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NTSB Report
February 9, 1993 · Cobb Intl EXEC 90 · N89678
Chandler, AZ
Overview
Report Status
Probable Cause
Event Type
Accident
Date
February 9, 1993
Injury Outcomes
No injuries (1 uninjured)
Location
Chandler, AZ
Aircraft
Cobb Intl EXEC 90
Tail Number
N89678
Operator
Cobb International
Injuries
None
Aircraft Damage
Substantial
NTSB Number
LAX93LA111
THE HELICOPTER'S ENGINE FAILED WHILE ON THE CROSSWIND LEG. THE SURROUNDING TERRAIN WAS CONGESTED FORCING THE PILOT TO LAND IN AN AREA WHICH WAS DOWNWIND. THE HELICOPTER NOSED DOWN ON LANDING IN THE SOFT TERRAIN. EXAMINATION OF THE ENGINE DISCLOSED THAT AN INTAKE VALVE FAILED AND LODGED IN THE PISTON. METALLURGICAL EXAMINATION REVEALED THAT THE VALVE STEM FAILED IN FATIGUE. THE FATIGUE WAS PRECIPITATED BY THE MANUFACTURER'S IMPROPER QUALITY CONTROL WHICH FAILED TO ASSURE THAT THE VALVE WAS GROUND BEFORE IT WAS PLATED.
NTSB Probable Cause
THE MANUFACTURER'S INADEQUATE QUALITY CONTROL WHICH RESULTED IN THE FATIGUE OF THE VALVE STEM. THE SOFT TERRAIN CONTRIBUTED TO THIS ACCIDENT.
Full Narrative
THE HELICOPTER'S ENGINE FAILED WHILE ON THE CROSSWIND LEG. THE SURROUNDING TERRAIN WAS CONGESTED FORCING THE PILOT TO LAND IN AN AREA WHICH WAS DOWNWIND. THE HELICOPTER NOSED DOWN ON LANDING IN THE SOFT TERRAIN. EXAMINATION OF THE ENGINE DISCLOSED THAT AN INTAKE VALVE FAILED AND LODGED IN THE PISTON. METALLURGICAL EXAMINATION REVEALED THAT THE VALVE STEM FAILED IN FATIGUE. THE FATIGUE WAS PRECIPITATED BY THE MANUFACTURER'S IMPROPER QUALITY CONTROL WHICH FAILED TO ASSURE THAT THE VALVE WAS GROUND BEFORE IT WAS PLATED.
Flight
Event TypeAccident
Event Time14:55 MST
Nearest Airport0nm N
Runway0
Flight Plan FiledNone
Aircraft FireNo
Aircraft ExplosionNo
Aircraft
AircraftCobb Intl EXEC 90
Tail NumberN89678
Aircraft CategoryHeli
DamageSubstantial
OperatorCobb International
Operating RulePart 91
Engines1
Engine TypeReciprocating
Engine DetailsRotorway · 162 · Reciprocating · 150
Seats2
People & Injuries
Injury SummaryNo injuries (1 uninjured)
Fatal0
Serious0
Minor0
Uninjured1
Total1
Crew 1Age 37 · Second Class
Conditions
ConditionsVMC
LightDaylight
Wind270° @ 12 kt
Visibility35 sm
CeilingNone
Temperature / Dew Point61 F / 0 C
Altimeter0
Weather SourcePILO