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Egg Gearbox Failure

Y

Yukon

Well Known Member
Here is some info on a recent Gen 2 gearbox failure (


See answers below


Steve


--- In [email protected], "Larry" <simpsonl@...> wrote:
>
> Steve,
>
> Could you provide a few more details about your failure? I do not
> recall seeing it mentioned on the group before. Appearance of your
> oil at change?

-------- The oil at the time of failur had 36 hours (mobile 1 75W-90
synthetic)The oil color was light and no observable particles in the
tube.



Any other warning signs before the failure? Noise?

-------- My Gen II Gearbox temps always ran hotter than the engine
and the oil temps. (Normal temps for me were 205 - 210F with climbing
temps for any power above 2100 rpm) In retrospect I have learned
that this was probably a warning sign. After the failure, I used a
loaner gearbox to get the plane home and it ran significanlty cooler
(15-20F)than my original gearbox so I speculate that there was
something amiss with my original gearbox. The day of the failure, it
was very hot in Atlanta and my GB temps were running about 215, this
was probably another warning sign that I did not notice.


> Spiking temps? How catastrophic was the failure? Did it occur in
> flight?

-------- Failure was in flight, After cruising for about 1 1/2 hours
on the day of failure. There was a sudden appearance of loud
squealing noise and the gearbox failed about 3 minutes later. (gears
stripped and engine raced, I shut the engine down in flight) Pure
speculation on my part is that one of the bearings failed and after
the bearing siezed, it lead to a failure of the gears. Again, in
retrospect, I think the high temps were telling me about a problem
that I did not recognize. The dramatic difference in the loaner
Gearbox (much cooler temps) tells me that this was an issue
associated with my gearbox that may or may not be present in other
units. The new Gen III gearbox is much much cooler running in my
plane.



>
> I am also running a Gen 2 (blue front) PSRU and it typically runs
in
> the 200-210F range at full throttle and any prop setting above 2000
> RPM. My engine temps are usually about 30 degrees lower. I have a
2
> inch blast tube and a 1.25 inch blast tube to the bottom and left
> sides of the unit respectively. Aircraft Spruce delivered another
2
> inch tube and some scat today which will be installed next week for
> the right side.
>
> At 25 hours TT and 10 hours since the previous change, the Mobil 1
> 75W-90 oil looked slightly gray but there were no visible metal
> flakes on the fine screen that I strained the oil through. I am
> letting the oil "settle" for 48 hours and then will see if there is
> any sediment and if so, if it is magnetic. Then I will send to for
> analysis.
>
> I am upgrading to the Gen 3 in January, but am concerned that I may
> need to curtail my flying until then.
>
> Thanks for your information.
>
> Larry
>
> --- In [email protected], "n62km" <n62km@> wrote:
> >
> > David, I did have a complete gearbox failure on my H6 normally
> > aspirated Gen II gearbox after about 100 hours. It appears my
> > particular unit was behaving differently than most units (running
> hot)
> > so it might not have be a representative sample of most units in
> the
> > field.
> >
> > I have sinced moved to Gen III and have about ten hours on it.
The
> new
> > unit is running much cooler.
> >
> > Steve RV8 H6
>
 
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I was sorry to hear abour Steves gear box failure. I did the first flight on that plane. Report here http://www.vansairforce.com/community/showthread.php?t=12643.

Having watched "Subob" (flying friend who used to have a non-egg subaru in his 4) drop 8 Subie engines in his RV-4, there is no chance Id do it. He never failed a gear box, always the lower end of engine. All dead sticks. He had a Ross concentric planetary gear box 2.17:1, Marcotte drive terrain dampener... and through metalergical analysis, concluded that harmonics from the gear box was killing the lower end. He now has a lyco bart 180 in his RV-4. Do not equate Eggs to Subobs, its just one mans experience.

I also went to friend Egg6 RV-10 Dans funeral. Hated that.
 
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What a Gen II gearbox

What is a Gen II gear box? Is it the latest and greatest from Egg? NEVER MIND I read Yukon's link above, explains it all. The Gen III gearbox was on the tragic RV-10; Kahuna, that must have been very sad indeed, my sincere sympathies.)

Whats a "Subob", a particular brand of engine conversion or just roll your own Subaru?

Ross where are you? What ya think.

Sounds like a TEMP gauge with a real red line temp and and particle sensor for the gearbox would be good idea.
 
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gmcjetpilot said:
Ross where are you? What ya think.
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I'm dodging the troll and staying out of these discussions as I said before. I had hoped people would wait for the full NTSB report on Dan's crash before saying anything. The initial report drew no conclusions and there seems to be unusual circumstances involved hence further investigation is merited. We don't know the cause of the power loss in a 7A accident 3 days later either. I don't see the point is speculating about either accident.
 
Yukon said:
Of course you are Ross. You are an Egg vendor.
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As is often the case, I'm not sure what your point is here? I can only assume you are trying to warn older Egg customers that their gearboxes might fail. This is being discussed out in the open on Jan's site as you have said.

I do think it is counterproductive is to assume that Dan's accident was caused by the Subaru engine any more than the 7A accident 3 days later was caused by the Lycoming engine in it. I know nothing more than anyone else here on either accident. Let's just wait for the facts and maybe we can learn and apply that knowledge to prevent similar circumstances from bringing one of us down.

