Delta Air Lines Flight 9931
Boeing 757-2Q8 · Incident: fire/smoke (non-impact) while standing
From Minneapolis–Saint Paul International Airport / Wold–Chamberlain Field (KMSP) to John F. Kennedy International Airport (KJFK)
Narrative check · The NTSB narrative appears to contradict this record's location. Values are shown as recorded, not corrected; compare with the narrative.
Event
- NTSB case
- ENG11IA016
- Event typeAccident: someone killed or seriously injured, or the aircraft substantially damaged (NTSB definition). Incident: an occurrence that affected or could have affected safety, short of that. Glossary
- Incident
- InvestigationHow far the investigation had got when the record was published: preliminary, ongoing, final or completed. Unknown where the source does not say. Glossary
- Completed
- API-reported fatalities
- 0 · all aircraft and ground
- Ground fatalities
- Unknown
- OperationWhat kind of flying it was, grouped by the rules it flew under: airline (US Part 121), air taxi and commuter (Part 135), general aviation (Part 91 and similar), military or government. Glossary
- Airline
- WeatherVisual meteorological conditions (VMC): good enough to fly by looking outside. Instrument conditions (IMC): cloud or low visibility, flying by instruments. Glossary
- Visual Meteorological Cond
Boeing 757-2Q8
- Aircraft type
- Boeing 757
- Category
- Airplane
- RegistrationThe aircraft's tail number, such as N12345 or G-ABCD. Registrations are reissued, so the same one years apart can be a different aircraft. Glossary
- N704X
- Operator
- Delta Air Lines
- Onboard fatalities
- Unknown
- Route
- From Minneapolis–Saint Paul International Airport / Wold–Chamberlain Field (KMSP), Minneapolis, MNTo John F. Kennedy International Airport (KJFK), Jamaica, NY
- Aircraft age
- Not recorded
- Flight rulesThe regulations the flight operated under: in the US, Part 91 (general aviation), Part 121 (airlines), Part 135 (air taxi and commuter) and others; for flights abroad, the NTSB's coarser commercial or non-commercial code. Glossary
- Part 121: Air Carrier
- Phase of flightThe stage of the flight when things started to go wrong: standing, taxi, takeoff, initial climb, en route, maneuvering, approach or landing. Glossary
- Standing · engine(s) start-up
- Defining eventThe single coded event the NTSB judges best describes what happened (records from 2008 on). Older records name the first occurrence in the sequence instead. Glossary
- Fire/smoke (non-impact)
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- Minor
Cause areas
- Aircraft › Aircraft power plant
Approximate · Coordinates from the NTSB case API, which marks them as estimated or does not say; no uncertainty radius is established.
NTSB narrative
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.
Probable cause
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.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record ENG11IA016
- Event ID
- 20110209X55126
- Case number
- ENG11IA016
- Dataset
- full-current
- Source SHA-256
- 5cf380f0061817c0331a6b2d8cc7e0ee3a79bea469a1001dc5c10e56f35f5ab3
Source notes (4)
- Unreviewed is an editorial label, not an investigation status. API-sourced is not report-checked or human-reviewed. Explicit event totals are used without summing aircraft injury tables; onboard allocation is withheld. Unknown values remain unknown. The operation category is mapped from the NTSB-reported FAR part and has not been reviewed.
- Filled from the NTSB case API where the bulk record had no value: investigation status, coordinates. Values present in the bulk record are kept.
- The date is the local date, which is the same as the UTC date the NTSB stores.
- API snapshot SHA-256: 67f4a8746bef9d5e81cc594448696527350565ce1c015523e68374c507cd4253; retrieved 2026-09-15T15:47:42.535Z.