Primary finding
Probable cause
A partial loss of engine power due to a tear in the fuel manifold diaphragm, which prevented sufficient fuel flow to the engine.
Investigator assessment
Analysis narrative
The airplane sustained a partial loss of engine power while maneuvering to apply fertilizer to a corn field. The pilot initiated a forced landing to a clearing, during which the airplane struck trees and powerlines before it came to rest upright in an open field; a postaccident fire ensued. Examination of the of the airplane revealed that the cockpit and fuselage structure was mostly destroyed by thermal and impact damage. Examination of the engine revealed a tear on the fuel manifold assembly diaphragm. The tear in the diaphragm likely result in the fuel manifold’s inability to provide sufficient fuel pressure to maintain engine power, resulting in a partial loss of engine power.
Source record
Factual narrative
On June 7, 2023, about 1415 central daylight time, a Cessna A188B, N731UF, was destroyed when it was involved in an accident near Chillicothe, Missouri. The pilot sustained minor injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 137 agricultural flight. The pilot reported that the airplane sustained a partial loss of engine power while he was maneuvering to apply fertilizer to a corn field about ½ mile from the departure airport. He ensured the throttle was in the full forward position and turned on the emergency electric auxiliary fuel pump to no avail. Unable to maintain altitude, the pilot elected to conduct an off-airport landing and, during the descent, the airplane struck trees and powerlines before it came to rest upright in an open field; a postaccident fire ensued. Postaccident examination of the airplane revealed that the cockpit and fuselage structure was mostly destroyed by thermal and impact damage. The engine, engine mount, firewall, main landing gear, instrument panel, flight controls, and seats were separated and exhibited varying degrees of thermal and impact damage. Examination of the fuel manifold revealed it remained attached to its respective mount and was undamaged. The No. 6 fuel injector line and the nozzle pressure gauge fitting were fracture separated. The fuel manifold assembly was removed and subsequently disassembled. The internal diaphragm exhibited an approximate 1-inch tear and the spring was undamaged. No additional anomalies were noted with the engine or airframe. No reference to any maintenance performed on the fuel manifold was observed within the engine and airframe logbooks. The engine was last overhauled on July 10, 2009.