Bellanca 17 30 N39819 accident near Kidron, Ohio

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 analysis

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. The pilot conducted a forced landing, and the airplane impacted 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.

Text from the NTSB. Open the NTSB docket for CEN17LA081 for the full record.