Developing Alert Level for Aircraft Components

In the aircraft industry maintenance is considered to be one of the key contributors to business success of an air carrier. By this, efforts are made to achieve maximum aircraft utilization with a reliability level as high as possible and minimal operating costs. As a result, aiming to increase profitability, and monitoring the reliability of an aircraft, its components and systems is of great benefit to aircraft carriers. As per Hong Kong Civil Aviation Department (HKCAD) requirements, all registered aircraft must have an approved maintenance schedule (AMS) to ensure aviation safety. In the AMS, system or component reliability plays an important role in condition-monitored maintenance program. To assist in the assessment of reliability of aircraft components, alert levels are established for the components which are to be controlled by the program. An alert level can help the operator to monitor engineering performance of an aircraft system or component during routine operations. Besides a consideration of the quality management processes to be contained within the AMS, this paper illustrates the development of an alert level for a helicopter air-conditioning system (ACS). The function of an ACS is to regulate the temperature, humidity, and air flow inside the helicopter. The reliability of the ACS is therefore important to an air operator. Once the alert level is triggered, approved maintenance actions need to be executed, such as component repair or replacement. In this paper, ACS of the helicopter McDonell Douglas 902 Explorer was chosen to illustrate the development of an alert level for the purpose of improving operational performance.