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Atlas / NTSB / LAX03LA052

NTSB CAROL · Event

Event LAX03LA052

2002-12-18 Los Banos, California, United States Airport · LSN None 1 aircraft Status: Completed

Aircraft involved

Probable cause & findings

The improper engine overhaul by other maintenance personnel, which resulted in an exhaust valve failure and a total loss of engine power while in maneuvering flight.

Factual narrative

On December 18, 2002, at 1521 Pacific standard time, a Schweizer 269C, N642KC, experienced a total loss of engine power and rolled over during a forced landing in a muddy field at Los Banos, California. The helicopter was operated by the pilot under 14 CFR Part 91. The commercial pilot and one passenger were not injured. The helicopter was substantially damaged. Visual meteorological conditions prevailed, and no flight plan had been filed. The flight originated at Los Banos about 1500. The pilot and aircraft maintenance technician were performing a post maintenance test flight when a vibration occurred followed by a total loss of engine power. Post accident examination revealed a failed exhaust valve in the number 3 cylinder. Further examination revealed two exhaust spring seats had been installed, one on top of the other, causing excessive spring/valve pressures. The operator had just overhauled the engine; the failure occurred about 1.5 hours after the overhaul. The pilot and aircraft maintenance technician were performing a post maintenance test flight when a vibration occurred, followed by a total loss of engine power. The commercial certificated helicopter pilot made a forced landing in a muddy field, during which the helicopter received structural damage. Post accident examination revealed a failed exhaust valve in the number 3 cylinder, and that two exhaust spring seats had been installed, one on top of the other, causing excessive spring/valve pressures. The engine had been overhauled about 1.5 service hours prior to the loss of engine power. Source: NTSB Aviation Accident Database (Pre-2008 Archive) Retrieved: 2026-02-12

Verbatim from NTSB's published report. Source file NTSB_2002_LAX03LA052.txt. Findings + structured fields enriched from FAA avall.mdb. Full investigation docket on data.ntsb.gov ↗.

Related research

What the literature says.

Academic papers and agency reports matching this event's aircraft type or causal vocabulary (stall, maintenance). Sourced from NASA NTRS, NTSB Safety Studies, FAA CAMI, AOPA Air Safety Institute, Embry-Riddle Scholarly Commons, arXiv, and the Semantic Scholar academic graph.

Browse the full corpus — academia portal ↗