As many of you know, Dan was an enthusiastic advocate of the Subaru engine and knew full well what he was getting into to I think. He offered his airframe up to Jan for the test program to validate the engine, propeller, gearbox, turbo, cooling and EM systems for several months and they flew the -10 to Oshkosh together earlier. Dan was a friend as well as a customer to Jan.

As David pointed out, there have been several Gen 1 and 2 gearbox failures over the years. They have shown generally good reliability on the atmo EJ25s to date. The Gen 3 is designed to replace those earlier boxes on the higher hp engines and Jan is recommending people upgrade to the stronger box. Seems reasonable with the better pieces now available and he is giving a price break. I view this similarly to the Van's nose gear thing and many other parts upgrades Van's has introduced over the years.

$50K Gearboxes fail on helicopters sometimes and I know that almost every brand of PSRU on the market has had issues or failures. We learn, we improve.

I gave up a month ago posting anything more on the auto vs. Lycoming debates as they are truly never ending and few people seem to care about what I say as someone who has some experience in the field. I can accept that. Let's just fly what interests us.

John, as I look back on your posts on various forums, clearly many of your posts seem directed in anger at Jan's business. You can have any opinion you want about anything you want of course. If this is your crusade so be it I guess.

Jan has made mistakes just as many of us have including Van's, Lycoming, Hartzell, MT, P-mag, IVO etc. The list is endless. Welcome to the human race. I think Jan is trying to make his products better and address known problem areas- nobody will be in business long otherwise. I don't think customers of earlier drives are happy about the new recommendations any more than any of us are when we have to spend money to upgrade something on our aircraft. You don't have to with experimentals of course.

I defend people like Jan because I come from the same field, not because I'm a supplier. To those who design, create, learn and fly their dreams, kudos. To those who hack at them, you'll garner little respect from me. It is so easy to criticize, much harder to do something that few others are doing. If you have a better way of doing something on your RV, share the knowledge here on VAF so that we all may benefit. I know I've learned a lot here.

Jan gives people a second powerplant choice for RVs, warts and all. While you may never buy one, hundreds of others have and like them. Dozens who have bought, don't like them just like many other products available to us. We are all adults here and have to cope with our decisions.

As long as we fly experimental, single engined aircraft there is some risk due to the relatively unproven systems many of us use and there are clearly still risks even using more proven assemblies as we have seen many times as well. The only way to ensure we won't be killed or injured flying is to never fly. I doubt if many of us including Dan would find that an acceptable solution.
 
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My hats off to you guys.

You give the true meaning to Experiment... al aircraft.

As well as a true test pilot.

same goes for those that want the full glass panel.
 
gmcjetpilot said:
ha ha ha ha ha ha :D
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George,

I am sure you love your dog but could you find a more flattering picture of it. He/she looks like he/she is spring loaded to bite. Is that item in its mouth a piece of someone's leg or what? :) I suppose it could be a ball.
 
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Ross, thank you for saying what I was having trouble figuring out how to say. (Does that make sense??)
When I made the decision to use an Eggenfellner engine on my RV6, it was after doing a lot of research and talking to people who had been using his engines. Yes, I do know that he is always improving the engine system as things are learned, and that upgrades will always be an ongoing thing. I would be worried if he suddenly stopped trying to improve the product. There are people who are uncomfortable with auto based conversions and would much rather stick to Lycomings. THERE IS NOTHING WRONG WITH THAT! A Lycoming is a fantastic engine and I wouldn't hesitate to use one on a plane. There is also nothing wrong with someone who would like to be a bit "outside the box" and try something different. I happen to be very comfortable with that.
I also take a certain offense to those who would try to criticize Jan's business practices. It's true that he is not a perfect person and has made mistakes and has had some missteps, but after dealing with him for several years I would not hesitate to buy another engine from him in the future. Personally, I think his biggest "flaw" is being a little over-enthusiastic about publicizing new ideas a little early, but at least he's not trying to hide what he's up to!
OK, I'll step down off of the soapbox now :)
 
rv6ejguy said:
I gave up a month ago posting anything more on the auto vs. Lycoming debates as they are truly never ending and few people seem to care about what I say as someone who has some experience in the field.
Click to expand...

Some of us are very interested in what you have to say. First hand experience is what it's all about. This forum is an amazing resource, but the first thing I had to learn was to sift out speculation from actual experience.

It's quite obvious that some of the posts on this topic have a hidden (not so much) agenda. There is no doubt whatsoever in my mind that a Subaru can be adapted to be just as safe as a traditional engine, but I'm not sure we're quite there yet. I hope the guys at the leading edge of this hobby keep pushing.
 
David-aviator said:
George,

I am sure you love your dog but could you find a more flattering picture of it. He/she looks like he/she is spring loaded to bite. Is that item in its mouth a piece of someone's leg or what? :) I suppose it could be a ball.
Click to expand...

That's a dog?! I thought it was a lab rat being electrocuted. :D
 
I think the Sube guys are lucky to have Jan. Jason Day who built my engine, PSRU and prop, didn't do any testing that I can tell. Luckily, there is another customer of his who is the Australian version of Ross doing the engine testing. David, "Australian Ross", almost destroyed his engine using the controller Jason sent out. I didn't run my engine that hard so it was saved. David was able to tell Tracy Crooks, the maker of the controller, how to reprogram it to run the LS2 correctly. Jason also did not do enough, if any, real testing of the PSRU's and props. His customers are the ones testing and finding the problems. The good thing though is Jason is coming up with some of the fixes and correcting them. I had to pay for the controller to be reprogrammed. It was only $82. I am just amazed that people can put stuff to market without thorough testing! I have to send my prop and PSRU back to Jason for some corrections. I am going to Jason's shop with the prop and PSRU to make sure it gets done in a timely and correct fashion. No more trusting of salespeople/manufacturers claims or statements!
 
