Schweizer 269A, 269A-1, 269B, 269C, 269C-1 and 269D helicopters fitted with main rotor bearings P/N 269A1231, delivered on, or after 17 June 2021.
This CAN is issued to draw attention to Schweizer Service Information Letter (SIL) No. L-188, which provides necessary information when replacing main rotor blade bearings P/N 269A1231, delivered on, or after 17 June 2021.
Schweizer has made a change to the configuration of the main rotor blade bearings identified above, which means that pitch bearing spacer P/N 269A1205 (previously matched to case assembly P/N 269A1220) may no longer be the correct size to ensure the necessary distance between the bearings. Refer to Figure 1 in this CAN.
The installation of an incorrectly sized spacer can result in binding and ratcheting of the bearing set, which may result in difficulty tracking the blades, and may be felt by the pilot during operation.
Maintainers must refer to Schweizer Service Information Letter (SIL) No. L-188 when installing main rotor bearing sets delivered on, or after 17 June 2021.
This SIL has been issued to provide instructions for maintainers to measure the internal dimension of the pitch bearing housing and ensure that the correct sized spacer is installed.
Note that bearings delivered on, or after 17 June 2021 retain the same P/N as those delivered prior to 17 June 2021.
Maintainers must be extremely vigilant to ensure that maintenance is carried out in accordance with the appropriate manufacturer ICA.
If maintainers and/or operators note any issues related to the main rotor blade bearings of Schweizer helicopters they should complete a CAA005D and submit the completed form to the CAA at CA005@caa.govt.nz or report findings via the online reporting system available at https://occurrences.caa.govt.nz/ProdUI/(external link)
Figure 1: Extract from Model 269C Basic HMI