SEA99LA031 · Hiller UH-12E
Valley Helicopter Services Hiller UH-12E · Accident: loss of engine power en route
From ID to an unrecorded destination
Event
- NTSB case
- SEA99LA031
- 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
Hiller UH-12E
- Aircraft type
- Hiller UH-12
- 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
- N67264
- Operator
- Valley Helicopter Services
- Onboard fatalities
- Unknown
- Route
- From IDTo 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 91: General Aviation
- 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
- En route · cruise
- 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
- Loss of engine power
- 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
- Fuel exhaustion
- 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
- Fluid, fuel › Exhaustion
- Pilot in command › Fuel management, inadequate
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
The pilot-in-command (PIC) took off with a full load of fuel (82 gallons) approximately 1230 pst. The main fuel tank contained 46 gallons of fuel (2.9 gallons unusable) with the remaining fuel in external saddle tanks. Approximately 1445 (2.25 hours after takeoff), the engine flamed out while the PIC was executing a zero airspeed pedal turn course reversal over high trees. The helicopter descended into the trees impacting terrain. The PIC reported that 'within moments preceding the flameout, he noted that his fuel level had reached approximately 15 gallons in the main tank. At that time he turned on the auxiliary fuel tanks transfer switch.' and that 'the time between turning on the transfer switch to the flameout was approximately 45 to 60 seconds.' Cruise fuel flow to the engine was reported at 17-20 gallons/hour (takeoff power fuel flow was reported as 32 gallons/hour). Post crash examination revealed less than one gallon of fuel in the rotorcraft's main fuel tank, and none in the fuel line which connects the tank to the engine fuel nozzle, none within the engine driven fuel pump filter, nor within the power turbine governor fuel filter. The aircraft's fuel gauge was observed to have no markings on the glass faceplate. No fuel leaks were found within the main fuel tank. A post crash test run of the engine revealed normal performance. No low fuel warning system was installed on the rotorcraft.
Probable cause
The pilot-in-command's inadequate fuel management which resulted in fuel exhaustion. Contributing factors were the absence of cautionary markings on the fuel gauge, and high trees at the accident site.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record SEA99LA031
- Event ID
- 20001204X00117
- Case number
- SEA99LA031
- 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: cfe8abdfa56ce57330343cdf5ace828448c454411a381ad7a680e91e38224135; retrieved 2026-09-21T11:14:40.103Z.