- Date
- October 28, 1991, 19:15 local (Oct 29, 1991, 02:15 UTC)
- Place
- Billings, MT
- Injuries
- 3 uninjured
- Damage
- Substantial damage
- Phase of flight
- Enroute
- Aircraft
- N101UCAerospatiale AS355F1
- Weather
- Visual (VMC) · Night/dark
- Status
- Completed · report May 27, 1993
- Report
- Approved by Office Director
- FAA report
- 19911028054699A
- Case key
- 41617
From the NTSB’s public API. By law, NTSB reports can’t be used as evidence in lawsuits over the accident.
On this page
Probable cause
The unlatching and subsequent opening inflight of the left-rear engine cowl door. A factor contributing to the accident was the failure of company maintenance personnel to execute the manufacturer's service bulletin.
Sequence of events
NTSB’s coding before 2008: each occurrence and phase of flight, and the causes and factors under it. The codes are defined in NTSB’s coding manual.
Analysis
Shortly after the company initiated abort of the medevac flight, the flight crew of the aerospatiale AS355 felt a shudder which they attributed to gusty wind conditions. Upon landing at Billings international airport, Montana, a portion of the left-rear engine cowl door was found to be separated, along with damage to the main rotor blades necessitating replacement of the blades. The crew had previously notified company personnel of the cowl door latch problem and had preflighted the cowl prior to the accident flight. The manufacturer was aware of the problem and had issued a relevant service bulletin. The service bulletin had not been implemented on the accident aircraft.
Aircraft
- Registration
- N101UC
- Reported as
- Aerospatiale AS355F1
- Category
- Helicopter
- Serial number
- 5186
- Engine
- Allison 250-C20, 420 horsepower, turbo shaft
- Damage
- Substantial damage
- Flight
- Part 91
- Operator
- Omni Flight Helicopters, Inc
- Departed
- MT25 · Billings, MT
- Flight plan
- Company VFR
Matched to the registry by N-number and the event date; the registry’s history has gaps, so older matches can be wrong. Compare the reported make and model.
Flight crew
As NTSB recorded them. NTSB leaves out names.
- Role
- Pilot
- Age
- 46
- Certificate
- Commercial
- Airplane ratings
- Single-engine land
- Instrument ratings
- Helicopter, Airplane
- Medical
- Class 2, Valid Medical--no waivers/lim.
- Flight hours
- 2,826 total · 154 in this make and model · 2,513 as pilot in command · 59 in the last 90 days · 21 in the last 30 days
Weather
- Conditions
- Visual (VMC) · Night/dark
- Wind
- 220° at 4 knots
- Visibility
- 20 statute miles
- Lowest ceiling
- 2,800 ft broken
- Temperature
- -0 °F, dew point -0 °F
FAA reports on this event · 1
The FAA’s own accident and incident reports, matched to the aircraft by N-number and date.
Other investigations on N101UC · 2
Matched to the same aircraft by N-number and date.