LAX05LA022 · Bell 47D1
Bell 47D1 · Accident: loss of engine power on approach
From Reid-Hillview Airport of Santa Clara County (RHV) to San Martin Airport (E16)
Event
- NTSB case
- LAX05LA022
- 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
- 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 47D1
- Aircraft type
- Bell 47
- 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
- N903B
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From Reid-Hillview Airport of Santa Clara County (RHV), San Jose, CATo San Martin Airport (E16), San Martin, CA
- 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
- Approach · VFR pattern base
- 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
- 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
- Reason for occurrence undetermined
Approximate · Coordinates from the NTSB case API, which marks them as estimated or does not say; no uncertainty radius is established.
NTSB narrative
The helicopter experienced a loss of engine power and rolled over during an attempted autorotation to a soft, muddy field. The helicopter departed for a 22-nautical mile training flight with 10 gallons of fuel remaining in the 28-gallon fuel tank. While en route, both the certified flight instructor (CFI) and student pilot noted that an unusually high application of carburetor heat was required to keep the inlet temperature needle within the normal range. With the intention of entering the traffic pattern at the destination airport, the student pilot initiated a descent and maneuvered the helicopter in a right turn. With the helicopter configured in the right turn, about 500 feet above ground level (agl), the engine experienced a momentary power interruption and subsequently stopped. The student pilot executed an autorotation and the helicopter touched down in a crop field. The right skid dug into the soft muddy field, resulting in the helicopter rotating around the skid and coming to rest on its right side. The fuel tank contained about 5 gallons of fuel just prior to the accident. Due to the orientation of the fuel outlet port inside the fuel tank, the helicopter is susceptible to unporting with low quantities of fuel present during maneuvers. With the outlet located on the left side of the tank, when a helicopter is in a right turn with minimal fuel onboard, the outlet can intake air resulting in fuel starvation to the engine. According to a standard reference icing probability chart, the atmospheric conditions present at the time of the accident were in the range considered favorable for carburetor ice formation.
Probable cause
A loss of power for undetermined reasons.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record LAX05LA022
- Event ID
- 20041202X01905
- Case number
- LAX05LA022
- 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, 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: 84eecb48f455a6302da4c7b548a0a58b00eab14a02832ea34bc9c0aa63af57b8; retrieved 2026-09-22T06:33:24.362Z.