MRO and test

Every repair station that works on US-registered aircraft holds a certificate under Part 145 of the federal aviation regulations, and the certificate is public.¹ The FAA publishes the certificate number, the ratings and the address, so the first check in this category costs nothing: look the shop up before you call it, and read what its certificate actually permits.²

What the certificate says

A rating names what the shop may work on: airframe, powerplant, propeller, radio, instrument or accessory, each by class, plus limited ratings that name specific work item by item.¹ The rating is the boundary of the shop's own authority. A quote that reaches outside it means the work is going to a subcontractor, which is normal and often sensible, but you should know it is happening. Ask which certificate the work will be released under and who signs the release.

A shop that also holds an EASA approval can release work on European-registered aircraft, and an operator with a mixed registry should ask for both certificate numbers up front.³

What the certificate does not say

Part 145 sets the floor: housing, facilities, personnel, a capability list, a quality system.¹ It does not measure turn time, parts support or how the shop behaves when an inspection finds more than the work scope covered. Those you buy on evidence of a different kind.

Ask for measured turn times on your aircraft or component type, as a distribution and not an average, and ask what the shop counts as the clock starting. Ask how work-scope growth is priced and approved before you sign, because that conversation is cheap now and expensive later. Ask what paperwork returns with the part and with the aircraft, and check that the release documentation matches the registry you fly under.

Parts are half the purchase

Component work stands or falls on parts provenance. Ask whether the shop fits new, overhauled or approved alternative parts by default, who its distributors are, and how it documents traceability back to the source. A good shop answers in one email. A shop that cannot say where its parts come from is telling you something about the rest of its paperwork.

Questions that sort shops quickly

Ask which ratings on the certificate the quoted work falls under. Ask for the capability list entry that covers your part number. Ask which work goes out of house and to whom. Ask for two customers with a similar fleet or component mix. None of these questions is hostile, and every competent shop has been asked all of them before.

The companies listed below are in this category on the strength of a public fact, a certificate or a register entry, and each line under a company's name links to the source it came from. Open the certificate before you open negotiations, and the rest of the purchase gets easier.