The "Aging Aircraft Safety Rule" refers to a set of regulations and guidelines implemented by the Federal Aviation Administration (FAA) in the United States to address the safety concerns associated with aging aircraft. The rule aims to ensure the continued airworthiness of older aircraft and prevent safety risks that may arise due to age-related degradation.

In 2007, the FAA introduced the Aging Aircraft Safety Rule (14 CFR Part 121, Amendment 121-338) to address the growing concern of aging aircraft in the commercial airline fleet. The rule applies to commercial airliners that have reached or exceeded their design service objective (DSO) of 15,000 to 20,000 flight cycles, or have been in service for more than 20 to 25 years.

Key aspects of the Aging Aircraft Safety Rule include:

1. Damage Tolerance Evaluation (DTE): Airlines must perform a DTE to assess the aircraft's structural integrity and identify potential safety risks.
2. Repair Assessment Guide (RAG): Airlines must use a RAG to evaluate the effectiveness of repairs and ensure that they meet FAA standards.
3. Aging Aircraft Inspection Program (AAIP): Airlines must implement an AAIP to detect and address age-related degradation, such as corrosion, fatigue, and other forms of damage.
4. Corrosion Prevention and Control Program (CPCP): Airlines must establish a CPCP to prevent and control corrosion, which can be a significant safety risk in aging aircraft.
5. Widespread Fatigue Damage (WFD) assessment: Airlines must assess the risk of WFD, which can occur when an aircraft has accumulated a large number of flight cycles.

The Aging Aircraft Safety Rule is designed to ensure that aging aircraft are maintained and operated safely, and that airlines take proactive measures to address age-related safety risks. The rule has been effective in reducing the risk of accidents and incidents related to aging aircraft, and has set a precedent for similar regulations globally.