The pilot was conducting the Cessna 206’s first flight since the engine had undergone maintenance several months earlier.
He reported that, after about 45 minutes of flight, he noticed that the exhaust gas temperature (EGT) had increased but that he was able to reduce the temperature by increasing the fuel flow.
Shortly after, the EGT again increased, and the pilot began to troubleshoot the issue.
The pilot noted that, after he turned the electric fuel boost pump on a second time, the engine ran normally for about two minutes and then lost power.
He determined that the airplane would be unable to reach the airport, so he initiated a forced landing to a road near Saint Ignatius, Montana. During the landing roll, the airplane struck vegetation and a fence.
During a post-accident examination of the airplane, blue fuel stains were observed on the top of the engine. The fuel line attached to the fuel flow transducer was found finger tight and leaking.
A review of the airplane’s maintenance records indicated that, during the maintenance conducted several months before the accident, three cylinders, including the No. 6 cylinder, had been removed and reinstalled. The fuel line attached to the fuel flow transducer was just above the No. 6 cylinder and, therefore, it would have been removed to access the cylinder during the maintenance.
It is likely that maintenance personnel did not adequately tighten the fuel line during its reinstallation, which led to the loss of fuel pressure and the subsequent loss of engine power.
Probable cause: Maintenance personnel’s failure to tighten a fuel line, which resulted in a loss of fuel pressure and a subsequent loss of engine power during cruise flight and an off-airport landing and collision with obstacles.
NTSB Identification: WPR15LA229
This August 2015 accident report is provided by the National Transportation Safety Board. Published as an educational tool, it is intended to help pilots learn from the misfortunes of others.
No engine run open cowl check after cylinder exchanges? I hope the costs were paid by the stupid mechanic !
This is something I pointed out to my A&P IA years ago – all these safety wires, cotter pins, lock nuts, lock washers all over my Mooney
But the fuel lines are as is. Oil lines too.
This is a primary reason at least a half hour of pattern flying be done after an annual or major maintenance.
As geebigs recommends I think this is a good idea. I recently got my 182 out of annual and after a complete nuts and bolt preflight, which I always perform anyway, my flight instructor and I remained in the pattern and did three full stop landings prior to heading off for some training. I also believe that it’s important to find a trusted and experience mechanic to do the annual each year rather than taking pot luck.
Before the 1st flight after maint., we always do a short ground run with the cowl off to check for any leaks. After that, we then check the security of everything we ‘touched’ .
Only then do we do 2-3 laps of the pattern, land and look under the cowl again…
Then we release the aircraft for flights away from the airport.
A half hour in the pattern or within gliding distance of the airport is a good idea, I do it myself (solo) after any maintenance. Unfortunately in this case the problem manifested itself after 45 minutes of flight time!
Very lucky pilot. An engine fire could have resulted from the finger tight fitting. Or a post crash fire. Kudos to the pilot.