chevy licensed you the development suite (unlikely for this market) so you could rewrite the code to create aviation oriented operating modes you are always going to be stuck with some potential states where the ECM is doing exactly what it is told to do so far as power output, etc that are exactly not what you want it to do so far as keeping the airplane flying.

I imagine, for example, the ECM won't let the engine operate for sustained times where it is killing itself (over-temp, etc) where in the aviation mode you might be quite willing to have the engine go there for as long as possible while you seek a suitable emergency landing site.

All relatively easy to design into the ECM (a simple matter of programming as they say) if you have access to the ECM innards and code base. Of course testing, debugging, optimizing this code takes lots of time and money neither of which are likely to be available for the market segment we live in.

Not that I don't wish that it would be done or even that I think it probably will be done at some point. I just don't think it will be done with a stock ECM from a major (does the new GM even qualify anymore for that adjective?) automobile manufacturer.

I don't follow the market but I'd think the aftermarket racing people might have a suitable ECM platform.

All this is uninformed speculation and in no way is disparaging toward those folks working on this. I have nothing but admiration for their pioneering spirit and very real efforts to advance the market's choices for viable poweplants.
 
<<but having an ECM decided when it wants to let me have full power or not really makes me nervous>>

It should.

If a software-commanded power reduction was indeed the cause, this accident was completely unnecessary. The "limp home mode" issue has been around 10-15 years, and this sure isn't the first time somebody earned a bent flying machine by ignoring it.
 
brianwallis said:
....( Is there anywhere that compiles statistics on car engines installed on airplanes? (no flame wars allowed!) (not that I will ever ever ever have a car engine in my airplane)
Best
Brian Wallis
Click to expand...

The only data I have seen came from Ron Wantajja's analysis of accident data from NTSB reports (see link here). He found that for accidents involving fixed wing aircraft with autoconversion engines, in 37.5% of the time the source of the problem was power loss, whereas only 12.3% of all accidents involving fixed wing aircraft with aircraft engines resulted from power loss.

On interesting thing he found was that the auto-engines seemed to have a lower internal failure rate than aircraft engines, but their problems were in the ignition, cooling, and reduction drive systems.
 
This was discussed a year or so ago looking at NTSB data and various search strings. It appears you are quite a bit more likely to suffer a power loss event with an automotive conversion however it is hard to agree by what percentage.

From the same data, my conclusion was also that the core engines, at least in the case of Subarus were in fact more reliable than certified engines. Most events were triggered by supporting system failures- fuel, spark, electrical, cooling, lubrication, gearbox etc.

Bud Warren's previous Wheeler V8 used a carb and distributor type (non ECU) EI and worked well for about 500 hours.

Carb manifolds are available for the LS engines and frankly I'd feel better with that than an OE ECU which just plain scares me.
 
Another option that I have only seen mentioned once before, is to throw away the EFI, and put on mechanical injection.

Airflow Performance makes units for auto engines, as well as aircraft engines, and the hardware seems to be identical other than the manifolds.

Or, if you really want to go EFI, there is this company called SDS that I suspect can help.

Ross, does your brain box speak Chevy??
 
We developed a system specifically for the LS engines mainly for desert racing and kit cars. Sales have been slow and a couple users have had odd issues with it. We have not accumulated enough hours in ground use to release the system for aviation use especially in light of the technical issues on this new board design. It uses a completely different board, microprocessor and software from the proven EM44/46 designs.

Many people have bugged us for the new system for V8 aviation apps including Geared but our policy is not to release anything for aviation until a good 10,000+ trouble free hours have been accumulated in automotive use first. To do otherwise is simply counterproductive to safety and our reputation. At present, there is no timetable for release to this market.

Mechanical injection would be another way to go or with something like Motec who has considerable experience with direct fire V8 apps.
 
Last edited:
ECMs in Light Airplanes...Not sure about that.

Hi, first post. I've been working in automotive powertrain controls for 9+ years now, first for an ECM supplier, Visteon, and now for GM Powertrain. My area is diagnostics calibration, so I've troubleshot just about every piece of an engine management system that can go wrong. Even in a simple system (engine only, no transmission), I wouldn't really trust flying in an ECU-equipped light plane with an automotive motor unless there was almost two of every key control component. Dual plugs, dual ECUs with fully independent power supplies, etc. Preferably dual engines...

Automotive ECUs are very durable, designed to operate -40 F to 150F, for 150000 miles. But the airplane 'drive cycle' is so different than a car, there's just too many unknown failure modes out there that can bite you. Temperature gradients for one, sustained high output from the output drivers on the circuit board, power supply fluctuations, etc. One obvious area is altitude compensation. Most automotive baro tables are limited to 12,000 feet, which is basically the highest road in the world. Anything above that is all error buildup.

