RANS S12 — Colville, WA

What happened

The owner of the airplane, who was not a pilot, was selling the airplane to his friend, who was a pilot. The two spent the winter rebuilding the airplane, which had previously been involved in an accident and had been in storage, in pieces, for the previous 5 years. On the day of the accident, the pilot announced to an acquaintance that the airplane’s maintenance issues had been corrected and they were going to take the airplane on a test flight.

A witness who saw the airplane’s takeoff and initial climb reported that the airplane’s climb rate was “not impressive” and that it was only “slightly climbing.” Two witnesses who saw the airplane before the accident stated that the engine was “sputtering” and that the airplane was “losing altitude quickly.” Photos of the airplane just before the accident showed the airplane flying toward a set of power distribution lines before entering a steep bank away from the lines, after which the airplane impacted terrain.

The airplane came to rest in a nose-down attitude in an open field adjacent to the power distribution lines. Examination of the wreckage revealed that both carburetors’ float brackets were not adjusted in accordance with the manufacturer’s maintenance manual, which likely restricted the amount of fuel in the carburetor bowls.

Multiple people stated that the owner and pilot had been troubleshooting a carburetor issue before the accident flight. One person described it as, “over-producing fuel, and the fuel was running out of the back [of the airplane].”

The repair work on the airplane was overseen by a mechanic with inspection authorization who advised the two as they went and gave the two general maintenance advice. The mechanic was aware that neither the owner nor the pilot were certificated mechanics or light sport repairmen; however, he described the owner as a competent mechanic. About 1 month before the accident, the mechanic completed an entry in the airplane’s maintenance logbook stating that the condition inspection had been completed and that the airplane was “found to be in an airworthy condition” and “approved for return to service.” The mechanic was aware of the carburetor issue but did not know who worked on the carburetors and thought that the carburetors had been sent away for repair. After the carburetors were reinstalled, the mechanic observed the pilot conduct ground runs and thought that the engine “sounded fine.”

It is likely that the engine was not producing full power as a result of the improperly adjusted carburetor float brackets, which resulted in degraded climb performance or the airplane’s inability to climb. Based on the witness statements and photos, it is likely that the pilot was maneuvering to avoid powerlines when he exceeded the airplane’s critical angle of attack and the airplane entered an aerodynamic stall.

An editorial "what led to it / how to avoid it" analysis for this accident is generated separately and will appear here.