Repair or replace an aircraft component: how to choose between a repair order, an exchange and buying another unit
A unit has come off the aircraft with an unserviceable tag. You can send it to a shop for repair, take an exchange, or buy another unit outright: overhauled, serviceable or new. This guide works through what decides it: repair cost against replacement price, turnaround against downtime, fees you pay even if nothing is repaired, the shop's rating, what the release will say, and what your old unit is still worth. A checklist closes it.
The options on the table
Exchange terms (core charge, core deadline, over-and-above charges) are covered in our exchange guide.
| Route | You pay | The aircraft waits for | Main risk |
|---|---|---|---|
| Repair your own unit | Evaluation, repair, freight both ways | Transit, evaluation, your approval, repair, return | Estimate grows after teardown; unit found beyond economical repair (BER) |
| Exchange | Exchange fee, then any over-and-above or BER charge on your core | Delivery of the exchange unit | Charges settled weeks later, after your core is evaluated |
| Buy overhauled (OH) or serviceable (SV) | Outright price | Delivery | Remaining life, and what the release actually covers |
| Buy new (FN, NE, NS) | Outright price, usually the highest | Delivery or the manufacturer's lead time | Price and lead time rather than condition |
The routes combine. With an aircraft waiting, a common pattern is to buy or exchange now and repair the removed unit afterwards as a spare.
Repair cost against replacement price
Count the whole repair, not the estimate. Add to the estimate the evaluation or bench-check fee, freight both ways, any expedite charge, and the cost of covering the gap (a loan, an exchange or a spare).
Compare with the right replacement. If an overhauled unit is acceptable to you, compare the repair with an overhauled price, not with new.
In supplier quotes we received between June and September 2026, on part numbers offered both new and in another condition, we compared the median price in each condition with the lowest new-condition median (NE, NS or FN) for the same part number. The median ratio was 0.48 for overhauled (742 part numbers), 0.59 for serviceable (552) and 0.24 for as removed (190). The rows cover different part numbers, so SV above OH is a feature of the sample, not a market rule. The point for this decision: a repair that looks cheap against new may not be cheap against overhauled.
This is the idea behind "beyond economical repair": past some share of the replacement price, repairing stops making sense. No regulation sets that share. Published exchange agreements set their own, from 60% to 75%, and measure it against different bases: the outright price, the OEM catalogue price or the exchange price (examples in the exchange guide). For your own repair order, choose your limit before the unit ships and write it on the order (see not-to-exceed below).
Round numbers, not prices of MG AVIATION TECH or of any seller. New unit $20,000; overhauled unit $10,000. Shop estimate $3,800, evaluation $500, freight both ways $300: $4,600 in total, 23% of new but 46% of the overhauled price.
Turnaround against aircraft downtime
A repair quote's turnaround time (TAT) rarely covers the whole trip. One avionics manufacturer's 2025 repair terms give a standard repair TAT of 20 business days, counted from the date the approved quote reaches the repair department, and an expedited one of 5, and say the TAT "is not guaranteed". Build the whole timeline for each route:
- Repair: transit to shop + evaluation + quote and your approval + repair TAT + transit back, and customs across a border.
- Exchange or purchase: the seller's lead time + transit. "Stock" on a quote is not the same as time to your door; see lead time on a quote.
With the aircraft on the ground, the repair route usually makes sense only when you have a spare to fit meanwhile. For the first hours of an AOG, see the AOG checklist.
Evaluation fees and "no fault found"
In the same 2025 terms, the bench check is "the minimum charge of evaluating the unit whether a repair, overhaul or a return as-is is requested", and a bench test adds no warranty. Ask about three outcomes that are not a repair:
- No fault found (NFF). The unit passes on the bench. You pay for the test and freight, and the unit comes back released as inspected or tested, not repaired.
- Return as is. You decline the quote. The evaluation fee is still due.
- BER. The shop finds the unit uneconomical to repair. Ask whether it comes back to you or is scrapped, and at whose cost.
The cheapest protection against an NFF bill is the removal record: the fault as the crew and the line saw it, fault codes and any troubleshooting done. Get all three charges in writing before the unit ships. NFF on a warranty claim against a seller is a separate case, covered in our warranty returns guide.
Not-to-exceed: cap the repair before the unit is opened
A not-to-exceed (NTE) figure on the repair order authorizes the shop to repair up to that amount without asking again, and requires a new quote above it. It turns the BER question into a number you set in advance.
