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S3C11 - DEFERMENT OF REQUIRED MAINTENANCE
Table of Contents
1. Approved Maintenance Organisations (AMOs) are often required to operate aircraft at high tempo and in harsh environments, which can be detrimental to the serviceability state of the aircraft. In order to meet the demands of operational availability and increase maintenance efficiency, it may be appropriate to defer required maintenance. The deferment of required maintenance process allows an aircraft to operate prior to rectification of the required maintenance.
2. This chapter prescribes the requirements to effectively manage the deferment of required maintenance.
DEFERMENT OF REQUIRED MAINTENANCE PROCESS
3. Deferment of required maintenance is achieved through the Carried Forward Unserviceability (CFU) process.
4. CFU authority is administered in accordance with the DGTA–ADF approved Maintenance Management System (MMS) described in the AMO Maintenance Management Plan (MMP).
CARRIED FORWARD UNSERVICEABILITY COMPETENCY STANDARDS AND DELEGATION
5. All CFUs must be authorised by the SMM or delegate within the scope of their authority. Prior to delegating the authority to authorise CFUs, the SMM must ensure that designated personnel have attained and retained, as a minimum, the following competency standards:
Delegation of CFU Authority
6. The SMM may delegate CFU authority to the following personnel:
7. Promulgation of CFU Delegates. The AMO is responsible for the promulgation of a list of personnel with CFU authority in local instructions. Personnel authorised with CFU Authority must be monitored by the SMM to ensure competence is maintained and authorisation remains valid.
8. Scope of CFU Authorisation. The scope of the CFU authorisation must be defined in local instructions and must be based on the delegates:
CARRIED FORWARD UNSERVICEABILITY PROCESS
10. Before the rectification of an unserviceability is carried forward, the Senior Maintenance Manager (SMM) or delegate must consider the following:
11. Seeking CFU Advice. The SMM or delegate may seek advice to inform their CFU assessment. They may seek advice from anyone considered as value adding to their decision. People providing advice do not need to be authorised to do so.
12. Technical advice that would assist the SMM or delegate in making the CFU decision include risk-relevant advice on the:
13. The SMM or delegate may also seek:
14. The SMM or delegate who seeks advice from another person is not transferring the CFU decision responsibility to the person providing the advice. The person asked to provide advice will never have complete understanding of all the relevant considerations. In many situations the person giving advice will be geographically distant and cannot see the unserviceable component or even photographs or diagrams of it. Receiving advice in no way diminishes the responsibility of the SMM or delegate for the CFU decision.
15. The extent to which good advice can be provided to support the SMM or delegate in their CFU assessment depends on the information provided to the person from whom advice is sought, and the questions asked by the SMM or delegate when seeking advice.
CFU Assessment Process
16. The SMM or delegate must ensure that they have:
17. If the SMM or delegate does not have the competence or expertise to make the appropriate assessment, assistance must be sought from the relevant Systems Program Office (SPO).
18. Before authorising a CFU which affects the handling or operating characteristics of an aircraft, the SMM or delegate must obtain an operational endorsement from an appropriately authorised aircrew representative.
19. Prior to accepting the aircraft, the Aircraft Captain will also make an independent assessment of its mission worthiness. The final decision on whether an aircraft is acceptable for an intended mission lies with the Aircraft Captain. If an aircraft is not accepted because of an outstanding CFU, the matter must be referred to the SMM for direction.
20. CFU Pre-assessment. To simplify the CFU process and to allow greater delegation of CFU authority within the AMO, unserviceabilities may be pre-assessed. Pre-assessment involves the SMM or other authority considering possible unserviceabilities, completing the engineering and operational and technical airworthiness analysis, and promulgating the outcomes in a local instruction. The concept of referring to an unserviceability with a pre-assessed impact simplifies the decision making process for the SMM or delegate. Unserviceabilities with pre-assessed impacts on operational and technical airworthiness include:
21. Lists of pre-assessed unserviceabilities are not an automatic authority to carry forward an unserviceability and must be treated in the same way as advice when making a CFU decision. Additionally, the SMM or delegate must consider the combined impact of the unserviceability on operational and technical airworthiness.
CFU Documentation, Authorisation and Management
22. The reasoning and justification leading to authorising of a CFU must be documented. The minimum recording requirements must address:
23. An example CFU Authorisation Form is illustrated in Annex A. CFU authorisation forms may be tailored to meet specific AMO requirements. The form and the procedures for its use must be promulgated in local instructions.
Original CFU authorisations forms must not travel with the parent aircraft.
24. Electronic CFU Management. For CFU management in electronic recording and certification systems, deferment periods may be scheduled maintenance events.
25. Paper-based CFU Management. The practice of using ‘Until Spares Available’ (‘TSA’), ‘Next Rx’ or similar annotations must not be used as they do not provide a valid period of deferment. However, ‘30 Jul 03 (TSA)’, ‘1234.5 hrs (Next R1)’ is acceptable as a definite period of deferment has been specified.
26. Electronic CFU Authorisation Forms. Entries in an electronic recording and certification system must be in accordance with the relevant system approved instructions.
27. Paper-based CFU Authorisation Forms. Current CFU authorisation forms must be filed by Aircraft Tail Number in a dedicated CFU folder and kept readily accessible, eg flight line area, so the SMM and Aircraft Captains can easily access all CFU decisions. Closed CFU authorisation forms must be retained in the applicable Aircraft Log Pack in CFU order.
28. CFU Traceability. AMOs must develop and promulgate in local instructions a process in that, all CFUs are traceable to the original Serial Number of Work (SNOW) and any subsequent authorisation ‘SNOW’.
29. If the unserviceability is authorised for deferment, the unserviceability must be transferred to the CFU Section in accordance with the recording and certification system instructions.
30. The CFU authorisation form ‘Registration Number’ must be referenced against the applicable unserviceability in the recording and certification system.
31. The CFU section is a consolidated record of all current approved CFUs for the aircraft and any associated limitations. CFUs must be presented in a format that displays their impact on operational and technical airworthiness to the aircraft captain on acceptance of the aircraft. If, as a result of a CFU, there are limitations effecting aircraft role capability, the limitation must be identifiable.
32. CFUs must be re-assessed when:
33. When the CFU is to be re-assessed, the CFU must be administered in accordance with the recording and certification system instructions. The CFU must be completely re-assessed and revised decisions must be developed in accordance with this chapter.
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