Boeing 737-524 accident near El Paso, Texas, January 16, 2006

The NTSB's narrative final · quoted from the NTSB record

The flight crew of the Boeing 737-524 discovered a puddle of fluid on the tarmac under the number 2 (right) engine during the prefight inspection of a scheduled passenger airline flight. Airline station personnel had received authorization to call contract maintenance to investigate the oil leak from one of the airline's senior maintenance controllers. As a result, three mechanics from a fixed base operator (FBO) at the airport were called by the airline station personnel. The FBO had previously entered into an agreement with the airline to provide contract maintenance at the airport. All of the airline's maintenance manuals were maintained at the airline's headquarters maintenance control base. According to the airline's procedures, extracts of those manuals with specific procedures were required to be transmitted prior to the contractor performing maintenance, and only after authorization by the airline's maintenance control. After becoming concerned about the delay in hearing back regarding the investigation into the engine leak, a senior maintenance controller for the airline attempted to contact airline station personnel, and the FBO, several times to determine what instructions and authorizations would be needed. The investigation revealed that the FBO did not make contact with the airline to obtain the requested maintenance approval and required documentation to work on the engine. Meanwhile, both sides of the engine fan cowl panels were opened by the mechanics to conduct the engine inspection and check for leaks. The mechanics made a request to the captain (via ground-to-cockpit intercom system) for an engine run to check for the leak source. One mechanic positioned himself on the inboard side of the right engine and the other mechanic on the outboard side of the engine. The third mechanic was positioned clear of the engine because he was assigned to observe the procedure as part of his on-the-job training. The engine was started and stabilized at idle RPM for approximately 3 minutes while the initial leak check was performed by the two journeymen mechanics that were working around the engine. One of these two mechanics then called the captain on the ground intercom system and reported that a small oil leak was detected, and he requested that the captain run the engine at 70 percent power for 2 minutes to conduct further checks. The captain complied with the request, after verifying with the mechanic that the area around the airplane was clear. Witnesses on the ground and in the airplane stated that they saw the mechanic on the outboard side of the engine stand up, step into the inlet hazard zone, and become ingested into the intake of the engine. This occurred about 90 seconds into the 70-percent-power engine run. The mechanic was not wearing any type of safety equipment or lanyard to prevent the ingestion. Upon sensing a buffet, the captain immediately retarded the power lever back to the idle position. The first officer stated to the captain that something went into the engine and the captain immediately cut off the start lever to stop the engine run. The mechanic who was fatally injured was hired by the FBO in November 1997, and had been a certified mechanic for 40 years. He received maintenance training from the airline regarding on-call maintenance procedures in March 2004, nearly two years prior to the accident. The airline provided training to contract maintenance stations in the form of classroom instruction, interactive computer based scenarios, and training videos. Specific training (either initial or recurrent) regarding ground engine runs and associated hazards was not provided to the contract mechanics by the airline. According to the surviving contract mechanic that worked around the engine with the fatally injured mechanic, maintenance instructions were not needed for the engine run because engine oil leaks were a common occurrence, and because of his past experience as a mechanic. Under the section entitled "Engine Run Rules - General" in the airline's general maintenance manual, the following procedure was cited: "Engines will not be operated above idle at terminal or gate positions for maintenance purposes, unless specifically authorized by the local airport authority." At the time of the accident, a letter of agreement, dated April 1996, was in effect between the airport's control tower and the airport operations office that restricted engine power to no more than idle RPM to one engine at a time for a maximum of 5-minutes "while on any parking or service apron areas, including the terminal ramp." Additionally, about 3 months prior to the accident, on October 19, 2005, the control tower reiterated this policy via a "Priority Briefing Item" cover memorandum that was addressed to "All Personnel" at the airport. However, the letter of agreement and priority memo had not been distributed to the airline's airport operations, the fixed based operator, or any of the tenants at the airport. Following the accident, the airline developed and implemented numerous safety enhancements, including revised procedures and training regarding ground engine runs.

The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.