What happened
On December 8, 2022, at approximately 21:30 UTC, a Cessna A188B, registration PR-ADK, was performing a takeoff roll from an unpaved agricultural landing area at Fazenda Amauri, in Inaciolândia, Goiás. The aircraft was engaged in a scheduled agricultural chemical application flight with a single pilot on board.
As the aircraft accelerated and the tail became airborne, the propeller assembly suffered a sudden failure. One propeller blade separated from the hub, creating a severe dynamic imbalance. This imbalance caused the remaining blade to strike the ground, which subsequently led to the crankshaft fracturing due to torsional overload. The resulting forces caused the entire powerplant assembly to detach from the fuselage. The pilot lost directional control, and the aircraft veered off the airstrip, traveling approximately 100 meters before coming to a stop at the right edge of the landing area. The pilot was uninjured, but the aircraft sustained substantial damage, including the separation of the engine, deformation of the forward fuselage, and the collapse of the left landing gear.
The investigation
CENIPA investigators conducted a detailed metallographic analysis of the propeller hub and the wreckage. The investigation focused on the McCauley two-blade, constant-speed propeller assembly. While maintenance records indicated that the propeller had undergone an overhaul and that all logs were up to date, investigators discovered a dent on the internal face of the propeller hub. This specific area of the hub is only accessible during disassembly, such as during blade replacement.
Testing of the engine subsystems, including fuel injectors, magnetos, and cylinder compression, showed that the engine was functioning normally prior to the structural failure. The investigation determined that the aircraft was within weight and balance limits and that meteorological conditions were well within required minimums for the operation.