NTSB Identification: DFW06FA056
HISTORY OF FLIGHT
On January 16, 2006, at 0905 mountain standard time, (unless otherwise noted, all times in this report are mountain standard time based on a 24-hour clock) a Boeing 737-524, N32626, operated by Continental Airlines as flight 1515, was parked at the gate in preparation for departure from El Paso International Airport, El Paso, Texas, when a mechanic was fatally injured while performing maintenance on the right engine. The right engine was substantially damaged. The scheduled domestic passenger flight was operated under the provisions of Title 14 Code of Federal Regulations (CFR) Part 121, and an instrument flight rules flight plan was filed. Visual meteorological conditions prevailed, and the flight's intended destination was Houston, Texas. The airline transport rated captain, first officer, 3 flight attendants, and 114 passengers reported no injuries.
During the preflight inspection conducted by the first officer, a puddle of fluid was noticed on the tarmac under the right engine. Both the captain and the first officer re-inspected the puddle of fluid under the right engine and agreed that it appeared to be an oil leak. The captain notified Continental El Paso Operations via radio from the cockpit to request authorization for contract maintenance to check for problems on the right engine.
Continental El Paso Operations contacted Continental Headquarters Maintenance Control and received authorization for contract maintenance to respond to the aircraft based on the captain's report. Three mechanics from Julie's Aircraft Services, Inc., a fixed based operation at the airport, arrived at the airplane and began to investigate the source of the reported oil leak. Both sides of the right engine fan cowl panels were opened for inspection, and the mechanics requested that the captain conduct an engine run to check for the oil leak.
Witnesses on the ramp and in the airplane observed one mechanic position himself on the inboard side of the right engine and another mechanic position himself on the outboard side of the right engine. The third mechanic was positioned several feet clear of the engine during the accident sequence; this mechanic was assigned by the lead mechanic to observe the maintenance procedure as part of his on-the-job training.
At this point in the accident sequence, the airplane was completely boarded with all passengers and crew via an air stair truck (the jetway was inoperative), except for one passenger in a wheel chair who was being prepared to be boarded on a lift truck. (The accident occurred prior to this passenger boarding the airplane).
The engine was started and stabilized at idle RPM for approximately three minutes while the initial oil leak check was performed. One of the mechanics called the captain on the ground intercom system and reported that a small oil leak had been detected. The mechanic requested that the captain increase the engine power to 70 percent for three minutes. According to conversations recorded on the cockpit voice recorder (CVR) just prior to the accident, the captain asked the mechanic on the intercom: "clear back there?" and the mechanic replied "yeah, we're all clear." The captain then stated: " 'kay here goes."
Shortly after the engine power was increased, two witnesses on the ground (mechanics) and one witness in the airplane (passenger) observed the mechanic on the outboard side of the right engine stand up, step into the inlet hazard zone, and become ingested into the engine.
The captain stated that approximately one minute and 30 seconds after increasing the RPM to 70 percent, he sensed an engine buffet which increased in intensity, and this was followed by an engine compressor stall. The captain stated that he retarded the power lever back to the idle position. The first officer informed the captain that something went into the engine, and the captain immediately cut off the start lever.
The mechanic who was fatally injured, age 64, held a Federal Aviation Administration (FAA) airframe and power plant certificate, issued on July 13, 1966. In addition, the mechanic held a private pilot certificate with ratings for airplane single engine land, issued on July 6, 1962. The mechanic was hired by Julie's Aircraft Services in November 1997. According to Continental Airline training documents, the mechanic received line maintenance training from the Continental Airlines in on-call maintenance paperwork, policy, and procedures on March 2, 2004. The records also indicate that he received training regarding alternate fueling, auxiliary power unit operations, and contractor tow procedures for the B737, B757, and MD-80 series airplanes. He also received additional audiovisual training in extended operations (ETOPS) and CAT awareness. The documents did not indicate any specific training regarding ground engine runs.
The Boeing 737-524 transport category airplane (serial number 27530), was manufactured in 1995 and was powered by two CFM-56 series engines. According to the airport operations manual for Continental Airlines, the ingestion danger zone for this type configuration covers a 13-foot radius around the front of each engine and extends to 5-feet behind the front of each engine. The maintenance practices manual for Boeing Aircraft defines a similar area as the inlet hazard zone and encompasses a 9-foot radius around the front of each engine and extends to five feet behind the front of each engine on the inboard side and four feet behind the engine on the outboard side of the engine.
The 0851 surface weather observation at the El Paso International Airport reported wind from 110 degrees at 14 knots, gusting to 20 knots, visibility 10 miles, few clouds at 5,500 feet, scattered clouds at 12,000 feet, temperature 43 degrees F, dew point temperature 18 degrees F, and an altimeter setting of 29.92 inches of Mercury.
There was no communication between the flight crew and El Paso air traffic control during the engine run and maintenance check. Communication was established between the flight crew and the maintenance personnel on the ground via the airplane's ground intercom system.
