ASN Wikibase Occurrence # 295471
This information is added by users of ASN. Neither ASN nor the Flight Safety Foundation are responsible for the completeness or correctness of this information.
If you feel this information is incomplete or incorrect, you can submit corrected information.
| Date: | Thursday 24 July 2003 |
| Time: | 18:00 LT |
| Type: |  Hughes 269C |
| Owner/operator: | Private |
| Registration: | N500HS |
| MSN: | 170554 |
| Total airframe hrs: | 4137 hours |
| Engine model: | Lycoming HIO-360-D1A |
| Fatalities: | Fatalities: 0 / Occupants: 2 |
| Aircraft damage: | Substantial |
| Category: | Accident |
| Location: | Marblemount, Washington -
 United States of America
|
| Phase: | Unknown |
| Nature: | Private |
| Departure airport: | Mount Vernon-Skagit Regional Airport, WA (MVW/KBVS) |
| Marblemount, WA | |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
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.
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.
Accident investigation:
 |
|
Sources:
NTSB SEA03LA156
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 13-Oct-2022 08:56 | ASN Update Bot | Added |
Corrections or additions? ... Edit this accident description
The Aviation Safety Network is an exclusive service provided by:
Quick Links:
| ASN Home | Send Correction / Feedback |
| FSF Home | Disclaimer | Copyright |
| Contact Us | Privacy Policy |
| Press / Media |
CONNECT WITH US:
©2024 Flight Safety Foundation