CEN18LA321

The commercial pilot was conducting an agricultural application flight. He stated that he felt a loss of engine power when he pulled up during a second pass over a field. He pushed the throttle and mixture controls forward, but the engine power did not increase. He dumped the payload and then located a landing area. The pilot flew the airplane at its best glide speed, and the airplane struck a tree short of the landing area. Subsequently, the airplane spun right. He pulled the control stick back and applied right rudder to maintain the airplane in an upright attitude before it impacted the ground and erupted into a postimpact fire. Postaccident examination of the airplane revealed that the two propeller blades were relatively straight, consistent with a lack of torsion, indicating that the engine lost all power before impact. Postimpact fire destroyed the engine, engine accessories, and airframe, which precluded functional testing of any components. The reason for the loss of engine power could not be determined.

On August 6, 2018, at 1515 central daylight time, a Cessna A188B, N4996R, experienced a total loss of engine power and impacted terrain during an aerial application flight about 10 miles north of Sedalia, Missouri. The airplane was destroyed by impact forces and post-crash fire. The commercial pilot sustained minor injuries. The airplane was registered to an individual and operated by Lloyd Darter Aviation under Title 14 Code of Federal Regulations Part 137 as an aerial application flight that was not operating on a flight plan. Visual meteorological conditions prevailed at the time of the accident. The local flight originated from Marshall Memorial Municipal Airport (MHL), Marshall, Missouri about 1430. The pilot did not submit a National Transportation Safety Board Pilot/Operator Aircraft Accident/Incident Report (form 6120), as required under Part 830. The pilot provided a written statement to the Federal Aviation Administration Inspector assigned to the accident investigation. The pilot stated that during the second pass over an agricultural field, he pulled up and "felt a loss of power." He stated that he pushed the throttle and mixture controls full forward but there were "no results." He dumped the payload and located a landing area. He said he flew the airplane's best glide speed and struck a tree short of the landing area, spinning the airplane to the right. He pulled the control stick back and applied right rudder to maintain the airplane in an upright attitude prior to impacting the ground. Post-accident examination of the airplane revealed the airframe was consumed by post-crash fire from the empennage, to the engine firewall, and to the mid-wingspan of both wings. Ground scarring was limited to the airplane's planform with nose-down crushing. The flaps were in the retracted position. Neither of the two propeller blades displayed S-shaped bending and were relatively straight, consistent with a lack of torsion. The bottom half of the engine case was melted to the accessory section exposing the crankshaft and accessory gears. The internal engine drive and valve train components were connected, secure, and did not display any fractures. The engine accessories were destroyed by the fire. The number four-cylinder fuel line with an attached adapter leading from the fuel manifold was loose and was pulled out by hand. The remaining fuel lines were attached and secure in the fuel manifold. The fuel line, the fuel line adapter fitting, and the manifold were removed for metallurgical examination at the National Transportation Safety Board Material Laboratory. The metallurgical examination revealed the fuel line with its adapter fitting were separated from the fuel manifold. The adapter had tapered pipe thread where it would screw into the fuel manifold. Examination of the adapter fitting did not reveal evidence of thread deformation on the fitting. The first few threads of the adapter appeared to contain aluminum material from the fuelmanifold. The threaded port on the fuel manifold for the number-four fuel line exhibited deformation and the appearance of incipient melting of the aluminum housing.