# NTSB SEA03LA156: Hughes 269C, N500HS, Marblemount, WA, July 25, 2003 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: July 24, 2003, 19:00 local (Jul 25, 2003, 02:00 UTC) - Place: Marblemount, WA - Coordinates: 48.57611, -121.150276 - Nearby events: https://openairdocs.org/map.md?lat=48.5761&lon=-121.1503&mi=10 - Phase of flight: [Taxi](https://openairdocs.org/ntsb-phases/250) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report June 30, 2004 - Report: Approved by Office Director - Parties: Seattle FSDO - NTSB case key (mKey): 57591 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=SEA03LA156 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/57591/pdf - Page: https://openairdocs.org/ntsb/SEA03LA156 ## Probable cause The partial failure of a magneto during hover taxi over water, leading to a forced landing in shallow water near the shoreline. Factors include the aircraft being over a lake at the time that the partial loss of power made it impossible to keep it airborne. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of engine power(partial) - mech failure/malf, taxi - aerial - ignition system,magneto - failure,partial (cause) - Forced landing, emergency descent/landing - In flight collision with terrain/water, emergency descent/landing - terrain condition - water,glassy (contributing factor) ## Analysis Once he arrived in the area of the lake where he was planning on camping, the pilot made two high reconnaissance passes in order to look the area over before descending to a lower level so he could take a closer look at possible camping sites along the lake's edge. The pilot completed a systems flow check prior to initiating a hover taxi over the lake, and then once the hover was established, the oil pressure and oil temperature was rechecked. The pilot then began "hovering down the middle of the lake," looking at possible landing sites, but ultimately, when he reached the far end of the lake, he decided that the best spot was at the other end where he had first passed over the shoreline. Just about the time he was getting ready to turn back, he noticed a gradual drop in engine rpm's, and the aircraft began to slowly descend toward the surface of the lake. Although he increased the throttle, he was unable to increase or stabilize the rpm, and the helicopter eventually settled into the water in a level and upright position. The rpm had initially been 3,200, but by the time the aircraft touched the surface of the water it had dropped to 2,400. Ultimately the aircraft came to rest upright on its skids in about six to eight feet of water, but the main rotor blades were damaged when they contacted the water's surface. As part of the investigative process, the older left magneto was removed from the aircraft and tested at various rpm’s (the right magneto was newly installed, and not removed for testing). During the subject testing, the left magneto performed erratically, and did not produce a consistent continuous spark at high rpm's. After the testing was terminated, the magneto was disassembled and inspected, but the specific reason for its inconsistent performance was not able to be determined. ## Factual narrative On July 24, 2003, approximately 1900 Pacific daylight time, a Hughes 269C helicopter, N500HS, impacted the waters of Olson Lake, which is located about five miles north of Marblemount, Washington, during an attempted forced landing. The commercial pilot and his passenger were not injured, but the aircraft, which is owned and operated by the pilot, sustained substantial damage. The 14 CFR Part 91 personal pleasure flight, which departed Skagit County Airport about one hour earlier, was being operated in visual meteorological conditions. No flight plan had been filed. According to the pilot, once he arrived in the area of the lake, he made two high reconnaissance passes in order to look the area over before descending to a lower level so he could take a closer look at possible camping sites along the lake's edge. The pilot completed a systems flow check prior to initiating a hover taxi over the lake, and then once the hover was established, the oil pressure and oil temperature was rechecked. The pilot then began "hovering down the middle of the lake," looking at possible landing sites, but ultimately, when he reached the far end of the lake, he decided that the best spot was at the other end where he had first passed over the shoreline. Just about the time he was getting ready to turn back, he noticed a gradual drop in engine rpm's and the aircraft began to slowly descend toward the surface of the lake. Although he increased the throttle, he was unable to increase or stabilize the rpm, and the helicopter eventually settled into the water in a level and upright position. The rpm had initially been 3,200, but by the time the aircraft touched the surface of the water it had dropped to 2,400. Ultimately the aircraft came to rest upright on its skids, in about six to eight feet of water, near the shoreline of the lake. Although the airframe was undamaged, the main rotor blades where damaged when they came in contact with the surface of the water. As part of the investigative process, the older left magneto was removed from the aircraft and tested at various rpm’s (the right magneto was newly installed, and not removed for testing). During the subject testing, the left magneto performed erratically, and did not produce a consistent continuous spark at high rpm's. After the testing was terminated, the magneto was disassembled and inspected, but the specific reason for its inconsistent performance was not able to be determined. ## Aircraft - Registration: [N500HS](https://openairdocs.org/aircraft/N500HS), registered now, S/N 170554 (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: 170554 - Airframe hours: 4137 - Engines: Lycoming HIO-360-D1A 190 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Registered owner: Richard L. Daniels - Airworthiness certificate: Standard, Normal - Last inspection: Annual, July 10, 2003, 8.5 hours before - Departed: BVS, Skagit Regional, WA - Destination: Marblemount, WA ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 46; injuries: none; commercial, flight instructor; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 2, valid medical--w/ waivers/lim; last flight review July 11, 2003; seat: left; flight hours: 2,520 total, 82 in this make and model, 2,393 as pilot in command, 170 in the last 90 days, 36 in the last 30 days, 2 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: calm - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 70 °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 20030724018179A](https://openairdocs.org/incident/20030724018179A), Jul 24, 2003: Hughes 269C, Olsen Lake, WA, Substantial damage. (-23) While hovering over lake looking for a place to land pilot experienced gradual RPM decrease and put the rotorcraft down in the water. Olsen Lake is at… 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.