- Date
- April 30, 1992, 10:45 local (15:45 UTC)
- Place
- Dousman, WI
- Injuries
- 1 serious, 1 minor
- Damage
- Substantial damage
- Phase of flight
- Enroute
- Aircraft
- N52HBBell 47-G2A
- Weather
- Visual (VMC) · Day
- Status
- Completed · report July 29, 1993
- Report
- Approved by Office Director
- FAA report
- 19920430012239A
- Case key
- 15435
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 in-flight loss of the swash plate drive link bolt which allowed the swash plate drive assembly to disconnect.
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
The flight instructor (CFI) reported the dual instructional flight proceeded without incident for the first hour. While returning to the airport in cruise flight, a sudden and very violent vibration occurred. The CFI took the flight controls and began an autorotation to an off-airport site, striking trees during the descent. Inspection of the rotor head discovered a missing swash plate drive link bolt, which allowed the drive link to disconnect. Both the CFI and student recalled checking the bolt and associated nut and cotter pin prior to the flight and found no anomalies. The bolt was never located.
Aircraft
- Registration
- N52HB
- Reported as
- Bell 47-G2A
- Category
- Helicopter
- Serial number
- 3244
- Airframe hours
- 8,600
- Engine
- Lycoming VO-435-A1F, 240 horsepower, reciprocating
- Damage
- Substantial damage
- Flight
- Instructional · Part 91
- Operator
- Mc Dermott Enterprises, Inc., doing business as Ideal Helicopter Service
- Registered owner
- Mc Dermott Enterprises, Inc.
- Airworthiness certificate
- Standard, Normal
- Last inspection
- 100 hour · February 7, 1992 · 94 hours before
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
- 51
- Certificates
- Flight instructor, Commercial
- Airplane ratings
- Multi-engine land, Single-engine land
- Instrument ratings
- Helicopter, Airplane
- Medical
- Class 2, Valid Medical--w/ waivers/lim
- Seat
- Right
- Flight hours
- 17,000 total · 5,000 in this make and model
Weather
- Conditions
- Visual (VMC) · Day
- Wind
- 50° at 10 knots
- Visibility
- 8 statute miles
- Lowest ceiling
- None
- Temperature
- 55 °F
- Altimeter
- 30.00 inHg
- Observed at
- UES, 10 nm away
FAA reports on this event · 1
The FAA’s own accident and incident reports, matched to the aircraft by N-number and date.