"Instructions for Continued Airworthiness" (ICAs) refers to a set of guidelines and procedures provided by the aircraft manufacturer or the regulatory authority to ensure that an aircraft remains airworthy throughout its operational life.

ICAs are typically included in the aircraft's maintenance manual or documentation and outline the necessary maintenance, inspections, and repairs that must be performed at regular intervals to maintain the aircraft's airworthiness. The purpose of ICAs is to:

1. Ensure the aircraft remains compliant with regulatory requirements and safety standards.
2. Prevent degradation of the aircraft's performance, safety, and reliability.
3. Identify and address any potential safety concerns or hazards.
4. Provide a framework for maintenance, inspection, and repair activities.

ICAs typically cover aspects such as:

1. Maintenance schedules and intervals
2. Inspection procedures and frequencies
3. Repair and replacement procedures
4. Modification and upgrade requirements
5. Corrosion prevention and control measures
6. Age-related maintenance requirements
7. Special inspections or checks required due to specific aircraft configurations or operational conditions

ICAs are essential for ensuring the continued airworthiness of an aircraft, and compliance with these instructions is mandatory for operators and maintenance organizations. Regulatory authorities, such as the Federal Aviation Administration (FAA) in the United States, also require that aircraft manufacturers provide ICAs as part of the aircraft's certification process.

By following ICAs, aircraft operators and maintenance personnel can help ensure that the aircraft remains safe, reliable, and compliant with regulatory requirements, which is critical for protecting the lives of passengers, crew members, and people on the ground.