Quicksilver Sprint II N3521A accident near Lebanon, Illinois

Probable cause

The total loss of engine power due to a fatigue failure of the crankshaft, attributed to the relative movement between the crankshaft and flywheel assembly.

NTSB analysis

The pilot reported that there were no anomalies during the before-takeoff engine run-up or when he applied power for takeoff. He stated that during the initial climb, about 35 feet above the ground, the engine suddenly lost power. The pilot reported that he reduced pitch in order to maintain airspeed but that the airplane impacted the ground in a nose-low attitude. The airplane immediately nosed over at impact, coming to rest inverted. A postaccident examination of the engine revealed that the crankshaft had fractured at the flywheel/crankshaft interface as a result of fatigue. The fracture originated from a single initiation point on the outer crankshaft surface that coincided with circumferential wear marks indicative of fretting. The observed wear marks matched those found on the flywheel and were likely the result of relative movement between the crankshaft and flywheel. The engine had accumulated 152.9 hours since new.

Text from the NTSB. Open the NTSB docket for CEN12LA309 for the full record.