Introduction
An airline transport pilot was landing a turboprop airplane equipped with retractable landing gear on a 10,900-foot-long, 150-foot-wide paved runway. The landing occurred under clear conditions, but a sequence of events after touchdown led to a significant accident.
Accident Sequence
According to the pilot, during the approach to land, he selected 10 degrees of wing flaps and then moved the landing gear selector switch to the down position. This was followed by the illumination of three green lights, indicating that the landing gear was down, locked, and safe for landing. However, after touchdown during the initial landing roll, the landing gear retracted, causing the airplane to slide on the underside of the fuselage. The aircraft then veered to the right of the runway centerline, and the right wing struck numerous runway edge lights. A post-crash fire ensued when the right wing's fuel tank was breached.
Damage and Marks
The airplane sustained structural damage to the underside of the fuselage, and the right wing was destroyed. Propeller strike marks originated near the touchdown point and extended approximately 2,200 feet to the airplane's final resting position. The fire consumed the right wing and further damaged the aircraft.
Investigation
A postaccident inspection was conducted by the Investigator-in-Charge (IIC) and another NTSB air safety investigator. The inspection revealed no evidence of any preaccident mechanical malfunction of the landing gear assembly or its associated operating systems. The airplane was placed on jack stands, and hydraulic pressure was supplied to the system using a ground power unit. The landing gear retraction system was cycled numerous times, and no mechanical anomalies were noted.
Probable Cause
The National Transportation Safety Board determined the probable cause of this accident to be the pilot's failure to lower the airplane's landing gear during landing, which resulted in an inadvertent wheels-up landing. Despite the pilot's indication of having received landing gear down indications, no mechanical issues were found to explain the gear retraction.