The most aggravating issues to solve are the one-off cases that come out of nowhere; where it took a perfect alignment of multiple factors to reveal the issue. The thing is, no matter how robust the calibration and validation is, there's always one fault mode out there that doesn't show itself during development, no matter how many hours on the dyno, test vehicle miles, or development trip hours you have.

I'm glad to see yet another application of the venerable small block Chevy, though.

Rob Weiss
 
Read the string on the alternative engine forum. A couple things are clear and reinforce my beliefs on the auto engine vs Lycoming debate. First, auto engine converts are passionate about their endeavors. Second, they tend to put credulity aside (see for example the ludicrous speed and fuel flow numbers quoted for the accident airplane - and defended).

I'm going to get flamed for that last comment which I may deserve.

As the previous post notes, most of the failures come from the accessories. Regardless, the prop stops nevertheless. I have to tip my hat to the auto engine afficianados because they are true experimenters.
 
Rob Weiss said:
Hi, first post. I've been working in automotive powertrain controls for 9+ years now, first for an ECM supplier, Visteon, and now for GM Powertrain. My area is diagnostics calibration, so I've troubleshot just about every piece of an engine management system that can go wrong. Even in a simple system (engine only, no transmission), I wouldn't really trust flying in an ECU-equipped light plane with an automotive motor unless there was almost two of every key control component. Dual plugs, dual ECUs with fully independent power supplies, etc. Preferably dual engines...

Automotive ECUs are very durable, designed to operate -40 F to 150F, for 150000 miles. But the airplane 'drive cycle' is so different than a car, there's just too many unknown failure modes out there that can bite you. Temperature gradients for one, sustained high output from the output drivers on the circuit board, power supply fluctuations, etc. One obvious area is altitude compensation. Most automotive baro tables are limited to 12,000 feet, which is basically the highest road in the world. Anything above that is all error buildup.

The most aggravating issues to solve are the one-off cases that come out of nowhere; where it took a perfect alignment of multiple factors to reveal the issue. The thing is, no matter how robust the calibration and validation is, there's always one fault mode out there that doesn't show itself during development, no matter how many hours on the dyno, test vehicle miles, or development trip hours you have.

I'm glad to see yet another application of the venerable small block Chevy, though.

Rob Weiss
Click to expand...

Nice post Rob. yes, I quite agree. As the complexity of control goes up, the chances of an IF, AND, AND, AND, THEN problem can surface. These are so much harder to see for the non OEM tuner. A simple IF coolant temp exceeds 235F THEN shut off injector outputs might be easy to see and alter. The problem is when several seemingly unrelated things come together to trigger the same response- well then Houston, we have a problem...

With most aftermarket ECUs, we don't need all the diagnostics and complexity. There are far less IFs and ANDs. The mission is far more simple- proper spark timing and mixtures to make the engine run well is job one and maybe the only job in fact. No chassis, emissions, self learning and minimal diagnostics tie-ins. Sometimes we don't even use hard code to give the response we want, we just alter a value in the user programmable lookup tables.

As an example for a MAP sensor failure, the lowest and highest values in the table (where the engine never actually operates) we enter a value equivalent to WOT at sea level. If the MAP sensor fails either open or shorted (usually one of these two), fueling reverts to near full power so by moving the throttle open, the engine will continue to run and produce good power despite the dead sensor. We use a board resistor to pull the failed input high even these days. The same goes for temperature sensors where open or shorted failures simply defaults fueling to a warm engine on a summer day. In these cases, there is no code operating in between.
 
Nukeflyboy said:
Read the string on the alternative engine forum. A couple things are clear and reinforce my beliefs on the auto engine vs Lycoming debate. First, auto engine converts are passionate about their endeavors. Second, they tend to put credulity aside (see for example the ludicrous speed and fuel flow numbers quoted for the accident airplane - and defended).

I'm going to get flamed for that last comment which I may deserve.

As the previous post notes, most of the failures come from the accessories. Regardless, the prop stops nevertheless. I have to tip my hat to the auto engine afficianados because they are true experimenters.
Click to expand...

I think most auto engine experimenters (maybe not vendors though!) want to post accurate information about weight, fuel flow and performance. As many things are new, often fuel flow sensors and black boxes are not calibrated. I always encourage people to read up and use the best test methods they can to get a true picture of overall engine/ airframe performance.

