This is an excerpt from a report made to the Aviation Safety Reporting System. The narrative is written by the pilot, rather than FAA or NTSB officials. To maintain anonymity, many details, such as aircraft model or airport, are often scrubbed from the reports.
I had a catastrophic engine failure taking off in the first flight since a major overhaul of my Continental IO520CB engine. I feathered my left engine, and continued the takeoff, entered right traffic, came around and landed back on the takeoff runway.
I suspect the mechanic/IA who performed the field overhaul failed to properly torque the piston rods to the crank shaft. I have not had the engine disassembled to confirm my theory.
Additionally, I feel the mechanic created this situation by not performing the overhaul in a timely manner. He would work for a few hours, leave the hangar and not get back to the job for days or weeks. This caused him to lose track as to where he was in the overhaul process, and consequently, miss a very important step.
The engine is not repairable, a total loss, but I made it back safely.
Primary Problem: Procedure
ACN: 1838421
Some people are really mechanical inclined and others will never be! The big question is how to know when you find a real mechanic!!
Mitch, I think the answer to your very valid point is to participate in owner assisted annuals. Not only do you learn the inner workings of your aircraft, but you learn about the quality of work being done on it. And no, I’m not an A&P myself, but have participated in the annuals on every aircraft I ever owned and a couple of birds I was only flying quite a bit.
If your mechanic won’t let you participate, then you’re using the wrong mechanic.
Factory remans fail, new and old components get recalls and ADs.
Not much the analyze without the exact failure.
A Rod let loose on a C172 I was flying, landed in a farmers field. Engine had 105 SMOH, found the mechanics during overhaul had failed to properly secure one of the rod bolts. It was from the same type of situation where work was stopped and restarted before completion of a specific task. Fortunately the overhaul company replaced the engine.
Curious as to why the owner suspects the cause was failure “torque the piston rods to the crank shafts”.
Let me guess. The pilot / owner looked for the cheapest ” overhaul ” and was surprised.
Cheapest is sometimes the best. Better to be able to judge who you’re dealing with.
I would be nice to pull a jug or two and check your suspensions. Not sure, but if that 520 engine has crank counterweights, one could have let go. Had that happen on a brand new C402 demo flight.
I like these little excerpts. There is always a lesson learned from experiences.
That is why I read these. And why I make some of the comments I do. We need to learn from these things just as the airlines have learned and why 121 has so few injury or death incidents/accidents.
I read NTSB reports critically (background includes non-aviation mechanic work, electro-mechincal items, etc). This is why I am sometimes quite critical of NTSB findings for GA reports. They just seem too often to be rubber stamp probable causes.