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NTSB Report
January 30, 1990 · Mbb BK-117A-1 · N117M
Janesville, WI
Overview
Report Status
Probable Cause
Event Type
Accident
Date
January 30, 1990
Injury Outcomes
No injuries (2 uninjured)
Location
Janesville, WI
Aircraft
Mbb BK-117A-1
Tail Number
N117M
Operator
Omni Flight Helicopters
Injuries
None
Aircraft Damage
Substantial
NTSB Number
CHI90LA074
THE PILOT STATED THAT HE AND A COMPANY MECHANIC WERE IN CRUISE FLIGHT AT 2,000 FEET MSL ON A MAINTENANCE FLIGHT TEST, WHEN HE HEARD A NOISE, 'OBSERVED DEBRIS IN ALL DIRECTIONS FROM THE MAIN ROTOR...(AND) SEVERE VIBRATION WAS EXPERIENCED.' THE PILOT MADE AN EMERGENCY LANDING IN A SNOW-COVERED FIELD. POST-ACCIDENT EXAMINATION REVEALED THAT THE ENGINE COWLING ON THE LEFT SIDE OF THE AIRCRAFT HAD SEPARATED WHILE IN FLIGHT, CONTACTING AND DAMAGING THE MAIN ROTOR BLADES. SEVERAL PIECES OF THE SEPERATED COWLING WERE RECOVERED AND INSPECTED. THE LATCHES SHOWED NO MALFORMATION/STRETCHING, AND APPEARED TO BE CAPABLE OF NORMAL OPERATION.
NTSB Probable Cause
THE PILOT-IN-COMMAND FAILED TO ENSURE THAT THE ENGINE COWLING LATCHES WERE PROPERLY SECURED PRIOR TO DEPARTING ON THE MAINTENANCE TEST FLIGHT; THE COWLING CAME LOOSE DURING FLIGHT, AND CONTACTED THE MAIN ROTOR BLADES BEFORE IT SEPARATED FROM THE HELICOPTER.
Full Narrative
THE PILOT STATED THAT HE AND A COMPANY MECHANIC WERE IN CRUISE FLIGHT AT 2,000 FEET MSL ON A MAINTENANCE FLIGHT TEST, WHEN HE HEARD A NOISE, 'OBSERVED DEBRIS IN ALL DIRECTIONS FROM THE MAIN ROTOR...(AND) SEVERE VIBRATION WAS EXPERIENCED.' THE PILOT MADE AN EMERGENCY LANDING IN A SNOW-COVERED FIELD. POST-ACCIDENT EXAMINATION REVEALED THAT THE ENGINE COWLING ON THE LEFT SIDE OF THE AIRCRAFT HAD SEPARATED WHILE IN FLIGHT, CONTACTING AND DAMAGING THE MAIN ROTOR BLADES. SEVERAL PIECES OF THE SEPERATED COWLING WERE RECOVERED AND INSPECTED. THE LATCHES SHOWED NO MALFORMATION/STRETCHING, AND APPEARED TO BE CAPABLE OF NORMAL OPERATION.
Flight
Event TypeAccident
Event Time13:10 CST
Nearest Airport0nm N
Runway0
Runway Length0
Runway Width0
Flight Plan FiledNone
Aircraft FireNo
Aircraft ExplosionNo
Aircraft
AircraftMbb BK-117A-1
Tail NumberN117M
Aircraft CategoryHeli
DamageSubstantial
OperatorOmni Flight Helicopters
Operating RulePart 91
Engines2
Engine TypeTurboshaft
Engine DetailsLycoming · LTS-101-650B1 · Turboshaft · 600
Seats8
People & Injuries
Injury SummaryNo injuries (2 uninjured)
Fatal0
Serious0
Minor0
Uninjured2
Total2
Crew 1Age 36 · Second Class
Conditions
ConditionsVMC
LightDaylight
Wind280° @ 18 kt, gusting 25 kt
Visibility15 sm
CeilingNone
Temperature / Dew Point41 C / 0 C
Altimeter29.00 inHg
Weather SourcePILO