Jabiru 3300 Prop strike

[buffmaintainer]

Hey guys,

I got a Jabiru 3300A hydraulic lifter version engine with 250 hours that suffered a low speed prop strike with a seinsenich composite wood prop. It happened in the dirt at idle, only taking about 4.5 inches off the tips. The airplane nosed over after the owner pulled the brakes and they were a little more effective than he thought. The spinner is the machined part from Aeroconversions and it was slightly scuffed so I know it didn't hit the concrete or nose over hard enough to damage anything. The engine mount and airframe is perfect, only damage was a slightly bent landing leg from when he skidded and the already weak tail wheel bracket which split.

Since then, I did a runout check and the flange was at 0.05mm and crank 0.03, which was right in spec with the manual. I also replaced the flange bolts and put in belleview washers, as well as replaced the flywheel bolts. I I replaced the caps, distributor, plugs, coils, and all the components that I felt could be replaced easily. I then borescoped the engine. I saw no abnormalities.

I'm getting mixed responses, as I'm hesitant to rebuild a 250 hour engine, and the manual is very vague on whether I can return it to service upon good checks. (Basically it says it's up to me). I noticed that Arion is selling two propstriked engines for around 8k. They told me a crank check with performed ADs would cost close to 10k with shipping, and a new engine is 18k... so I just dont know what to do. Anyone have any suggestions on how I should proceed?

[tx_swordguy]

Take this with a HUGE dose of I’m NOT an A&P ! If at idle when it went over the prop didn’t stop suddenly but continued at close to the speed it would if you turned the switches off, you should IMO be ok. If it went from idle to a solid stop the chances are much greater for a twisted crank. I had a full throttle strike on a Rotax 582 that shredded the blades and stopped very quickly. Although the motor turned by hand the reduction gear flange was bent pretty good and I assumed the crank was twisted up. If you decide to use it I would stay over the airport and put the engine through it’s paces ( wot to idle etc) After extensive ground testing! Again use that info at your own risk.
Mark

[Jgibson]

All major engine manufacturers have specific requirements for ANY prop strike. Lycoming recommends tear down for anything including a grass strike.
Continental recommends AT MINIMUM shaft keys and gear bolts among other things.
If it were me, I'd put a prop on it and run it on the ground (cooling it properly) for at least two hours.
I would THEN tear it down and have the crank magnafluxed. IF you were to magnaflux that crank now, a possible non-propagated crack wouldn't show up until that crank was further 'stressed'.
Crank run-out ONLY shows major damage bad enough to actually bend that crank but will NEVER show a possible crack at a later time.
I realize the cost is high to do this correctly, but that 10 thousand dollars or more won't buy much hospital time.
I only say these things because I lost two friends to this same thing. Hydraulic lock on a radial, no obvious damage, engine ran fine with no hint of any problem.
Until it didn't when the crank broke later.
It's just not worth the risk to either you or your passengers to NOT do this as thoroughly as possible.

Joe Gibson

[tx_swordguy]

I can’t say Joe’s advice is bad at all despite what I said earlier

[sonex1374]

Speaking with Pete and Ben Krotje (formerly owners of Jabiru USA) at their engine workshop, they seemed to believe that many of the engines that came in with bottom-end issues had prop strikes in their past. Ben told several stories about rebuilding engines where the owner "forgot" to mention a "mild" prop strike that happened sometime in the past, but everything dialed out OK. My take away from this was that mild prop strikes take time to develop into full engine failures. The engine may run just fine for a while, building confidence all the while the crank/bearings/rods/fastener screws/whatever are slowly marching towards failure. It's all fine until it isn't.

If it was my engine, I'd either tear it down and inspect/repair as needed, or sell the entire engine being as upfront and honest as I could about the condition and history of the engine. Price it right and someone will buy it. Disclose the history and they know what they're getting, while you have a clean conscious. Conceal any material facts and you're complicit in any damages that may follow. For my own peace of mind I would not fly it as-is and hope for the best.

