About a year ago, Service Bulletin SB25328 (Controlled Service Use) was released by Pratt & Whitney. This Service Bulletin allowed new carbon face seals to be installed in a few PW306C engines. These new seals replaced the magnetic seals at the alternator and starter gear shaft locations in the accessory gearbox. Also, PW306C operators have been replacing pre-SB25328 seals every 400 hours per Scheduled Maintenance Checks in the maintenance manual since February 09, 2007.
Recently, Pratt & Whitney released Service Bulletin SB25353 allowing the rest of the PW306C operators to have the new carbon face seal put in their engines. At the starter gear shaft location you may replace the existing magnetic seal with a carbon face seal. Please note that before installing the carbon face seal at the gear shaft location, the gear shaft must be replaced or modified by removing it from the gearbox.
Pratt & Whitney recently released Commercial Support Program Notification 1004445 providing labor and parts support for those wishing to comply with SB25353. Pratt & Whitney may revise the Scheduled Maintenance Checks of the maintenance manual to possibly do away with the 400 hour inspection for engines that have complied with SB25353.
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