# NTSB IAD97LA028: Hughes 269C, N1105P, Mayfield, KY, December 4, 1996 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: December 4, 1996, 16:35 local (21:35 UTC) - Place: Mayfield, KY - Coordinates: 36.730258, -88.639068 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=36.7303&lon=-88.6391&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report March 31, 1998 - Report: Approved by Office Director - NTSB case key (mKey): 28164 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=IAD97LA028 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/28164/pdf - Page: https://openairdocs.org/ntsb/IAD97LA028 ## Probable cause disengagement of the main transmission aft pinion nut, allowing the tail rotor splined drive sleeve to disengage from the pinion, which resulted in loss of directional control and an emergency (autorotative) landing. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Airframe/component/system failure/malfunction, cruise - rotor drive system,tail rotor drive shaft - disengaged (cause) - directional control - not possible - Forced landing, emergency descent/landing - autorotation - performed, pilot in command - In flight collision with object, emergency landing - object - fence ## Analysis The pilot stated that the purpose of the flight was to ferry the helicopter. The helicopter had been cruising at 1,200 feet MSL for over an hour, when the nose started to yaw to the right. Unable to control the yaw, the pilot entered an autorotation at about 70 mph to a field. During the forced landing, the helicopter collided with a fence. Examination of the helicopter revealed that the aft pinion nut of the main transmission had disengaged, which allowed the tail rotor splined drive sleeve to disengage from the pinion and tail rotor drive shaft. Investigation did not determined why the aft pinion backed off. The last annual inspection was completed on 6/7/96. The helicopter had accumulated 66 hours of flight time, since the annual inspection. ## Factual narrative On December 4, 1996, at 1635 eastern standard time, a Hughes 269C, N1105P, was substantially damaged when it collided with a fence during a forced landing near Mayfield, Kentucky. The certificated commercial pilot and passenger were not injured. Visual meteorological conditions prevailed and a flight plan was not filed. The ferry flight was conducted under 14 CFR Part 91, and originated in Henning, Tennessee, at 1530. The intended destination was Indianapolis, Indiana. The pilot reported that he was ferrying the helicopter to the new owner. He said that the had been cruising at 1,200 feet MSL for about an hour, when the nose of the helicopter began to yaw to the right, followed by a change in aircraft noise. He attempted to correct the yaw by applying full left pedal, but was unsuccessful. He entered autorotation at about 70 mph, and attempted a forced landing to the middle of a field. During touchdown, the helicopter collided with a fence. The helicopter was examined after the accident by an FAA Inspector. The examination revealed that the aft pinion nut of the main transmission disengaged during flight, which disengaged the tail rotor splined drive sleeve from the pinion, and the tail rotor drive shaft. It was not determined why the aft pinion nut backed off causing the drive spline to disengage. The last annual inspection was completed on June 7, 1996, and the helicopter had accumulated 66 hours since the annual inspection. ## Aircraft - Registration: [N1105P](https://openairdocs.org/deregistered/N1105P-1997-03-05), registration cancelled 1997-03-05, S/N 211028 (OpenAirDocs) - Reported make and model: Hughes 269C - Registry model: [Hughes 269C](https://openairdocs.org/model/hughes-269c) (registry code 4470504) (OpenAirDocs) - Category: Helicopter - Serial number: 211028 - Airframe hours: 8640 - Engines: Lycoming HIO-360-D1A 190 horsepower reciprocating - Damage: Substantial damage - Flight: Ferry, Part 91 - Registered owner: Dr. Charles Hassel - Airworthiness certificate: Standard, Normal - Last inspection: Annual, June 7, 1996, 66 hours before - Departed: HENNING, TN - Destination: I21, INDIANAPOLIS, IN ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 32; commercial, flight instructor; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 2, valid medical--no waivers/lim.; seat: left; flight hours: 966 total, 119 in this make and model, 877 as pilot in command, 168 in the last 90 days, 61 in the last 30 days, 3 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 39 °F, dew point 36 °F - Altimeter: 30.00 inHg ## 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 19961204037109A](https://openairdocs.org/incident/19961204037109A), Dec 4, 1996: Hughes 269C, Mayfield, KY, Substantial damage. Helicopter experienced a power failure and skids struck a fence. (-23) pilot states that in cruise flight, approx. altitude 1500', he experienced loss of tail… 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.