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rodrv6 said:
Ross, thank you for saying what I was having trouble figuring out how to say. (Does that make sense??)
When I made the decision to use an Eggenfellner engine on my RV6, it was after doing a lot of research and talking to people who had been using his engines. Yes, I do know that he is always improving the engine system as things are learned, and that upgrades will always be an ongoing thing. I would be worried if he suddenly stopped trying to improve the product. There are people who are uncomfortable with auto based conversions and would much rather stick to Lycomings. THERE IS NOTHING WRONG WITH THAT! A Lycoming is a fantastic engine and I wouldn't hesitate to use one on a plane. There is also nothing wrong with someone who would like to be a bit "outside the box" and try something different. I happen to be very comfortable with that.
I also take a certain offense to those who would try to criticize Jan's business practices. It's true that he is not a perfect person and has made mistakes and has had some missteps, but after dealing with him for several years I would not hesitate to buy another engine from him in the future. Personally, I think his biggest "flaw" is being a little over-enthusiastic about publicizing new ideas a little early, but at least he's not trying to hide what he's up to!
OK, I'll step down off of the soapbox now :)
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I agree with all your points here. That's pretty much how I see this topic as well. I do like to see posts from actual customers here, (yes good or bad).
 
TSwezey said:
I think the Sube guys are lucky to have Jan. Jason Day who built my engine, PSRU and prop, didn't do any testing that I can tell. Luckily, there is another customer of his who is the Australian version of Ross doing the engine testing. David, "Australian Ross", almost destroyed his engine using the controller Jason sent out. I didn't run my engine that hard so it was saved. David was able to tell Tracy Crooks, the maker of the controller, how to reprogram it to run the LS2 correctly. Jason also did not do enough, if any, real testing of the PSRU's and props. His customers are the ones testing and finding the problems. The good thing though is Jason is coming up with some of the fixes and correcting them. I had to pay for the controller to be reprogrammed. It was only $82. I am just amazed that people can put stuff to market without thorough testing! I have to send my prop and PSRU back to Jason for some corrections. I am going to Jason's shop with the prop and PSRU to make sure it gets done in a timely and correct fashion. No more trusting of salespeople/manufacturers claims or statements!
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Todd, this is the reality of new engines, gearboxes, ECUs and props. I considered Jason's props for my RV but as they were essentially unproven, I bit the bullet and wrote the check for an MT instead. I'll find out if that was a good choice or not! Todd's advice should be remembered- if the products have not been flight tested, beware and even if they have, be aware that a few hundred hours may not mean much either. In many instances, you are taking a bigger chance for problems putting an auto conversion on your aircraft in my view.
 
Come on Ross

Ross,

My concerns about the Egg engine are not personal in regards to Jan. I have written here many times about other products which I feel are not worthy of installation on our aircraft, with equal fervor.

You mention in one of your posts that you decided against Jason's prop in favor of a tested and proven MT, so I know that you understand the concept of conservative judgement. Listening to Todd Sweeny's recent posts, he too seems to be grasping the seriousness of pairing of an untested airplane, prop,engine and pilot (Think Dan Loyd).

You have been in this business long enough to know that the Feds will spend precious little time investigating the cause of the Loyd accident, due to it's experimental certification. I feel fairly certain that the unfortunate two day 40 hr flyoff on Dan Loyd's RV-10 won't be investigated either, because the Feds just don't have the manning. Our time would be better spent educating our fellow pilots about the dangers they are facing with this equipment, rather than waiting for the FAA.

The pilot of the RV-8 Gen2 failure stated that the GB squealed for three minutes, the teeth stripped off the reduction gear, the engine decoupled and raced. That means I am not speculating, I am stating first-person fact.
 
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By all means keep us informed of problems with products but it is more helpful and factual when information comes from first hand experience.

I'd encourage any Egg users to report here what your experiences have been, good or bad. I always appreciate David's well tempered posts on the subject. It seems like he is telling it like it is. The weight, speed, fuel burn and issues do mirror what many people have reported to me.

Most people I know of in the Eggenfellner circle know there have been drive failures. I'm certainly not denying them but Gen 1 and 2 failures have nothing to do with the engine management systems we sell today. If the Gen 3s start exploding in large numbers, we may sell less EMS units to Jan, true, won't be a big deal to us.

The facts don't support any conclusion that there were serious, widespread failures of Gen 1 or 2 boxes on the original atmo EJ25s of which several hundred were sold. It is no secret that these early boxes will probably not last a long time with an EZ30 or supercharged EJ behind them. Jan is publicly stating this! No conspiracy-again. You conveniently ignore David's post about high time units. This is the rule rather than the exception.

This is not being kept secret. Has been discussed on the forums for a 2-3 months or longer. Anyway the Gen 1 and 2 are no longer being sold.

So, this is like the top rudder hinge doubler Van's sent me to install on my RV10 after discovering cracks there on their prototype- I de-rivet the fin and install- not happy in one way but happy in another way that it is better now and may not cause me problems in the future after the plane is painted. We improve and move on.
 
