Airline Perspectives on the Constraints of Bonded Repair Size Limits

Transcription

1 May 17th, 2011 Presented by: Todd M. Herrington Principal Engineer Composite / Bonded Repair

2 May 17th, 2011 Part 1 Examples of OEM authorized repairs by part type Part 2 Examples of damages not supported by OEM repairs Part 3 Available resources at Airline / MRO organizations

3 Part 1: Examples of OEM Authorized Permanent Repairs by Part Type PSE / FCS Structure Non-FCS Flight Control Structure Secondary Structure

4 PSE / FCS: Flight Control Assemblies Company A Narrow Body Rudder - OEM authorized splice of rear spar (right) and significant trailing edge skin replacement. Techniques consist of pre-cured autoclave patches cured at 350 degrees F (using original materials) and secondarily bonded to part using 250 degree F vacuum pressure.

5 PSE / FCS: Flight Control Assemblies Company B Wide Body Rudder In non-critical areas, OEM SRM authorizes unlimited size repair of rear spar and skins. Techniques consist of vacuum bag cured repairs cured at 350 degrees F (using original materials). Critical areas are usually supported as well on case by case basis.

6 PSE / FCS: Flight Control Assemblies Company B Wide Body Aileron - OEM SRM authorizes replacement of skins and core with use of 250 degree F prepreg repair processes in non-critical areas. This repair example extends into critical areas and was approved by the OEM.

7 PSE / FCS: Flight Control Assemblies Company B Wide Body Aileron - OEM SRM authorizes replacement of skins and core with use of 250 degree F prepreg repair processes in non-critical areas. This repair example extends into critical areas and was approved by the OEM.

8 PSE / FCS: Flight Control Assemblies Company A Narrow Body Elevator - OEM SRM authorizes some repairs of limited size, however, on case by case basis, repairs are authorized for significant sizes using 350 degree F prepreg using same materials as the original structure. Example shown used pre-cured patches secondarily bonded to original structure using 250 degree F film adhesive.

9 PSE / FCS: Flight Control Assemblies Company D Narrow Body Aileron - OEM SRM authorizes some repairs of limited size, however, on case by case basis, repairs are authorized for significant sizes using 350 degree F prepreg using same materials as the original structure. Example shown used OEM approved wet lay up repair methods which are close to maximum size allowed on this component.

10 Non-FCS Flight Control Structure Company B Narrow Body Aileron - OEM SRM authorizes replacement of skins and core with use of 350 degree F prepreg repair processes using original materials in noncritical areas. This repair example extends into critical areas, including the spar and was approved by the OEM.

11 Non-FCS Flight Control Structure Company B Narrow Body Aileron - OEM SRM authorizes replacement of skins and core with use of 350 degree F prepreg repair processes using original materials in noncritical areas. This repair example extends into critical areas, including the spar and was approved by the OEM.

12 Non-FCS Flight Control Structure Company B Narrow Body Aft Flap - OEM SRM authorizes replacement of skins and core with use of 350 degree F prepreg repair processes using original material. There are no size, proximity or any other restrictions. There are no critical areas.

13 Non-FCS Flight Control Structure Company A Narrow Body Spoiler - OEM SRM authorizes some repairs of limited size, however, on case by case basis, repairs are authorized for significant sizes using 350 degree F prepreg using similar materials to the original structure.

14 Non-FCS Flight Control Structure Company B Wide Body Aft Flap - OEM SRM authorizes virtually unlimited size repairs using original materials and processes common to the original structure. All metal bond repairs, regardless of location on the aircraft or structural classification have the same reparability for this aircraft type.

15 Non-FCS Flight Control Structure Company A Narrow Body Spoiler - OEM SRM authorizes some repairs of limited size, however, on case by case basis, repairs are authorized for significant sizes using 350 degree F prepreg using similar materials to the original structure.

16 Secondary Structure Company B Narrow Body Fan Cowl - OEM SRM authorizes unlimited size repairs in non-critical areas using 350 degree F prepreg repair processes using same materials as original structure. This example shows an OEM approved repair in a critical area near a latch.

17 Secondary Structure Company B Narrow Body Fan Cowl - OEM SRM authorizes unlimited size repairs in non-critical areas using 350 degree F prepreg repair processes using same materials as original structure. This example shows an OEM approved repair in a critical area near a hinge.

18 Secondary Structure Company C Narrow Body Fan Cowl - OEM SRM authorizes very small damage sizes using wet lay-up repairs. There are no 350 degree F repair options. This example shows one of the largest size repairs that have been authorized for a 250 degree F prepreg repair.

19 Part 2: Examples of damages not supported by OEM repairs PSE / FCS Structure Non-FCS Flight Control Structure Secondary Structure Company Trend Comparisons

20 PSE / FCS: Flight Control Assemblies Company D Narrow Body Aft Flap - OEM SRM authorizes some bonded repairs of limited size, however, on case by case basis, bolted repairs can be authorized of significant sizes. Example shown represents a repair that is beyond bonded repair but is within a bolted repair limits.

