Maintenance error leads to oil starvation

The airline transport pilot was conducting a local flight and had been airborne for about 40 minutes when he heard a “bang.”

The engine then began to shake and experienced a total loss of power.

He conducted a forced landing near Kidron, Ohio, and the Bellanca 17-30 hit a stand of pine trees before coming to rest.

An onsite examination of the airplane found oil on the underside of the airframe and the back of the engine, with no oil showing on the dipstick.  Additionally, the nuts securing the engine vacuum pump appeared loose.

Disassembly of the engine found only a small amount of oil in the engine sump, as well as numerous metal pieces.

The crankshaft No. 5 rod journal exhibited heat damage, and the connecting rod had separated from the journal, consistent with the lack of oil lubrication.

A review of the engine’s maintenance records revealed that the engine had accumulated about 263 hours since overhaul. The records also indicated the vacuum pump was replaced and had accumulated 1.19 hours at the time of the accident.

The accident is consistent with the loss of engine oil from the vacuum pump drive, likely as a result of maintenance personnel improperly securing the vacuum pump following replacement.

Probable cause: Maintenance personnel’s failure to properly secure the vacuum pump, which resulted in a loss of engine oil and the subsequent total loss of engine power due to oil starvation.

NTSB Identification: CEN17LA081

This January 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.