Walkaround

Technology · On the aircraft

Composite primary structure

Carbon fibre fuselage and wings, composite fan blades, damage assessment

mature on current widebodies 2 min read · updated 15 October 2026 · checked 15 October 2026

Two independent sources on every claim.

Why it is here

Composite damage can be severe and nearly invisible, so inspection relies on instruments rather than the eye.

At a glance

What it is

A composite primary structure is made from carbon fibre reinforced plastic laid up in plies and cured, rather than machined or riveted from metal. It is lighter for the same strength, does not corrode, and has no fatigue limit in the way aluminium does.

In plain terms

Metal bends and dents, and a crack in it grows in a way engineers can predict and inspect for. A composite is layers of fibre in resin. An impact can separate those layers inside while leaving the surface looking almost untouched, so the obvious inspection, looking at it, is the one that misses the damage.

Why it matters on the line

On the line

Treat impact damage on a composite as an instrumented problem, not a visual one. A bird strike or a ground handling impact that would leave an obvious dent in aluminium may leave little surface evidence here while having delaminated internal plies. Follow the manufacturer's inspection method rather than visual judgement, and resist the instinct that an unmarked panel is an undamaged panel. The same applies to GEnx fan blades: an unmarked blade is not evidence of an undamaged blade.

The manufacturing side has produced most of the regulatory activity so far. On the 787 the live directives concern excessive gaps and pull up in the forward pressure bulkhead, and nonconforming shim gaps between composite structures found during build. The common thread is that these originate in production quality rather than in service degradation, which is consistent with the broader scrutiny that programme has been under.

That distinction matters for planning. A fatigue mechanism gets worse with cycles and can be managed with an interval. A manufacturing escape is present from delivery or not present at all, so the question is effectivity rather than accumulation.

Where to read more

The composite airframes are the 787 and the A350. The composite fan is on the GEnx.

Sources