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NTSB Report
June 10, 1984 · Hiller UH-12E · N93431
Merrimac, WI
Overview
Report Status
Preliminary report
Event Type
Accident
Date
June 10, 1984
Injury Outcomes
1 injury (1 fatality)
Location
Merrimac, WI
Aircraft
Hiller UH-12E
Tail Number
N93431
Injuries
Fatal
Aircraft Damage
Destroyed
NTSB Number
CHI84FA226
THE ACFT CRASHED AND BURNED AFTER AN IN-FLT EXPLOSION AT ABOUT 75 FT AGL AS THE ACFT APPROACHED TO LAND. THE ACFT HAD EXPERIENCED ELECTRICAL PROBLEMS OF OVERHEATING GENERATORS AND IRREGULAR VOLTAGE OUTPUTS ON 2 PREVIOUS OCCASIONS. THE PLTWAS TOLD AFTER SOME REPAIRS THAT IF HE SMELLED ANYTHING HOT TO PULL THE GENERATOR CIRCUIT BREAKER. POST-ACCIDENT ACFT EXAMINATION SHOWED A CONDITION OF THE VOLTAGE REGULATOR WHICH WOULD HAVE CAUSED CONTINUOUS CHARGING OF THE BATTERY. THE GENERATOR SHOWED SIGNS OF OVERHEATING AND THE BATTERY HAD EXPLODED AWAY FROM THE WRECKAGE WITH THE TERMINAL POLES MELTEDOFF.
Full Narrative
THE ACFT CRASHED AND BURNED AFTER AN IN-FLT EXPLOSION AT ABOUT 75 FT AGL AS THE ACFT APPROACHED TO LAND. THE ACFT HAD EXPERIENCED ELECTRICAL PROBLEMS OF OVERHEATING GENERATORS AND IRREGULAR VOLTAGE OUTPUTS ON 2 PREVIOUS OCCASIONS. THE PLTWAS TOLD AFTER SOME REPAIRS THAT IF HE SMELLED ANYTHING HOT TO PULL THE GENERATOR CIRCUIT BREAKER. POST-ACCIDENT ACFT EXAMINATION SHOWED A CONDITION OF THE VOLTAGE REGULATOR WHICH WOULD HAVE CAUSED CONTINUOUS CHARGING OF THE BATTERY. THE GENERATOR SHOWED SIGNS OF OVERHEATING AND THE BATTERY HAD EXPLODED AWAY FROM THE WRECKAGE WITH THE TERMINAL POLES MELTEDOFF.
Flight
Event TypeAccident
Event Time13:36 CDT
Nearest Airport0nm N
Runway0
Runway Length0
Runway Width0
Flight Plan FiledVFR
Aircraft FireBoth
Aircraft ExplosionIflt
Aircraft
AircraftHiller UH-12E
Tail NumberN93431
Aircraft CategoryHeli
DamageDestroyed
Operating RulePart 91
Engines1
Engine TypeReciprocating
Engine DetailsLycoming · VO-4540-C2A · Reciprocating · 305
Seats3
People & Injuries
Injury Summary1 injury (1 fatality)
Fatal1
Serious0
Minor0
Uninjured0
Total1
Crew 1Age 38 · Second Class
Conditions
ConditionsVMC
LightDaylight
Wind230° @ 23 kt, gusting 33 kt
Visibility10 sm
CeilingNone
Temperature / Dew Point57
Altimeter29.00 inHg
Observation Time18:45
Weather SourceWFAC