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NTSB Report
March 27, 1988 · Enstrom 280C · N5692P
Fremont, CA
Overview
Report Status
Probable Cause
Event Type
Accident
Date
March 27, 1988
Injury Outcomes
No injuries (2 uninjured)
Location
Fremont, CA
Aircraft
Enstrom 280C
Tail Number
N5692P
Operator
Pegasus Aviation
Injuries
None
Aircraft Damage
Substantial
NTSB Number
LAX88FA140
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.
NTSB 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.
Full Narrative
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.
Flight
Event TypeAccident
Event Time15:45 PST
Nearest Airport0nm N
Runway0
Runway Length0
Runway Width0
Flight Plan FiledNone
Aircraft FireNo
Aircraft ExplosionNo
Aircraft
AircraftEnstrom 280C
Tail NumberN5692P
Aircraft CategoryHeli
DamageSubstantial
OperatorPegasus Aviation
Operating RulePart 91
Engines1
Engine TypeReciprocating
Engine DetailsLycoming · HIO-360-E1BD · Reciprocating · 205
Seats2
People & Injuries
Injury SummaryNo injuries (2 uninjured)
Fatal0
Serious0
Minor0
Uninjured2
Total2
Crew 1Age 31 · First Class
Conditions
ConditionsVMC
LightDaylight
Wind330° @ 15 kt, gusting 20 kt
Visibility50 sm
CeilingNone
Temperature / Dew Point0 C
Altimeter30.00 inHg
Weather SourceWIT