Shop Replaceable Unit
SRUSection 11: Aircraft & Avionics Architecture
Definition
A component or sub-assembly within an LRU that is designed to be removed and replaced in a repair shop (not at the aircraft line) using appropriate shop tooling and procedures. SRUs are the fundamental unit of shop-level (bench) maintenance and include items such as circuit board assemblies, power supply modules, display subassemblies, and other modules within the LRU.
Where This Shows Up
SRU-level repair takes place at authorized repair facilities (14 CFR Part 145 / EASA Part 145) where technicians can open the LRU enclosure, diagnose the fault to the SRU level using component maintenance manuals (CMM) and test equipment, and replace the faulty SRU. The repaired LRU is then functionally tested per the CMM acceptance test procedures before being returned to serviceable stock. The SRU architecture of an LRU directly affects repair turnaround time and cost: a well-designed LRU with clearly defined SRU boundaries and effective built-in test enables rapid fault isolation and repair.
Primary Sources
Defines the SRU concept within the maintenance program framework for shop-level repair activities.
Related Terms
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