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NTSB Report
July 20, 1987 · Piper PA-28-161 · N91338
Milpitas, CA
Overview
Report Status
Preliminary report
Event Type
Accident
Date
July 20, 1987
Injury Outcomes
1 injury (1 minor injury)
Location
Milpitas, CA
Aircraft
Piper PA-28-161
Tail Number
N91338
Operator
Flying Country Club
Injuries
Minor
Aircraft Damage
Substantial
NTSB Number
LAX87LA275
WHILE CLIMBING TO CRUISE PLT HEARD A LOUD KNOCKING NOISE FOLLOWED BY 'VIOLENT VIBRATIONS' & A LOSS OF POWER. PLT MADE A FRCD LNDING IN A NEWLY EXCAVATED CONSTRUCTION SITE & WENT OVER AN EMBANKMENT. INVES REVEALED DEFORMATION OF THE #4 CYLINDER VALVE COVER. #4 EXHAUST VALVE ROCKER ARM WAS FOUND TO BE BROKEN. REVIEW OF ACFT MAINTENANCE RECORDS REVEALED THAT AD 87-10-06 WHICH INCORPORATES LYCOMING SERVICE BULLETIN (SB) 477A WAS ACCOMP 78.7 HRS PRIOR TO THE ACCIDENT. THE SB REQUIRES ROCKER ARMS THAT DO NOT HAVE A WALL THICKNESS OF.075 BE REPLACED. IF THE ROCKER ARM PASSES THE THICKNESS EXAM THE ROCKER ARM OIL DRIP HOLE OUTER EDGE MUST BE 'BURRED' TO THE APPROX .030 RADIUS PRIOR TO REASSEMBLY. THE ROCKER ARM WAS MEASURED USING A ROUND ANVIL MICROMETER. THE MEASUREMENT MET THE MIN DIMENSION OF .075. AFTER THE ACCIDENT, MET LAB EXAM REVEALED FRACTURE FEATURES OF HIGH CYCLE FATIGUE & OVERSTRESS. THE ORIGIN OF THE FATIGUE WAS TRACED TO THE REWORKED OIL DRIP HOLE WHICH DID NOT MEET .030 RADIUS. THE WALL THICKNESS MEASURED .055 USING A MEASURING MICROSCOPE.
Full Narrative
WHILE CLIMBING TO CRUISE PLT HEARD A LOUD KNOCKING NOISE FOLLOWED BY 'VIOLENT VIBRATIONS' & A LOSS OF POWER. PLT MADE A FRCD LNDING IN A NEWLY EXCAVATED CONSTRUCTION SITE & WENT OVER AN EMBANKMENT. INVES REVEALED DEFORMATION OF THE #4 CYLINDER VALVE COVER. #4 EXHAUST VALVE ROCKER ARM WAS FOUND TO BE BROKEN. REVIEW OF ACFT MAINTENANCE RECORDS REVEALED THAT AD 87-10-06 WHICH INCORPORATES LYCOMING SERVICE BULLETIN (SB) 477A WAS ACCOMP 78.7 HRS PRIOR TO THE ACCIDENT. THE SB REQUIRES ROCKER ARMS THAT DO NOT HAVE A WALL THICKNESS OF.075 BE REPLACED. IF THE ROCKER ARM PASSES THE THICKNESS EXAM THE ROCKER ARM OIL DRIP HOLE OUTER EDGE MUST BE 'BURRED' TO THE APPROX .030 RADIUS PRIOR TO REASSEMBLY. THE ROCKER ARM WAS MEASURED USING A ROUND ANVIL MICROMETER. THE MEASUREMENT MET THE MIN DIMENSION OF .075. AFTER THE ACCIDENT, MET LAB EXAM REVEALED FRACTURE FEATURES OF HIGH CYCLE FATIGUE & OVERSTRESS. THE ORIGIN OF THE FATIGUE WAS TRACED TO THE REWORKED OIL DRIP HOLE WHICH DID NOT MEET .030 RADIUS. THE WALL THICKNESS MEASURED .055 USING A MEASURING MICROSCOPE.
Flight
Event TypeAccident
Event Time12:30 PDT
Nearest AirportReid Hillview (0nm N)
Runway0
Flight Plan FiledVFR
Aircraft FireNo
Aircraft ExplosionNo
Aircraft
AircraftPiper PA-28-161
Tail NumberN91338
Aircraft CategoryAir
DamageSubstantial
OperatorFlying Country Club
Operating RulePart 91
Engines1
Engine TypeReciprocating
Engine DetailsLycoming · O-320-D3G · Reciprocating · 160
Seats4
People & Injuries
Injury Summary1 injury (1 minor injury)
Fatal0
Serious0
Minor1
Uninjured0
Total1
Crew 1Age 50 · Third Class
Conditions
ConditionsVMC
LightDaylight
Wind270° @ 8 kt
Visibility50 sm
CeilingNone
Temperature / Dew Point0 C / 0 C
Altimeter29.00 inHg
Observation Time18:50
Weather SourceWIT