Robinson R44 II helicopters fitted with the Lycoming IO-540 engine.
This Continuing Airworthiness Notice (CAN) is revised to inform aircraft operators and maintainers that Robinson Helicopters Corporation (RHC) have revised the component maintenance requirements in Chapter 1.102 of the R44 Series Maintenance Manual dated December 2021. Refer: https://robinsonheli.com/r44-maint-manual/(external link)
The revised component maintenance requirements include:
CAN 73-006 originally issued in August 2021 highlighted a CAA finding with the Fuel Pressure Relief Valve (PRV) fitted on a Robinson R44 II involved in an accident on 12 June 2021.
The PRV on that aircraft was found to be bypassing an excessive amount of fuel at a much lower pressure than specified. This failure in itself was considered unlikely to cause an engine failure.
The CAA is aware of another Robinson R44 II helicopter which the pilot couldn’t start. The PRV on this aircraft was also found bypassing an excessive amount of fuel, due to an internal leak.
RHC provide a method for checking the PRV in situation. Refer to page 12.27 in the RHC R44 Maintenance Manual. This check is not included as a scheduled maintenance activity in the RHC Maintenance Schedule.
CAA recommend that R44 operators assess their aircraft records and ensure that they meet the maintenance requirements in the revised RHC R44 Maintenance Manual.
The CAA would like to know if operators have any issues related to their fuel systems, including if they have any findings from PRV inspections (RHC R44 Maintenance Manual). Please report any negative findings to the CAA by completing a CA005 Defect Report form. Please provide as much engineering detail as possible. This will enable us to determine the extent of any issue with the PRVs and the R44 fuel system. The form can be obtained from https://www.aviation.govt.nz/assets/forms/CA005D_Form.pdf The completed form can be emailed to the CAA at firstname.lastname@example.org