Denso W24EMR-C spark plugs installed on, but not limited to Guimbal Cabri G2 helicopters.
This Continuing Airworthiness Notice (CAN) is issued to advise operators and maintainers that a Denso W24EMR-C spark plug fitted to a Cabri G2 helicopter may have been defective and contributed to an in-flight fire which subsequently destroyed the aircraft shortly after landing.
This CAN is prompted by a TAIC investigation of an in-flight fire on a Guimbal Cabri G2. Examination of the engine found that one of the four upper spark plugs fitted to the engine was missing its insulator which appeared to have been ejected.
The centre spark plug in the attached photograph with missing insulator is the faulty spark plug from the aforementioned aircraft. You will notice that the swaging at the top of the plug has not been crimped, and there is also no bulging of the plug body below the hexagon. To the left in the photograph is another plug removed from the affected engine, and to the right is a new plug.
The investigation is continuing and further action may follow.
The CAA strongly recommends that operators/maintenance providers inspect Denso W24EMR-C spark plugs for defects. If any defects are found, replace affected plugs before further flight.
To assist with this investigation, please report any defects found with Denso W24EMR-C spark plugs to the CAA by completing a CA005 Defect Report form. Please provide as much engineering detail as possible, including the details of the parts supplier and release documentation provided with the parts. The defect report form can be obtained from http://www.caa.govt.nz/Forms/CA005D_Form.pdf(external link)
The completed form can be emailed to the CAA at CA005@caa.govt.nz