At the time of the accident, a Letter of Agreement (LOA) was in effect between the El Paso Air Traffic Control Tower and the El Paso International Airport, with an effective date of April 16, 1996. The subject of the LOA was "Engine Run-up Procedures". A cover letter was attached to the LOA. The letter was dated October 19, 2005, and titled "Priority Briefing Item." These documents outlined engine run-up procedures while aircraft are parked at the gate. The LOA states: "Except for power-up associated with beginning taxi, engine power is restricted to idle RPM on one engine at a time for a maximum of five minutes while on any parking or service apron areas, including the terminal ramp."
Neither Continental Airlines El Paso Operations nor the contract maintenance company had a copy of this document on file. A survey of all tenant aviation units at the airport revealed that this directive had not been distributed by the El Paso International Airport.
The airplane was equipped with a Fairchild model A-100S, 30-minute, digital cockpit voice recorder (CVR), and a Honeywell Universal Flight Data Recorder (UFDR), Model 980-4100. The recorders were removed from the aircraft following the accident and shipped to the Vehicle Recorder Laboratories of the National Transportation Safety Board on January 18, 2006. The recorders arrived in working condition and data was recovered from both devices.
MEDICAL AND PATHOLOGICAL INFORMATION
The El Paso County Medical Examiner stated that neither an autopsy nor toxicological tests were possible due to the nature of the accident and the condition of the remains.
TESTS AND RESEARCH
Airline Maintenance Procedures.
Interviews with airline representatives, and review of airline procedures, indicate that contract maintenance is used frequently at airports where airline maintenance is not available. Once the ground services support agreement was signed by the contract maintenance station, the airline provided training that was conducted by classroom, interactive computer based scenarios, and training videos.
According to the airline's General Maintenance Manual (GMM) that was in effect at the time of the accident, Julies Aircraft Services was listed as an "approved contract agency" that had "entered into a contractual agreement to provide on-call maintenance resources."
All maintenance manuals were maintained at Continental Headquarters Maintenance Control, and extracts of those manuals were transmitted to the contractor when specific maintenance was to be performed. This procedure was developed by the airline to insure that the most current procedures were used, and to eliminate the need for several airport contractors to maintain publications libraries.
According to the airline GMM that was in effect at the time of the accident, under the section entitled "Approved Contract Maintenance Arrangements", the following instructions are cited: "The Pilot-in-Command or the station personnel must make contact with approved contract maintenance personnel, however, maintenance is not to be performed on the aircraft until Maintenance Control is contacted by telephone and has approved the action to be taken." The GMM also states: "The [airline] Maintenance Controller will send a teletype message authorizing the mechanic to perform the maintenance and execute the required maintenance release."
According to the senior maintenance controller at Continental Airlines Maintenance Control who was working the accident flight, he was contacted by the airline's El Paso operations that the captain noticed the oil leak. The controller stated that he advised El Paso operations to notify Julies Aircraft Services to "investigate the pilot report." The controller further stated: "Some time went by and I heard nothing back from [Julies] or [El Paso] operations. As departure time became near, I tried to contact operations to find out the outcome of the problem, and still could not reach anybody." The controller then attempted to call Julies directly several times. He stated that when he finally contacted them, the accident had already occurred.
The investigation revealed that Julies Aircraft Services did not make contact with Continental Airlines Maintenance Control to obtain the required maintenance approval and required documentation.
In an interview with the surviving mechanic who was assisting in the troubleshooting of the engine, the mechanic was asked how and why he conducted the engine run with no maintenance procedures from the airline. The mechanic responded that engine oil leaks were a common occurrence, and that he continued without the instructions because of his past experience.
There were no written procedures in place at the airport requiring the flight crew to contact either the Continental El Paso Operations or El Paso Airport Air Traffic Control prior to starting the engines.
Awareness of the Use of Lanyards.
The airline reported that interviews were conducted with aircraft mechanics at their main maintenance facility in Houston, Texas, to determine the use and awareness of the Boeing recommended safety lanyard while performing maintenance related functions in the vicinity of running engines. Nearly all of the mechanics indicated they never use lanyards and expressed concerns with quick release and escape during an emergency.
Post-Accident Airline Safety Efforts.
Following the accident, Continental Airlines developed the following safety enhancements:
-- An interface system requiring coordination and communication with the appropriate Maintenance Control Center by mechanics and the airline's System Operations Control Center by pilots prior to engine runs.
-- A series of checklists to coordinate communication and documentation between flight crew pilots, mechanics, and the System Operations Control Center prior to performing any required engine run.
-- Requirements and a maintenance training system to include an enhanced Contract Maintenance training syllabus utilizing Computer Based Training (CBT) technology.
-- An Enhanced Engine Safety Training Video to highlight the hazards of running engines. This video was made mandatory viewing for all maintenance providers.
-- Evaluation and audit checklists for contract and on-call maintenance providers. The checklists were included in the GMM.
-- Policies and procedures for Flight Operations in support of engine run procedures at non-maintenance stations.
-- The airline purchased an additional 23 safety lanyards following the accident and reinforced procedures for their optional use.