Aero Commander 100 180 N3718X accident near Port Lavaca, Texas

Probable cause

Loss of engine power due to failure of a connecting rod.

NTSB analysis

The pilot had departed on a local flight. He reported that, about 15 minutes after takeoff and when the airplane was about 1,100 ft above ground level, he felt a vibration and heard a "bang." The engine subsequently began to lose power. The oil pressure dropped to zero, the pilot heard another "bang," and the propeller stopped turning. The pilot executed a forced landing to a pasture, which resulted in substantial damage to the airplane when the nose landing gear collapsed in soft ground.

An engine examination revealed that the No. 4 connecting rod had separated from the crankshaft. However, all fracture surfaces sustained secondary mechanical damage, which precluded further examination. The last engine overhaul was accomplished about 25 years before the accident. The engine manufacturer recommended engine overhauls every 12 years; however, the operator was not required to comply with that recommendation because the airplane was operated under Part 91. Given the available information, the reason for the connecting rod failure could not be determined.

Text from the NTSB. Open the NTSB docket for CEN16LA249 for the full record.