Instructions for Continuing Airworthiness (ICA): From Certification to Operation

Instructions for Continuing Airworthiness (ICA) are the descriptive data, maintenance planning and accomplishment instructions required to ensure that an aircraft remains airworthy — meaning it conforms to its approved design and is safe for operation —throughout its operational life.

ICA are developed by the Design Approval Holder (DAH) in accordance with the applicable certification basis and are intended to allow operators to develop their own Aircraft Maintenance Program (AMP) and also for approved maintenance organizations to accomplish maintenance tasks.

Note: ICAO generally calls them “Instructions for Continuing Airworthiness”, while EASA and FAA use “Instructions for Continued Airworthiness”. Despite the differences in terminology, the point is to follow them to remain compliant with continuing airworthiness requirements.

ICA at the Time of Certification

The design approval of a new aircraft, engine, or propeller through the issuance of a Type Certificate (TC) requires the availability of mandatory ICA. These include the Airworthiness Limitations Section (ALS) and Certification Maintenance Requirements (CMR). The Maintenance Review Board Report (MRBR), developed alongside the type certification with the minimum schedule maintenance requirements to be used in the development of an approved maintenance program, is normally provided, but may be replaced by alternative means of compliance if approved by the competent authority.

These ICA define the mandatory limitations and baseline maintenance tasks necessary to demonstrate compliance with the certification requirements.

Some portions of the ICA, usually related to overhaul, heavy maintenance, or tasks that occur at longer intervals may be delayed until the aircraft, engine, or propeller has entered into service, but must be provided before reaching the applicable age or maintenance threshold. This ensures that all long-term or major maintenance activities can be performed in compliance with the approved design without affecting the aircraft’s safety during initial operations.

ICA Availability Before Entry into Service

Before an aircraft enters into service, the operator must have access to all relevant ICA, including unscheduled maintenance items that may arise during initial operations. While scheduled tasks such as those in the ALS, CMR, and MRBR provide a structured framework for scheduled maintenance, the majority of ICA tasks are unscheduled, covering inspections, servicing, and procedures that cannot always be planned in advance.

Examples:

• Detecting a hydraulic leak during pre-flight checks, requiring guidance from the Aircraft Maintenance Manual (AMM).

• Identifying a worn part that must be cross-referenced in the Illustrated Parts Catalogue (IPC).

• Structural repair procedures from the Structural Repair Manual (SRM) for minor airframe damage.

• Troubleshooting unexpected system faults using the Troubleshooting Manual (TSM).

All of these manuals and instructions must be available at or before entry into service to ensure the aircraft can be maintained safely from its first flight.

ICA During Aircraft Operation

After entry into service, ICA continue to evolve. Further testing, analysis, and worldwide fleet experience may lead to changes intended to maintain or improve safety. This process ensures that ICA remain aligned with the actual operational behaviour of the aircraft.

Operator in-service experience, typically monitored through a Reliability Program, may result in additional maintenance tasks, the implementation of manufacturer or vendor recommendations, and the incorporation of modifications that were not anticipated during certification. Modifications and repairs may also arise from new or revised mandatory requirements, such as Airworthiness Directives (ADs) or operational regulations.

When a modification affects the continuing airworthiness of the aircraft, the Design Approval Holder (DAH) is responsible for issuing new or revised ICA. Major modifications approved by the TC holder are generally incorporated through Service Bulletins (SBs), while modifications approved by other design organizations are issued as Supplemental Type Certificates (STCs), with associated ICA included in the certification basis.

Repairs following aircraft damage may also generate ICA. If the repair follows the Structural Repair Manual (SRM), repetitive inspections defined in the manual are considered ICA. For repairs outside the SRM, the holder of the repair design approval must provide the necessary ICA to ensure the aircraft continues to conform to its approved Type Certificate.

ICA Responsibilities

Design organizations are responsible for developing and providing ICA to the aircraft owner and any person or organization required to comply with them. They must also ensure that any changes or revisions to the ICA are distributed appropriately. Operators and continuing airworthiness management organizations integrate the applicable ICA into the Aircraft Maintenance Program (AMP) and ensure that all maintenance, modifications, and corrective actions are carried out according to these instructions. Approved maintenance organizations execute maintenance in accordance with the ICA.

Conclusion

Instructions for Continuing Airworthiness guide both scheduled and unscheduled maintenance from certification through daily operation. With responsibilities assigned to design organizations, operators, and maintenance organizations, an aircraft can remain airworthy at all times. Proper understanding and use of ICA supports regulatory compliance and safe operations throughout the aircraft’s lifecycle.

Understanding the role of each ICA in scheduled maintenance can be complex. Our Advanced Expert course shows you how to turn ICA and in-service experience into a clear, compliant, and effective Aircraft Maintenance Program.