What happened
On December 16, 2015, a Bell 407 helicopter, registration TG-PJV, was conducting a flight when the engine experienced an abrupt shutdown. The aircraft was operating over the Condado el Naranjo area in the municipality of Mixco, Guatemala. Following the loss of engine power, the pilot successfully executed an emergency autorotation maneuver. The aircraft impacted the ground, but the pilot and passengers escaped the crash without physical injuries.
The investigation
The DGAC/UIA investigation focused on the engine's performance and maintenance history. Although the aircraft was not equipped with flight recorders, investigators extracted engine performance data from the FADEC system, which confirmed the sudden engine shutdown during flight.
Physical inspections of the wreckage revealed evidence of an oil leak, with oil residue found on the main fuselage and the tail boom. Investigators also noted that the engine compartment doors were open at the time of the inspection; the pilot, who also held maintenance technician qualifications, had opened them during the flight to inspect the engine for potential failures.
Further examination of the accessory gearbox revealed that the metal particle detector had been removed from its normal operating position. Subsequent analysis of the engine by Rolls-Royce in the United States determined that the only possible source of the lubricant leak was the installation hole of this particle detector. The investigation found that improper installation or removal of the detector can create a false appearance of a correct installation, leading to an oil leak through the mounting orifice.
Findings
- The engine suffered a total loss of lubrication due to an oil leak.
- The metal particle detector was found detached or improperly seated within the accessory gearbox.
- Improper installation of the particle detector allowed oil to escape from the installation hole, leading to the engine failure.
- The pilot's successful execution of an emergency autorotation prevented injuries to all occupants.