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

Chapter 2 - Schedule Development

5. General

6. Application

7. Small Aircraft Schedules

8. Large Aircraft Schedules

9. Schedules Amendment

10. Tolerances

5. General

5.1 Transport Canada must first approve the initial maintenance schedule. Similarly, all amendments to the schedule must also be approved, unless the operator's incorporating changes solely on the basis of the operator's own analysis.

5.2 The operator must ensure that the tasks listed in the maintenance schedule are completed within the intervals specified.

5.3 In addition to addressing all tasks arising out of the initial analysis of the aircraft's Maintenance Significant Items (MSI) all maintenance schedules must include any additional items necessary to ensure compliance with Airworthiness Limitations such as component life limits, etc. The schedule must take into account the aircraft's operational role, in particular the need for compliance with operational requirements such as those for Instrument Flight Rules, Extended Range Operations, Category II &III approach minima and operation with Reduced Vertical Separation. The schedule must also address any maintenance requirements resulting from modifications or repairs, particularly major changes authorized by Supplemental Type Certificates, Limited Supplemental Type Certificates or Repair Design Approvals.

Information Note: The operational role of the aircraft may have a significant effect on the Maintenance Schedule, for example: Aircraft engaged in agricultural operations may be authorized to operate at increased take off weights, or carry corrosive materials etc

5.4 Pre-flight walk around checks performed by flight crew or daily and pre-departure checks intended to be performed by unlicensed personnel, need not form part of the approved maintenance schedule. These tasks should be addressed in other sections of the appropriate maintenance control manual, or in the case of private aircraft, will be performed at the discretion of the operator. Similarly, compliance with Airworthiness Directives need not be included in the maintenance schedule, but must be managed directly by the operator, using a control system appropriate to the operation concerned.

5.5 Except where specifically authorized otherwise in the operator's MCM, Transport Canada must approve all maintenance schedule amendments that relate to changes in the aircraft's operational role, deletion of tasks, increase in task intervals, or any other significant changes. Prior approval is not required for the addition of tasks or reductions of task intervals, however the operator must notify Transport Canada of such changes at the earliest convenient opportunity.

5.6 In the interests of standardization, and to simplify the approval process, Transport Canada has developed documents to identify approved maintenance schedules. These documents are referred to throughout this document, and samples are provided in the appendices. Equivalent locally produced or computer generated documents may be accepted in lieu, provided they conform to the basic structure and content of the Transport Canada documents.

6. Application

6.1 Application for approval of a maintenance schedule must be submitted in accordance with STD 625 Appendix D. To simplify the process for operators of small aircraft, the schedule may be based upon the applicable items contained in the list provided in STD 625 Appendix B, supplemented by the applicable out of phase requirements of STD 625 Appendix C. Approval of small aircraft and Balloon schedules is accomplished though the use of Appendix A of this document. Approval of all other schedules is by means of Appendix B of this document.

7. Small Aircraft Schedules

7.1 Operators of small aircraft should submit to Transport Canada a completed Maintenance Schedule Approval (Appendix A) in duplicate, containing or referencing the applicable maintenance schedules, and make the schedule available for review.

7.2 If the schedule is approved in accordance with STD 625 Appendix B, Part 1, the tasks listed must be performed at intervals not exceeding 100 hours air time or 12 months, whichever occurs first. The schedule may include additional tasks performed at greater intervals, provided that all the items addressed in Appendix B Part 1 are inspected at intervals no greater than 100 hours air time or 12 months. The schedule may be a progressive type schedule, whereby not all of the tasks need be performed at the same time, provided that no item listed in Appendix B Part 1 is inspected less frequently than 100 hours air time or 12 months.

7.3 The operator of a small aircraft may choose to seek approval for a maintenance schedule in accordance with STD 625, Appendix D. In such cases, application should be made using Appendix A to this document and the procedures specified in paragraph 8 below would apply.

8. Large Aircraft Schedules

8.1 When complying with the requirements of STD 625 Appendix D, the proposed maintenance schedule must be based on one of the following sources;

8.2 Maintenance Review Board (MRB) reports.

8.2.1 Schedules based on an MRB report must include all the tasks listed in the report, plus any additional tasks arising from the role in which the aircraft is to be employed or the environment in which it is to be operated. The intervals between tasks specified in the MRB should be regarded as the maximum intervals for the operator's initial schedule, and may be adjusted downward if the operation is in any way nonstandard.

8.2.2 MRB reports usually address only the "green" aircraft and must therefore be supplemented by additional tasks to ensure the serviceability of optional equipment, including galley and passenger service equipment, life jackets, medical kits, etc.

