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NTSB Report
February 29, 1992 · Enstrom TH-28 · N8631E
Leadville, CO
Overview
Report Status
Probable Cause
Event Type
Accident
Date
February 29, 1992
Injury Outcomes
No injuries (1 uninjured)
Location
Leadville, CO
Aircraft
Enstrom TH-28
Tail Number
N8631E
Operator
Enstrom Helicopter
Injuries
None
Aircraft Damage
Substantial
NTSB Number
DEN92LA036
THIS WAS ONE OF A SERIES OF EXPERIMENTAL TEST FLIGHTS LEADING TOWARDS FAA CERTIFICATION OF THE MODIFIED HELICOPTER. DATA POINTS FOR THE HEIGHT VELOCITY CURVE HAD BEEN COLLECTED AND THE PILOT WAS ATTEMPTING TO CONFIRM THEIR ACCURACY. AT 46 KNOTS AND 400 FEET AGL, THE PILOT MADE AN INTENTIONAL AUTOROTATION. HE SAID THE SINK RATE WAS HIGHER THAN PREVIOUSLY NOTED, AND HEAVY ROTOR BLADE STALL MADE THE FLARE INEFFECTIVE. THE PILOT SAID A DOWNDRAFT MAY HAVE PRECIPITATED THE ACCIDENT.
NTSB Probable Cause
THE PILOT MISJUDGING THE DESCENT RATE AND CONSEQUENTLY DELAYING THE FLARE. A FACTOR WAS: DOWNDRAFT.
Full Narrative
THIS WAS ONE OF A SERIES OF EXPERIMENTAL TEST FLIGHTS LEADING TOWARDS FAA CERTIFICATION OF THE MODIFIED HELICOPTER. DATA POINTS FOR THE HEIGHT VELOCITY CURVE HAD BEEN COLLECTED AND THE PILOT WAS ATTEMPTING TO CONFIRM THEIR ACCURACY. AT 46 KNOTS AND 400 FEET AGL, THE PILOT MADE AN INTENTIONAL AUTOROTATION. HE SAID THE SINK RATE WAS HIGHER THAN PREVIOUSLY NOTED, AND HEAVY ROTOR BLADE STALL MADE THE FLARE INEFFECTIVE. THE PILOT SAID A DOWNDRAFT MAY HAVE PRECIPITATED THE ACCIDENT.
Flight
Event TypeAccident
Event Time10:22 MST
Nearest AirportLake County (0nm)
Runway34
Runway Length5300 ft
Runway Width75 ft
Flight Plan FiledNone
Aircraft FireNo
Aircraft ExplosionNo
Aircraft
AircraftEnstrom TH-28
Tail NumberN8631E
Aircraft CategoryHeli
DamageSubstantial
OperatorEnstrom Helicopter
Operating RulePart 91
Engines1
Engine TypeTurboshaft
Engine DetailsAllison · 250-C20W · Turboshaft · 420
Seats3
People & Injuries
Injury SummaryNo injuries (1 uninjured)
Fatal0
Serious0
Minor0
Uninjured1
Total1
Crew 1Age 46 · First Class
Conditions
ConditionsVMC
LightDaylight
Wind340° @ 5 kt
Visibility30 sm
CeilingNone
Temperature / Dew Point39 C / 21 C
Altimeter30.00 inHg
Weather SourceWIT