# NTSB SEA99LA092: Hughes 369D, N1089Y, Shelton, WA, June 22, 1999 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: June 22, 1999, 14:30 local (21:30 UTC) - Place: Shelton, WA - Location: 47.2336° N, 123.1476° W: Placed by OpenAirDocs at SANDERSON FLD (SHN), within about a mile (OpenAirDocs) - Nearby events: https://openairdocs.org/map.md?lat=47.2336&lon=-123.1476&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report August 3, 2000 - Report: Approved by Office Director - NTSB case key (mKey): 46656 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=SEA99LA092 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/46656/pdf - Page: https://openairdocs.org/ntsb/SEA99LA092 ## Probable cause The pilot's failure to maintain rotor RPM during an autorotation. ## Analysis The pilot was practicing autorotations from an altitude of approximately 200 feet above ground level (AGL) and an airspeed of approximately 50 knots. During the second practice autorotation, the pilot reduced power with throttle and used collective to adjust rotor speed to 410 RPM (minimum RPM for practice autorotations). The rotor RPM decreased below 410 RPM and the aircraft rapidly started to descend. Before the pilot was able to recover, the aircraft collided with the ground and rolled over. The aircraft sustained substantial damage to the main rotor blades, tail rotor, tail boom and fuselage. The pilot reported no mechanical failures or malfunctions with the aircraft at the time of the accident. ## Factual narrative On June 22, 1999, about 1430 Pacific daylight time, a Hughes 369D, N1089Y, registered to and operated by Olympic Air, Incorporated, was substantially damaged during landing following a practice autorotation. The accident occurred at Shelton Airport, Shelton, Washington. The commercial pilot, the sole occupant of the aircraft, was not injured. A company VFR flight plan was filed and visual meteorological conditions prevailed for this 14CFR91 flight. The flight originated from Rockaway, Oregon, approximately one hour prior to the accident. The pilot stated he was practicing autorotations from an altitude of approximately 200 feet above ground level (AGL) and an airspeed of approximately 50 knots. During the second practice autorotation, the pilot reduced power with throttle and used collective to adjust rotor speed to 410 RPM (minimum RPM for practice autorotations). The pilot stated the rotor RPM "quickly" decayed and the aircraft rapidly started to descend. Before the pilot was able to recover, the aircraft collided with the ground and rolled over. The aircraft sustained substantial damage to the main rotor blades, tail rotor, tail boom and fuselage. The pilot reported no mechanical failures or malfunctions with the aircraft at the time of the accident. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Hard landing, landing - flare/touchdown - autorotation - performed, pilot in command - rotor rpm - inadequate, pilot in command (cause) ## Aircraft - Registration: [N1089Y](https://openairdocs.org/deregistered/N1089Y-2020-08-15), registration cancelled 2020-08-15, S/N 510962D, built 1981 (OpenAirDocs) - Reported make and model: Hughes 369D - Registry model: [Hughes Helicopters HUGHES 369D](https://openairdocs.org/model/hughes-helicopters-hughes-369d) (registry code 4470706) (OpenAirDocs) - Registry engine: [Allison 250 SER 250HP](https://openairdocs.org/engine/allison-250-ser-250hp) (registry code 03002, turbo-shaft) (OpenAirDocs) - Category: Helicopter - Serial number: 510962D - Airframe hours: 15399 - Engines: Allison C20-B 420 horsepower turbo shaft - Damage: Substantial damage - Flight: Business, Part 91 - Registered owner: Olympic Air Inc. - Airworthiness certificate: Standard, Normal - Last inspection: Annual, June 10, 1999, 59 hours before - Departed: ROCKAWAY, OR - Destination: SHN, WA - Flight plan: Company VFR - Airport: SHN, Sanderson Field ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 41; commercial, private; airplane ratings: single-engine land; medical: class 2, valid medical--no waivers/lim.; seat: left; toxicology performed; flight hours: 8,000 total, 5,000 in this make and model, 7,900 as pilot in command, 160 in the last 90 days, 91 in the last 30 days, 1 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 220° at 17 knots, gusting 24 - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 63 °F - Altimeter: 30.00 inHg - Observed at: KLS ## 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 19990622007449A](https://openairdocs.org/incident/19990622007449A), Jun 22, 1999: Hughes 369D, Shelton, WA, Destroyed. 1981 Hughes 369D helicopter landed hard during a simulated engine failure and was destroyed, other circumstances are unknown. (-23) the pilot was practicing… 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.