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NTSB Report
November 4, 1989 · Bell UH-1E · N138US
Mesa, AZ
Overview
Report Status
Probable Cause
Event Type
Accident
Date
November 4, 1989
Injury Outcomes
No injuries (2 uninjured)
Location
Mesa, AZ
Aircraft
Bell UH-1E
Tail Number
N138US
Operator
Gilman D Christopher
Injuries
None
Aircraft Damage
Destroyed
NTSB Number
LAX90DUJ05
INVESTIGATION DISCLOSED THAT THE TAIL ROTOR SEPARATED FROM THE HELICOPTER IN FLIGHT. THE TAIL ROTOR ASSEMBLY WAS SENT TO THE MANUFACTURER FOR ANALYSIS. ON TAIL ROTOR BLADE 'A' THE BOLT, NUT AND ASSOCIATED HARDWARE THAT ATTACHED THE PITCH CHANGE LINK TO THE BLADE GRIP WERE MISSING. THE BOLT BUSHING WAS WORN BEYOND THE SERVICE LIMITS THAT MANDATED REPLACEMENT. ON BLADE 'B' THE ATTACHING BOLT, NUT AND HARDWARE WERE DETERMINED TO BE THE WRONG SIZE. IN ADDITION, THE WRONG SPACER WAS ATTACHED TO THE BOLT. FOUR MORE WASHERS THAN ALLOWED WERE UNDER THE TRAILING EDGE BLADE RETAINING BOLT NUT. ACCORDING TO THE PREFLIGHT INSPECTION REQUIREMENTS, THE DISCREPANCIES ON THE BLADE 'A' BUSHING AND THE INCORRECT HARDWARE ON THE BLADE 'B' PITCH CHANGE LINK SHOULD HAVE BEEN DETECTED DURING THE DAILY INSPECTION EVENT.
NTSB Probable Cause
THE INFLIGHT SEPARATION OF THE TAIL ROTOR DUE TO IMPROPER MAINTENANCE PROCEDURES AND THE INSTALLATION OF INCORRECT ATTACHMENT HARDWARE ON THE TAIL ROTOR BLADE PITCH CHANGE LINKAGES.
Full Narrative
INVESTIGATION DISCLOSED THAT THE TAIL ROTOR SEPARATED FROM THE HELICOPTER IN FLIGHT. THE TAIL ROTOR ASSEMBLY WAS SENT TO THE MANUFACTURER FOR ANALYSIS. ON TAIL ROTOR BLADE 'A' THE BOLT, NUT AND ASSOCIATED HARDWARE THAT ATTACHED THE PITCH CHANGE LINK TO THE BLADE GRIP WERE MISSING. THE BOLT BUSHING WAS WORN BEYOND THE SERVICE LIMITS THAT MANDATED REPLACEMENT. ON BLADE 'B' THE ATTACHING BOLT, NUT AND HARDWARE WERE DETERMINED TO BE THE WRONG SIZE. IN ADDITION, THE WRONG SPACER WAS ATTACHED TO THE BOLT. FOUR MORE WASHERS THAN ALLOWED WERE UNDER THE TRAILING EDGE BLADE RETAINING BOLT NUT. ACCORDING TO THE PREFLIGHT INSPECTION REQUIREMENTS, THE DISCREPANCIES ON THE BLADE 'A' BUSHING AND THE INCORRECT HARDWARE ON THE BLADE 'B' PITCH CHANGE LINK SHOULD HAVE BEEN DETECTED DURING THE DAILY INSPECTION EVENT.
Flight
Event TypeAccident
Event Time09:15 MST
Nearest Airport0nm N
Runway0
Runway Length0
Runway Width0
Flight Plan FiledNone
Aircraft FireNo
Aircraft ExplosionNo
Aircraft
AircraftBell UH-1E
Tail NumberN138US
Aircraft CategoryHeli
DamageDestroyed
OperatorGilman D Christopher
Operating RulePart 137
Engines1
Engine TypeTurboshaft
Engine DetailsLycoming · T5311 · Turboshaft · 1100
Seats2
People & Injuries
Injury SummaryNo injuries (2 uninjured)
Fatal0
Serious0
Minor0
Uninjured2
Total2
Crew 1Age 46 · Second Class
Conditions
ConditionsVMC
LightDaylight
WindCalm
CeilingNone
Temperature / Dew Point0 C / 18 C
Altimeter29.00 inHg
Weather SourceWIT