Enstrom 280C accident near Fremont, California, March 27, 1988
On March 27, 1988 at about 11:45 pm local time, a Enstrom 280C (helicopter), registered N5692P, was substantially damaged in an accident near Fremont, California. It was an instructional flight under general aviation rules (Part 91). No one was hurt; 2 people were on board or involved. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
FAILURE OF THE ENGINE TO MAIN ROTOR DRIVE SYSTEM DUE TO A DRIVE BELT SLIPPAGE CAUSED BY A DRIVE PULLEY WORN BEYOND ITS SERVICE LIMIT. CONTRIBUTING TO THE ACCIDENT WAS THE INADEQUATE FACTORY MAINTENANCE MANUALS WHICH DID NOT PROVIDE THE SERVICEABLE LIMITS FOR THE DRIVE BELT PULLEYS.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- March 27, 1988 · about 11:45 pm local time
- Place
- Fremont, California
- Type
- Accident
- Injuries
- No one was hurt; 2 people were on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Enstrom 280C · all 280Cs on the register
- Registration
- N5692P · no longer on the register · serial 1185
- Damage
- Substantial damage
- Flight
- Instructional flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
WHILE WORKING IN THE TRAFFIC PATTERN ON A LOCAL INSTRUCTIONAL FLIGHT, THE CFI NOTICED THE MAIN ROTOR RPM WAS BELOW THE GREEN ARC. HE ENTERED AN AUTOROTATION AND TRIED UNSUCCESSFULLY TO GET THE ROTOR RPM BACK INTO THE GREEN ARC. THE HELICOPTER COLLIDED WITH THE GROUND DURING THE ATTEMPTED AUTOROTATION WITH A LOW MAIN ROTOR SPEED. INVESTIGATION REVEALED THAT THE ENGINE DRIVE PULLEY WAS WORN BEYOND THE FACTORY ESTABLISHED LIMIT, WHICH ALLOWED THE DRIVE BELT TO SLIP. THE MINIMUM SERVICEABLE WEAR LIMIT FOR THE DRIVE PULLEY WAS NOT PUBLISHED IN THE FACTORY MAINTENANCE PROCEDURES.
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: flight instructor, commercial pilot
- Ratings: multi-engine land; single-engine land; instructor: airplane multi-engine; instructor: airplane single-engine; instructor: helicopter; instructor: instrument airplane; instrument: airplane; rotorcraft: helicopter
- Flight time: 1,701 hours in all; 18 in this make and model; 273 in the last 90 days; 99 in the last 30 days; 1,494 as pilot in command; 957 on instruments
- Medical certificate: Class 1 (valid medical--no waivers/lim.)
- Seat: left
The aircraft
- Airframe total time: 1,673 hours
- Last inspection: 100-hour inspection, February 29, 1988; 20 hours since
- Maximum gross weight: 2,350 lb
- Seats: 2
- Landing gear: fixed
- Engine: Lycoming HIO-360-E1BD (piston); 0 hours total
- Operator: Pegasus Aviation Corporation
The flight
- Departed from: PAO Palo Alto CA at 10:30 pm
- Destination: PAO
- Flight plan: none
- Runway 0
- A second pilot was aboard
Weather at the time
- Light: daylight
- Wind: from 330° at 15 knots, gusting 20
- Visibility: 50 statute miles
- Sky: clear
- Temperature: 75°F (24°C), dew point 0°F (-18°C)
- Altimeter: 30.00 inHg
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Crew | 2 |
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.
Other NTSB records under N5692P the same tail number, which may have belonged to a different aircraft at the time
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.