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This is "Experimental Aviation"

I am the guy who had the gearbox failure. Did I like the Gearbox failure no. Did I know this was an experimental airplane and an experimental engine yes.

This is how me make advances in our hobby, you make some mistakes, you learn, you hopefully get better. If I wanted to fly a more stable, more reliable, less expensive airplane, I would still have my Piper.

I cannot speak highly enough of Jan's support with my gearbox failure. Within days, I had all the spare parts at my house to help me ferry my plane back home. I have called him numerous times on weekends with questions and I get answers. That type of support is very important to me, and speaks to the strong support Jan gives his customers.

I went flying in my Egg RV8 today in Atlanta (beautiful day) and God willining I will be flying more tomorrow morning. (Yes, I will probablly take the cowling off and tinker with something....it's "Experimental Aviation")

Kahuna, I saw your takoff this morning at KLZU, Awesome!! That climb angle looks like 60 degrees from the ground, guess that is why they call it a super-8

Fly safe

Steve
 
Yukon said:
Ross,


In the past 18 months, according to the NTSB, at least 54 RV's have fallen - most of them powered by Lycoming or a clone. How come when you go fishing the hook is baited only for Subaru?

I am not minimizing the problems we have experienced but your messages on the subject are so biased they lack credibility. By omission, you project an image that Lycoming accidents are OK and not worthy of discussion. Of the 54 RV events, there were a number of body bags with Lycoming stamped on them, not Subaru. How come you start threads on Subaru problems so quick but are so slow on Lycoming? Seems to me I read about a huge crank shaft recall recently but no comment from Arizona on that issue.

The start message of this thread had no new news. Most pilots tuned into alternative engines, Subaru in particular, were aware of the PSRU issues before your copy and paste post. It was clearly a fishing expedition and as usual a few of us rose to the bait. This is a lose-lose discusion. Nothing ever is settled. We need solutions to problems not more flush it down the drain thinking - run up the flag and everyone go with Lycoming - man I get tired of that line. Lycomings are OK but that is not an exclusive situation. There's more to life than one brand of beer.
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Statistics, please?

As a newbie on this site, I really appreciate the knowledge and facts and experience that is evident here. OTOH, sometime some emotionalism creeps in.

Has anyone done any kind of proper statistical analysis of crash causes, with respect to engines?

In RV's,

1. How many are powered by Lyc/clones? What percentage of them have crashed due to mechanical engine failure? How many engine failures total, including those ending in a safe/non-damage landing?

2. How many are powered by Subaru variants? What percentage of them have crashed due to mechanical engine failure? How many engine failures total, including those ending in a safe/non-damage landing?

How about a little more science, and a little less heat?

:(Sorry about the rant........ :eek:
 
I like my Lyc.

Alt engine guys do the following:

-Work on increasing power plants to provide alternatives

-Keep the price of Lycs somewhat in check by creating the threat of competition.

-Are will to take financial and personal risk I am not willing to take to provide information to the community.

With sincere respect my hat is off to the alt engine guys. You do a service for the Lyc guys. I don't see how the favor is returned so, THANK YOU.
 
asav8tor said:
I like my Lyc.

Alt engine guys do the following:

-Work on increasing power plants to provide alternatives

-Keep the price of Lycs somewhat in check by creating the threat of competition.

-Are will to take financial and personal risk I am not willing to take to provide information to the community.

With sincere respect my hat is off to the alt engine guys. You do a service for the Lyc guys. I don't see how the favor is returned so, THANK YOU.
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Amen! In the past I have flown behind Small block Oldsmobile and Chevy engines for hundreds of hours back and forth across the US and I have had failures.

I think it is important to leverage the "experiment" by looking beyond the venerable Lycomings if that is the reason - research and developement. If someone is strapping on an alternative engine with little to no expertise to save a buck, that is a recipe for disaster unless the engine is extremely proven - IMHO (and no I can't quantify "proven").

I worked for a kit manufacturer that used automotive engines as a basis for it's design (FEW 2/3 P-51D) back in the early 90s as their test and demo pilot (not engineering test - someone else did the 1st flights and spins). I had a full time crew chief that was intimately familiar and maintained the aircraft so I am NOT claiming to be any kind of alternate engine expert, more of an end-user with some seat time.

I wish the manufacturers and airplane builders who use these systems all the best.
 
I have deleted 2 posts and edited several others.

Please do not sling mud at each other or vendors.
 
PCHunt said:
As a newbie on this site, I really appreciate the knowledge and facts and experience that is evident here. OTOH, sometime some emotionalism creeps in.

Has anyone done any kind of proper statistical analysis of crash causes, with respect to engines?

In RV's,

1. How many are powered by Lyc/clones? What percentage of them have crashed due to mechanical engine failure? How many engine failures total, including those ending in a safe/non-damage landing?

2. How many are powered by Subaru variants? What percentage of them have crashed due to mechanical engine failure? How many engine failures total, including those ending in a safe/non-damage landing?

How about a little more science, and a little less heat?

:(Sorry about the rant........ :eek:
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Your point is very well taken.
Dave Dormier stated 54 RV accidents in last 18 months.
Percentage wise of the almost 5500 RV's flying. That is a very small percentage. How many were engine related?

How many RV Subies are flying and have had engine related accidents?
Don't get me wrong here, I almost went with the Sub setup and even had a demo ride ride with Jan. I made the decision to go with Superior as it was still too experimental for me at the time.
 
