# NTSB LAX97LA285: Bell 47G2, N9021R, Mojave, CA, August 12, 1997 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: August 12, 1997, 10:00 local (17:00 UTC) - Place: Mojave, CA - Coordinates: 35.070648, -118.179565 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=35.0706&lon=-118.1796&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report November 10, 1998 - Report: Approved by Office Director - NTSB case key (mKey): 29873 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX97LA285 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/29873/pdf - Page: https://openairdocs.org/ntsb/LAX97LA285 ## Probable cause The student's improper use of the throttle and collective controls and the flight instructor's inadequate supervision of the flight. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Hard landing, landing - flare/touchdown - throttle/power control - improper use of, dual student (cause) - collective - improper use of, dual student (cause) - rotor rpm - not maintained, dual student (cause) - supervision - inadequate, pilot in command(cfi) (cause) ## Analysis The dual student had a fixed wing pilot certificate issued by a foreign country, and no prior rotorcraft flight experience. The flight instructor reported that he was doing pattern work with the student and that he was 'guarding the controls while the left seat pilot was flying.' He further stated that on the third pattern, the student allowed the rpm to decrease and he cautioned the student to 'watch the RPM.' The student then raised the collective without adding additional throttle. As the instructor reached for the throttle, the student quickly raised the collective without any other action. The aircraft then yawed to the right and the rotor rpm decreased even further. The student then applied a rearward cyclic input in an attempt to flare the aircraft. The tail rotor struck the ground, destroying the tail rotor and shearing the tail rotor driveshaft. The aircraft touched down in a right turn and the skids collapsed. The instructor reported that during the accident sequence he was 'attempting to regain aircraft control while calling for [the student] to release the controls.' ## Factual narrative On August 12, 1997, at 1000 hours Pacific daylight time, a Bell 47G2, N9021R, landed hard on runway 4 at the Mojave, California, airport. The local area instructional flight was operated by National Test Pilot School of Mojave. Visual meteorological conditions prevailed at the time, including calm winds, and no flight plan was filed. The helicopter sustained substantial damage. The flight instructor and dual student onboard were not injured. The flight originated at Mojave about 0930 on the day of the accident. In his written report, the flight instructor reported that the dual student had a fixed wing pilot certificate issued by a foreign country, but no prior rotorcraft flight experience. The instructor reported that during their pattern work, he was "guarding the flight controls while the left seat pilot was flying." He further reported that on the third pattern the student allowed the rpm to decrease and the instructor cautioned him to "watch the RPM." The student then raised the collective control slightly without adding additional throttle. As the instructor reached for the throttle, the student quickly raised the collective without any other action. The aircraft yawed to the right, and the rotor rpm decreased even further. The student then applied a rearward cyclic input in an attempt to flare the aircraft. The tail rotor then struck the ground, destroying the tail rotor and shearing the tail rotor driveshaft. The aircraft touched down in a right turn and the skids collapsed. The instructor reported that during the accident sequence he was "attempting to regain aircraft control while calling for [the student] to release the controls." ## Aircraft - Registration: [N9021R](https://openairdocs.org/aircraft/N9021R), registered now, S/N CCI-165 (OpenAirDocs) - Reported make and model: Bell 47G2 - Registry model: [Bell-Continental Copters 47G2](https://openairdocs.org/model/bell-continental-copters-47g2) (registry code 1181069) (OpenAirDocs) - Registry engine: [Lycoming VO-435-A1F](https://openairdocs.org/engine/lycoming-vo-435-a1f) (registry code 42200, reciprocating) (OpenAirDocs) - Category: Helicopter - Serial number: CCI-165 - Airframe hours: 7751 - Engines: Lycoming VO-435-AIF 210 horsepower reciprocating - Damage: Substantial damage - Flight: Instructional, Part 91 - Operator: National Test Pilot School - Registered owner: Joseph Pike - Airworthiness certificate: Standard, Normal - Last inspection: 100 hour, July 20, 1997, 54 hours before - Departed: MHV - Airport: MHV, Mojave, runway 4, 3,960 × 50 ft, asphalt ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 45; airline transport, flight instructor; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 2, valid medical--no waivers/lim.; seat: right; flight hours: 3,273 total, 101 in this make and model, 1,633 as pilot in command, 88 in the last 90 days, 55 in the last 30 days, 3 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: calm - Visibility: 50 statute miles - Lowest ceiling: none - Temperature: 73 °F ## FAA reports on this event (1) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Accident 19970812021809A](https://openairdocs.org/incident/19970812021809A), Aug 12, 1997: Bell 47G2, Mojave, CA, Substantial damage. On August 12, 1997, at 1000 pacific daylight time, a Bell 47G2, N9021R, la ned hard on runway 4 at the Mojave, California airport. The local area instructional… ## Other investigations on N9021R (3) From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. - [NTSB CEN12LA120](https://openairdocs.org/ntsb/CEN12LA120), Jan 1, 2012: Continental Copters 47G2 (N9021R), Lohn, TX, substantial damage. Probable cause: The improper installation of the tail rotor gearbox by maintenance personnel, which led to accelerated wear of the ring and pinion gears, resulting in the loss of tail rotor effectiveness and… - [NTSB LAX99LA047](https://openairdocs.org/ntsb/LAX99LA047), Dec 12, 1998: Bell 47G2 (N9021R), Helendale, CA, substantial damage. Probable cause: The pilot's failure to follow proper procedures to recover from main rotor blade aerodynamic retreating blade stall. - [NTSB NYC72FHJ01](https://openairdocs.org/ntsb/NYC72FHJ01), Jul 11, 1971: Bell-Cci 47G2 (N9021R), Amityville, NY, substantial damage From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.