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When discussing the subject of service bulletins (SB’s), there is sometimes confusion about what is required at the time of shop visit or under normal maintenance practices. Every engine OEM has varied requirements in how they instruct the operator to adhere to SB's. Some are ‘REQUIRED’, some ‘RECOMMENDED’ with caveats, some ‘OPTIONAL’ or ‘INFORMATION’ only. Most OEMs have adopted a category system to instruct how and when the services should be performed to better clarify the level of urgency. The following is a breakdown of Pratt & Whitney Canada's (P&WC’s) system for engine SBs.
Pratt & Whitney Canada Service Bulletin Compliance Codes:
Category 1 "P&WC recommends to do this service bulletin before the next flight."
Category 2 "P&WC recommends to do this service bulletin the first time the aircraft is at a line or maintenance base that can do the procedure."
Category 3 "P&WC recommends to do this service bulletin within ____ hours or ____ cycles."
Category 4 "P&WC recommends to do this service bulletin the first time the engine or module is at a maintenance base that can do the procedures, regardless of the scheduled maintenance action or reason for engine removal."
Category 5 "P&WC recommends to do this service bulletin when the engine is disassembled and access is available to the necessary subassembly (i. e. module, accessories, components, or build groups). Do all spare subassemblies."
Category 6 "P&WC recommends to do this service bulletin when the subassembly (i. e. module, accessories, components, or build groups) is disassembled and access is available to the necessary part. Do all spare sub-assemblies.”
Category 7 "You can do this service bulletin when the supply of superseded parts is fully used."
Category 8 "This service bulletin is optional and can be done at the discretion of the operator."
Category 9 Spare Parts Information.
As Designated Overhaul Facilities for P&WC, Dallas Airmotive and H+S Aviation are required to make every effort to bring the standard of the fleets we service to the highest level of safety and reliability, as part of the OEM Service Network. Due to the financial implications that come with SBs, operators sometimes request a lower SB level to be applied when we service their engines while others elect to incorporate bulletins that are considered optional, with needs varying by operating environment and customer preference.
Service bulletins have descriptions of the changes and intended benefits to help customers determine what’s right for their operations. When servicing engines that are covered under the P&WC Eagle Service Plan™ (ESP™) program, the general rule is that we must incorporate category 1 through category 6 SBs at the time the engine is in work. In addition, each ESP-covered engine is accompanied by a specific Work Authorization (WA) providing definitive instructions on what level of SB category is needed.
While there are no mandatory service bulletins (unless associated with an Airworthiness Directive), following the manufacturers recommendations for SB compliance can positively affect product reliability and warranty.
For additional information on service bulletin compliance or questions about your next engine maintenance event, please contact the experts.