This story originally appeared on AirlineGeeks.com.
The National Transportation Safety Board said an improperly installed borescope plug led to a January engine fire on an Atlas Air Boeing 747. Maintenance on the aircraft was performed just four days before the incident.
On Jan. 18, Atlas Air flight 3885 was flying between Miami and San Juan, Puerto Rico, when the crew received a fire indication in the Boeing 747-8F’s No. 2 engine at approximately 3,000 feet. An emergency was declared and the aircraft returned to Miami with no injuries reported.
No signs of an uncontained engine failure were found, the NTSB’s final report noted, though minor burn damage was reported on the GEnx engine’s thrust reverser fan duct. The aircraft returned to service nine days later on Jan. 27.
According to the agency’s report, a third-party maintenance contractor was tasked with performing a borescope inspection on the No. 2 engine, requiring the removal of a plug. Both the mechanic and inspector certified that the inspection had been completed in line with maintenance manual standards.
The removed plug was found loose in the engine cowling, which resulted in the fire.