- Date
- September 30, 1997, 14:45 local (19:45 UTC)
- Place
- Pipestone, MN
- Injuries
- 1 serious
- Damage
- Substantial damage
- Phase of flight
- Maneuvering
- Aircraft
- N9005TBell 47
- Weather
- Visual (VMC) · Day
- Status
- Completed · report November 17, 1999
- Report
- Approved by Office Director
- FAA report
- 19970930029419A
- Case key
- 10713
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 fracture of the pitch control rod assembly.
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 pilot stated that while he was ferrying the helicopter to the next field he, 'heard a loud bang from behind.' He said that the cyclic control, 'jerked,' the helicopter began to vibrate, and the rotor RPM decreased. He increased the throttle, but the engine responded as if there was no load on the engine. He initiated autorotation, but was unable to regain control, and the aircraft impacted the terrain. Post accident investigation revealed that one of two pitch control rod assemblies had fractured between the clevis and turnbuckle. Examination of the fracture showed areas of fatigue striations and multiple crack initiation sites on the machined surface.
Factual narrative
On September 30, 1997, at 1445 central daylight time, a Bell 47, N9005T, registered to Aerial Blades, Inc., of Flandreau, South Dakota, piloted by a commercial pilot, impacted the terrain, while positioning the aircraft for an aerial application mission. The helicopter was substantially damaged. The pilot reported serious injuries. The local 14 CFR Part 137 flight was operating in visual meteorological conditions. No flight plan was on file. The flight originated from a farm field in Pipestone, Minnesota, exact time unknown.
The pilot stated, in an interview with the Federal Aviation Administration, that while he was ferrying the helicopter to the next field he, "heard a loud bang from behind." The pilot stated that the cyclic control, "jerked," helicopter began to vibrate, and rotor RPM decreased. The pilot stated that he increased the throttle, but the engine responded as if there was no load on the engine. The pilot initiated autorotation, but was unable to regain control, and the aircraft impacted the terrain.
Post accident investigation revealed that one of two pitch control rod assemblies had fractured between the clevis and turnbuckle. The Material Laboratory Division of the National Transportation Safety Board, Washington D.C., examined the fractured control rod assembly. Examination of the fracture showed areas of fatigue striations and multiple crack initiation sites on the machined surface. For additional information, see attached Material Laboratory Factual Report.
Aircraft
- Registration
- N9005T
- Reported as
- Bell 47
- Category
- Helicopter
- Serial number
- CCI-74-1
- Engine
- Lycoming VO-435, 260 horsepower, reciprocating
- Damage
- Substantial damage
- Fire
- On-Ground
- Flight
- Aerial application · Part 137
- Registered owner
- Aerial Blades, Inc.
- Airworthiness certificate
- Special, Restricted (Special)
- Last inspection
- Annual · April 29, 1997 · 367 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
- 29
- Certificate
- Commercial
- Airplane ratings
- Multi-engine land
- Instrument ratings
- Airplane
- Medical
- Class 2, Valid Medical--w/ waivers/lim
- Seat
- Center
- Flight hours
- 2,600 total · 30 in this make and model
Weather
- Conditions
- Visual (VMC) · Day
- Wind
- 260° at 6 knots
- Visibility
- 10 statute miles
- Lowest ceiling
- None
- Temperature
- 73 °F, dew point 37 °F
- Altimeter
- 30.00 inHg
- Observed at
- PQN
Docket · 2
The files NTSB released with the investigation on April 19, 1999, on NTSB’s docket system: statements, records, photos and specialists’ reports. 1.3 MB in all.
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 N9005T · 2
Matched to the same aircraft by N-number and date.