Using the right/ left tank method and filling before and after the flight using one for taxi, takeoff, climb and the other for a timed cruise at a constant power setting combined with 4 way GPS data is pretty simple and accurate. Randy Crothers eventually used this method to confirm the ECU FF data. It is very hard to dispute results using this method after a few longer flights and getting similar results. Sometimes we are surprised, sometimes disappointed but the facts are the facts either way.

My mind is still open that the LS engines might produce similar or better FF vs. TAS figures compared to a Lycoming. Once Todd or Bill does a few runs as above, we will know one way or the other.

You are quite right in saying that certain accessory failures can often cause the prop to stop just as surely as an ECU issue so these are just as important as the engine itself. Careful design and testing must be carried out on the entire system.
 
Last edited:
Interesting.....

All the talk about the engine in this thread instead of the other one. I'm more curious about the weight of the plane at the time of the accident, and the approximate rate of descent that caused the gear to fail:confused:
 
No dog in the Hunt...........

I'll never forget my aunt Alice, she was a very devote Baptist. Back in the early 60's when space exploration was really getting started, she made the following comment that stuck with me for life. I have used it to reflect & evaluate human opinion of future events.

Her comment was as follows: "All this foolishness on space exploration, If Man ever walks on the Moon, the Moon will turn to Blood."

Well, it didn't.

Maybe not today, maybe not tomorrow, but "This flag will rise!"

Bud / Bill stay after it. If we were all " Aunt Alice's", we would still be barking at the moon. We as "experimental builders" owe a lot to your trials & tribulations.

and Aunt Alice, God rest your soul, I loved you dearly.
 
1:1 Scale said:
All the talk about the engine in this thread instead of the other one. I'm more curious about the weight of the plane at the time of the accident, and the approximate rate of descent that caused the gear to fail:confused:
Click to expand...

In my forced landing a few years back on my 6A, the main gear splayed badly but not as much as on Bill's -10 here. The telltale on the G meter was pegged at 7 Gs. We were about 100 pounds under gross at the time.

Believe me, elevator authority in the flare, deadstick, below 65 knots with a forward C of G and full flaps... well there just isn't any.:(
Hence my warning about using flaps on RVs in a power loss situation. Think of it this way, full flaps, drag is high, nose is way down, you let speed slip down to 65 knots, descent rate around 25 fps. At 100 feet, the ground is rushing up at you at an alarming rate and you will be on the ground in 4 seconds. In that last 4 seconds, the instinctive thing is to actually pull back to arrest the scary descent rate but there is no energy left and this will actually increase descent rate or make you stall. You are out of options at this point and are going to hit hard. This has hurt and killed a number of RV pilots faced with a power loss.

Keep it clean and keep your 80-85 knots right down to your flare.
 
Last edited:
But the RV-10 is advertised as a short field plane...

80-85 on approach with no flaps is more for a nice long concrete runway, isn't it? I haven't flown in quite a while, almost all my time was in Piper Warriors/Archers, but I would do that same trick to increase the odds of a nicer landing if I had the space. Only one or two notches of flap, come in 10 kts faster than I normally would, and minimal flare just to make sure the mains touched first; let the airplane find the runway.

I heard some other RVs had a nose gear colllapse AD, which has been subsequently addressed. The gear still looks a little too spindly for me, especially if it's supposedly for short, unimproved fields.
 
Rob Weiss said:
I heard some other RVs had a nose gear colllapse AD, which has been subsequently addressed. The gear still looks a little too spindly for me, especially if it's supposedly for short, unimproved fields.
Click to expand...

The "other" RV's nosegears are quite different. While it may appear the same from the outside, the differ significantly. Also, the RV main gears are actually quite a bit more robust than many other planes out there. This isn't the first RV-10 to have a rather "firm" landing. There have been at least 2 others that I know of (not very public) where they had extremely hard landings...to the point in one of the planes where rivets were popped, windows were cracked, tail was crooked, etc..

Anyway, my point is that looks can be deceiving. I've been flying RV's off of our short grass strip for a lot of years, and so have a number of my friends in their RV-10's, etc.. Never really been an issue with proper technique....

My 2 cents as usual.

Cheers,
Stein

PS, no AD's for experimentals - only SB's, SL's etc..
 
Yep, talking deadstick here, no residual thrust. I can only guess that a -10 with full flaps at 65 knots is coming down at least 1500 FPM with no power at a rather alarming deck angle...

Not a big deal to fly a power on approach with full flap at 65 knots.

The main gear on all the RVs is pretty strong and the -10 even more so I'd say. Takes a heck of a hard arrival to permanently bend the main gear legs. The nose gear on the -10 is much stronger than the other A models.
 
You must log in or register to reply here.
Back
Top