- Set it from your replacement price. Start from the price of the replacement you would accept, take off what you will have spent anyway (evaluation, freight both ways), and keep a margin.
- Say what happens above it: stop and quote, or return as is.
- Check the terms for silence. One exchange agreement we read deems a repair estimate accepted if the customer does not answer within three calendar days. Look for such a clause, and know who on your side can approve.
- Ask what the NTE includes: evaluation, parts, service bulletin work and return freight, or labor only.
Is the shop rated for this part?
Under 14 CFR 145.201, a US repair station may maintain and approve for return to service only articles for which it is rated, and may not work on a rated article if the job needs special technical data, equipment or facilities it does not have.
- Rating. Part 145 ratings are by class: airframe, powerplant, propeller, radio, instrument and accessory (145.59). A limited rating covers, for example, a particular make and model or a specialized service (145.61).
- Capability list. A shop with a limited rating may work on an article only if it is on a current capability list acceptable to the FAA, or on its operations specifications. The list identifies each article by make and model or the manufacturer's nomenclature, and an article goes on it only after the shop's self-evaluation of its housing, facilities, equipment, data and trained personnel (145.215). Ask for the entry that covers your part number and dash number.
- Who does the work. A repair station may arrange for another person to perform the maintenance (145.201(a)(2)). Ask whether your unit will be repaired in-house or sent on.
- Europe. An EASA Part-145 approval has ratings too. For components other than complete engines or APUs they run from C1 to C22 by ATA chapter (C14, landing gear, is ATA 32), and the organisation's exposition sets its scope of work. For an EU-registered aircraft, EU authorities recognize a US shop's Form 8130-3 only from a shop that also holds an EASA Part-145 approval, as a dual release (see which certificate you need).
What comes back: overhauled, repaired or inspected/tested
The status on the release says how much work was done. Since September 2025, the FAA's instructions for completing FAA Form 8130-3 as a return to service after maintenance sit in Advisory Circular 43-9D; Order 8130.21J now covers the form's Part 21 (production and export) uses and refers maintenance releases to AC 43-9. AC 43-9D gives four block 11 terms, and EASA gives the same four for block 11 of the EASA Form 1:
| Block 11 | What it means (AC 43-9D, Table B-1) | For the buyer |
|---|---|---|
| OVERHAULED | At least disassembled, cleaned, inspected, repaired as necessary, reassembled and tested to approved data (see also 14 CFR 43.2) | The fullest work scope |
| REPAIRED | Repair of the defect(s) using an applicable standard | The fault was fixed; the rest of the unit was not necessarily worked on |
| INSPECTED and/or TESTED | Examination or measurement to an applicable standard, e.g. visual inspection, functional or bench testing | It passed; the usual result of an NFF |
| MODIFIED | Alteration to conform to an applicable standard | For example, service bulletin work |
- A release covers the work performed. Under 14 CFR 43.9(a)(4), the signature constitutes the approval for return to service "only for the work performed". A repaired unit and an overhauled unit are different products.
- Block 12 carries the detail. AC 43-9D lists what it may include: the work and the data used, AD or service bulletin compliance, repairs and modifications carried out, replacement parts installed, life-limited part status, PMA parts used. Ask for the work order or teardown report with it. A repair station must give the owner or operator a copy of the maintenance release (145.219(b)).
- The release is not an installation approval. AC 43-9D says a Form 8130-3 return to service "does not constitute approval to install" on a particular aircraft, engine or propeller; that decision stays with the installer.
On a quote to buy, the same statuses hide behind condition codes: OH should mean an overhauled release, while SV can mean repaired or inspected/tested. Our condition codes guide maps one to the other.
A repair warranty covers the repair
A warranty on a repair is usually narrower than a warranty on a unit you buy. In the 2025 avionics repair terms quoted above, a bench test adds no warranty, a repair carries 12 months on "applicable parts only", an overhaul 12 months, and a later clause limits the warranty "to only those areas of the unit serviced during the repair" and gives 90 days on workmanship and replaced parts. Get the period for your order confirmed in writing.
Compare it with the warranty on an overhauled or new unit; examples by condition are in our warranty returns guide.
Two things people forget: core value and modification status
Your removed unit has value even if you do not repair it. If you buy outright, the unserviceable unit can still serve as a core in an exchange or be sold as removed. Count that value on the "replace" side. If you take an exchange instead, your unit is the core and its condition decides the final bill; the terms are in the exchange guide.