8.2.3 The holders of the aircraft type certificate will usually produce a Maintenance Planning or other such document (MPD) to assist operators in planning and structuring a maintenance program. Normally the holder of the aircraft type certificate will include within the MPD a copy of the MRBR with the tasks packaged in a manner that is usable to the air operator. They will also include other tasks derived from processes other than the MRBR. For example tasks that may be included are Airworthiness Limitations, which would include structural fatigue related tasks for damage tolerant aircraft, life limited parts, certification maintenance requirements and fuel tank system mandatory replacement times and inspection intervals. They would also include recommended tasks for equipment and parts of the aircraft not addressed by the Maintenance Review Board Report such as those mentioned in 8.2.2 above. The applicant for a maintenance schedule approval should ensure that these aspects of the MPD or the aircraft type certificate holder's recommendations are included within their maintenance program.

8.2.4 In the case of older aircraft where the holder of the type certificate has not kept the MRBR current, the Maintenance Planning Document or other documents may have incorporated informal or supplementary information, which amount to type certificate holder's recommendations and which result in different maintenance tasks than those that were originally developed as part of the MRB. In the past when this kind of situation was encountered the inspector approving the maintenance schedule would normally utilize the latest information. However with current agreement at the International Maintenance Review Board Policy Board, the regulatory authorities responsible for the MRBRs have undertaken to keep them current. Should an out-of-date MRBR be encountered, the Civil Aviation Safety Inspector (CASI) is requested to inform the Aircraft Evaluation Section, Operations Division (AARPG) so that they might take corrective action to ensure currency of the document. The MRBR must reflect the current experience of the type certificate holder with their aircraft, therefore annual reviews are required. The desired end result will be that the MRBR is kept current in accordance with the guidelines given to the holder of the type certificate, pursuant to TP 13850.

8.2.5 There are occasions in the MRB process where the analytical logic did not identify tasks that address the type certificate holder's warranty considerations or the type certificate holder's driven inspection criteria. In situations such as this, the type certificate holder may use the MPD as a repository to record these types of requirements. These requirements need not be included in the base maintenance schedule of an air operator unless the air operator desires them to be included.

8.3 Type certificate holder's recommendations.

8.3.1 Schedules based upon the type certificate holder's recommendations will generally be approved after a minimum of investigation, provided that all necessary additional items resulting from the operator's role, environment and optional equipment are also included.

8.3.2 It should be noted that the term "type certificate holder's recommendations" is not limited to the basic recommended schedule. Recommendations issued in the form of Instructions for Continued Airworthiness (ICAs) and/or publications issued by the Type Certificate (TC) holder (airframe, engine, or propeller) and the holder of design approvals such as Supplementary Type Certificates (STC), Repair Design Approvals (RDA) or Part Design Approvals (PDA), are instructions that need to be evaluated.

8.3.3 In certain cases, individual tasks recommended by the type certificate holder may be omitted from the operator's initial schedule, but approval for such action will be dependent upon the operator's ability to demonstrate to the satisfaction of the Minister, that the omission will not have any adverse effect on safety.

8.4 Maintenance Schedules approved for other Canadian operators.

8.4.1 Although maintenance schedules are not transferable, operators may base their schedules upon those of another Canadian operator. Analysis of schedules developed in this way will involve a comparison between the two operations. Approval will depend upon the applicant's ability to demonstrate that the role, aircraft configuration, route structure, type of evaluation program and environment are essentially the same in both cases. A comparison of the reliability programs of the previous operator and the applicant would be required. In addition, the assessment will take into account the relative experience of each operator with the aircraft type, or with similar types. An operator may not take credit for another operators established TBO, or other intervals, unless the operator can show equivalent competence and experience.

8.4.2 Applications to base a schedule upon that of another operator usually occur when an operator purchases or leases an aircraft, and wishes to take over the seller's maintenance schedule as part of the package. If the assessment of the application results in changes to tasks or intervals, it will be necessary to re-calculate (prorate) the times when the tasks are next due. This subject is addressed in STD 625.87. It should be noted that the approval of a new maintenance schedule and the transfer of aircraft on to that schedule are two separate operations. Approval of the schedule does not in itself establish when the tasks are next due for a particular aircraft.

8.5 Other data acceptable to the Minister.

8.5.1 This heading covers a wide range of possible sources, including schedules approved by other airworthiness authorities, military schedules, and in rare cases, completely new schedules resulting from the operator's analysis of the aircraft design. The depth of review required for approval will depend upon the circumstances of the individual case.

