FTW85FA188 · Bell UH-1B
Bell UH-1B · Accident: partial loss of engine power (mechanical failure) while maneuvering
Event
- NTSB case
- FTW85FA188
- 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
- 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
- General aviation
- 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
Bell UH-1B
- Aircraft type
- Bell UH-1
- Category
- Helicopter
- 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
- N2252A
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From not recordedTo not recorded
- 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 133: Rotorcraft Ext. Load
- 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
- Maneuvering · hover
- 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
- Partial loss of engine power (mechanical failure)
- Also codedOther events the NTSB coded in the sequence, such as a wire strike after a loss of power. Flight Findings uses them for its kinds of event. Glossary
- Tree(s)
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- Destroyed
Cause areas
- Bleed air system, actuator › Loss, partial
- Company maintenance personnel › Maintenance, adjustment, improper
- Company maintenance personnel › Maintenance, inspection, poor
- Fuel system, fuel control › Incorrect
- Object › Tree(s)
- Terrain condition › None suitable
- Turboshaft engine, free turbine governor › Incorrect
- Turboshaft engine, gas generator › Dirty(foggy)
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
THE PLT HAD STABILIZED ACFT IN A 125' HOVER, PRIOR TO PICKING UP A LOAD, WHEN THE ENG SPOOLED DOWN AND ACFT ENTERED TALLTREES WITH LOW ROTOR RPM AND PITCHED NOSE DOWN AS IT DESCENDED THRU THE TREES. GROUND WITNESSES HEARD 2 LOUD 'BANGS' PRIOR TO THE ACFT ENTERING THE TREES. INVESTIGATION OF THE ENG REVEALED THAT THE FUEL CONTROL AND PWR GOVERNOR SCHEDULES WERE SET ABOVE THE SPECIFIED LIMITS. THESE SETTINGS WOULD INCREASE FUEL FLOW AND ENG PWR AVAILABLE WHILE DECREASING OPERATING TEMPERATURES; HOWEVER, IT ALSO REDUCES THE ENG SURGE MARGIN AND INCREASES THE POSSIBILITY OF ENG SURGE (COMRESSOR STALL) AND PWR DROP. IN ADDITION, THE COMPRESSION WAS FOUND DIRTY AND THE BLEED AIR LINE WAS LOOSE, WHICH WOULD HAVE FURTHER REDUCED THE SURGE MARGIN. THE NATURE OF THE LONG LINE OPERATION AND THE SURROUNDING TALL TREES PRECLUDED THE SUCCESSFUL COMPLETION OF THE ENG OUT EMERGENCY PROCEDURE.
Verbatim NTSB analysis from the NTSB dataset
Sources
NTSB record FTW85FA188
- Event ID
- 20001214X36170
- Case number
- FTW85FA188
- Dataset
- historical-pre2008
- Source SHA-256
- 89e2df6d848e7ab3b42e7d7c7a03ff403303057a26ca04c95b3ea67201c3ce74
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. 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: 584e27887b21a066c45394a43ede8dfbbfa47fed2dfa1a3f994be9d30fa524bd; retrieved 2026-09-21T17:19:08.091Z.