A shop visit is the natural time to incorporate service bulletins. Ask the shop to quote the repair with and without the bulletins you want, and to record them on the release (block 11 "MODIFIED", or in block 12). A bulletin can change the part number or dash number, so check the interchangeability of the result with your aircraft's configuration. For a replacement, ask for its modification status on the quote.
Decision checklist
| Question | Points to repair | Points to exchange or buy |
|---|---|---|
| Total repair cost against the replacement you would accept | Well below it, with an NTE in place | Close to it, or the estimate is open-ended |
| Turnaround against downtime | You have a spare to fit, or the aircraft is not waiting | Aircraft on the ground, no spare |
| Removal reason | Clear, reproducible fault | Intermittent fault; NFF likely |
| Evaluation, NFF, return-as-is and BER charges | Known, and small against the repair | Unknown, or large against the repair |
| Shop capability | Rated, part on the capability list, work done in-house | No rated shop, or only one with a long queue |
| Release you need | The shop can issue it, including a dual release if needed | It cannot |
| Status you will get | Repaired is enough for your use | You need an overhauled unit or more life |
| Warranty | The repair warranty is acceptable | You need a warranty on the whole unit |
| Core value | Low | High enough to offset a purchase |
| Modification status | You want bulletins done during the visit | A replacement is already at the standard you need |
On the repair order: the removal reason and fault data; the NTE and what happens above it; the release you need (8130-3, EASA Form 1 or dual release) and the status you expect; service bulletins to incorporate; a request for the work order or teardown report; the return address and who pays freight.
On the RFQ for a replacement: the conditions you accept (for example "OH, SV acceptable") and, if you want to compare, "exchange and outright". The outright price is the number the whole decision is measured against, even if you plan to repair. For what that number costs to your door, see the true cost of an aircraft part.
If you send that RFQ to us, each line comes back with its condition, certificates, lead time in days, minimum order and, where the supplier states it, the country it ships from, so you can set a replacement price against the repair quote.
Get the replacement price before you approve the repair
Send the part number and the conditions you would accept to [email protected], in the file you already have: Excel, PDF, a scan or the email body, five lines or five hundred. Your inquiry will be reviewed by a specialist within one business day. Prices are Ex Works our warehouse in Orlando, FL, and the cost of bringing a line to Orlando is shown separately.
Our client portal, RFQ Radar, keeps every quote, order and invoice in one place.
Before you buy, check what certificates and trace come with each part. Aircraft on ground? See how our 24/7 AOG desk works.
Sources
All checked on 23 September 2026.
- 14 CFR 43.2, Records of overhaul and rebuilding — eCFR.
- 14 CFR 43.9, Content, form, and disposition of maintenance records — eCFR, paragraph (a)(4).
- 14 CFR 145.59, Ratings and 145.61, Limited ratings — eCFR.
- 14 CFR 145.201, Privileges and limitations of certificate — eCFR.
- 14 CFR 145.215, Capability list — eCFR.
- 14 CFR 145.219, Recordkeeping — eCFR, paragraph (b).
- AC 43-9D, Maintenance Records and FAA Form 8130-3 Return to Service (22 September 2025, editorial update 30 April 2026), paragraphs 1.1, 23.2 and 23.6, Appendix B (B.11, Table B-1; B.12) — Federal Aviation Administration.
- Order 8130.21J, Completion of FAA Form 8130-3 under Part 21 (25 September 2025), paragraphs 1 and 5 — Federal Aviation Administration.
- FAQ: correct statements for block 11 of EASA Form 1 after maintenance — EASA.
- AMC and GM to Part-145 (Annex II to ED Decision 2015/029/R), AMC 145.A.20 Terms of approval — EASA.
- 2025 Terms & Conditions of Sale — FreeFlight Systems / Flight Data Systems (industry practice: bench check as minimum evaluation charge, repair turnaround, warranty by type of service).
- Exchange Agreement — Davenport Aviation (repair estimate deemed accepted after three calendar days without a response).
- Exchange BER thresholds of 60% to 75% on different bases: the published agreements listed in our exchange guide's sources (JALUX Americas, Satair, BAS Part Sales, Zenith Aviation).
- MG AVIATION TECH supplier quote data, 15 June – 18 September 2026: priced offer lines in US dollars; ratios are medians, on the same part number, of each condition's median price against the lowest NE, NS or FN median (method in our condition codes guide).