- Date
- May 22, 1992, 11:30 local (18:30 UTC)
- Place
- Glendale, AZ
- Injuries
- 2 uninjured
- Damage
- Substantial damage
- Phase of flight
- Enroute
- Aircraft
- N7656TCobb Intl Exec 90
- Weather
- Visual (VMC) · Day
- Status
- Completed · report September 28, 1993
- Report
- Approved by Office Director
- Case key
- 27622
From the NTSB’s public API. By law, NTSB reports can’t be used as evidence in lawsuits over the accident.
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Probable cause
The improper carburetor idle adjustment by company maintenance personnel. Contributing to this accident was the cfi's inability to attain adequate RPM and the soft dirt.
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 departed the airport on a local instructional flight. When the flight returned to the airport the CFI instructed the noncertificated student pilot to execute a simulated engine out autorotation. The student pilot entered the autorotation at a low main rotor RPM, but during the descent the RPM increased to the low side of its normal operating range. The CFI attempted to terminate the autorotation at 200 feet AGL because of the marginal low rotor RPM, but when he applied rapid full throttle the engine faltered and then failed. The CFI executed an emergency autoroative landing. On touchdown the helicopter bounced, the skids dug into the soft dirt on the second touchdown and the helicopter came to an abrupt stop and rolled over. The post accident engine examination disclosed that the engine operated normally throughout its normal operational parameters but when the throttle was rapidly applied after a prolonged idle the engine faltered. The idle RPM was marginal and the carburetor had recently been replaced.
Aircraft
- Registration
- N7656T
- Reported as
- Cobb Intl Exec 90
- Category
- Helicopter, amateur-built
- Serial number
- RI-5001
- Airframe hours
- 235
- Engine
- Rotorway RI-162, 150 horsepower, reciprocating
- Damage
- Substantial damage
- Flight
- Instructional · Part 91
- Operator
- Cobb International, Inc., doing business as Rotorway International
- Registered owner
- Cobb International, Inc.
- Airworthiness certificate
- Special, Experimental (Special)
- Last inspection
- Continuous airworthiness · April 24, 1992 · 38 hours before
- Airport
- GEU · Glendale Muni Airport, runway 19, 5,350 × 75 ft, asphalt
Flight crew
As NTSB recorded them. NTSB leaves out names.
- Role
- Pilot
- Age
- 36
- Certificates
- Commercial, Flight instructor
- Airplane ratings
- Single-engine land
- Medical
- Class 2, Valid Medical--no waivers/lim.
- Seat
- Right
- Flight hours
- 695 total · 246 in this make and model · 615 as pilot in command · 174 in the last 90 days · 57 in the last 30 days · 5 in the last 24 hours
Weather
- Conditions
- Visual (VMC) · Day
- Wind
- Calm
- Visibility
- 35 statute miles
- Lowest ceiling
- None
- Temperature
- 81 °F