Maintenance data


145.A.45(a) Availability

(a) The organisation shall hold and use applicable current maintenance data in the performance of maintenance, including modifications and repairs. ‘Applicable’ means relevant to any aircraft, component or process specified in the organisation’s approval class rating schedule and in any associated capability list.

In the case of maintenance data provided by an operator or customer, the organisation shall hold such data when the work is in progress, with the exception of the need to comply with point 145.A.55(c).

Shall the maintenance data be available and controlled at all times, even if there is no maintenance work going, or shall it be available only during the performance of maintenance?

Maintenance data has direct influence on many processes of the approved maintenance organisation (AMO) and contributes to demonstrate the overall capability of the organisation to perform maintenance.
The maintenance data either can be arranged directly by the AMO or provided by the customer/operator as specified by 145.A.45(a), M.A.609 or CAO.A.055(a). In both cases, the AMO should demonstrate that the maintenance data used, regardless of the source, is up-to-date. To discharge this responsibility, a procedure should be established to:

(a) control the amendment status of any documents being used;

(b) regularly check that all amendments are being received, e.g. by subscribing to a document amendment scheme (sufficient in case of direct access to the maintenance data through the DAH/OEM. The subscription to the maintenance data distribution system of the customer/operator is insufficient, additional independent verifications through the original author shall be done).

When the maintenance data is arranged directly by the AMO it shall be available and controlled continuously.

There are certain situations when the maintenance data can be obtained only through the customer/operator. One of the examples would be the maintenance data for the large aircraft. The maintenance data coming from the TC holder is usually customised because of the model/configuration/modification/order of aircraft, so it is normally not possible for the AMO to have this customised maintenance data directly from TC holder without having an aircraft of that type under the contract.

When the maintenance data is provided by the customer/operator, it shall be held and controlled by the AMO during maintenance on the concerned aircraft/component. Whenever the maintenance data is not available or not current, the maintenance shall not be performed and released.

Additionally, as part of the obligation for maintenance records, used maintenance data shall be:

- recorded (in compliance with 145.A.55(c), M.A.614(c) or CAO.A.090(b)) 
- Remark: Manuals issued by the (S)TC (Supplementary Type Certificate) holder such as  AMM and CMM do not need to be stored as a record. Recording the revision status of such manual may be sufficient [AMC 145.A.55(c), AMC M.A.614(c)]; and
- accessible for auditing purpose

to demonstrate that the organisation worked in compliance with their respective requirements.

145.A.45(b) Applicable maintenance data

(b) Applicable maintenance data is the data specified in point M.A.401(b) of Annex I (Part-M) or in point ML.A.401(b) of Annex Vb (Part-ML), as applicable.

GM1 145.A.45(b) References to maintenance data

The provisions of GM1 M.A.401(b)(3) and (b)(4), GM1 M.A.401(b)(4) and GM1 ML.A.401(b) apply.

145.A.45(c) Ambiguous, inaccurate maintenance data

(c) The organisation shall establish procedures to ensure that if found, any inaccurate, incomplete or ambiguous procedure, practice, information or maintenance instruction contained in the maintenance data used by maintenance personnel is recorded and notified to the author of the maintenance data.

AMC 145.A.45(c) Procedures

1. The referenced procedure should ensure that when maintenance personnel discover inaccurate, incomplete or ambiguous information in the maintenance data they should record the details. The procedure should then ensure that the Part-145 approved maintenance organisation notifies the problem to the author of the maintenance data in a timely manner. A record of such communications to the author of the maintenance data should be retained by the Part-145 approved organisation until such time as the type certificate holder has clarified the issue by e.g. amending the maintenance data.

2. The referenced procedure should be specified in the maintenance organisation exposition.

145.A.45(d) Maintenance data modification

(d) The organisation may only modify maintenance instructions in accordance with a procedure specified in the maintenance organisation’s exposition. With respect to those changes, the organisation shall demonstrate that they result in equivalent or improved maintenance standards and shall inform the type-certificate holder of such changes. Maintenance instructions for the purposes of this point means instructions on how to carry out the particular maintenance task: they exclude the engineering design of repairs and modifications.

