AAIB investigation to Leonardo AW189, G-MCGU
Emergency landing following failure of heating duct, 3 nm south-east of Porthcawl, Wales, 4 March 2021.
Summary:
While returning from a SAR training sortie, shortly after selecting the cabin and cockpit heating ON, a heating duct failed causing fragments of duct insulation material to be discharged through the heating vents. The heating system was turned OFF but the subsequent presence of smoke, and a smell of burning, prompted an emergency landing. Several weeks later, a similar heating duct failure occurred on another of the operator’s AW189 helicopters. The occupants of both helicopters suffered respiratory irritation.
The investigation determined that the heating ducts failed due to non-uniform adhesion at joints between rigid and flexible sections of duct. Interim safety action taken by the manufacturer includes the publication of a Service Bulletin to inspect and modify the installation of the heating duct. A further heating duct failure occurred on another AW189 following embodiment of the Service Bulletin and that event will be reported separately by the AAIB. At the time of publication of this report, the investigation into the recent duct failure is ongoing and the aircraft manufacturer is continuing to work with the duct manufacturer to achieve a permanent design solution.
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