Jeff

[frkatck@yahoo.com]

I had a crank break on my AeroVee powered Sonex while I was flying. I was able to land on a county road. Some people say my emergency precedure was excellent. I say the good Lord reached out and gently set me down! Do it right, take no chances. Time for a rebuild or new engine. I went back to flying my Cessna. I no longer fly Sonex aircraft. I would if it had a aircraft engine. It was a excellent airplane.
FW

[Jgibson]

Please don't think that because it's a certified engine that you are immune to issues.
ALL engines can fail at some point, especially if they've been subjected to abuse, misuse, or as in this case, a prop strike.
I was severely injured in 2000 in the crash of a 'certified' Continental engine that was rebuilt with nothing but the best parts and most care possible.
And ironically the cause was a carb failure that had been rebuilt and CERTIFIED by one of the most reputable carb repair shops in the country.
I'm certainly not a fan of ANY VW conversion (I'm a staunch Corvair advocate myself for an appropriate experimental including the Sonex) but that's just my personal belief. But not having a 'certified' engine is certainly not a reason to condemn or indict the Sonex, but merely a reason to do your homework and power a Sonex with a better choice and better track record.
Certified engines and certified planes are still built/rebuilt by human beings. Human beings ALL make mistakes and whether certified or experimental: either engines have risks.
JMHO

Joe Gibson

[gyroron]

Personally, I come from a back ground of flying 2 stroke ultralight airplanes, then gyroplanes that were powered by either 2 stroke engines or backyard converted auto engines.

I was taught to NEVER trust the engine. To expect the engine to flame out at any time.

And I did have a few flame outs. Had 2 Rotax 2 strokes quit on me ( both were on new builds I was test flying for the builders, so was in the pattern and had uneventful landings.... and one of those was not the fault of the engine, gas tank wasn't vented and built up a vacuum causing fuel starvation ) and had a few Subaru conversions quit, and a Yamaha four stroke sled engine quit ( during testing )

So actually I have always been shocked at how people that were introduced to flying through GA, and got their private rating first, how trusting they are of their engines. Flying at night ( where you can't see where to land ) and flying over large forests and or urban areas with no good places to set down in a emergency. I always flew, and still do for the most part, from field to field... always trying to keep a reasonably suitable place within gliding distance just in case.

I don't know how I would feel about that Jabiru. I feel that if the engine was actually and truly at idle, and it just broke the tips off the prop, and the engine never quit, or if it did quit it wasn't suddenly, and the crank is not bent.... I would probably fly it. But my guess is you bought it and that is the story you were told.... do you trust that the story is 100 percent truthful?

And maybe I am confusing you for someone else, but weren't you just given this plane? Basically you got a free airplane????? If so, then pony up some money, take the engine off the plane and have all the internal moving parts checked over, put the engine back together and you will be able to have a lot more confidence in it. Plus if you go to sell the thing down the road you will be able to get more money for it.

[builderflyer]

I see that builder Marty Smiltneek's Sonex N173CP was just listed and sold on Barnstormers. It only had 175 hours total time on airframe and 3300 engine and appeared to be a good buy. But I wonder if it's engine had ever been torn down after Marty's prop strike many years ago. Maybe the current owner and buyer are not even aware of this history. Just thinking out loud.

Art,,,,,,,,,,,,,,,,,,,Sonex taildragger #95,,,,,,,,,,,,,,,,,,Jabiru 3300 #261

[Jgibson]

To me, it's unconscionable to sell an engine that had a prop strike without making the buyer aware. We tend to think that aviation people are 'different' in that they are more honest and more inclined to do the right thing.
But sadly that's not the case any more.
At this time, I have a Corvair engine with less than 45 minutes flight time on it at WW's that had a prop incident. No sudden stoppage, but both blades 'scraped' on the front side when the plane was on it's broken nose gear. The seller was marketing it as 'probably okay to bolt on and go'. I bought it knowing it has to come apart and even if the crank checks out, I'll more than likely change it out.
IF I decide to sell it (because I haven't been able to find the right Sonex needing just a firewall forward) I will absolutely disclose the history of the engine. To me it's all about karma.
How could anyone live with themselves if someone was injured or worse because the sale was more important than integrity?

Joe Gibson