Reinforcing fibers
Where to buy| Fiber | Density | Tensile strength | Tensile modulus | Role and warning | Page |
|---|---|---|---|---|---|
| E-glass | not stated | fabric 80–750 lbf/in | not stated | Low cost, non-conductive; secondary structure | E-glass |
| S-glass / S2 | not stated | +15% over conventional glass (AGY, strand) | +25% (AGY) | Structural fiberglass | S-glass |
| Carbon, standard (T700S) | 1.80 g/cm³ | 711 ksi (4,900 MPa) | 33.4 Msi (230 GPa) | Stiff; lightning, galvanic | Standard modulus |
| Carbon, intermediate (T800S) | 1.80 g/cm³ | 853 ksi (5,880 MPa) | 42.7 Msi (294 GPa) | Stiffer, stronger | Intermediate modulus |
| Kevlar 49 (aramid) | 1.44 g/cm³ | 435 ksi yarn (3,000 MPa) | 16.3 Msi yarn (112,400 MPa) | Impact tough; weak in compression; absorbs water | Kevlar |
Toray T700S and T800S data sheets, DuPont Kevlar guide Table II-1 (yarn), AGY product page (relative claims). Fiber values are not laminate values.
Core materials
| Core | Key point | Data in this site | Page |
|---|---|---|---|
| Nomex honeycomb | Most common aircraft core | HRH-10 1.8–9.0 lb/ft³ | Nomex honeycomb |
| Aluminum honeycomb | Best strength-to-weight | CR III 5052, 3.1–8.1 lb/ft³ | Aluminum honeycomb |
| Foam | Heavier and weaker than honeycomb | Rohacell 31–110 IG-F | Foam core |
Resins, prepreg and consumables
| Item | Key point | Page |
|---|---|---|
| Epoxy | High strength, brittle, moisture-sensitive; 250–350 °F most common cures | Epoxy |
| Polyester | Cheap, fast; low-smoke grades for interiors | Polyester |
| Vinyl ester | Polyester handling, better corrosion and mechanical properties | Vinyl ester |
| Phenolic | Low smoke and flammability; interiors | Phenolic |
| Prepreg | Frozen, limited out life, hot cure | Prepreg |
| Peel ply | Cured on, torn off before bonding | Peel ply |
| Bagging consumables | Breather weight follows pressure | Core and consumables |
| Glass cloth styles | 7781, 120, 1581, 1080 and more | Glass fabric styles |
| Carbon fabric and tape | 3K fabrics; UD tape | 3K fabrics, UD |
The one rule
The repair material must preserve the strength, weight, aerodynamics and electrical properties of the part, best done with identical material or a manufacturer-approved substitute (AC 43.13-1B, paragraph 3-1a). Every page here is for identifying and understanding, not for choosing a substitute.
Fibers at a glance
Glass
- Best at
- Cost, corrosion and electrical properties
- Watch
- Lower strength than carbon
Carbon
- Best at
- Stiffness and strength
- Watch
- Cost, galvanic corrosion, lightning
Aramid
- Best at
- Impact resistance
- Watch
- Compression, water, cutting
Quick check
A part calls for carbon fabric and you want to use E-glass of similar weight. Which statement fits AC 43.13-1B?
- Fine if the weight matches.
Not this one. The rule is the same chemical composition or a manufacturer-approved substitute.
- Use identical material or a manufacturer-approved substitute.
Best fit. Right: paragraph 3-1a.
- Fine for secondary structure only.
Not this one. The substitute must still be approved.
On a real job, the SRM decides.
Limits — when NOT to use this
- Not a selection tool.
- Values come from different manufacturers’ sheets and test methods.
- Quartz fabric not covered: no publishable data sheet could be verified.
Where to buy
AmericaDistributor coming soonOur partner for this region is on its way
EuropeDistributor coming soonOur partner for this region is on its way
OceaniaDistributor coming soonOur partner for this region is on its way
Distributors coming soon.
Sources
- FAA-H-8083-31B, AMT Handbook — Airframe, Volume 1 (2023), Chapter 7 — fibers (p. 7-5), resins (pp. 7-6 to 7-7), prepreg (p. 7-8), core (p. 7-11).
- AC 43.13-1B, Change 1, Chapter 3, Fiberglass and Plastics — paragraph 3-1 (p. 3-1).
- Toray Composite Materials America, TORAYCA T700S Standard Modulus Carbon Fiber Data Sheet (Rev. 11/24/2025) — fiber and composite properties, tow sizes, resin compatibility.
- Toray Composite Materials America, TORAYCA T800S Intermediate Modulus Carbon Fiber Data Sheet (Rev. 04/13/2018) — fiber and composite properties, tow sizes, resin compatibility.
- DuPont, Kevlar Aramid Fiber Technical Guide, Section II, Table II-1 (pp. 5-6) and thermal properties (p. 12) — typical yarn properties of Kevlar 29 and Kevlar 49.
- AGY, S-2 Glass fiber product page — S2 Glass strength, modulus and temperature claims against conventional glass fiber.
- Hexcel HexWeb CR III Corrosion Resistant Specification Grade Aluminum Honeycomb, Product Data Sheet (2017) — designation, alloys and temper, density tolerance, Table I (5052 mechanical properties).
- Evonik, ROHACELL IG and IG-F mechanical properties (January 2014) — density, compressive, tensile and shear properties of 31, 51, 71 and 110 grades.
- Hexcel HexPly 8552 Product Data Sheet (US units, 2020) — neat resin properties, prepreg physical properties, cure procedure, storage life.
Educational reference only. not approved data. Always consult the applicable SRM, AMM, or AC 43.13-1B and your certifying authority.