Process Fragility in the Manufacture of Kevlar Wing Root Panels

Location of wing root panel

2m

James Curran

• Complex curvature• Kevlar• Sandwich panel• Geometrical tolerances• Foiling cure• Increased production rate

• RED panels further down production line• Unconventional• No destructive analysis• Production item (no interference, limited changes)

Increasing scrap rate NDT (ultrasonic, X-ray, geometry)

Plan to double production rate

Roll-out in Toulouse

1

2

3

4

1*

1*

NDT Failures

Simplified cross-section

14 plies

Steel ToolPlies 1-7

Honeycomb

AdhesivePly 8

Vac bag

Key operations half-way through build

Problems:• Bridging• Core (positioning & moisture content)• Volatiles• Filler material• Poor consolidation

Areas signalled for more intensive working

Steel ToolPlies 1-7

Honeycomb

Adhesive

Vac bag

Bleed pack

Bleed pack introduced for improved consolidation

12 3 (4)

Adhesive lay-up modified

1

2

3

4

1*

1*

Steel ToolPlies 1-7

Honeycomb

Vac bag

Plies 8-14Intensifier

Inadequate moisture management

1

2

3

4

1*

1*

Problems with honeycomb trim under floating intensifier:

2: Resin bleed 3: Poor consolidation

Core filler

Kevlar prepreg volatile content

19.4

19.6

19.8

20.0

20.2

15:00 15:30 16:00 16:30 17:00 17:30 18:00

Time

Mas

s (g

)

1

2

3

4

1*

1*

• New adhesive lay-up• Use of a bleed pack for all consolidation operations• Core moisture control• Core trimming• Core filler control• Kevlar moisture management

• Perforated adhesive• Self-adhesive foil / elimination of separate foiling cure• New tooling

Solutions: