American Airlines Flight 334
Fokker F-28 MK-100 · Accident while standing
From Dallas Fort Worth International Airport (DFW) to Nashville International Airport (BNA)
Event
- NTSB case
- FTW02LA088
- 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
- Accident
- 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
- Instrument Meteorological Cond
Fokker F-28 MK-100
- Aircraft type
- Fokker F-28
- 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
- N1425A
- Operator
- American Airlines
- Onboard fatalities
- Unknown
- Route
- From Dallas Fort Worth International Airport (DFW), Dallas, TXTo Nashville International Airport (BNA), Nashville, TN
- 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
- First occurrenceThe 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
- Miscellaneous/other
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- Substantial
Cause areas
- Auxiliary power unit › Overspeed
- Fluid, anti-ice additive › Ingested
- Turbine assembly, turbine wheel › Burst
Approximate · Coordinates from the NTSB case API, which marks them as estimated or does not say; no uncertainty radius is established.
NTSB narrative
The F-100 commercial passenger airplane experienced an uncontained rupture of the auxiliary power unit's (APU) turbine wheel while standing during de-icing procedures. Approximately ten minutes after de-icing began, the Captain reported that he heard and felt a "thud-like" noise from outside the aircraft. At the same time, the APU shutdown. One of the de-icing crewmembers on the ground stated he saw a flame come from the APU exhaust and had activated the ground APU fire bottle discharge switch. Examination of the APU revealed two large holes in the APU's compressor case in line with the turbine wheel's plane of rotation. The turbine wheel was broken into several pieces. A fragment of the turbine wheel was found embedded into a first aid kit that was mounted inside the cabin on the aft wall directly in front of the aft pressure bulkhead. Metallurgical examination of the fractured pieces of the turbine wheel were confirmed that the APU had experienced an overspeed. Further examination did not reveal evidence of fatigue on any of the fracture surfaces. The APU's electronic control unit (ECU) was removed from the engine to interrogate the ECU's non-volatile memory (NVM) and perform a diagnostic test. The NVM indicated that the APU had experienced an overspeed, which is a rotor speed of 107 percent or greater, and had commanded a shutdown. The diagnostic test showed that there were no discrepancies with the ECU. The Automated Surface Observing Station for DFW at 0700 reported winds from 320 degrees at 20 knots gusting to 27 knots. The members of the de-icing crew stated that at the time they were de-icing the airplane, the wind was blowing at 20 knots and gusting. Due to the windy conditions, the drivers of the de-icing trucks had coordinated prior to de-icing the airplane to start at opposite ends of the airplane so the bucket operators would not be spraying each other as they de-iced the airplane. According to company records, all 5 members of the de-icing crew were trained and experienced, and were aware not to spray de-ice fluid in the area of the F-100's APU inlet.
Probable cause
The ground crew inadvertent application of deicing fluid in the auxiliary power unit resulting in an overspeed and turbine wheel burst. A contributing factor was the gusty wind.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record FTW02LA088
- Event ID
- 20020319X00362
- Case number
- FTW02LA088
- Dataset
- historical-pre2008
- Source SHA-256
- 89e2df6d848e7ab3b42e7d7c7a03ff403303057a26ca04c95b3ea67201c3ce74
Source notes (5)
- 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: fcbc6911eb00a33710e3a3f192c609e52e7b3733d2bfa51399a9f68f0dbc8dda; retrieved 2026-09-18T16:05:05.742Z.
- The NTSB's operator name is blank for N1425A; the operator shown is the name the NTSB records it doing business as.