What happened
During a preflight inspection of a Boeing 737-524, the flight crew discovered a puddle of fluid under the number 2 (right) engine. Airline station personnel authorized contract maintenance from a fixed base operator (FBO) to investigate the oil leak. The mechanics opened the engine fan cowl panels and requested an engine run via the ground-to-cockpit intercom to identify the leak source.
After the engine was stabilized at idle for approximately three minutes, a mechanic reported a small oil leak and requested the captain increase power to 70 percent for two minutes. The captain complied after verifying the area around the aircraft was clear. Approximately 90 seconds into the high-power run, a mechanic positioned on the outboard side of the engine stood up, stepped into the inlet hazard zone, and was fatally injured by ingestion into the engine intake. The captain immediately retarded the power lever to idle and cut off the start lever upon sensing a buffet.
The investigation
The investigation found that the FBO had not contacted the airline to obtain required maintenance approvals or documentation for the engine work. While the airline's manual prohibited operating engines above idle at terminal positions without specific authorization, the mechanics proceeded with the high-power run based on their own judgment and experience.
Furthermore, although an agreement existed between the airport control tower and airport operations restricting engine power to idle RPM, this policy had not been distributed to the airline, the FBO, or other airport tenants. The investigation also noted that the mechanic was not wearing any safety equipment or a lanyard to prevent ingestion.