The Piper PA-32R-301T was in cruise flight when the engine’s forward main seal — the crankshaft seal — began to leak engine oil.
Shortly thereafter, the engine lost power, and the pilot subsequently performed a forced landing to a field near Dalhart, Texas, about five miles west of the departure airport.
Post-accident examination of the engine revealed that the bottom half of the crankshaft seal had slipped forward from its placement, which allowed engine oil to leak from the engine. The seal had an approximate time in service of 21 hours since its replacement. It is likely that maintenance personnel installed an improperly sized crankshaft seal, which led to it slipping, allowing the engine oil to leak.
Probable cause: The failure of the engine’s front bearing seal due to maintenance personnel’s installation of an improperly sized crankshaft seal, which resulted in oil starvation and a forced landing.
NTSB Identification: CEN17LA226
This June 2017 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.
If it is the seal that I am thinking of it looks similar to a soft plug on your cars engine only this one goes down the center of your crankshaft behind the propeller. There could be a chance that the mechanic tried and re-used the old one instead of using a new one.
Per the docket, the A&P used the 0.050 in. oversize seal…
see the docket pics. https://dms.ntsb.gov/pubdms/search/document.cfm?docID=466103&docketID=61490&mkey=95364
The seal has some glue on it, but it looks like it was installed backwards .
Also, this engine has 6,000 hr on it, and no mention of an overhaul. Lycoming warns to maintain clearance from the oil slinger to the seal. The nose thrust bearing can wear and allow the slinger to contact the seal and push it out of it’s retaining grooves..!
Should get the mechanic’s input before passing judgement. Did an IA sign off?
Also, are we saying that no oil was visible underneath during the preflight, that it leaked all at once?
JimD,
An A&P would certainly have had to sign off on the repair. An IA has to sign off on the annual inspection.
It could have been leaking a little, but the docket photo shows most of the lower seal is blown out of it’s seat. I would have expected to see a retainer holding the seal in place. There is 60-80 psi oil pressure here….more if the oil is cold and the relief valve is set for a higher pressure.
Yes, all of the 8-12 qts of oil could be dumped overboard in a few minutes.
The docket photo of the aircraft shows the entire fuselage covered in oil.!
To some degree I can understand shoddy workmanship on the car, a boat, a snowblower. I just don’t understand how a mechanic can do anything but his absolute best to maintain a machine when a life depends on it. I am sure that rather than get the correct part from the dealer he decided to use one that he thought would do the job that he had on hand. I hope he sleeps well at night. Some day this mechanic is going to kill someone. He needs to forfeit his certificate.
I would not call this incident to have been caused by a ‘leak’. With the front seal blown out, the oil pump will pump all the oil overboard in minutes, since the main oil gallery runs to the front of the engine where the pressure relief valve is.
It’s interesting that it took 22 hours of operation to blow the seal out.
The failure occurred 9 minutes after takeoff, so I might expect that the oil pressure was very high with cold oil and a cold engine …
I always run my engine, in the run up area, until I see the oil temp come off the peg, so I know that the oil temp is 90 degF. It usually takes only 5 minutes at 1,500 rpm.[ in California ]
So, is the mechanic responsible to replace the engine and repair the aircraft ?