The Manual COC (Customer-Requested Change) Service is initiated by the customer to incorporate their unique modifications and procedures into customized manuals and documents as part of a technical publication revision service. The correctness and reasonableness of the COC revisions are the responsibility of the customer, and the customer must obtain approval from the local aviation authorities.

Products eligible for inclusion in the Manual COC service include:
- Specific airline engineering notices (e.g., cabin refurbishments, passenger entertainment systems, TCAS installation).
- Transforming the initial text provided by COMAC according to the customer’s specific requirements.
- Merging the customer’s special procedures and data, canceling/changing/removing previously merged changes (e.g., for aircraft resale).
- Incorporating service bulletins issued by BFE suppliers, and special procedures for FOCM/QRH.

The service content includes the following for Quick Reference Handbooks (QRH) and Flight Crew Operating Manuals (FCOM):
- COC Additions: Adding COC information to the manuals based on the customer’s provided requirements and relevant materials.
- COC Technical Content Revisions: Modifying existing COC information in the manuals.
- COC Deletions: Removing existing COC information from the manuals.
- COC Validity Revisions: Changing the scope of validity for existing COC information in the manuals or maintaining its validity based on the customer’s preset conditions and information.

The customer benefits from enhanced manual management convenience, reduced usage error rates, and ensuring the normal operation and maintenance of COMAC aircraft.