# NTSB FTW94LA304: Mooney, Dan Rotorway Exec 90, N92RE, Owasso, OK, September 16, 1994 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: September 16, 1994, 15:30 local (20:30 UTC) - Place: Owasso, OK - Coordinates: 36.280864, -95.829414 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=36.2809&lon=-95.8294&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report March 27, 1995 - Report: Approved by Office Director - NTSB case key (mKey): 19165 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=FTW94LA304 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/19165/pdf - Page: https://openairdocs.org/ntsb/FTW94LA304 ## Probable cause THE FLIGHT INSTRUCTOR'S INADEQUATE SUPERVISION OF THE STUDENT. A FACTOR WAS THE STUDENT'S FAILURE TO MAINTAIN ADEQUATE ROTOR RPM. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of control - in flight, hover - adequate rotor rpm - not maintained, dual student (contributing factor) - supervision - inadequate, pilot in command(cfi) (cause) - In flight collision with terrain/water, descent - uncontrolled - Roll over, landing - flare/touchdown ## Analysis THE STUDENT PILOT WAS PRACTICING HOVERING. A LEFT YAW DEVELOPED AND THE INSTRUCTOR ADDED FULL THROTTLE AND RIGHT PEDAL; HOWEVER, THE LEFT YAW INCREASED IN SEVERITY. THE COLLECTIVE WAS LOWERED AND THE RIGHT SKID CONTACTED THE GROUND. THE HELICOPTER ROLLED TO THE RIGHT, SEVERING ONE MAIN ROTOR BLADE AND BENDING THE TAILBOOM. ## Factual narrative On September 16, 1994, at 1530 central daylight time, a Rotorway Exec 90 homebuilt helicopter, N92RE, was substantially damaged while landing at Gundy's Airport, Owasso, Oklahoma. The helicopter, flown by a helicopter instructor pilot, was on an instructional flight. There was no flight plan filed and visual meteorological conditions prevailed. The pilot and student were uninjured. The instructor pilot reported the following information. The student was practicing hovering using the collective, throttle, and anti-torque pedals while the instructor controlled the cyclic. A left yaw developed and the instructor noticed the engine RPM in the lower portion of the green arc. The instructor then added full throttle and right pedal, but the left yaw continued to increase in severity. At this point the collective was lowered until the skids contacted the ground. The right skid contacted first, the helicopter then rolled to the right, severing one main rotor blade and bending the tailboom. The aircraft came to rest on its right side. The instructor pilot also stated that the hover seemed normal until the left yaw occurred and there were no low RPM indications such as collective position or sound. He believed the yaw was caused by either low main rotor RPM or possibly by low tail rotor RPM resulting from belt slippage or an unknown cause. An examination of the helicopter by a Federal Aviation Administration inspector revealed no mechanical anomalies that could have contributed to the mishap. ## Aircraft - Registration: [N92RE](https://openairdocs.org/deregistered/N92RE-2013-05-23), registration cancelled 2013-05-23, S/N 5144 (OpenAirDocs) - Reported make and model: MOONEY, DAN ROTORWAY EXEC 90 (ROTORWAY E) - Registry model: [Mooney Dan ROTORWAY EXEC 90](https://openairdocs.org/model/mooney-dan-rotorway-exec-90) (registry code 05623RP) (OpenAirDocs) - Category: Helicopter, amateur-built - Serial number: 5144 - Airframe hours: 63 - Engines: ROTORWAY RI 162 reciprocating - Damage: Substantial damage - Flight: Instructional, Part 91 - Registered owner: Stewart, Bryon R. - Airworthiness certificate: Special, Experimental (Special) - Last inspection: Annual, April 4, 1994, 13 hours before - Departed: OK16 - Destination: OK16, OK - Airport: OK16, Gundy'S, runway 35, 1,900 × 100 ft, grass/turf ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 60; flight instructor, commercial; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane, helicopter; medical: class 2, valid medical--w/ waivers/lim; seat: right; flight hours: 8,457 total, 7 in this make and model, 6,363 as pilot in command, 82 in the last 90 days, 28 in the last 30 days, 1 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 360° at 10 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 82 °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 19940916029189A](https://openairdocs.org/incident/19940916029189A), Sep 16, 1994: Amtr ROTORWAYEXEC, Owasso, OK, Substantial damage. Hovering. Yaw began. Low RPM. CFI added power and pedal. Skid touched runway. Exec rolled over. No anomalies. 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.