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NTSB Report
July 6, 1986 · Texas Helicopter OH-13H/M · N51856
Valencia, CA
Overview
Report Status
Preliminary report
Event Type
Accident
Date
July 6, 1986
Injury Outcomes
1 injury (1 serious injury)
Location
Valencia, CA
Aircraft
Texas Helicopter OH-13H/M
Tail Number
N51856
Operator
Aerohead Helicopters
Injuries
Serious
Aircraft Damage
Substantial
NTSB Number
LAX86LA283
THE PILOT REPORTED THAT HE HEARD A LOUD BANG AND GRINDING NOISE FROM THE ENGINE/MAIN TRANSMISSION AREA WHILE ON A SWATH RUN. HE STATED THAT THE MAIN ROTOR RPM DECAYED IMMEDIATELY AFTER HE HEARD THE NOISE. AS THE HELICOPTER DESCENDED TO ABOUT 50 FEET ABOVE THE GROUND THE PILOT SAID HE FLARED FOR THE TOUCHDOWN. THE HELICOPTER LANDED HARD SEVERING THE SKIDS, TAIL AND SPRAY BOOMS. THE PILOT SAID THE ENGINE CONTINUED TO RUN AFTER THE ACCIDENT, HOWEVER, THE ROTOR WAS NOT TURNING. POST ACCIDENT INSPECTION OF THE TRANSMISSION REVEALED A MASSIVE OVERLOAD FAILURE OF THE LOWER PINION GEAR ASSEMBLY. BOGUS PINION GEARS WERE FOUND INSTALLED IN THE TRANSMISSION.
Full Narrative
THE PILOT REPORTED THAT HE HEARD A LOUD BANG AND GRINDING NOISE FROM THE ENGINE/MAIN TRANSMISSION AREA WHILE ON A SWATH RUN. HE STATED THAT THE MAIN ROTOR RPM DECAYED IMMEDIATELY AFTER HE HEARD THE NOISE. AS THE HELICOPTER DESCENDED TO ABOUT 50 FEET ABOVE THE GROUND THE PILOT SAID HE FLARED FOR THE TOUCHDOWN. THE HELICOPTER LANDED HARD SEVERING THE SKIDS, TAIL AND SPRAY BOOMS. THE PILOT SAID THE ENGINE CONTINUED TO RUN AFTER THE ACCIDENT, HOWEVER, THE ROTOR WAS NOT TURNING. POST ACCIDENT INSPECTION OF THE TRANSMISSION REVEALED A MASSIVE OVERLOAD FAILURE OF THE LOWER PINION GEAR ASSEMBLY. BOGUS PINION GEARS WERE FOUND INSTALLED IN THE TRANSMISSION.
Flight
Event TypeAccident
Event Time08:20 PDT
Nearest AirportVANNUYS (10nm NW)
Runway0
Runway Length0
Runway Width0
Flight Plan FiledNone
Aircraft FireNo
Aircraft ExplosionNo
Aircraft
AircraftTexas Helicopter OH-13H/M
Tail NumberN51856
Aircraft CategoryHeli
DamageSubstantial
OperatorAerohead Helicopters
Operating RulePart 137
Engines1
Engine TypeReciprocating
Engine DetailsLycoming · VO-435A/F · Reciprocating · 260
Seats1
People & Injuries
Injury Summary1 injury (1 serious injury)
Fatal0
Serious1
Minor0
Uninjured0
Total1
Crew 1Age 39 · Second Class
Conditions
ConditionsVMC
LightDaylight
WindCalm
Visibility7 sm
CeilingOvercast 2000 ft
Temperature / Dew Point61 F / 61 F
Altimeter30.00 inHg
Observation Time14:46
Weather SourceWFAC