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NTSB Report
April 7, 1991 · Piper J-4A · N23179
Mahopac, NY
Overview
Report Status
Probable Cause
Event Type
Accident
Date
April 7, 1991
Injury Outcomes
2 injuries (2 minor injuries)
Location
Mahopac, NY
Aircraft
Piper J-4A
Tail Number
N23179
Operator
Michael Demaio
Injuries
Minor
Aircraft Damage
Substantial
NTSB Number
NYC91LA104
DURING AN INITIATED GO-AROUND AT MAHOPAC AIRPORT, MAHOPAC, NEW YORK, THE ENGINE EXPERIENCED PARTIAL POWER LOSS. FULL POWER COULD NOT BE DEVELOPED RESULTING IN DETERIORATED CLIMB CAPABILITIES. THE AIRPLANE COULD NOT CLEAR RISING TERRAIN AND HIT TREETOPS, EVENTUALLY CONTACTING THE GROUND. POST ACCIDENT EXAMINATION OF THE ENGINE REVEALED THAT THE LEFT MAGNETO WAS EXCESSIVELY WORN AND DETERIORATED CAUSING THE SPARKS TO BE ERRATICALLY DISPLACED TO THE SPARK PLUGS.
NTSB Probable Cause
THE ERRATIC PERFORMANCE OF THE LEFT MAGNETO RESULTING IN INADEQUATE CLIMB CAPABILITIES AND IN FLIGHT COLLISION WITH TERRAIN.
Full Narrative
DURING AN INITIATED GO-AROUND AT MAHOPAC AIRPORT, MAHOPAC, NEW YORK, THE ENGINE EXPERIENCED PARTIAL POWER LOSS. FULL POWER COULD NOT BE DEVELOPED RESULTING IN DETERIORATED CLIMB CAPABILITIES. THE AIRPLANE COULD NOT CLEAR RISING TERRAIN AND HIT TREETOPS, EVENTUALLY CONTACTING THE GROUND. POST ACCIDENT EXAMINATION OF THE ENGINE REVEALED THAT THE LEFT MAGNETO WAS EXCESSIVELY WORN AND DETERIORATED CAUSING THE SPARKS TO BE ERRATICALLY DISPLACED TO THE SPARK PLUGS.
Flight
Event TypeAccident
Event Time12:48 EDT
Nearest Airport0nm N
Runway0
Flight Plan FiledNone
Aircraft FireNo
Aircraft ExplosionNo
Aircraft
AircraftPiper J-4A
Tail NumberN23179
Aircraft CategoryAir
DamageSubstantial
OperatorMichael Demaio
Operating RulePart 91
Engines1
Engine TypeReciprocating
Engine DetailsContinental · A-65 · Reciprocating · 65
Seats2
People & Injuries
Injury Summary2 injuries (2 minor injuries)
Fatal0
Serious0
Minor2
Uninjured0
Total2
Crew 1Age 49 · Third Class
Conditions
ConditionsVMC
LightDaylight
Wind250°
Visibility15 sm
CeilingNone
Temperature / Dew Point48
Altimeter0
Weather SourceWIT