The maintenance data either can be arranged directly by the part-145 maintenance organisation (AMO) or provided by the customer/operator as specified by 145.A.45(a) and 145.A.45(g). 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; and
(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, as mentioned by 145.A.50(a) and 145.A.80 of the Regulation 1321/2014 correspondingly.
Additionally, maintenance data has direct influence on many processes of the AMO therefore it should also be available during the initial approval and continuous surveillance audits on the AMO to demonstrate the overall capability of the organisation to perform maintenance.