Thrush Aircraft Inc S2R-H80 N3045R accident near Gypsum, Kansas

Probable cause

A total loss of engine power during a low-altitude agricultural application flight for reasons that could not be determined during detailed examinations. Contributing to the accident was the pilot’s failure to follow the airplane manufacturer's emergency procedures to recover engine power, which resulted in a forced landing.

NTSB analysis

The commercial pilot stated that, after completing a portion of a low-level agricultural application flight, the engine power decreased "significantly." The pilot pushed the power lever full forward, but the engine did not respond. He made several more passes to get more weight off the airplane to see if the engine would regain power; however, engine power did not increase, so the pilot flew the airplane back toward the departure airport. The pilot tried to climb the airplane but there was insufficient power to do so, and he then saw smoke coming out both exhausts. The engine then lost all power. Subsequently, the pilot conducted a forced landing in a field, and the airplane slid through a fence and then stopped, which resulted in substantial damage to the fuselage.

A review of data downloaded from the engine monitor revealed engine operation consistent with a fuel interruption and a subsequent loss of engine power. During postaccident examination, the main electric fuel boost pump was found operational. However, it did not meet standard acceptance test criteria. The engine was not test run; however, component level testing of the fuel control unit, the emergency electric fuel pump, and the starting and limiting unit revealed no anomalies that would have prevented normal operation. Thus, the reason for the interruption in fuel flow and the subsequent loss of engine power could not be determined. However, the airplane manufacturer has subsequently developed a redesign and has issued a service bulletin to address the fuel system, including electric fuel pumps and plumbing.

The Airplane Flight Manual (AFM) contained a Failure of Automatic Fuel Scheduling checklist, and the first step of this checklist was to engage the emergency governor. The pilot reported that he did not follow these procedures when the engine power decreased. Further, the AFM contained an Engine Failure In-Flight checklist, and the first step of the checklist was to dump the hopper. The pilot reported that he did not dump the hopper when the engine lost power. The pilot's failure to subsequently follow the emergency procedures to recover engine power likely necessitated the forced landing.

Text from the NTSB. Open the NTSB docket for CEN17LA176 for the full record.