Bell 206B accident near Lucerne Valley, California, August 4, 1998
On August 4, 1998 at about 2:45 pm local time, a Bell 206B (helicopter), registered N5016G, was substantially damaged in an accident near Lucerne Valley, California. It was a positioning flight under general aviation rules (Part 91). No one was hurt; 1 person was on board or involved. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
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.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- August 4, 1998 · about 2:45 pm local time
- Place
- Lucerne Valley, California · map
- Type
- Accident
- Injuries
- No one was hurt; 1 person was on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Bell 206B · all 206Bs on the register
- Registration
- N5016G · no longer on the register · serial 2624
- Damage
- Substantial damage
- Flight
- Positioning flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
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.
The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.
The factual record from the NTSB's investigation tables, in plain English
Pilot
- Certificate: commercial pilot
- Ratings: instrument: helicopter; rotorcraft: helicopter
- Flight time: 9,900 hours in all; 6,100 in this make and model; 68 in the last 90 days; 59 in the last 30 days
- Medical certificate: Class 2 (valid medical--w/ waivers/lim.)
- Seat: rgt
The aircraft
- Airframe total time: 5,788 hours
- Last inspection: annual inspection, May 1, 1998; 68 hours since
- Maximum gross weight: 3,200 lb
- Seats: 5
- Landing gear: fixed
- Engine: Allison 250-C20B (turboshaft); 0 hours total
The flight
- Departed from: RAL Riverside CA at 2:20 pm
- Destination: FLG Flagstaff AZ
- Flight plan: VFR
- Runway 0
Weather at the time
- Light: daylight
- Wind: from 280° at 10 knots
- Visibility: 35 statute miles
- Sky: scat at 22,000 ft
- Temperature: 88°F (31°C), dew point 50°F (10°C)
- Altimeter: 30.00 inHg
- Observation at 2:49 pm from DAG, 34 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Crew | 1 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
The docket, the folder of records gathered during an investigation (maintenance records, photographs, witness statements, examinations), has not been read from the NTSB for this case yet; the list appears here once it has. Open the docket at the NTSB.
Everything on this page comes from the NTSB's public records. The narrative, probable cause and findings are the NTSB's own words; the coded tables behind the report are written out in plain English, with pilots' ages, home towns and medical details left out. The documents and photographs are the NTSB's docket, shown as the NTSB released them. This site's own text never names anyone involved. A preliminary report can change; the final report usually follows one to two years later, and the page is refreshed when it does.