Line Maintenance
Section 11: Aircraft & Avionics Architecture
Definition
Maintenance activities performed on an aircraft at the gate, ramp, or hangar by line maintenance personnel, without requiring the aircraft to be taken out of the operational fleet for an extended period. Line maintenance encompasses pre-flight checks, transit checks, daily checks, troubleshooting, and LRU replacements. It is characterized by the use of standard tools, limited ground time, and the objective of returning the aircraft to service as quickly as possible.
Where This Shows Up
Line maintenance is the first level of aircraft maintenance and is critical to fleet dispatch reliability. For avionics, line maintenance typically involves fault isolation using built-in test (BIT) indications, central maintenance computer (CMC) fault messages, or troubleshooting manual procedures, followed by LRU replacement if a hardware fault is confirmed. Line maintenance does not involve opening LRUs or replacing SRUs. The effectiveness of avionics line maintenance depends heavily on the quality of fault isolation to the LRU level, the accessibility of LRU installations, and the availability of spare LRUs.
Primary Sources
Regulatory framework for approved maintenance organizations, including line and base maintenance capabilities.
Maintenance program development logic that structures line maintenance tasks and intervals.
Related Terms
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