It is very difficult to compile accurate stats from the NTSB reports due to lacking info and solid conclusions for engine stoppages but if anyone wants to try, it would be interesting.

Having been involved in this field for some time and meeting and talking to many others- yes a fair number who have flown auto engines have had a lot of issues. Some would not repeat the experience, others would.

I've never said that an auto engine with a PSRU is better than a Lyco, just another choice. There are many issues to address when using a PRSU and auto engine in aircraft.
 
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Yukon

I spent a good deal of time this morning editing your posts to some semblence of civilised communication and yet you continue with criticism of others.

You now have 2 infractions and I will now no longer edit your posts I will just delete them and continue to add infractions until either you are booted from the forum or the moderator buttons no longer show up on my computer. I would consider either option as not unpleasant.
 
N395V said:
Yukon

I spent a good deal of time this morning editing your posts to some semblence of civilised communication and yet you continue with criticism of others.

You now have 2 infractions and I will now no longer edit your posts I will just delete them and continue to add infractions until either you are booted from the forum or the moderator buttons no longer show up on my computer. I would consider either option as not unpleasant.
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The choice is yours Milt. However, shooting the messenger isn't going to make our members any safer.
 
One man's opinion

I've got an Eggenfellner engine (not yet flying) and I'm happy to read Yukon's posts. I don't agree with everything he writes, but I very often learn from his comments. Criticism of the Eggenfellner package has prompted me to ensure that my systems are as solid as possible.

The current rash of Gen2 gearbox failures has me very concerned. I have not yet flown, but I'm faced with buying a new gearbox for over $3000. I'm not happy about this. I'm planning to wait until the last moment before I purchase the new gearbox, since as far as I understand there have already been 2 revisions of the Gen3 gearbox. I suspect there will be more before I'm ready for it.

In any case, I'm all for rabble rousing!
 
rv8ch said:
I've got an Eggenfellner engine (not yet flying) and I'm happy to read Yukon's posts. I don't agree with everything he writes, but I very often learn from his comments.

In any case, I'm all for rabble rousing!
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I find it pretty amazing how the usefulness of information can be lost through the delivery.

Yukon does bring up good points, but sometimes his delivery overshadows the message to the point that I, for one, loose sight of the info he is presenting.

And then there was a post -----now deleted----that had no info, only a cheap shot at Ross.

I came very close to doing the same as Milt, but was not quite there----Milt must have a .01% lower tolerance level than I do.

Anyway, Yukon please continue to raise issues as you see fit, but please consider how you present them.

Thanks.
 
Spur gear PRSU

TSwezey said:
Can you tell us about them and what caused the failure?
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I left that out on purpose, but it was a PSRU failure on the ZZ3 Chevy 350. I don't recall the guy who built it - this was back in 1993. The prop shaft separated in steady-state cruise flight after about 150 hrs (including some acro). The helical gear box we had on the 300 Olds did great, but wasn't dealing with much power or a C/S prop (160-180 hp-IIRC).

The machining was farmed out and they machined the spines on the shaft to end abruptly without a decreasing depth and that caused a stress riser. The shaft was 2" diameter solid steel with a pencil size hole for the C/S prop. The prop wasn't hooked to the engine anymore but stayed on the airplane. I was effectively pushing a 6' foot umbrella through the air. The engine at time of separation went to red line like a governor failure. I throttled back and landed in an open field in North Texas (was on my way to Copperstate). The field was very rough so the airplane didn't fare well.

I ended up moving on as the company was starting to lose interest in this project (costs) and I was looking to build time.

Would I fly another high performance auto conversion - sure I would fly it, not own it. I am fairly handy, but I feel my level of expertise is inadequate, especially if I am loading up my family and flying in the weather at night, etc.

For clarification, I am not talking about a corvair or VW powered low and slow machine like a Pietenpol, I'm talking 200+ HP replacements for IO-360s and IO-540s.
 
The choice is yours.
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On this point you are 110% correct



However, shooting the messenger isn't going to make our members any safer.
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Which is why I didn't delete everythig. I might add, however, that taking cheap shots at Ross does nothing to enhance safety.
 
panhandler1956 said:
I left that out on purpose, but it was a PSRU failure on the ZZ3 Chevy 350. I don't recall the guy who built it - this was back in 1993. The prop shaft separated in steady-state cruise flight after about 150 hrs (including some acro). The helical gear box we had on the 300 Olds did great, but wasn't dealing with much power or a C/S prop (160-180 hp-IIRC).

The machining was farmed out and they machined the spines on the shaft to end abruptly without a decreasing depth and that caused a stress riser. The shaft was 2" diameter solid steel with a pencil size hole for the C/S prop. The prop wasn't hooked to the engine anymore but stayed on the airplane. I was effectively pushing a 6' foot umbrella through the air. The engine at time of separation went to red line like a governor failure. I throttled back and landed in an open field in North Texas (was on my way to Copperstate). The field was very rough so the airplane didn't fare well.

I ended up moving on as the company was starting to lose interest in this project (costs) and I was looking to build time.

Would I fly another high performance auto conversion - sure I would fly it, not own it. I am fairly handy, but I feel my level of expertise is inadequate, especially if I am loading up my family and flying in the weather at night, etc.

For clarification, I am not talking about a corvair or VW powered low and slow machine like a Pietenpol, I'm talking 200+ HP replacements for IO-360s and IO-540s.
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The fellow I crewed for at Reno this year in Sport Class used to own a Stewart Mustang with a V8 and PSRU. I think he had two drive failures and two forced landings. Not surprisingly, his view of PSRUs is not too positive. After seeing Darryl Greenameyer's PSRU problems across the hangar, he was glad to have a direct drive Conti up front.

