Aviation Accident Summaries

Aviation Accident Summary SEA00LA141

GRAND VIEW, ID, USA

Aircraft #1

N4925X

Rockwell S-2R

Analysis

The pilot reported that while returning from an aerial application flight about 20 minutes after takeoff, while on 2-mile final with about 1 mile to touchdown, the aircraft experienced low fuel pressure and the engine subsequently stopped. The pilot performed a forced landing into a dry, flat grassy area. During the forced landing, the aircraft struck a barbed-wire fence. A post-accident examination of the aircraft revealed a 12- to 18-inch section of fuel line (Stratoflex hose) between the fuel shutoff valve and the fuel pump that had deteriorated and collapsed internally, blocking fuel flow through the line.

Factual Information

On July 21, 2000, approximately 0830 mountain daylight time, a Rockwell International S-2R agricultural airplane, N4925X, being operated by Nyssa Ag Service, Inc. of Nyssa, Oregon, was substantially damaged in a forced landing in uneven desert terrain following a loss of engine power near Grand View, Idaho. The commercial pilot of the aircraft received minor injuries in the accident. Visual meteorological conditions existed and no flight plan was filed for the local 14 CFR 137 agricultural aerial application flight, which was returning empty to a loading strip (consisting of a section of dirt road between agricultural fields) after completing a spray run at the time of the accident. The pilot reported that he took off on the accident flight with 61 gallons of fuel on board, and that the aerial application took about 20 minutes. The pilot stated that upon the return trip, while on a 2-mile final with about 1 mile to touchdown, the aircraft experienced low fuel pressure. The pilot stated that as the fuel pressure dropped to about 19 pounds per square inch (PSI), he engaged the boost pump with no results. He stated that the engine then "unspooled", at an altitude of about 2,500 feet above ground level (AGL). The pilot subsequently attempted a forced landing in a dry, flat grassy area. The pilot reported that during the forced landing, the aircraft struck a barbed-wire fence. The aircraft was equipped with an AlliedSignal TPE331 turboprop engine. The pilot did not report any information on the date or type of the aircraft's last inspection, or flight hours since the last inspection, or airframe or engine times, on his NTSB accident report. An FAA inspector from the Boise, Idaho, Flight Standards District Office (FSDO) reported that the aircraft, which was manufactured in 1974, had 4,100 total airframe hours. The FAA inspector reported to the NTSB that during post-accident examination, over 10 gallons of fuel was found aboard the aircraft; however, an engine fuel supply line (identified as Stratoflex hose, part number 111-312-312-8-0770) was found with internal blockage (a 12- to 18-inch section of the inside wall of the hose had deteriorated and collapsed.) Felt material was also found blocking about 50 percent of a fuel screen. The internally collapsed hose section was located between the fuel shutoff valve and the fuel pump. The FAA inspector and the pilot reported that the hose had 281 flight hours in service.

Probable Cause and Findings

Internal deterioration of a fuel line, resulting in loss of engine power. Factors included obstruction of the fuel line, fuel starvation, and a fence in the forced landing area.

 

Source: NTSB Aviation Accident Database

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