- Date
- April 11, 1989, 10:31 local (15:31 UTC)
- Place
- Milwaukee, WI
- Injuries
- 1 serious
- Damage
- Substantial damage
- Phase of flight
- Maneuvering
- Aircraft
- N4247USikorsky S-58T
- Weather
- Visual (VMC) · Day
- Status
- Completed · report June 30, 1992
- Report
- Approved by Office Director
- FAA report
- 19890411007609A
- Case key
- 14250
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
Disconnect of the tailrotor drive shaft coupling.
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 accident helicopter descended into sloping terrain and rolled over while performing external load operations. The helicopter had just picked up a load and was moving laterally when it sustained a loss of anti-torque control and the fuselage started an uncommanded and uncontrolled rotation to the right. The PIC was able to jettison his external load into a clear area and move the helicopter away from obstructions before initiating an out of ground effect hovering autorotation.
Aircraft
- Registration
- N4247U
- Reported as
- Sikorsky S-58T
- Category
- Helicopter
- Serial number
- 58-1537
- Airframe hours
- 4,326
- Engine
- P&W PT6T-6, 970 horsepower, turbo shaft
- Damage
- Substantial damage
- Flight
- Other work use · Part 133
- Registered owner
- Midwest Truxton
- Airworthiness certificate
- Standard, Transport
- Last inspection
- Continuous airworthiness · March 15, 1989 · 17 hours before
- Departed
- MKE · Milwaukee, WI
Flight crew
As NTSB recorded them. NTSB leaves out names.
- Role
- Pilot
- Age
- 44
- Certificate
- Commercial
- Instrument ratings
- Helicopter
- Medical
- Class 2, Valid Medical--no waivers/lim.
- Seat
- Right
- Flight hours
- 9,562 total · 3,400 in this make and model · 8,275 as pilot in command · 99 in the last 90 days · 48 in the last 30 days · 3 in the last 24 hours
Weather
- Conditions
- Visual (VMC) · Day
- Wind
- 210° at 10 knots, gusting 20
- Visibility
- 7 statute miles
- Lowest ceiling
- 25,000 ft overcast
- Temperature
- 43 °F, dew point 18 °F
- Altimeter
- 30.00 inHg
- Observed at
- MKE, 3 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.