NTSB Factual Report

On June 20, 2002, approximately 1247 Pacific daylight time, a Cessna 172E, N5383T, registered to two individual co-owners and being flown by an airline transport pilot on a 14 CFR 91 maintenance test flight, was substantially damaged during a forced landing and nose gear collapse following an in-flight loss of power. The aircraft landed in a marshy area east of runway 25 at Portland-Troutdale Airport, Troutdale, Oregon. The pilot was not injured in the accident. Visual meteorological conditions were reported at Troutdale at 1253 and no flight plan had been filed. The local flight had originated at Troutdale approximately 1150.

The pilot departed Troutdale for a second flight following an earlier one hour flight. The purpose of both flights was to conduct a maintenance check following the replacement of all six cylinder piston rings and a re-honing of all six cylinders. The first flight was uneventful and the pilot had the aircraft topped off with fuel before departing on the second flight. The second flight was uneventful until the aircraft was established on a high, long final to runway 25 at the Troutdale airport. The pilot reported that he "...went through some very rough turbulence as [he] was reducing power - [the] engine appeared to quit...." The pilot elected to reverse course and execute an off airport landing due to the distance to the end of the runway and the objects under his flight path. He landed in an area of soft, marshy terrain with high grass and the nose gear collapsed during the landing. An inspector assigned to the Federal Aviation Administration’s (FAA) Hillsboro Flight Standards District Office (FSDO) responded to the accident site and reported that fuel was observed draining from the aircraft's under wing vent line following the accident.

A post-crash examination of the aircraft's fuel, air intake, and ignition systems as well as the Continental O-300-D engine was conducted under the oversight of an FAA inspector. No evidence of any mechanical malfunction was noted with any system. The engine was test run with satisfactory results. The carburetor was disassembled, examined, reassembled and run on the engine during a second test with no mechanical malfunctions noted. The fuel system was examined and verified no blockages within any of the lines. It was noted that FAA Airworthiness Directive 79-10-14R1 had been complied with as the aircraft's right wing fuel cap was equipped with a vent (refer to Attachment AD-I). An examination of the right gas cap determined that the vent was not functioning and revealed that the rubber gasket would not unseat and allow normal venting. The left fuel tank vent was examined and found to function satisfactorily. No particulates were found in any of the fuel filters. Refer to attached engine examination report FAA-I).

NTSB Probable Cause

A loss of engine power for an undetermined (non-mechanical) reason. Contributing factors were high grass and soft terrain which lead to the collapse of the nose gear during the landing roll.