# NTSB LAX88FA140: Enstrom 280C, N5692P, Fremont, CA, March 27, 1988

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Field investigation · Final report
- Date: March 27, 1988, 15:45 local (23:45 UTC)
- Place: Fremont, CA
- Location: 37.5483° N, 121.9886° W: Placed by OpenAirDocs: center of Fremont, CA, within about 6 miles (OpenAirDocs)
- Nearby events: https://openairdocs.org/map.md?lat=37.5483&lon=-121.9886&mi=10
- Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 2 uninjured
- Status: Completed, report July 9, 1990
- Report: Approved by Office Director
- NTSB case key (mKey): 25818
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX88FA140
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/25818/pdf
- Page: https://openairdocs.org/ntsb/LAX88FA140

## Probable cause

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.

## Sequence of events

In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf).

- Airframe/component/system failure/malfunction, approach - vfr pattern - downwind
  - rotor drive system,main rotor driving pulley - worn (cause)
  - maintenance,inspection - information insufficient, manufacturer (contributing factor)
  - rotor system - underspeed (cause)
- Forced landing, descent - emergency
  - autorotation - delayed, pilot in command
- In flight collision with terrain/water, landing - flare/touchdown
  - rotor system - underspeed (cause)
  - proper descent rate - not possible

## Analysis

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.

## Aircraft

- Registration: [N5692P](https://openairdocs.org/deregistered/N5692P-2011-05-18), registration cancelled 2011-05-18, S/N 1185 (OpenAirDocs)
- Reported make and model: ENSTROM 280C
- Registry model: [Enstrom Helicopter 280C](https://openairdocs.org/model/enstrom-helicopter-280c) (registry code 3300505) (OpenAirDocs)
- Category: Helicopter
- Serial number: 1185
- Airframe hours: 1673
- Engines: LYCOMING HIO-360-E1BD 205 horsepower reciprocating
- Damage: Substantial damage
- Flight: Instructional, Part 91
- Operator: Pegasus Aviation Corporation
- Registered owner: Joseph R. Reinhard
- Airworthiness certificate: Standard, Normal
- Last inspection: 100 hour, February 29, 1988, 20 hours before
- Departed: PAO, PALO ALTO, CA
- Destination: PAO

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 31; commercial, flight instructor; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 1, valid medical--no waivers/lim.; seat: left; flight hours: 1,701 total, 18 in this make and model, 1,494 as pilot in command, 273 in the last 90 days, 99 in the last 30 days, 3 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 330° at 15 knots, gusting 20
- Visibility: 50 statute miles
- Lowest ceiling: none
- Temperature: 75 °F, dew point -0 °F
- Altimeter: 30.00 inHg

## FAA reports on this event (1)

The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs).

- [Accident 19880327008969A](https://openairdocs.org/incident/19880327008969A), Mar 27, 1988: Enstrm 280C, Fremont, CA, Substantial damage. Worn main rotor drive pulley allowed belt slippage and rotor decay. Unable to arrest autorotation descent. Crashed.

## Other investigations on N5692P (1)

From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model.

- [NTSB LAX86LA291](https://openairdocs.org/ntsb/LAX86LA291), Jul 13, 1986: Enstrom EN-280-C (N5692P), Los Altos, CA, substantial damage

From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model.

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