NTSB Identification: ENG11IA016
Scheduled 14 CFR Part 121: Air Carrier operation of DELTA AIR LINES INC (D.B.A. Delta Air Lines)
Incident occurred Wednesday, February 09, 2011 in Minneapolis, MN
Probable Cause Approval Date: 10/21/2013
Aircraft: BOEING 757-2Q8, registration: N704X
Injuries: 2 Uninjured.

NTSB investigators traveled in support of this investigation and used data obtained from various sources to prepare this aircraft incident report.

A Delta Air Lines Boeing 757-2Q8 airplane, N704X, experienced a tailpipe fire in the No.2 (right) engine, a Pratt & Whitney (P&W) PW2037, during engine start at the Minneapolis-St. Paul International Airport, Minneapolis, Minnesota. The main and aft inboard flaps and inboard flap track fairing on the right wing were blistered, charred, and delaminated, and the right main landing gear fairing was blistered. During engine start, the pilots stated that the No. 2 engine lit off immediately. The pilots stated that immediately after the engine lit off, they were distracted by a yellow glow on the right side of the airplane that grew in intensity; the captain initially thought it was an airport vehicle approaching the airplane. The pilots then heard a low frequency rumbling sound; and also heard people talking on the ground control frequency about an airplane on fire. The captain stated that when he looked back at the engine indications, the No. 2 engine fuel flow was 8,300 pounds per hour (pph); the normal is 1,000 pph. The captain then called for the engine to be shut down. The interrogation of the engine indicating and crew alerting system electronic propulsion control system page revealed several fault codes indicating that the fuel control unit (FCU) fuel metering valve (FMV) did not move to the position commanded by the electronic engine control. The disassembly of the FCU revealed corrosion on the FMV sleeve and slide. According to the FCU manufacturer, when the PW2037 engine is shut down, the FCU FMV is in the full open position. The airplane had been parked outside on the ramp in subzero temperatures for about 36 hours before the incident occurred. Naturally present water in the fuel nucleated on the corrosion on the FMV sleeve and slide, freezing it in position, which prevented it from during before engine start. The manufacturer also stated that at the time of the event, when the high pressure rotor speed was about 40 percent, the fuel flow with the FCU FMV in the full open position would be in the 8,000 pph range.

The National Transportation Safety Board determines the probable cause(s) of this incident to be:

the failure of the right engine's fuel control unit to operate correctly when the fuel metering valve became frozen in the full open position because of corrosion on the fuel metering valve slide and sleeve, which caused the engine to be overfueled during engine start and resulted in a tailpipe fire.

Full narrative available

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