A preliminary report by the US National Transportation Safety Board (NTSB) reveals that an Air Wisconsin CRJ200 that landed with its left main gear retracted at the Philadelphia International Airport the night of 14 December had undergone maintenance on the main gear system before the flight.
Flight 3918, flying for US Airways, carried only its flight crew due to several hours of delays in Norfolk, Virginia, its origin airport and one of three Air Wisconsin maintenance bases.
An Air Wisconsin spokeswoman had initially said the aircraft had indeed experienced a maintenance delay in Norfolk, but that it was "unrelated to the emergency landing" in Philadelphia.
"The post-incident investigation of the aircraft revealed that the upper attach bolt for the left main landing gear uplock assembly, which is designed to be attached to both the uplock mechanism and the structure, was attached to the airplane structure only," the NTSB explains.
Minor damage to the aircraft included "scuff marks" to the left wing tip and the outboard end of the left aileron. Investigators noted "more extensive damage" to the flaps on the left wing, which had been ground down from the flap trailing edge, through the upper and lower skins, to the ribs.
Air Wisconsin could not immediately be reached for additional comments on the NTSB's preliminary findings.