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NTSB Report
June 22, 1991 · Cessna 180G · N4700U
Challis, ID
Overview
Report Status
Probable Cause
Event Type
Accident
Date
June 22, 1991
Injury Outcomes
1 injury (1 minor injury), 1 uninjured
Location
Challis, ID
Aircraft
Cessna 180G
Tail Number
N4700U
Operator
Maxl Willis
Injuries
Minor
Aircraft Damage
Substantial
NTSB Number
SEA91LA139
THE CESSNA 180 WAS IN CRUISE FLIGHT A FEW MINUTES AFTER DEPARTURE WHEN THE ENGINE BEGAN RUNNING ROUGH AND LOST POWER. THE PILOT WAS UNABLE TO RETURN TO A SAFE LANDING SITE, SO ELECTED TO ATTEMPT A FORCED LANDING NEAR A RIVER. AN ENGINE TEARDOWN REVEALED THAT THE EXHAUST VALVE ROCKER SHAFT BOSS ON ONE CYLINDER HAD FAILED AND THE BROKEN PIECE MIGRATED UNDER THE INTAKE ROCKER SHAFT, WHERE IT CAUSED THE VALVE PUSH ROD TO BEND.
NTSB Probable Cause
THAT THE PILOT ENCOUNTERED UNSUITABLE TERRAIN DURING A FORCED LANDING AFTER A POWER LOSS DUE TO A FRACTURED CYLINDER BOSS AND A BENT ENGINE PUSHROD.
Full Narrative
THE CESSNA 180 WAS IN CRUISE FLIGHT A FEW MINUTES AFTER DEPARTURE WHEN THE ENGINE BEGAN RUNNING ROUGH AND LOST POWER. THE PILOT WAS UNABLE TO RETURN TO A SAFE LANDING SITE, SO ELECTED TO ATTEMPT A FORCED LANDING NEAR A RIVER. AN ENGINE TEARDOWN REVEALED THAT THE EXHAUST VALVE ROCKER SHAFT BOSS ON ONE CYLINDER HAD FAILED AND THE BROKEN PIECE MIGRATED UNDER THE INTAKE ROCKER SHAFT, WHERE IT CAUSED THE VALVE PUSH ROD TO BEND.
Flight
Event TypeAccident
Event Time09:45 MDT
Nearest Airport0nm N
Runway0
Flight Plan FiledNone
Aircraft FireNo
Aircraft ExplosionNo
Aircraft
AircraftCessna 180G
Tail NumberN4700U
Aircraft CategoryAir
DamageSubstantial
OperatorMaxl Willis
Operating RulePart 91
Engines1
Engine TypeReciprocating
Engine DetailsContinental · O-470R · Reciprocating · 230
Seats4
People & Injuries
Injury Summary1 injury (1 minor injury), 1 uninjured
Fatal0
Serious0
Minor1
Uninjured1
Total2
Crew 1Age 46 · Unknown
Conditions
ConditionsVMC
LightDaylight
WindCalm
Visibility40 sm
CeilingNone
Temperature / Dew Point0 C / 0 C
Altimeter0
Weather SourcePILO