Hughes 269C N500HS

Summary

On 25 July 2003 at about 02:00 local time, a Hughes 269C registered N500HS was involved in an accident near Marblemount, Washington, United States. 2 people were on board and nobody was injured. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

25 July 2003 at 02:00

Classification

Accident

Location

Marblemount, Washington, United States

Coordinates

48.5761, -121.1503

Aircraft

Hughes 269C

Registration

N500HS

Category

Helicopter

Engines

1

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Personal

Phase of flight

Not recorded

Route

Skagit Regional → Marblemount

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

SEA03LA156

Nobody was injured.

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.

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full NTSB narrative

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.

Quoted verbatim from the NTSB record.