- Date
- July 1, 1991, 15:00 local (21:00 UTC)
- Place
- Grand Junction, CO
- Injuries
- 3 uninjured
- Damage
- Substantial damage
- Phase of flight
- Enroute
- Aircraft
- N20703Bell 412
- Weather
- Visual (VMC) · Day
- Status
- Completed · report February 8, 1993
- Report
- Approved by Office Director
- FAA report
- 19910701025659A
- Case key
- 18109
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 pilot's failure to maintain adequate main rotor RPM prior to touchdown. Factors were: the disconnected engine to transmission drive shaft and the inadequate inspection by company maintenance personnel.
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
During cruise flight, the engine to transmission drive shaft forward coupling overheated and failed. The pilot execute an autoratation. During the landing flare, the pilot did not maintain adequate rotor RPM and the helicopter landed hard resulting in skid collapse. Company maintenance personnel dispatched the helicopter with a known drive shaft coupling grease leak which they had attempted to stop by using an unapproved silicon sealant. They had repacked the 500 plus hour coupling two times prior to the accident. The normal repack interval was once every 600 hours. Examination of the failed drive shaft did not reveal any misalignment, but did isolate heat related failure areas of the forward coupling end.
Aircraft
- Registration
- N20703
- Reported as
- Bell 412
- Category
- Helicopter
- Serial number
- 33017
- Engine
- P&W PT6T-3B, 1,350 horsepower, turbo shaft
- Damage
- Substantial damage
- Flight
- Positioning · Part 91
- Operator
- Air Methods Corporation
- Registered owner
- Air Methods Corporation
- Departed
- GJT · Grand Junction, CO
- Destination
- U43 · Monticello, UT
Flight crew
As NTSB recorded them. NTSB leaves out names.
- Role
- Pilot
- Age
- 42
- Certificate
- Airline transport
- Airplane ratings
- Multi-engine land
- Instrument ratings
- Helicopter
- Medical
- Class 1, Valid Medical--no waivers/lim.
- Flight hours
- 4,010 total · 300 in this make and model · 2,500 as pilot in command · 40 in the last 90 days · 12 in the last 30 days · 2 in the last 24 hours
Weather
- Conditions
- Visual (VMC) · Day
- Wind
- 180° at 7 knots
- Visibility
- 70 statute miles
- Lowest ceiling
- None
- 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.