Fabric data
| Fabric | Weave | Weight, oz/yd² | Weight, g/m² | Thickness | Count per in |
|---|---|---|---|---|---|
| Carbon, 3K, Hexcel style 282 | Plain | 5.80 | 197 | 10.10 mil (0.26 mm) | 12 × 12 |
| Carbon, 3K, Hexcel style 284 | 2/2 twill | 5.80 | 197 | 9.1 mil (0.23 mm) | 12 × 12 |
| Aramid (Kevlar), 195 denier, style 120 plain weave, BGF | Plain | 1.8 | 61 (converted) | 0.0039 in (0.10 mm, converted) | 34 × 34 |
Carbon: Hexcel HexForce 282 and 284 data sheets, 3K carbon 33 MSI warp and fill. Aramid: BGF Industries data sheet, untreated, breaking strength 200 / 200 lbf/in. The BGF sheet header reads “Style 5120” while the supplier listing is Kevlar 120; we show it as listed and flag it. Weights converted at 33.9 g/m² per oz/yd².
Carbon fabric
The K in 3K means 1,000 filaments per tow (AMT Handbook, p. 7-3). Plain weave and 2/2 twill come at the same weight and count here; the twill is a little thinner (9.1 against 10.10 mil).
The handbook says carbon fibers are 3 to 10 times stiffer than glass, used for floor beams, stabilizers, flight controls and primary fuselage and wing structure. It lists the disadvantages: lower conductivity than aluminum, so lightning protection mesh or coating is needed; high cost; and a high potential for galvanic corrosion with metallic fasteners and structures (p. 7-6).
Aramid (Kevlar) fabric
Aramid is light, strong and tough, with high resistance to impact damage, so it goes where impact is likely. Its weak points are compression strength and moisture: some parts absorb up to 8 percent of their weight in water, so they must be protected from the environment (AMT Handbook, p. 7-4).
It is difficult to drill and cut. The fibers fuzz, and special scissors are needed to cut the material. Aramid bundles are sized by weight, not by number of fibers (p. 7-4 to 7-5). Its natural color is yellow.
Style 120 aramid is a very light cloth: about 20 percent of the weight of 7781 glass (1.8 against 8.81 oz/yd²).
Questions people actually ask
How does 3K carbon compare in weight with style 120 glass?
5.80 oz/yd² carbon is about 1.8 times the weight of 3.16 oz/yd² style 120 glass in the Hexcel data.
Can I cut aramid with normal shears?
The AMT Handbook says special scissors are needed because the fibers fuzz easily and the material is difficult to cut.
Limits — when NOT to use this
- Not a ply schedule or a substitution table. Carbon for glass, or aramid for carbon, changes stiffness, galvanic behaviour and the whole repair. Approved data decides.
- Carbon against metal is a galvanic risk. The handbook flags it for metallic fasteners and structures. The SRM sets the isolation and the fastener type.
- Typical dry values only. Cured ply thickness depends on resin and compaction.
- Mechanical properties are not on this page. Fabric strength depends on the laminate; use the material qualification data in the SRM.
Sources
- Hexcel HexForce Style 282 Carbon Fabric Product Data (DSF_282) — 3K carbon 33 MSI, plain, 5.80 oz/yd² (197 g/m²), 12 × 12, 10.10 mil (0.26 mm).
- Hexcel HexForce Style 284 Carbon Fabric Product Data (DSF_284) — 3K carbon 33 MSI, 2/2 twill, 5.80 oz/yd² (197 g/m²), 12 × 12, 9.1 mil (0.23 mm).
- BGF Industries aramid data sheet, Kevlar 120 (via PC Composites) — plain weave, 195 denier Kevlar, 34 × 34, 1.8 OSY, 0.0039 in, 200 / 200 lbf/in. Listing: https://www.pccomposites.com/product/kevlar-120.
- FAA-H-8083-31, AMT Handbook — Airframe, Volume 1, Chapter 7, pp. 7-3 to 7-6 — tow size, aramid and carbon properties, weave styles (Figure 7-5).