- Date
- May 18, 1994, 18:30 local (23:30 UTC)
- Place
- Sulphur, OK
- Injuries
- 1 uninjured
- Damage
- Substantial damage
- Phase of flight
- Maneuvering
- Aircraft
- N933BBell 47G
- Weather
- Visual (VMC) · Day
- Status
- Completed · report November 14, 1994
- Report
- Approved by Office Director
- FAA report
- 19940518011819A
- Case key
- 19061
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 loss of engine power due to the failure of an engine accessory oil pump gear. A factor was the lack of suitable terrain for the autorotation.
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
A total loss of engine power occurred at 50 feet above the ground during the initial phase of a turn-around maneuver. Trees hindered the pilot's completion of the autorotation. The helicopter bounced during the landing and the main rotor blade flexed and severed the tailboom. An examination of the engine by the operator revealed the failure of an engine accessory oil pump gear.
Factual narrative
On May 18, 1994, at 1830 central daylight time, a Bell 47G, N933B, sustained substantial damage during a forced landing near Sulphur, Oklahoma. The commercial pilot did not receive injuries. Visual meteorological conditions prevailed for the local aerial application flight.
The pilot reported a total loss of engine power at 50 feet above the ground during the initial phase of a turn-around maneuver. He further said that trees in the area and the height of the helicopter hindered his completion of a successful autorotation. The helicopter bounced during the hard landing and the main rotor blade flexed and severed the tailboom.
During a telephone interview the operator reported the total loss of engine power was due to the failure of the oil pump drive gear in the accessory case.
Aircraft
- Registration
- N933B
- Reported as
- Bell 47G
- Category
- Helicopter
- Serial number
- 662
- Engine
- Franklin 6V-335-A, 210 horsepower, reciprocating
- Damage
- Substantial damage
- Flight
- Aerial application · Part 137
- Registered owner
- B & S Flying Service, Inc.
- Airworthiness certificate
- Special, Restricted (Special)
- Last inspection
- Annual · May 5, 1994 · 21 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
- 27
- Certificate
- Commercial
- Airplane ratings
- Single-engine land, Multi-engine land
- Instrument ratings
- Airplane
- Medical
- Class 2, Valid Medical--no waivers/lim.
- Seat
- Right
- Flight hours
- 1,618 total · 1,164 in this make and model · 1,488 as pilot in command
Weather
- Conditions
- Visual (VMC) · Day
- Wind
- 60° at 3 knots
- Visibility
- 10 statute miles
- Lowest ceiling
- None
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 N933B · 1
Matched to the same aircraft by N-number and date.