Investigation Summary
During preflight for Continental Airlines Flight 1515, the crew discovered an oil puddle under the number 2 engine. Three contract mechanics from Julie's Aircraft Services were called to investigate. Although Continental's General Maintenance Manual (GMM) required mechanics to obtain specific maintenance extracts and authorization from the airline's Maintenance Control before starting work, the contract crew proceeded based on their own experience. One mechanic later stated that maintenance instructions were not needed because engine oil leaks were a common occurrence and he relied on his past experience. They opened the engine cowlings and requested the captain perform an engine run. After an initial idle check, a mechanic requested 70 percent power for two minutes to further troubleshoot the leak. Despite the captain confirming the area was clear via intercom, one mechanic on the outboard side of the engine stood up and entered the suction hazard zone approximately 90 seconds into the high-power run. The engine suffered a compressor stall and buffet as the mechanic was ingested. The investigation highlighted that the airport had a policy prohibiting engine runs above idle at the terminal, but this policy had not been disseminated to tenants or the airline. Furthermore, the contract mechanics had not received specific training from the airline regarding the hazards of ground engine runs.
Final Conclusions
The National Transportation Safety Board determined the probable cause was the mechanic's failure to maintain proper clearance with the engine intake and the failure of contract maintenance personnel to follow written procedures in the airline's general maintenance manual. Contributing factors included insufficient training provided to contract mechanics by the airline and the airport's failure to disseminate a policy prohibiting high-power engine runs in the terminal area. The investigation was concluded with the Final Report published on January 31, 2008.
Video Analysis
No video analysis linked for this case file yet.
Airframe & Maintenance
Crew Experience
Captain
Held ATP and Flight Engineer certificates.
First Officer
Held ATP, Commercial, and Flight Instructor certificates.
Systems & Failure Modes
CFM56-3B1 Engine
The high-bypass turbofan engine creates significant suction at high power settings, creating an inlet hazard zone that can ingest personnel standing too close to the intake.
Ground Intercom System
The primary communication link between the mechanics on the tarmac and the flight crew in the cockpit during the maintenance engine run.
Interesting Facts
- 01The aircraft (MSN 27530/2686) was manufactured in 1994.
- 02The ingestion danger zone for the Boeing 737-500 extends in a 13-foot radius around the front of the engine.
- 03The fatally injured mechanic had 40 years of experience and had been with the contractor since 1997.
- 04Continental Airlines' maintenance manuals were kept at headquarters, and contractors were supposed to receive teletype extracts before performing work.
- 05A 1996 Letter of Agreement restricted engine power to idle only at terminal gate positions, but the airline and contractor were unaware of it.
- 06The mechanic who requested the run-up believed instructions were unnecessary due to his experience with common oil leaks.
- 07The mechanic was not wearing a safety lanyard, a tool recommended by Boeing but rarely used by airline mechanics due to escape concerns.
Safety Actions & Advisories
Revised Engine Run Procedures
Continental Airlines implemented new checklists and coordination requirements between Maintenance Control, System Operations, and flight crews prior to any engine run.
Enhanced Contractor Training
The airline developed a mandatory high-definition safety video and computer-based training specifically highlighting the hazards of running engines for all contract maintenance providers.
Safety Lanyard Procurement
The airline purchased 23 additional safety lanyards and reinforced procedures for their optional use during maintenance near operating engines.
Known Controversies & Unanswered Questions
Safety Lanyard Usage and Resistance
Reference ↗While Boeing recommended the use of safety lanyards to prevent ingestion, the NTSB investigation found that Continental mechanics almost never used them. Mechanics expressed significant safety concerns regarding the lanyards, specifically that they could hinder a quick release or escape during an emergency, leading to a cultural resistance against the equipment despite manufacturer recommendations.
Location
ACCIDENT SITE · Coordinates taken from the ntsb final report.