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NTSB Report
February 20, 1991 · Hughes 269C · N8955F
North Mankato, MN
Overview
Report Status
Probable Cause
Event Type
Accident
Date
February 20, 1991
Injury Outcomes
3 injuries (2 serious injuries, 1 minor injury)
Location
North Mankato, MN
Aircraft
Hughes 269C
Tail Number
N8955F
Operator
Helicopter Flight
Injuries
Serious
Aircraft Damage
Destroyed
NTSB Number
CHI91LA097
THE PILOT REPORTED THAT DURING THE AERIAL OBSERVATION FLIGHT HE HEARD A LOUD NOISE FROM THE BACK OF THE HELICOPTER. THE HELICOPTER THEN BEGAN ROTATING CLOCKWISE AND DESCENDED TO IMPACT WITH THE TERRAIN IN A WOODED AREA. POST ACCIDENT IMSPECTION REVEALED A FATIGUE FAILURE OF THE TAIL BOOM SUPPORT STRUT CLUSTER FITTING (LEFT SIDE). AN AIRWORTHINESS DIRECTIVE ISSUED IN 1976 CALLED FOR A DAILY VISUAL INSPECTION AND A 200 HOUR DYE PENETRANT INSPECTION OF THE FITTING. A LOGBOOK ENTRY DATE AUGUST 15, 1990, STATED ALL AD'S HAD BEEN COMPLIED WITH.
NTSB Probable Cause
THE FATIQUE FAILURE OF THE TAIL BOOM SUPPORT STRUT ATTACHMENT CLUSTER AND THE IMPROPER INSPECTION OF THE CLUSTER ATTACHMENT.
Full Narrative
THE PILOT REPORTED THAT DURING THE AERIAL OBSERVATION FLIGHT HE HEARD A LOUD NOISE FROM THE BACK OF THE HELICOPTER. THE HELICOPTER THEN BEGAN ROTATING CLOCKWISE AND DESCENDED TO IMPACT WITH THE TERRAIN IN A WOODED AREA. POST ACCIDENT IMSPECTION REVEALED A FATIGUE FAILURE OF THE TAIL BOOM SUPPORT STRUT CLUSTER FITTING (LEFT SIDE). AN AIRWORTHINESS DIRECTIVE ISSUED IN 1976 CALLED FOR A DAILY VISUAL INSPECTION AND A 200 HOUR DYE PENETRANT INSPECTION OF THE FITTING. A LOGBOOK ENTRY DATE AUGUST 15, 1990, STATED ALL AD'S HAD BEEN COMPLIED WITH.
Flight
Event TypeAccident
Event Time10:00 CST
Nearest Airport0nm N
Runway0
Flight Plan FiledNone
Aircraft FireNo
Aircraft ExplosionNo
Aircraft
AircraftHughes 269C
Tail NumberN8955F
Aircraft CategoryHeli
DamageDestroyed
OperatorHelicopter Flight
Operating RulePart 91
Engines1
Engine TypeReciprocating
Engine DetailsLycoming · HIO-360-D1A · Reciprocating · 190
Seats3
People & Injuries
Injury Summary3 injuries (2 serious injuries, 1 minor injury)
Fatal0
Serious2
Minor1
Uninjured0
Total3
Crew 1Age 41 · Second Class
Conditions
ConditionsVMC
LightDaylight
Wind210° @ 6 kt
Visibility15 sm
CeilingOvercast 10000 ft
Temperature / Dew Point0 C / 0 C
Altimeter0