Key Takeaways
- Aircraft composite and bonded-structure repair is governed by FAA AC 43-214A, which sets requirements from frozen raw-material storage to personnel qualification. It isn’t the same trade as boat or car fiberglass work.
- Moisture is the hidden risk. The FAA has documented that moisture absorbed in composite or honeycomb material can cause delaminations away from the repair site during cure, or “blown face sheets” in honeycomb structure.
- Even a mostly-aluminum airliner carries real composite scope: about 10% of a 737 MAX’s aerostructure and about 15% of an A320’s is composite, concentrated in radomes, fairings, and flight control surfaces.
- A compliant repair needs an environmentally controlled layup room, tracked material out-time, and NDT verification, X-ray or ultrasonic, before the part goes back on the aircraft.
A cracked radome or a dinged wingtip fairing looks like a bodywork job. It isn’t. Aircraft composite repair sits under its own set of FAA requirements, and a repair that looks fine from the outside can still fail the way it was actually damaged, from the inside.
This guide explains what counts as aircraft composite repair, what the FAA actually requires of a shop doing it, and why the process matters more than the patch.
What Counts as Aircraft Composite Repair?
Aircraft composite structure means fiber-reinforced material, carbon, aramid, and glass-reinforced polymers, bonded together with resin, per the scope the FAA sets in AC 43-214A. On most commercial aircraft, it shows up in radomes, wingtips and winglets, fairings, engine cowlings, and flight control surfaces like ailerons and spoilers.
Even aircraft built mostly from aluminum carry meaningful composite scope. A 737 MAX’s aerostructure is about 10% composite by weight, and an A320’s about 15%, according to CompositesWorld, against roughly 50% for a 787 and 53% for an A350. That’s a smaller share of the airframe, but it’s concentrated in exactly the parts most exposed to ground handling damage: nose, wingtips, and fairings.
Why Isn’t This Just a Fiberglass Repair Job?
Because the material doesn’t forgive shortcuts, and the FAA writes that into the requirements rather than leaving it to trade practice. AC 43-214A requires a repair organization to control temperature, humidity, air filtration, and contamination in the layup and clean room, store prepregs and adhesives frozen, and track how long each material has been out of the freezer before it’s used. Miss any of those, and the resin doesn’t cure the way it’s supposed to, even if the patch looks correctly shaped and painted.
What Happens When a Composite Repair Is Rushed?
The damage moves somewhere you can’t see it. The FAA notes that moisture absorbed in composite or honeycomb material can cause delaminations away from the repair location during the cure cycle, and in honeycomb structure, it can result in blown face sheets, where the outer skin separates from the core (AC 43-214A). A repair can look correctly shaped and painted and still be structurally compromised underneath, which is exactly why the process requires X-ray or ultrasonic inspection rather than a visual sign-off.
That’s also why the FAA requires personnel doing this work to be specifically qualified in composite and bonded-structure repair, and periodically requalified, not just trained on general airframe maintenance. A repair shop that skips the controlled room, the frozen storage, or the NDT step is gambling with a failure mode that’s invisible until the part is loaded in flight.
What to Ask Before You Approve a Composite Repair
| Ask for | Why it matters |
|---|---|
| The material’s out-time record | Confirms the prepreg or adhesive was used within its allowable window after leaving the freezer |
| How the repair was cured | Autoclave, oven, or heat blanket, with temperature and humidity controlled and documented |
| The NDT result | X-ray or ultrasonic confirmation that there’s no delamination away from the visible repair |
| Who signed it off | Personnel specifically qualified for composite and bonded-structure repair, not general airframe work |
Where This Shows Up on a B737 or A320 Check
Dolphin Air’s B737 and A320 base maintenance service includes zonal and structural inspection, with findings raised, documented, and agreed before rectification. Composite parts, radomes, fairings, and access panels are a common source of those findings on this aircraft family, so it’s worth asking upfront how composite findings are scoped and verified as part of the check, rather than assuming it’s covered by default.
Ask About Composite Findings on Your Next Check
Tell us the aircraft type and what you’re seeing, a damaged fairing, a cracked radome, or a routine check where you want composite scope confirmed upfront. Our operations team will tell you honestly what’s involved.
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Frequently Asked Questions
Is aircraft fiberglass repair the same as boat or car fiberglass repair?
No. Aircraft composite and bonded-structure repair is governed by FAA AC 43-214A, which requires environmentally controlled layup rooms, frozen material storage with tracked out-time, NDT verification, and specifically qualified personnel. General fiberglass repair skills don’t meet those requirements on their own.
What percentage of a commercial aircraft is actually composite?
It varies by generation. A 737 MAX’s aerostructure is about 10% composite by weight and an A320’s about 15%, against roughly 50% for a 787 and 53% for an A350, according to CompositesWorld.
Why does moisture matter in composite repair?
The FAA has found that moisture absorbed in composite or honeycomb material can cause delaminations away from the repair site during the cure cycle, or blown face sheets in honeycomb structure, damage that isn’t visible from the outside.
Does a composite repair need X-ray or ultrasonic inspection?
Yes. AC 43-214A requires NDT equipment, X-ray, ultrasonic, or other approved methods, to be available for inspecting composite parts and repairs before they’re returned to service.
