AAIB report: Guimbal Cabri G2 fire due to electrical short circuit

The U.K.’s Air Accidents Investigation Branch has released an investigation report into the Guimbal Cabri G2 helicopter that caught fire on July 22, 2019.

The investigation into a Guimbal Cabri G2 helicopter that caught fire in July 2019 found that the fire was caused by an electrical short circuit in the engine compartment. AAIB Photo
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The helicopter (G-CILR) had flown from Dunkeswell, Devon, to Wycombe Air Park, Buckinghamshire. As the pilot was shutting down the helicopter, he noticed smoke emanating from the left side of the rotor mast. He evacuated and the helicopter was destroyed by fire. No injuries were sustained.

The helicopter caught fire shortly after landing because the heat generated from a short circuit in the engine compartment ignited a nearby carbon fiber structure. The short circuit was made between the cable that connected the output of the alternator to the starter relay and the aluminium air baffle through which the cable passed.

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It is likely that the cable clips that should have held the cable as it passed though the baffle were either not present or, most likely, incorrectly fitted. The upward movement of the engine as a result of the clutch disengagement was sufficient to allow the unsecured cable to contact the unprepared edge of the aluminium baffle, allowing the insulation to be cut and initiate the short circuit.

As a result of this investigation, the helicopter manufacturer has issued a service bulletin to instruct operators to inspect for correct installation of the cable clips. It has also completed a redesign of the clips to ensure they cannot be fitted incorrectly.

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