Cessna 182 N3889D accident near Arecibo, Puerto Rico

Probable cause

Maintenance personnel's failure to properly apply torque to the engine through bolts, which ultimately resulted in the crankshaft failure and the total loss of engine power.

NTSB analysis

The pilot stated that shortly after takeoff on the skydiving flight, the airplane's engine made a "clicking" sound and lost power. The pilot subsequently performed a forced landing to a field, during which the airplane flipped over and sustained substantial damage to the fuselage, right wing, and tail. Examination of the engine revealed the crankcase web mating surfaces at the Nos. 2, 3, and 4 bearing saddles exhibited pitting consistent with fretting, which was indicative of improper preloading (torque) of the through bolts. Additionally, the No. 2 main bearing was displaced from its saddle and severely worn, and the crankshaft fractured due to fatigue. A review of maintenance records revealed the engine's camshaft and lifters were replaced about 280 hours before the accident; this was the last documented time during which the applicable through bolts and associated nuts would have been assembled. Given this information, it is likely that maintenance personnel failed to properly apply torque to these through bolts during this maintenance, which ultimately resulted in the crankshaft failure and the subsequent loss of engine power.

Text from the NTSB. Open the NTSB docket for ERA18LA165 for the full record.