Advanced Composite materials

22/04/2023 New Technology composites 1

ADVANCED COMPOSITE MATERIALS

Used in construction on new technology aircraft and considerations in their use

Péter Marosszéky FRAeS MIFA MAOPA (USA)Adjunct Senior Lecturer & Research Fellow

University of New South Wales School of AviationFaculty of Science

IntroductionThe areas that need to be

considered:• Occupational Health and Safety• Advanced composites • Damage tolerance and assessment• Repair Assessments• Repair schemes & processes• Specialized equipment & tooling• Approved MRO’s• Training

Health & Safety Hazards• Risks & hazards can be controlled• Use of MSDS data• A wide range of safety procedures

have been developed and approved• Current FAR 145.163 and EASA

Advisory Circular 65-33 requirements

• High overheads & retraining • Manufacturer programs ie:

Boeing’s “Gold Care” program

Advanced CompositesA range of advanced composites in use

on new generation aircraft• Two primary advanced composites are in

use on the Boeing 787 and the Airbus A350XB

• Boeing have opted for the Torayca 3900-series highly toughened carbon fibre-

reinforced epoxy prepreg – unidirectional tape (various widths) & narrow slit tape (for fibre replacement) and woven fabric forms Majority of the 3900 – series made from intermediate modulus T800S fibre.

Advanced Composites • Boeing continued: • The surface finishing provides

resistance against moisture and contaminant ingress: Cytec SurfaceMaster 905.

• A high-temperature bisaleimide composite material, that allows application & removal of paint without compromising the integrity of the sub-structure

Boeing 787 series

Boeing 787 continued• Other primary structures• Window frames & Engine Nacelles

use Hexcel HexMC trademarked as HexPly AS4 carbon fibre prepreg (350°C/177°F cure) 8552 epoxy prepreg resin (Nordam)

• Wing & Trailing edge components use Hexcel’s HexFlow RTM6 with Cytec Surface Master 905

• Some landing gear components utilize Hexcel IM-7 fibre.

Airbus A380 series • Primary structure:• Empennage – Carbon fibre reinforced

plastic (CFRP)• Fin leading edge – Glass fibre reinforced

plastic (GFRP)• Radome – Quartz fibre reinforced plastic

(QRFP)• Upper sections of fuselage – Glass

reinforced Aluminium Laminate (GLARE)

Airbus A380 series

Airbus A350XB series Airbus have selected the Hexcel

HEXPLY M-21E Carbon fibre toughened epoxy prepreg composite for primary

structures

Damage tolerance & assessment

• Advanced composites have Significant weight, stiffness and strength advantages over Aluminium

• Advanced composites are susceptible to damage with greater resistance than

Aluminium • Advanced composites are susceptible to

sunlight (infra-red) exposure, however pre-spun prepreg carbon fibre is less

affected due to the tight weave reducing surface area of resins/catalysts

Damage tolerance & assessment continued…• Boeing and Airbus tests have been

validated by the ASTMAdvanced Carbon fibre in use on the 787 and A350 has been certified to

allow continued airworthiness if impact contact does not leave a visible sign, no further action need be takenIf damage is visible then action must

be taken in accordance with the respective SRM (Structural Repair

Manual)

Damage tolerance & assessment continued…An example of the effects of damage and subsequent fatigue propagation, tests have shown that in tight weave carbon fibre a breach of the structure not exceeding 2.54cm/1.0in. Will not

propagate any furtherLarger areas of damage repaired and

processed in accordance with manufacturer specifications will have

permanent repair status.

Damage tolerance & assessment continued…

Airbus research and assessment (validated by (ASTM) has shown the

damage tolerance of GLARE is significantly better than Aluminium,

however not as resistant Carbon fibre prepreg

Damage tolerance & assessment continued

• Electrical and Fluid exposure damage.

• Electrical:• Advanced Carbon composites are

electrical conductors • Copper mesh is embedded in the

structure to provide for conductivity and earth return for electrical systems as the “earth return”

Damage tolerance & assessment continued…

• Fluid exposure:• Coatings applied during

manufacture provide protection against phosphate ester fluid (Hydraulic fluids) ingress

• Water and waste protection against ingress

• Corrosion is prevented by the use of Titanium fasteners

General & specific applications

Repair assessments• Considerations of damage

assessment• Area of damage• Location• Structural requirements• Type of material• Equipment and materials

available at location

Repair assessments continued…

• Repair must be in accordance with manufacturers SRM

• Must consider:• Proximity to major structural

elements• Aerodynamic cleanliness

especially for RVSM and RNP factors

• Repair permanency

Inspection products• Portable FTIR4100 Fourier Transform Infra-

Red (FTIR) spectroscopy to measure the effect of heat damage caused by lightning

strikes, fire and engine exhaust• Olympus NDT35RDC hand held device check

for possible impact damage include sub-surface damage

• BondMaster1000e multi-mode test device to check for disbonding & delaminations.

• OmniScan MX and Epoch 1000i using two similar ultrasonic phased array device to

detect cracks, delaminations and inclusions

Repair Schemes & processes

• Most repairs envisaged for in-service will be conducted in-situ, manufacturers have

designed specific repair schemes for the range of materials & structures

• MRO’s are developing processes for repair & maintenance of advanced composites eg;

Lufthansa Technik AG has developed a method for the semi-automated repair of fibre

composites, process uses scanning to within 1/100th of a millimetre using optical

measurement techniques & computer controlled milling machine to create the

bonded surface & perfectly matched pre-cuts of individual composite layers.

Specialized equipment & tooling

• Some of these include:• The HEATCON HCS9200B Dual zone

hot bonder• The HEATCON HCS9000B Single zone

hot bonder• The HEATCON HCS2046-02 Phosphoric

Acid Containment System (PACS) • A range of Composite Cutting Tools

(CCT) for accurate and damage free machining & shaping

Approved organizations

• Currently most MRO’s and airline MRO’s are gearing up for regulator

& manufacturer accreditation• OEM’s also provide after market

services for operators that do not have access to approved

organizations.

TrainingThere are a number of training

organizations that provide Advanced Composite training in addition to

OEM’s. This type of training is referred to as Advanced Skills training,

requiring on-going refresher training to retain qualifications and proficiency.A Part 145 organization must receive

training from a Part 147 training organization.

Questions

Thank you