Air Tractor Inc AT-301 N4345S accident near Nekoosa, Wisconsin

Probable cause

A total loss of engine power during initial climb for undetermined reasons.

NTSB analysis

The pilot reported that the engine backfired and lost power during the initial climb after takeoff. The airplane sustained substantial damage to the fuselage and wings during the forced landing. An engine teardown examination revealed a separation of three gear teeth on an intermediate gear located in the accessory section. The gear teeth exhibited signatures of overload failure; no evidence of fatigue failure was observed. Accordingly, separation of the gear teeth likely occurred during the forced landing and not as a result of a preimpact failure. No failures or malfunctions consistent with a preimpact loss of engine power were observed. At the time of the accident, carburetor icing was not probable when the airplane was under takeoff power.

Text from the NTSB. Open the NTSB docket for CEN11FA562 for the full record.