The private pilot reported that, as he approached the airport in the Beech V35, he noted “a sudden and severe noise and vibration” and “a…stream of gray smoke from under the right side of the engine cowling,” followed by a loss of engine power.
He made a forced landing near Katy, Texas, and the airplane sustained substantial damage to the fuselage and right wing.
Post-accident engine examination revealed two holes in the top of the crankcase near the Nos. 3 and 4 cylinders. A teardown examination of the engine revealed that the No. 4 connecting rod had failed due to oil starvation, which resulted in a catastrophic engine failure.
Foreign debris, which was similar to a paper towel, was recovered from the engine oil sump and the oil pickup screen. Most of the screen area was obstructed by the debris, which had interrupted the oil flow from the sump to the engine.
The airplane maintenance records noted that the alternator and alternator drive gear were replaced about eight weeks before the accident. The engine had been operated about 24 hours since the alternator replacement. The starter and starter adapter were replaced the day before the accident flight.
The engine had been operated about 15 minutes since the most recent maintenance work was performed. It is likely that maintenance personnel left the paper towel in the engine during the recent maintenance work, which resulted in oil starvation, the failure of the connecting rod, and the catastrophic engine failure and subsequent total loss of engine power.
Probable cause: Maintenance personnel’s failure to remove a paper towel from the engine during recent maintenance, which resulted in oil starvation, the failure of a connecting rod, and a catastrophic engine failure and subsequent total loss of engine power.
NTSB Identification: CEN18LA276
This July 2018 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.
I think an owner should be able to test out and perform their own maintenance to the degree they wish. In 45 years I’ve yet to receive a plane back from maintenance without a problem, usually flight critical. Many owners are more experienced than the A&P/IAs they’re required to utilize.
By far the most risk in aviation is after an annual or after a repair. It is sad mechanics do not seem to take pride in being careful these days. Shops should consider taking videos of work done on planes and have a quality check of viewing those vids before releasing the aircraft.
The “most risk in aviation” is pilot error. Second is mechanical failure, with about 1/2 of that risk being mechanical failures from various causes, and about 1/2 from errors of omission or commission by maintenance personnel. I can’t blame an A&P for negligent owner/operator decisions to knowingly fly unairworthy aircraft. Multiple examples are easily found in the NTSB accident reports. For example, take offs with flap problems (resulting in subsequent split flap experiences), auto pilot malfunctions, failure to perform flight control checks after maintenance on controls, taking off without oil, structural failure resulting from deliberate departures from ‘normal’ flight, etc., etc., etc. — those are all owned by pilots and owners who blow off known problems, omit necessary pre-flight inspections, and knowingly attempt to fly outside of the approved operating envelope.
OK but in this case there is no way the owner/pilot could have known that a paper towel was left inside the engine. How could they?