Composite Aircraft – Capability and Safety
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ATSB TRANSPORT SAFETY INVESTIGATION REPORT Aviation Research and Analysis Report – AR-2007-021 Final Fibre composite aircraft – capability and safety AR2007021.indd 1 30/5/08 12:11:21 PM ATSB TRANSPORT SAFETY RESEARCH REPORT Aviation Research and Analysis Report AR-2007-021 Final Fibre composite aircraft – capability and safety - i - Published by: Australian Transport Safety Bureau Postal address: PO Box 967, Civic Square ACT 2608 Office location: 15 Mort Street, Canberra City, Australian Capital Territory, Australia Telephone: 1800 621 372; from overseas + 61 2 6274 6440 Accident and incident notification: 1800 011 034 (24 hours) Facsimile: 02 6247 3117; from overseas + 61 2 6247 3117 E-mail: [email protected] Internet: www.atsb.gov.au © Commonwealth of Australia 2008. This work is copyright. In the interests of enhancing the value of the information contained in this publication you may copy, download, display, print, reproduce and distribute this material in unaltered form (retaining this notice). However, copyright in the material obtained from non- Commonwealth agencies, private individuals or organisations, belongs to those agencies, individuals or organisations. Where you want to use their material you will need to contact them directly. Subject to the provisions of the Copyright Act 1968, you must not make any other use of the material in this publication unless you have the permission of the Australian Transport Safety Bureau. Please direct requests for further information or authorisation to: Commonwealth Copyright Administration, Copyright Law Branch Attorney-General’s Department, Robert Garran Offices, National Circuit, Barton ACT 2600 www.ag.gov.au/cca ISBN and formal report title: see ‘Document retrieval information’ on page v. - ii - CONTENTS THE AUSTRALIAN TRANSPORT SAFETY BUREAU ................................ VI ABBREVIATIONS..............................................................................................VII EXECUTIVE SUMMARY .................................................................................. IX 1 INTRODUCTION .......................................................................................... 1 2 TYPICAL AIRCRAFT FIBRE COMPOSITES.......................................... 3 2.1 What are fibre composites? .................................................................. 3 2.2 What fibre composites are used in aircraft?.......................................... 4 3 FIBRE COMPOSITE USE IN AIRCRAFT – PAST, PRESENT AND FUTURE.......................................................................................................... 5 3.1 Fibre composite use in aircraft since WWII ......................................... 5 3.2 Fibre composite applications in airliners.............................................. 5 3.3 Fibre composite aircraft on the Australian register .............................. 8 3.4 Fibre composite aircraft in Australian military service ...................... 10 3.5 Future fibre composite aircraft projects.............................................. 10 4 COMPOSITE BEHAVIOUR UNDER LOAD........................................... 13 4.1 Overview ............................................................................................ 13 4.2 Tension and shear stress ..................................................................... 13 4.3 Compression ....................................................................................... 16 4.4 Bending............................................................................................... 17 4.5 Fatigue ................................................................................................ 18 Case study: Robinson R22 in-flight blade root failures...................................................................... 19 5 BEHAVIOUR OF COMPOSITES IN HIGH-LOAD AND IMPACT SITUATIONS................................................................................................ 21 5.1 Failure characteristics of fibre composite matrices ............................ 21 5.1.1 Delamination..................................................................... 21 5.1.2 Other failure mechanisms ................................................. 22 Case study: Rudder failure due to corrosion and debonding .............................................................. 23 5.2 Typical impact behaviour of fibre composite matrices....................... 24 5.2.1 Barely visible impact damage (BVID) ............................. 24 5.2.2 Impact behaviour research programs................................ 24 6 REPAIRABILITY OF COMPOSITE STRUCTURES............................. 27 6.1 Identifying damage to composite structures ....................................... 27 - iii - 6.2 Common techniques for repairing damaged/fatigued composite structures............................................................................................. 28 6.2.1 Non-patch repairs.............................................................. 28 6.2.2 Bonded external patch repairs........................................... 28 6.2.3 Bonded scarf repairs ......................................................... 29 6.3 Common techniques for repairing damaged/fatigued metallic structures using composite patches..................................................... 29 6.4 Industry awareness of correct composite repair procedures............... 30 7 POST-CRASH SAFETY AND HANDLING OF COMPOSITE MATERIALS ................................................................................................ 31 7.1 Response methods to accident sites where composites are present.... 31 7.1.1 What is the threat? ............................................................ 31 7.1.2 What equipment is required? ............................................ 32 7.1.3 What first responders should do ....................................... 33 7.2 Release of fibre composite particulates in post-crash fires................. 34 7.3 Health effects and toxicity of fibre composite materials used in aircraft................................................................................................. 35 7.3.1 Smoke ............................................................................... 35 7.3.2 Toxic gases ....................................................................... 35 7.3.3 Fibre dust .......................................................................... 36 7.4 Existing composite material safety programs..................................... 36 7.5 Australian emergency services first response procedures to aircraft accident sites .......................................................................... 38 7.5.1 Survey findings................................................................. 38 7.5.2 Survey recommendations.................................................. 39 8 CONCLUSION ............................................................................................. 43 9 GLOSSARY .................................................................................................. 45 10 REFERENCES.............................................................................................. 47 11 APPENDIX A: FIBRE COMPOSITE AIRCRAFT ON THE AUSTRALIAN CIVIL REGISTER............................................................ 51 - iv - DOCUMENT RETRIEVAL INFORMATION Report No. Publication date No. of pages ISBN AR-2007-021 9 June 2008 63 978-1-921490-33-0 Publication title Fibre composite aircraft – capability and safety Author Taylor, R. P. Prepared by Reference No. Australian Transport Safety Bureau June2008/Infrastructure 08164 PO Box 967, Civic Square ACT 2608 Australia www.atsb.gov.au Acknowledgements Thank you to the following state emergency services for their assistance in this report: ARFF Sydney Airport, Queensland Police, Country Fire Authority Victoria, New South Wales Fire Brigades, South Australian Ambulance Service, Melbourne Metropolitan Fire Board, Queensland Fire & Rescue, South Australia Police, and South Australian Metropolitan Fire Service. Cover photo courtesy of Lee Thomas. Abstract For many decades, fibre composites have been replacing traditional aluminium structures in a wide variety of aircraft types. From the first all-composite kit plane released in 1957, composites are widespread today in commercial aircraft and many other aircraft types. This is due to the cost and weight savings that materials such as glass/phenolic and carbon/epoxy offer aircraft manufacturers over aluminium, while maintaining or surpassing its strength and durability. This study provides an overview of fibre composite use in aircraft and the issues associated with its use, with a focus on aircraft operating in Australia that contain these materials. There are almost 2,000 aircraft on the Australian civil register made of, or containing, fibre composite materials. This includes most of the mainline jet fleet, effectively all sailplanes and gliders, many popular general aviation (GA) aircraft, and a third of the growing amateur-built aircraft category. There is a lot of conflicting or incorrect information in the aviation community about the safety and capability of fibre composite materials. Composite structures behave very differently under normal loads than equivalent metal structures. Fatigue and corrosion have been proven through trials of composite repair patches to be much less prevalent in composites compared with metals. Subsurface damage such as delamination however can go undetected for long periods and result