Airframe OEMs have the power—and incentive—to play a major role in resolving NFFs. Airbus’s NFF policy for A320s, A330s and A340s seeks to ensure that when avionics components show an error, all applicable maintenance actions and memory reading are done to identify the root cause of a fault message and avoid unnecessary removals. Thus, if a removed component is shipped to its supplier with all required supporting data and tests NFF, test costs will not be charged to the airline.
The decision on whether to remove a part is made by the airline. When a component is turned in, its OEM or the OEM’s authorized repair station contacts the airline to learn the reasons for removal and obtain historical data. Airbus may get involved to ensure all causes are documented, resolve interface issues and maintain its NFF policy.
Responsibilities are very specific. Airlines must supply data including the initiating pilot, maintenance or post-flight reports, results of built-in test equipment (BITE) tests, troubleshooting data or return-to-service tests and historical data on all its NFFs. Airlines must also follow Airbus’s flight crew operating manual, operation engineering bulletins and maintenance recommendations. They should keep maintenance records by component serial number. If the same component is NFF three times in a short period—typically 12 months—the airline should send it to the OEM for in-depth investigation. Rogue units can also be spotted with historical records.
Airbus’s avionics OEMs must keep historical data by serial number of all components repaired in their shops. Data must include warranty history, total repair history, reasons for removal, tests, NFFs, modifications and all work performed. The OEM should also do the in-depth investigation of high-frequency NFFs.
This policy applies to avionics electronic and electric equipment, but not to proximity switches, pressure transducers, circuit breakers and hydraulic, mechanical and engine parts.
The Airbus policy at least reduces airline NFF costs. Over time, it should also reduce NFFs, yield better understanding of centralized systems on the aircraft and greater understanding of NFFs by both airlines and suppliers and improve the troubleshooting manual.
A version of this article appears in the November 3/10 issue of Aviation Week & Space Technology.