I've seen many issues with redrives involve poor machining practices- misalignment of parts and sharp edges creating stress risers and other problems with poor or marginal design practices. These are best tackled by some one experienced in gearbox servicing or design with attention to those machining details which can make or break a good design.

In the auto racing world, small shafts and bearings coupled to flexible casings guarantee a short life. I look for everything to be massively oversized and that is why I like most parts of the Marcotte box. These did have a mod many years back to replace the pilot bushing with a ball bearing. As this was external to the box, it was an easy mod to do myself. No issues to date on the M-300 box that I'm aware of. http://www.sdsefi.com/air14.html
 
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rv6ejguy said:
The fellow I crewed for at Reno this year in Sport Class used to own a Stewart Mustang with a V8 and PSRU. I think he had two drive failures and two forced landings. Not surprisingly, his view of PSRUs is not too positive. After seeing Darryl Greenameyer' PSRU problems across the hangar, he was glad to have a direct drive Conti up front.

I've seen many issues with redrives involve poor machining practices- misalignment of parts and sharp edges creating stress risers and other problems with poor or marginal design practices. These are best tackled by some one experienced in gearbox servicing or design with attention to those machining details which can make or break a good design.

In the auto racing world, small shafts and bearings coupled to flexible casings guarantee a short life. I look for everything to be massively oversized and that is why I like most parts of the Marcotte box. These did have a mod many years back to replace the pilot bushing with a ball bearing. As this was external to the box, it was an easy mod to do myself. No issues to date on the M-300 box that I'm aware of.
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Ross,
Sounds like you have a good handle on what it takes and obviously some expertise so you should have good results. There is no doubt that this can and is done successfully. The diesels showing up on the name brand airplanes is especially encouraging for everyone, not just the alternate powerplant community. Best of luck with your airplanes and have fun!
 
The PSRU does not need to be a weak point. Very mature technology on turboprop aircraft. Nothing that money can't solve. Just dig deeper into the old billfold. :D
 
Weeee I'm glad

I'm glad I stayed out of this. When safety is involved everyone gets worked up. We all friends, no need get the blood pressure up, grab a beer or three.

>Originally Posted by panhandler1956
>Would I fly another high performance auto conversion -
>sure I would fly it, not own it. I am fairly handy, but I feel
>my level of expertise is inadequate, especially if I am loading
>up my family and flying in the weather at night, etc.

I am not trying to pick your words apart but they don't really make sense to me. "Sure I'd fly one, not own it." (PSRU) You feel your level of expertise is inadequate to fly behind a PSRU, especially with the family in weather and at night? What "expertise" and I'm not sure what family, weather and Sun position has to do with it. I don't think there should be two tiers or levels of safety to start with. You just don't trust PSRU's from experience, which is perfectly understandable and reasonable. Personally, if I felt a PSRU was not good enough to fly at night or with passengers, I would not fly it. I do fly a Lyc direct drive. No gear box has ever failed on a direct drive Lycoming. :rolleyes: Bottom line, you don't trust PSRU's from past experience.

As far as two tiers of safety, That's fine for racing, since you accept low level pylon racing is already very risky, somewhat like you accept it with an experimental PSRU's. For everyday flying, the safety level should be as high as possible solo or with passengers, in my opinion. Speaking of racing, remember the Pond Racer and Rick Brickert? :(

Personally I kind of like the belted power guys set-up on V6's from afar; I really do; no gears or oil and easy to inspect, BUT I'm such a boring predictable follower, therefore I'm using a Lycoming, like all sane intelligent people should. (HA, I'M KIDDING LIGHTEN UP FOLKS, A JOKE). :D

Mickey Coggins! Did you get your local engineering paper-work sorted out? Glad to hear from you! ha-ha, RON PAUL? He's my favorite nut. He makes too much sense to win.
 
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asav8tor said:
The PSRU does not need to be a weak point. Very mature technology on turboprop aircraft. Nothing that money can't solve. Just dig deeper into the old billfold. :D
Click to expand...

Agreed. I built and modded road racing gearboxes for many years. These were mostly Toyota T50 and W50 production boxes attached to some pretty powerful 4 cylinder turbo engines. The aluminum cased T50 boxes were designed for 100hp and were reliable to about 200. When you put 250+ through them, the bearings turned black and square and all the teeth came off 3rd gear in about 5 minutes. With the cast iron cased W50 and its bigger gears and shafts, 375+hp was no problem with a cooler. I ran the same box for 5 seasons and never touched a bearing or gear- brutalizing it with very fast shifts.

Modern manual longitudinal boxes are super reliable these days.

Aircraft PSRUs are relatively simple by comparison being only 1 speed affairs. Other than the gyroscopic loads which are easily handled by a large diameter shaft and twin tapered roller bearings, the box itself can be straightforward.

We do need to make sure that torsional vibration is not a factor so more flywheel weight and/or a good input damper is a must. I like the designs from Autoflight and EPI best.
 
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ok

gmcjetpilot said:
I'm glad I stayed out of this. When safety is involved everyone gets worked up. We all friends, no need get the blood pressure up, grab a beer or three.

