On November 13, 1992, a Mcdonnell Douglas DC-8-71 (registration N870SJ) operated by Southern Air Transport was involved in an aviation accident near Chicago, IL. Investigators recorded the probable cause as: AN IMPROPER REPAIR OF THE RETRACT PIN BOSS AREA BY THE OVERHAUL FACILITY. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive; 5 related events involving the same aircraft type or operator are linked below.
During climb, a DC-8 cargo aircraft experienced landing gear retraction issues; a metal object from the gear penetrated a home's roof. Investigation found a fractured retract pin with prior over-boring and chrome plating.
Incident
The crew of a McDonnell-Douglas DC-8 cargo airplane retracted the landing gear during climb to cruise altitude. They advised air traffic control that the landing gear had not retracted properly. While attempting to ensure the landing gear was in the down and locked position, the crew heard a loud bang. At the same time, a resident in a single-family home reported that a metal object had penetrated her home's roof and embedded itself in the floor. The airplane returned to land without further incident.
Investigation
An on-scene investigation revealed that the right main landing gear retract pin had separated from the landing gear leg. Portions of the gear leg retract pin boss area had also separated and were found wedged alongside the gear assembly. Subsequent metallurgical investigation indicated that the pin boss area exhibited metal fracture features consistent with overload, one of which was consistent with a preexisting fracture area. The pin boss area had previously been over-bored and chrome plated prior to a return to service. The airplane manufacturer stated that the pin boss bore should not be chrome plated.