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NTSB Report
September 28, 1989 · Hiller UH-12E · N4028T
Hudsonville, MI
Overview
Report Status
Probable Cause
Event Type
Accident
Date
September 28, 1989
Injury Outcomes
1 injury (1 minor injury)
Location
Hudsonville, MI
Aircraft
Hiller UH-12E
Tail Number
N4028T
Injuries
Minor
Aircraft Damage
Substantial
NTSB Number
CHI89DEM09
APPROXIMATELY 10 MINUTES AFTER TAKEOFF AT AN ALTITUDE OF 300 FT AGL AND AN AIRSPEED OF 60 KTS, THE PILOT EXPERIENCED A SEVERE VIBRATION AND A DECREASE IN RESPONSE TO CONTROL INPUTS. THE PILOT ENTERED AN AUTOROTATION AND WHEN APPROXIMATELY 10 - 15 FT AGL, THE TAIL BOOM WAS SEPARATED BY THE MAIN ROTOR. THE HELICOPTER THEN DESCENDED, NOSE FIRST, TO TERRAIN IMPACT. INSPECTION REVEALED A TENSION-TORSION PIN HAD FAILED AT THE DRAG BRACE BOLT HOLE. PRE-EXISTING CRACKS WERE FOUND EXTENDING FROM THE PIN SHANK TO THE BOLT HOLE.
NTSB Probable Cause
THE FATIGUE FAILURE OF ONE OF THE TENSION-TORSION PINS.
Full Narrative
APPROXIMATELY 10 MINUTES AFTER TAKEOFF AT AN ALTITUDE OF 300 FT AGL AND AN AIRSPEED OF 60 KTS, THE PILOT EXPERIENCED A SEVERE VIBRATION AND A DECREASE IN RESPONSE TO CONTROL INPUTS. THE PILOT ENTERED AN AUTOROTATION AND WHEN APPROXIMATELY 10 - 15 FT AGL, THE TAIL BOOM WAS SEPARATED BY THE MAIN ROTOR. THE HELICOPTER THEN DESCENDED, NOSE FIRST, TO TERRAIN IMPACT. INSPECTION REVEALED A TENSION-TORSION PIN HAD FAILED AT THE DRAG BRACE BOLT HOLE. PRE-EXISTING CRACKS WERE FOUND EXTENDING FROM THE PIN SHANK TO THE BOLT HOLE.
Flight
Event TypeAccident
Event Time07:45 EDT
Nearest Airport0nm N
Runway0
Flight Plan FiledNone
Aircraft FireNo
Aircraft ExplosionNo
Aircraft
AircraftHiller UH-12E
Tail NumberN4028T
Aircraft CategoryHeli
DamageSubstantial
Operating RulePart 137
Engines1
Engine TypeReciprocating
Engine DetailsLycoming · VO-540-C2A · Reciprocating · 305
Seats3
People & Injuries
Injury Summary1 injury (1 minor injury)
Fatal0
Serious0
Minor1
Uninjured0
Total1
Crew 1Age 42 · First Class
Conditions
ConditionsVMC
LightDaylight
Wind210° @ 7 kt
Visibility15 sm
CeilingNone
Temperature / Dew Point46 / 39 C
Altimeter30.00 inHg
Observation Time11:50
Weather SourceWFAC