Incident Summary
A Fairchild aircraft executed a full-flap landing followed by flap retraction in preparation for a no-flap takeoff practice. During rotation on the subsequent takeoff, the aircraft veered left and cartwheeled off the runway. It came to rest 557 feet left of the runway centerline and 6,000 feet from the takeoff end.
Findings
Examination of the aircraft after the accident revealed an asymmetrical flap configuration. The right inboard and outboard flaps were fully extended. The left inboard flap was extended 17 degrees, while the left outboard flap was fully retracted. This asymmetry resulted from a foreign object jamming the flap gear box and a malfunction of the rotary flap actuator assembly. The investigation also identified inadequate maintenance and inspection practices, as well as an inadequate function of the asymmetrical flap warning indicator, which failed to alert the flight crew of the discrepancy.
Probable Cause
The official probable cause is an asymmetrical flap condition during takeoff caused by foreign object jamming of the flap gear box and malfunction of the rotary flap actuator assembly, combined with inadequate maintenance and inspection, and inadequate function of the asymmetrical flap warning indicator.