9. Schedule Amendment

9.1 Each operator must employ appropriate means to assess the continued effectiveness of their approved maintenance schedules. Part IV or Part VII certificated operators are mandated to establish a formal process for this evaluation (CAR 406.47 and CAR 706.07 refer). While private operators need not have a formally documented process, they are nonetheless still responsible for ensuring the continued effectiveness of their approved maintenance schedules. Also, STD 625.86 refers to Maintenance Monitoring Programs and references Appendix E, which in turn refers to Airworthiness Manual Advisory (AMA) 571.101/1 Reliability Monitoring Programs. The operator's program should be sufficiently comprehensive to identify any need for changes to the maintenance schedule and would usually include at least the day-to-day analysis of flight crew reports (PIREPS), or a fully-fledged reliability program.

9.2 Changes to the maintenance schedule consist essentially of five types:

9.2.1 Addition of tasks or reduction of intervals, to ensure that acceptable levels of safety and reliability are obtained.

9.2.2 Deletion of tasks or extension of intervals, to achieve reductions in operating costs.

9.2.3 Re-arrangement of existing tasks and intervals into different check packages, to cater for changes in route structure or timetables, or to obtain improved equipment availability.

9.2.4 Changes to "tombstone" data involving fleet size, type of operation, etc.

9.2.5 Safety-related changes directed by Transport Canada, based on their own analysis or on the experience of other operators.

9.3 Transport Canada must approve maintenance schedule amendments, unless prior approval has been obtained to incorporate changes directly. When applying for approval for a schedule amendment, the request should indicate the affected items, the action to be taken, and the justification for the change. A sample amendment request is provided in the Appendix to this publication. When completed, the request will indicate which pages have been amended and the amendment status will be indicated on those pages. Each time an amendment is approved, the revision number and pages affected by the revision must be indicated on in the revision control block on page 1 of the maintenance schedule.

9.4 Certain air operators, whose programs are sufficiently detailed and mature, and who have demonstrated the effectiveness of these programs over a period of time, may be authorized to incorporate maintenance schedule changes directly, based solely upon their own analysis, without the need for prior Transport Canada approval for each change. The procedures for the exercise of this authorization must be detailed in the operators approved MCM.

10. Tolerences

10.1 The use of tolerances to scheduled maintenance task intervals is permitted only when the checks prescribed by the Maintenance Schedule, or supporting documents in support of the schedule, cannot be complied with due to circumstances that could not reasonably have been foreseen by the operator. Where an operator wishes to include tolerances in a maintenance schedule, the application must contain full details of the tolerance, including the means of control, and the applicant must demonstrate that the items concerned can safely be operated at the resulting higher intervals.

10.2 In the case of an aircraft operated pursuant to Subparts 406, 604 or 706, use of maintenance schedule tolerances shall be authorized and controlled in accordance with the operator's approved procedures as set forth in the applicable operations manual or maintenance control manual as the case may be;

10.3 In the case of an aircraft other than described in 10.2, prior to use of a maintenance schedule tolerance, the aircraft shall be inspected by the holder of an applicable and valid AME license to the degree necessary to confirm that it is in satisfactory condition to operate for the period of the tolerance.

10.4 The operator must amend the schedule to remove tolerances when directed by the Minister. This action may be required when the Minister believes that the operator has not used the tolerance appropriately, or has not followed the tolerance procedures set forth in the MCM.

10.5 No tolerances shall be applied to any Airworthiness Directive, Airworthiness Limitation, or any other task classified as mandatory by the responsible regulatory authority, unless the tolerance is specified therein, or specifically authorized in STD 625 Aircraft Equipment and Maintenance Standards.

10.6 The tolerance examples referenced below are for guidance purposes only and the Transport Canada Center having jurisdiction should approve tolerances on a conservative basis, taking into account the operator's past history of maintenance planning and tolerance use. Tolerances may apply to items controlled by flying hours, calendar time, and/or operating/cycles. Examples of tolerances that may be approved by Transport Canada are as follows:

10.6.1 Items Controlled by Flying Hours:

10.6.1.1 10% of the applicable task interval, or 500 hr., whichever is the lesser

10.6.2 Items Controlled by Calendar Time:

10.6.2.1 10% of the applicable task interval, or 3 months, whichever is the lesser

10.6.3 Items Controlled by Landings or Operating Cycles:

10.6.3.1 10% of the applicable task interval, or 50 Landings / Operating Cycles, whichever is the lesser

Note: For items controlled by more than one limit (e.g., items controlled by both flying hours and calendar time) the more restrictive limit must be applied. Items subject to Transport Canada approved trial programs, may vary the time trial periods by a maximum of 50 flying hours, provided that the agreed trial program does not specifically exclude such a variation.

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