TP 13094 - Civil Aviation Maintenance Schedule Approval Policy and Procedures Manual

Chapter 3 - Approval

11. General

12. STD 625, Appendix D, Approval

13. Schedule Amendment

14. Administrative Procedures

11 General

11.1 Upon receipt of a Maintenance Schedule Approval document, the Transport Canada Center having jurisdiction will determine if a formal submission of the check package is required or if it would be more appropriate to visit the operator's facility to review the applicable data. In either case, the Transport Canada office having jurisdiction will review the application, comparing it with the program basis and assessing its suitability to the operation.

11.2 In addition to the airframe and systems, the maintenance schedule must also address the engines, propellers, appliances, survival equipment, emergency equipment etc., and must take into account any modifications made to the aircraft. Some items to consider are listed below:

11.2.1 Type of operation, routes, stops, stage lengths, company experience with similar operations, etc.

11.2.2 Environment, such as industrial pollution, salt-air, arctic, desert, etc.

11.2.3 Maintenance history, Service Difficulty Reports, etc.

11.2.4 Age of aircraft in fleet.

11.2.5 Maintenance schedules for similar aircraft types in use by the company.

11.2.6 Additional equipment required by regulations.

11.2.7 Experience of operating personnel.

11.2.8 Compliance with Airworthiness Limitations, Supplemental Inspection Documents (SID), and Corrosion Prevention Control Programs (CPCP).

11.2.9 Repairs to damage tolerant structures.

All scheduled tasks not forming part of the actual check packages should be listed as "out of phase" items as per STD 625, Appendix C, or as referenced on the applicable Maintenance Schedule Approval document.

12 STD 625, Appendix D, Approval

12.1 When reviewing the requirements of STD 625 Appendix D, the correct basis for the maintenance schedule must be used. Where an MRB report exists, it will take priority over the recommendations of the type certificate holder. Type certificate holder's recommendations are generally preferred to schedules that were initially approved for other operators or based upon other data. Where an operator wishes to use data that is in conflict with the preferred program basis, the onus is on the applicant to demonstrate that the proposed program is the more appropriate to their operation.

12.2 If the schedule is based upon that of another operator, the applicant must be able to demonstrate that the new operation is for all practical purposes equivalent to the original one, and that his experience with similar types of aircraft is sufficient to justify assuming the other operator's inspection intervals. Where the operations differ substantially, the use of another operator's schedule as the schedule basis cannot be permitted. Where the operations are similar, but appropriate experience cannot be demonstrated, the operator may be allowed to base his schedule upon the other operator's, but without credit for the other operator's experience in the development of intervals.


13 Schedule Amendment

13.1 Approval of changes that consist solely of a re-arrangement of existing tasks and intervals is a simple matter, consisting primarily of ensuring that sufficient skilled personnel are available to perform the work, and that the operating schedule allows for sufficient down-time to enable rectification of likely defects which may be detected during the checks. Changes for economic reasons will require the demonstration of an acceptable level of reliability, in the form of workshop reports, inspection findings, etc. Increases in the times between overhaul (TBO) of major items such as engines and propellers should normally be based upon a trial/sampling program.

13.2 Substantive changes to tasks and intervals require detailed supporting data. This supporting data will usually result from an used in typical reliability programs.

13.3 A maintenance schedule amendment justification should be submitted for each amendment requested. Detailed supporting data will also be included with the amendment request, detailing the item changed, action to be taken, and justification of proposed change as indicated in the example below:


Item & page Action to be taken Justification
Page 1
- Change in type of operation.
- Change in name of Operator.
- Addition of aircraft models.
- Change in utilization, etc.
Replace with new page
Dated ____________.
Self explanatory
Page 3
- Changes to Out of Phase tasks & equipment requirements.
- Changes to Engine and Propeller TBO's.
Replace with new page
Dated ____________.
Revisions based on type certificate holder's recommendation, or Operator's reliability program, etc.
Page 4
- Changes to the checklist, its reference # or Rev. #.
- Changes to the basis of the schedule.
- Tolerance request.
Replace with new page
Dated ____________.
Self explanatory
Page 5
- Changes to tolerance
Replace with new page
Dated ___________.
Demonstrated satisfactory application of existing tolerances.

13.5 When the maintenance schedule amendment request is submitted, together with any affected pages for approval, the amendment request becomes a permanent record that should be placed in the company or aircraft file. The revision status and pages affected will be indicated on the first page of the maintenance schedule.

13.6 When authorizing an operator to incorporate maintenance schedule changes without prior Transport Canada approval, the procedures for control of these changes must be identified in the operator's MCM. This privilege will usually only be practical for a large aircraft operator.

14 Administrative Procedures

14.1 Operators should make allowance for the time needed to assess the application, which will be dependent upon the workload at the time. Applications will normally be assessed on a first come, first served basis. In the case of a new aircraft type, it is possible that the MRB report will not be completed early enough to allow the first operations to develop their maintenance schedules. In such cases, approval may be granted for an interim schedule based on the MPD, or for a partial schedule that addresses only the short interval items, such as A & B checks. This will enable the carrier to commence operation with the aircraft while developing the full schedule.

14.2 When satisfied that the proposed schedule is adequate, the Civil Aviation Safety Inspector Maintenance and Manufacturing should sign and stamp the applicable maintenance schedule and any continuation sheets, return the original to the applicant, and retain a copy on the aircraft and operator's file.