Fairchild SA227-AC N619BA incident near Minneapolis, Minnesota

Probable cause

Loose electrical connections to the hydraulic system and anomalies in the hydraulic shuttle valve and power pack, which resulted in an uncommanded gear unlock and collapse of the left main landing gear. Contributing to the accident was the operator’s failure to comply with the life limits outlined by the hydraulic power pack’s manufacturer.

NTSB analysis

All three green landing gear indicator lights were illuminated before the pilot landed the airplane. About 50 to 100 feet beyond the touchdown point, the left main landing gear collapsed and the airplane exited the left side of runway. A postincident examination of the airplane found two loose electrical connections to the hydraulic system and several anomalies in the hydraulic shuttle valve and the hydraulic power pack. It is likely that the hydraulic issues allowed for a movement in the landing gear shuttle valve, which resulted in an uncommanded gear unlock and subsequent collapse of the left main landing gear. The hydraulic power pack's manufacturer had issued a service letter regarding life limits on the pack; however, the operator was not in compliance with these limits at the time of the accident.

Text from the NTSB. Open the NTSB docket for CEN13IA059 for the full record.