Europe's safety regulator is drawing operators' attention to the possibility that items improperly approved by US firm Xtra Aerospace may have been installed on European-registered aircraft.
Xtra Aerospace's repair station certificate was revoked by the US FAA following the discovery that a crucial angle-of-attack sensor was improperly calibrated before it was fitted to the Lion Air Boeing 737 Max which crashed in October last year.
The Indonesian inquiry found that "inadequacy" of FAA oversight allowed Florida-based Xtra to carry out incorrect maintenance work.
In a 2 December bulletin the European Union Aviation Safety Agency says Xtra was found, by the FAA, to have systemically approved certain items for return to service without those items being included on its capabilities list.
The FAA discovered that Xtra did so without conducting self-evaluation to determine properly whether it had the appropriate and equivalent test equipment or tooling.
While EASA has stopped short of issuing an airworthiness directive on the matter, it says aircraft operators, maintenance organisations and parts suppliers should inspect their fleets and inventories for any items approved for return-to-service by Xtra.
"An appropriately-certificated person should carefully scrutinise these articles [or] parts to determine airworthiness," it adds. EASA's measure echoes a similar caution from the FAA – issued through a safety alert for operators – in early November.
Xtra Aerospace stresses that it co-operated with both US and Indonesian investigators during the Lion Air probe, and states that the FAA's separate findings "do not reference" the accident and are "not indications that Xtra was responsible" for the crash.
"While we recognise and respect the FAA’s regulatory oversight, we disagree with the agency’s findings," adds Xtra.
"An important consideration in reaching a settlement with the FAA was to minimise potential disruptions for Xtra’s customers."
It says the FAA's order was based on "procedural non-compliance" and points out that neither the order nor the safety alert identifies any specific unsafe conditions or particular instances of improper maintenance.
"The order did not include any findings that Xtra lacked adequate housing, facilities, technical publications, tools, material, test equipment or trained and qualified personnel for the articles it maintained," the company adds.
Xtra says that all FAA airworthiness approval tags it has issued remain valid.