LAX98LA256 · Bell 206B
Bell 206B · Accident: total loss of engine power (mechanical failure) en route
From Riverside Municipal Airport (RAL) to Flagstaff Pulliam Airport (FLG)
Event
- NTSB case
- LAX98LA256
- 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 206B
- Aircraft type
- Bell 206
- 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
- N5016G
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From Riverside Municipal Airport (RAL), Riverside, CATo Flagstaff Pulliam Airport (FLG), Flagstaff, AZ
- 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
- Total loss of engine power (mechanical failure)
- 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
- Other maintenance personnel › Procedures/directives, not followed
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
The pilot had been flying for about 25 minutes when he noticed that the oil pressure gauge and torque gauge were fluctuating. He initiated an approach to a precautionary landing spot on an asphalt pad. About 150 feet agl, the engine quit and the pilot autorotated to touch down on a paved road. The main rotor blades severed the tail boom aft of the horizontal stabilizer. The engine had received some maintenance work and had been reinstalled in the helicopter the night before the accident, at which time the pilot performed a test run and leak check of the engine, with no noted discrepancies. The pilot further stated that the engine had been running normally until the fluctuation of the oil pressure and torque gauges. During an examination of the engine, the oil output line was connected, but loose, and oil was seen dripping from the fitting area. Oil was observed over most of the fuselage and underneath the engine. There was approximately 1 pint of oil found in the sump. Further teardown of the engine revealed that the number 8 bearing was destroyed and no oil was found throughout the lubrication system. The Bell Helicopter maintenance manual specifies a torque value for the fitting on the oil output line; however, the mechanic who installed the engine reported that he did not use a torque wrench to tighten the line because he would have had to remove some other lines to get to it and he was in a hurry.
Probable cause
The failure of the mechanic who installed the engine to follow proper procedures by insuring the proper torque to the oil output line, resulting in a loose fitting, oil loss and subsequent bearing failure.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record LAX98LA256
- Event ID
- 20001211X10892
- Case number
- LAX98LA256
- 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: 947ba8b4f9cd5a48aa37db185ee2c88306df8f0ec629d4acfc2dca425a8caa29; retrieved 2026-09-22T17:15:16.128Z.