>Originally Posted by panhandler1956
>Would I fly another high performance auto conversion -
>sure I would fly it, not own it. I am fairly handy, but I feel
>my level of expertise is inadequate, especially if I am loading
>up my family and flying in the weather at night, etc.

You'd fly one but not own one? You feel your level of expertise is inadequate to fly behind a PSRU, espcially with the faimly in weather and at night? I don't think there should be two tiers or levels of safety. Not sure what family, weather and Sun position has to do with it. You just don't trust them. Personally if I felt it's not good enough to fly with the family, at night or beyond glide of the airport, its not good enough for me to fly, ever. I'm just asking, what skill are you talking about? I assume maintence and not actually designing a gear box. Not sure how hard maintence is or factors into the current issues of PSRU reliability. Bottom line, you don't trust PSRU's from your past experience, at least on higher HP applications. As far as racing, remember the Pond Racer and Rick Brickert? :(
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George,
I guess I wasn't clear. If I am flying for hire (test pilot) or doing a favor for a friend, I would strap one of these on - no problem. My point is, it isn't my cup of tea for a "daily driver" and I don't want to "tinker" with it. I trust them to a point, and that point begins and ends with me in the airplane, not my family. This is my level of comfort and it's completely subjective and I won't fault anyone for "experimenting" with alternative powerplants. As mentioned before, it is good for all of us in most instances.
Respectfully,
 
Roger Roger, Clearance Clarance

panhandler1956 said:
George,
I guess I wasn't clear. If I am flying for hire (test pilot) or doing a favor for a friend, I would strap one of these on - no problem. My point is, it isn't my cup of tea for a "daily driver" and I don't want to "tinker" with it. I trust them to a point, and that point begins and ends with me in the airplane, not my family. This is my level of comfort and it's completely subjective and I won't fault anyone for "experimenting" with alternative power plants. As mentioned before, it is good for all of us in most instances. Respectfully,
Click to expand...
Roger that. That makes sense, thank you Sir.

asav8tor & Ross said:
The PSRU does not need to be a weak point. Very mature technology on turboprop aircraft.
Click to expand...

Ross: Turbines are smooth and don't pulse out mass "suck-squeeze-bang-blow" pounding harmonics, as you know & said. However gear boxes, even on turbines do fail and big old props go flying, into fuselages, wings and the other engine sometimes. It has happened. Not being mean or throwing stones but those super reliable turboprop gear boxes are often massive and heavy even with exotic steel, magnesium and titanium, or the reduction is integrated into the engines case. My point? I don't have one as usual :rolleyes: (At least I'm honest), but it does point out some differences from what turboprop guys have, verses the add-it-on approach used in our experimental community. To do it right the engine and gear box would be made together, as one unit. The airframe would be designed around that specific engine/gearbox. We kind of "adapt" and compromise with our configurations, to use existing engines in existing airframes.

In cars you can make the gear box long and robust because you have the envelope. Trans weight is not super critical for a car, but even Ferrari's put the gear box in the rear of their front-engined cars for balance. In our little planes you can't really do much (unless you ran a drive shaft and that's another nightmare). We have to make a very flat gear box, that goes on the front of the plane. Aerodynamics is an issue as well. There's no doubt gear boxes can be made to work, but its the limits we have to work with, which challenge us, especially with the R&D budget we or vendors have. The design envelope is small and unforgiving. When a cars trans dies you pull over to the curb.

proploss1nl5.jpg
 
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If you throw enough money at the problem you can solve it. I'm not talking about a couple hundred grand and some guy in a home machine shop. I'm talking big money. As much money as it takes money. Like Government project money. Will the solution be economically viable? Maybe. Maybe not.

The debate is this: Proven mature technology vs new unknown technology

Proven mature:

Lyc
Mags
100LL
Hartzel
2024-T3
Alodine
Zinc Chromate
etc

I'm not going put the other list up. We know what is on it. I don't want to get someone going.

When I have a choice I will pick from the proven mature list. I acknowledge the "proven mature" list would not exist if someone a long time ago did not blaze the trail. The only way we move forward is if someone steps up and puts their money / safety / airplane at a higher level of risk to try something new. Again I thank these individuals. They are willing to lay it all on the line so the rest of us can benefit if they are successful. Many of them have paid with their lives.
 
No Dyno on the Subbies?

I'm still trying to get my head around someone selling an engine for aircraft who doesn't dyno them? This makes no sense to me. I don't understand this on the buying or selling side. No insult intended.

Hans
 
nucleus said:
I'm still trying to get my head around someone selling an engine for aircraft who doesn't dyno them? This makes no sense to me. I don't understand this on the buying or selling side. No insult intended.

Hans
Click to expand...

Not wanting to start a war, my bet is they have been dynoed, who wound't? But my gut tells me the results just wen't what they expected:eek:.
 
PCHunt said:
How about a little more science, and a little less heat?
Click to expand...

Several years ago at Sun 'n' Fun I was trying to get a little more information on the Egg conversion for my RV4, I own a Turbocharged Subaru Wagon and like the thought of having a "hi-tech" engine.

But when I asked Jan what his background was with engines, he stated rather sarcastically that he got his experience from working on his Volkswagen. I wasn't sure how to receive the response (funny?), and couldn't get anymore information about his qualifications as an engine builder. I wrote off the Egg conversion after that.
 
Yeah, I already mentioned that turbine gearboxes occasionally fail and in fact turbine engines do as well and more often than some manufacturers let on.

