Swearingen SA227 N681TR accident near El Paso, Texas

Probable cause

Failure of the left main landing gear to fully extend due to a lack of hydraulic fluid and during emergency extension procedures, which resulted in the collapse of the landing gear during landing and the subsequent runway excursion and collision with a sign.

NTSB analysis

The captain noted that the purpose of the flight was second-in-command pilot training for the first officer and the observer, in turn. He reported that after takeoff, the landing gear retracted normally. The captain executed a practice instrument approach to a missed approach. When they attempted to retract the landing gear after initiating the missed approach, the left main gear in-transit light remained illuminated. The right main and nose landing gears retracted normally. Both hydraulic system low pressure warning lights subsequently illuminated. Efforts to troubleshoot using the emergency checklist and to extend the landing gear manually were not successful. The captain ultimately landed the airplane with the left main landing gear partially extended and subsequently lost directional control, which resulted in a runway excursion and impact with an airport sign. The airplane sustained damage to the outboard left wing, left main landing gear, and left propeller.

During a postaccident examination, hydraulic fluid was observed in the left main landing gear wheel well; no hydraulic fluid was observed in the reservoir sight gauge or on the dip stick. Hydraulic pressure was subsequently applied to the airplane, and no leaks were observed in the landing gear system. Thus, the source of the hydraulic fluid leak could not be determined. In addition, the reason that the landing gear failed to fully extend during the emergency extension procedure could not be determined because no preaccident anomalies were observed.

Text from the NTSB. Open the NTSB docket for CEN19LA246 for the full record.