Delta Air Lines Boeing 757 232 incident
Boeing 757 232 · Incident: powerplant system/component malfunction/failure during initial climb
From Harry Reid International Airport (LAS) to John F. Kennedy International Airport (JFK)
Event
- NTSB case
- ENG17IA036
- 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
- 0
- 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 757 232
- 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
- N686DA
- Operator
- Delta Air Lines
- Onboard fatalities
- Unknown
- Route
- From Harry Reid International Airport (LAS), Las Vegas, NVTo John F. Kennedy International Airport (JFK), New York, NY
- Aircraft age
- About 22 years (built 1995)
- 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
- Initial climb
- 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
- Powerplant system/component malfunction/failure
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- None
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
The No. 1 engine fire was caused by an improperly installed #7 fuel nozzle located at the 3 o'clock position of the engine. The nozzle installation error resulted in a fuel leak that subsequently ignited on hot engine case surfaces. All the fuel nozzles had been replaced as part of engine overhaul at the Delta Tech Ops facility 53.7 flight hours/18 cycles prior to the incident flight.
The cross threaded condition was evident during visual examination, and an x-ray of the fuel nozzle assembly confirmed the fuel nozzle b-nut was not properly seated, with one or fewer threads engaged. The nozzle assembly featured two o-rings and a conical seal washer (Voi-Shan) that acted in conjunction with the torque applied to the fuel nozzle b-nut to provide a seal. The o-rings and seal washer temporarily compensated for the cross threaded condition, until one of the o-rings began to break apart.
The cross threaded b-nut should have been visually detected by the mechanic and inspector. Although, if not visually detected, the cross threaded b-nut may have given a proper torque indication during the required torque check and passed the pneumatic leak check step of the installation procedures.
Several fuel system components including the fuel flow transmitter and stator vane actuator are located near the #7 fuel nozzle. The fire thermally damaged the case housings of both of these components resulting in secondary fuel leaks.
The damage to the nacelle components including the fan cowl, thrust reverser, and core cowls was due to fire exposure. The area of thermal insulation on the right thrust reverser half that was minimally discolored with a wet and shiny appearance was located radially outboard of the #7 fuel nozzle. The fuel spray from the nozzle provided localized cooling where the fuel contacted the insulation and was too rich to ignite, preserving the fire insulation.
The fan blade shroud shingling and displacement noted on three fan blades was most likely a result of firefighting efforts. After the blades were dislodged from the rub strip, the fan spun smoothly.
Probable cause
A No. 1 (left) engine undercowl fire caused by a fuel nozzle installation error during engine overhaul at Delta TechOps. A fuel nozzle b-nut was cross threaded, which allowed fuel to leak on hot engine case surfaces and subsequently ignite.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record ENG17IA036
- Event ID
- 20170907X71900
- Case number
- ENG17IA036
- 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, damage. 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: e951d441f7095e3144769a845409e1b1c05f55e50a92717caeb2d6c80c65022e; retrieved 2026-09-16T05:48:42.431Z.