Integral engine/ gearbox designs like the Rotax 912/914 are going to cost what a Rotax does as these involve clean sheet designs. The whole point of auto conversions is the cheap, proven engine core. Of course this is sometimes offset by either an expensive PSRU (way more than that cheap engine) or a crummy, cheap PSRU which blows up, kind of defeating the whole idea- reliability is job 1.

A PSRU is WAY simpler than a 5 speed car transmission though. I've seen and worked on plenty of both. Obviously (to me anyway) bad design and machining are the primary causes of failure with TV coming a close third. Lack of testing, especially with TV seals the fate of many designs. You don't need millions to design a good PSRU. Give me about $40K to deliver a de-bugged sample (if I had time), fully tested and with 1000 flight hours on it.. The real ones out there are $5500-$15,000 for 200-500hp engines.

Some other ones like the Marcotte and Autoflight are strong IMO but lack proper TV testing. This is very difficult as these are installed on different engine types. Jan's Gen 3 is very strong IMO but needs more flight time to be well proven. MT has just completed vibration studies on the Egg EZ30 and their prop. This makes me a lot happier.

The dyno thing has been bandied about before. NSI "dynoed" their engines but their figures were complete nonsense. Because they were "dynoed" however, sales took off. One engineer there argued with me about this for weeks then admitted that there were "some" problems with their data but kept pushing out fabulous stories of 200mph Glastars with NSIs up front. The gullible never bothered to pull out a calculator and run the data, money was already on the way. Never swallow the sales pitch and never be the first in line is my advice.

I couldn't care less how an airplane engine dynos, do a head to head flight test against a known quantity and see how it stacks up. Van's has an open invitation and I like their methodology. No chance for BS here.
 
Dyno? What the auto manufacture said

Traditionally from what I have seen in the past, HP claims where good faith estimates based on peak HP the automotive manufactures stated in the glossy brochure specs for cars with the same engine. Even some auto HP numbers are suspect, but that was how they did it.

One example is a popular vendor of a do-it-yourself line of Rotary engine components claims 180HP. OK that seems reasonable, but when he races in the sun-N-fun 100, he competed in the Red class or 160HP class? Humm, he does pretty good in the 160 HP class, but in the 180 hp class he would be last. To be fair, alternative engines have shown they can make THRUST (what you really want) equivalent to 180 HP engine or more. However Egg's early stuff that claimed 180HP performed more like 150 or 160 HP.

The problem with using an auto manufactures dyno number is they are based on peak RPM (and sometimes inflated). Many conversions do not run the engine at max or peak HP RPM. Another example is a vendor or PSRU's for LS1's, the new later Gen aluminum small block V8, 350 cu-in Chevy. The max HP is say 6,000 RPM for argument sakes. The PSRUs is geared to turn the prop at an acceptable RPM's with engine RPM's less than 3,000 RPM. The LS1 is rated at 300 HP max @ 6000 rpm. Do the math. You don't have a 300 HP engine at 3,000rpm, may be 200HP at best. The other contraversy is running an engine at max RPM 100% all the time. This is also subject to debate wars, but a Lyc is made to run at 2,700 RPM all day long. Most auto engines in my opinion will not be long lived if ran at high RPM's required to make peak HP all the time. To get max RPM at take-off and get low RPM in cruise would take more than one gear ratio.

The other issue besides RPM is efficiency, loss of HP going thorugh the gear box. Again debate has raged. It's not free to gear or belt down. How much loss? There're ball park numbers you can look up. Bottom line is you don't know until you Dyno the engine set-up in the installed configuration, that is everything, prop, gearbox, exhaust, induction and ignition.
 
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From Wikipedia...

.....on the old Cessna 175, geared Conti's.:

The GO-300 engine
An unusual feature of the 175 is the use of the geared Continental GO-300 engine. Whereas most single-engine airplanes use direct drive, this engine drives the propeller through a reducing gearbox, so that the engine runs at 3200 rpm to turn the propeller at 2400 rpm. The engine was esssentially an O-300 engine with a gearbox mounted on the drive end, and some internal modifications to provide durability at higher engine speeds. The GO-300 engine has a TBO (Time Between Overhaul) of only 1200 hours[1], which compared unfavorably with the ungeared version. The GO-300 engine also suffered reliability problems and helped the 175 develop a poor reputation. Many Skylarks flying today have been converted to larger-displacement direct-drive engines.

The reputation of the GO-300 may not have been deserved, since the problems associated with it were the result of pilots who were familiar with direct-drive engines simply not operating the engine correctly. Pilots unfamiliar with the engine often operated the engine at low RPM settings (2300) appropriate to direct-drive engines, while the 175's Operating Handbook called for 2900 RPM. This prevented the engine's air-cooling system from operating effectively and resulted in a lack of reliability...END.

There are many hours on geared Lyc 0-540's, P-51's and others. As I stated earlier, my PT-6 has over 8000 hours on the original gearbox, absorbing 1200-1300 pounds of torque daily, for 8000 hours and takeoff torque of up to 1600 ft. lbs. during 12-15 takeoffs a day. Gearboxes can definitely be made to live under high power settings. Have any of the smaller boxes on Eggs, 350 Chevies and rotaries been tested to the extent of the aforementioned boxes...? I doubt it. Simply because Lycoming and Pratt and Whitney throw enormous dollars and brains into testing and testing more...often to destruction. IMHO, the smaller vendors are cash-restricted so can't/don't do the full on testing and engineering that the big guys do.

Regards,
 
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