What happened
On October 19, 2022, a Bell 407GX helicopter, registration PP-BDL, was conducting a local pre-purchase evaluation flight departing from Congonhas Airport (SBSP) in São Paulo. The flight was carrying one pilot and one passenger, a mechanic tasked with inspecting the aircraft for a potential sale.
During the en route phase of the flight, the aircraft suffered a sudden loss of engine power accompanied by anomalous indications on the instrument panel. The pilot initiated an autorotation maneuver, which was captured by local building surveillance cameras. The helicopter performed an emergency landing in a leisure area within the Campo Belo neighborhood. The impact caused substantial damage to the aircraft, including damage to the engine, main rotor, and tail rotor, as well as significant deformation of the fuselage. The aircraft also struck two concrete benches in the square. The pilot and the passenger both sustained serious injuries.
The investigation
CENIPA's investigation focused on the cause of the powerplant failure and the maintenance history of the aircraft. Laboratory analyses of fuel and lubricating oil samples showed no chemical abnormalities. However, data extracted from the Electronic Control Unit (ECU) confirmed a loss of torque signal minutes before the engine surge, which is consistent with a failure sequence caused by insufficient lubrication.
Investigators found that engine bearings 2 and 8 had failed due to severe damage. The investigation established that a generalized lubrication failure occurred because of an absence of oil in the system, caused by the disengagement of the Upper Magnetic Chip Detector (UMCD). Additionally, investigators noted that the maintenance organization (OM) failed to open the required Work Orders for the preliminary inspection, which prevented full traceability of the tasks performed and hindered the ability to identify unrecorded maintenance actions.