AMC 145.A.45(d) Procedure

The referenced procedure should address the need for a practical demonstration by the mechanic to the quality personnel of the proposed modified maintenance instruction. When satisfied the quality personnel should approve the modified maintenance instruction and ensure that the type certificate or supplementary type certificate holder is informed of the modified maintenance instruction. The procedure should include a paper/electronic traceability of the complete process from start to finish and ensure that the relevant maintenance instruction clearly identifies the modification. Modified maintenance instructions should only be used in the following circumstances:

(a) Where the type certificate / supplementary type certificate holders original intent can be carried out in a more practical or more efficient manner.

(b) Where the type certificate / supplementary type certificate holders original intent cannot be achieved by following the maintenance instructions. For example, where a component cannot be replaced following the original maintenance instructions.

(c) For the use of alternative tools / equipment.

Important Note: Critical Design Configuration Control Limitations (CDCCL) are airworthiness limitations. Any modification of the maintenance instructions linked to CDCCL constitutes an aircraft modification that should be approved in accordance with Part-21.

145.A.45(e) Work card, worksheet system

(e) The organisation shall provide a common work card or worksheet system to be used throughout relevant parts of the organisation. In addition, the organisation shall either transcribe accurately the maintenance data contained in points (b) and (d) onto such work cards or worksheets or make precise reference to the particular maintenance task or tasks contained in such maintenance data. Work cards and worksheets may be computer generated and held on an electronic database subject to both adequate safeguards against unauthorised alteration and a back-up electronic database which shall be updated within 24 hours of any entry made to the main electronic database. Complex maintenance tasks shall be transcribed onto the work cards or worksheets and subdivided into clear stages to ensure a record of the accomplishment of the complete maintenance task.

Where the organisation provides a maintenance service to an aircraft operator who requires their work card or worksheet system to be used then such work card or worksheet system may be used. In this case, the organisation shall establish a procedure to ensure correct completion of the aircraft operators’ work cards or worksheets.

AMC 145.A.45(e) Procedure

1. The maintenance organisation should:
— transcribe accurately the maintenance data onto such work cards or worksheets, or
— make precise reference to the particular maintenance task(s) contained in such maintenance data, which already identifies the task as a CDCCL where applicable.

2. Relevant parts of the organisation means with regard to aircraft base maintenance, aircraft line maintenance, engine workshops, mechanical workshops and avionic workshops. Therefore, engine workshops for example should have a common system throughout such engine workshops that may be different to that in the aircraft base maintenance.

3. The workcards should differentiate and specify, when relevant, disassembly, accomplishment of task, reassembly and testing. In the case of a lengthy maintenance task involving a succession of personnel to complete such a task, it may be necessary to use supplementary workcards or worksheets to indicate what was actually accomplished by each individual person.

145.A.45(f) Availability of maintenance data

(f) The organisation shall ensure that all applicable maintenance data is readily available for use when required by maintenance personnel.

AMC 145.A.45(f) Format

1. Data being made available to personnel maintaining aircraft means that the data should be available in close proximity to the aircraft being maintained for supervisors, mechanics and certifying staff to study.

2. Where computer systems are used, the number of computer terminals should be sufficient in relation to the size of the work programme to enable easy access, unless the computer system can produce paper copies. Where microfilm or microfiche readers/printers are used, a similar requirement is applicable.

145.A.45(g) Control of maintenance data

(g) The organisation shall establish a procedure to ensure that maintenance data it controls is kept up to date. In the case of operator/customer controlled and provided maintenance data, the organisation shall be able to show that either it has written confirmation from the operator/customer that all such maintenance data is up to date or it has work orders specifying the amendment status of the maintenance data to be used or it can show that it is on the operator/customer maintenance data amendment list.

AMC 145.A.45(g) Currency of maintenance data

To keep data up-to-date, a procedure should be set up to monitor the amendment status of all data and maintain a check that all amendments are being received by being a subscriber to any document amendment scheme. Special attention should be given to TC related data such as certification life-limited parts, airworthiness limitations and Airworthiness Limitation Items (ALI), etc.

Updated on 18/07/2022

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