21 Secondary Structure Company C Wide Body Fan Cowl - OEM SRM authorizes very small damage sizes using wet lay-up repairs. There are no 350 degree F repair options. This example shows a damage that the OEM considered beyond repair. DAMAGE AREA IN RED BOX (26 x 8 )

22 Secondary Structure Company C Wide Body Fan Cowl - OEM SRM authorizes very small damage sizes using wet lay-up repairs. There are no 350 degree F repair options. This example shows a damage that the OEM considered beyond repair.

23 Secondary Structure Company C Narrow Body Fan Cowl - OEM SRM authorizes very small damage sizes using wet lay-up repairs. There are no 350 degree F repair options. This example shows a small corner damage that the OEM considered beyond repair.

24 Secondary Structure Company C Narrow Body Nose Cowl - OEM SRM authorizes very small damage sizes using wet lay-up repairs. There are no 350 degree F repair options. This example shows minor outer face sheet damage that the OEM considered beyond repair.

25 Secondary Structure Company D Narrow Body Fairing - OEM SRM authorizes small damage sizes using wet lay-up repairs. There are slightly larger repair options that use prepreg materials. This example shows minor inner face sheet damage that the OEM considered beyond repair.

26 Secondary Structure Company C Wide Body Fan Cowl - OEM SRM authorizes very small damage sizes using wet lay-up repairs. There are no 350 degree F repair options. This example shows a damage that the OEM considered beyond repair, however, it was later learned that the OEM authorized its own repair station to repair the damage.

27 Company Trend Comparisons. Table 1: Trends in OEM Allowances, by Company, for PSE / FCS Structure Unlimited Size / Original Material* Some Prepreg Repairs (limiting) Small Wet Lay-up in Critical Areas / Medium Wet Layup in Field Areas Small Wet Layup in Field Areas Company A X X Case by case X Company B Case by case X Case by case X Company C N/A N/A N/A N/A Company D Case by case X * Critical areas can exist and are most common in areas that are near significant attach or hinge fittings / beams

28 Company Trend Comparisons. Table 2: Trends in OEM Allowances, by Company, for Non-FCS Flight Contol Structure Unlimited Size / Original Material* Some Prepreg Repairs (limiting) Small Wet Lay-up in Critical Areas / Medium Wet Layup in Field Areas Small Wet Layup in Field Areas Company A X X Case by case X Company B Mostly Supported X Case by case X Company C N/A N/A N/A N/A Company D X Case by case X * Critical areas can exist, however are slightly less common than in cases of PSE / FCS Structure

29 Company Trend Comparisons. Table 3: Trends in OEM Allowances, by Company, for Secondary Structure Unlimited Size / Original Material* Some Prepreg Repairs (limiting) Small Wet Lay-up in Critical Areas / Medium Wet Layup in Field Areas Small Wet Layup in Field Areas Company A X X X X Company B X X X X Company C X X Company D X Case by case X * Critical areas can exist, however are rarer than in cases of higher classification of structures

30 Part 3: Available resources at Airline / MRO organizations Technology Snap Shot Maintaining Critical Dimensions Maintaining Critical Processes and Cleanliness Recommendations

31 Complying with OEM Restorative Repair Procedures Manufacture data, technology for design and fabrication of proper tools, automation and equipment are widely available today in the repair station industry.

32 Complying with OEM Restorative Repair Procedures Reverse Engineering tools, loft data transfers from OEMs and bondline control tests are becoming more widely used by airlines and top tier repair stations.

33 Complying with OEM Restorative Repair Procedures Quality assurance tools such as various self generating surface check reports, NDI advances and First Article / Qualification plans help catch problems in the repair design before flight.

34 Complying with OEM Restorative Repair Procedures Advances in CAD desktop systems has increased the speed and comfort level for mechanics, engineers and inspectors during accomplishment of QA oversight procedures. On the floor, design can be overlaid digitally on the repair parts and tools so that a manufacturer s level of control can be maintained in a repair environment.

35 Complying with OEM Restorative Repair Procedures Many repair stations have pursued manufacture certifications for bonding, implementing Controlled Contamination controls, time and temperature sensitive QA environments and adherence to OEM specs and standards for bonding.

36 Recommendations Establish Proper Levels of Controls to Substantiate Trending Toward Company A Model Look at creating robust training / certificate standards at OEM levels and implement into repair requirements Share information from OEMs to repair stations to increase awareness of critical steps within repair processes Commit OEM resources into guidance documents (such as those being developed by the CACRC) to ensure a standard exists for accomplishing repairs reliably.

37 Questions?

38 Thank You