Aviation Accident Summaries

Aviation Accident Summary SEA04LA128

Arlington, WA, USA

Aircraft #1

N56PH

Hughes 269C

Analysis

While cruising at about 2,500 feet above the ground (agl), the pilot heard a "pop" and felt the helicopter yaw to the right. Almost immediately he noticed that the engine was starting to lose power, and he therefore lowered the collective and initiated a partial autorotation. He then attempted to get the engine to accelerate, but he continued to hear "sputtering and popping," and the engine continued to gradually lose power. The pilot therefore elected to perform a full autorotational landing in a nearby opening in the heavily wooded area he was flying over. Although he was able to touch down with only a very slow forward speed, the terrain he was landing on turned out to be a wet and muddy bog or swamp, and as the helicopter touched down, one of the skids sunk into the mud, and the aircraft rolled over onto its side. A post-accident inspection of the helicopter's engine and fuel system by an FAA Airworthiness Inspector and a fixed base operator's (FBO's) maintenance personnel did not find any evidence of an anomaly that would have lead to a loss of power in the engine. After the initial inspection was completed, the engine was mounted on an engine stand and run at various speeds for a period of about eight minutes. During the test run, the engine started easily and ran smooth at all tested speeds up to and including a maximum of 3,100 rpm.

Factual Information

On July 9, 2004, approximately 2010 Pacific daylight time, a Hughes 269C helicopter, N56PH, impacted the terrain during an attempted autorotational landing about 12 miles north of Arlington, Washington. 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 Bellingham, Washington, about 55 minutes prior to the accident, was being operated in visual meteorological conditions. The flight was en route to Arlington, Washington. No flight plan had been filed. According to the pilot, while cruising at about 2,500 feet above the ground (agl), he heard a "pop" and felt the helicopter yaw to the right. Almost immediately he noticed that the engine was starting to lose power, and he therefore lowered the collective and initiated a partial autorotation "...to take demands off the engine." He then attempted to get the engine to accelerate, but he continued to hear "sputtering and popping," and the engine continued to gradually lose power. The pilot therefore elected to perform a full autorotational landing in a nearby opening in the heavily wooded area he was flying over. Although he was able to touch down with only a very slow forward speed, the terrain he was landing on turned out to be a wet and muddy bog or swamp, and as the helicopter touched down, one of the skids sunk into the mud, and the aircraft rolled over onto its side. A post-accident inspection of the helicopter's engine and fuel system by an FAA Airworthiness Inspector and maintenance personnel from Precision Helicopters did not find any evidence of an anomaly that would have contributed to a loss of power in the engine. After the initial inspection was completed, the engine was mounted on an engine stand and run at various speeds for a period of about eight minutes. During the test run, the engine started easily and ran smooth at all tested speeds up to and including a maximum of 3,100 rpm.

Probable Cause and Findings

A significant power loss for undetermined reasons while in cruise flight, leading to a full autorotational landing. Factors include no suitable terrain in the area, and soft swampy terrain at the point where the pilot found it necessary to perform the forced landing.

 

Source: NTSB Aviation Accident Database

Get all the details on your iPhone or iPad with:

Aviation Accidents App

In-Depth Access to Aviation Accident Reports