SonexBuilders.net

All,
Attached is a synopsis of my recent engine failure. The engine is toast. I hope someone finds this useful.

Regards,

Robert E. Barber
N157SX (Sexy Hexy)

Thanks for the write-up, Robert. That's a sad thing.

Bummer. Glad you and the aircraft are ok.

Aluminum granola - a new term in my vocabulary.

What an odd piston failure. Not like the old classic hole in the top.

Robert, thanks for your current report and the earlier one regarding the loss of the propeller. I appreciate you documenting your adventures with your early 3300 and of your ability to pilot your Sonex to a safe conclusion after each event. But I do hope your story is unique and not applicable to to all if us who fly early 3300s, especially as my engine enters the "danger zone" in terms of numbers of hours.

Thanks again,

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

Sorry to read about your Jab 3300 problems. I have been pulling wrenches on aircraft for almost 60 years and I have never seen a piston crumble like that one. I own or maintain a 3300 and a 2200 and have been deep inside of these puppies on my engines and helping others. I must say that the pictures do paint a scene of of massive piston failure most easily explained by some form of a piston fabrication flaw.

Holy c**p! sure glad you did very well getting back down! I have seen this kind of thing happen in race cars years ago, but not in aviation. I agree with your conclusions. Maybe its time to actually do x-ray imaging on cast, or billiteted pistons prior to installation to catch imperfections, considering that one cant just coast off to the side of the race track to safty. Heilocopter blades were done by x-rays when I was working in medical imaging years ago.So, whats next for an engine?

Gen 4 Jab 3300. I hope to not have to deal with so much rework and forced landings though.

I'm no aircraft mechanic; but in my 20's I wrenched on a variety of race cars (NASCAR, SSCA, ICSCC, etc). I've seen what happens when a valve drops into high-revving V8 cylinder, I've seen what happens when a crankshaft breaks... But I've never seen "piston granola" without severe damage to the head and/or valves! Off the top of my head, the only other thing I could even think of that might cause this would be some kind of detonation event at exactly TDC or BDC - so instead of creating motion you had a shock/pressure-wave that pushed the piston hard enough to break it at the wrist-pin (but not so hard that it overloaded the rod and broke the crankshaft)... But its insanely improbable that such an event would happen with the precise amount of force and precise timing to cause that failure and not blast the head away from the case, or show signs of excessive leaning on the plugs, etc.

Sorry to hear about your loss, but glad its measured in dollars and not blood!

--Noel
Sonex #1339

Robert,
Glad you are ok after such a catastrophic failure. When he made his pass it coughed toward the end of the pass and was obviously not running right. He pulled up and made a close left hand pattern with it coughing. as he turned final the blade completely stopped in the vertical position and he made a great landing especially considering the "oh shit" factor going on. Not that I have that much knowledge of engine failures but DAMN! I don't have the final-landing point on video (was kinda worried so quit video) but do have the pass on video and you can hear the coughing toward the end of the run. Hopefully the gen 4 will be as tough as you are lol.
Mark

Thanks Mark. I hope to see you soon.

Robert E Barber.