Sealant Removal from A-10 Center Wing Sealant Removal from A-10 Center Wing Fuel Tanks Using a Portable Hand-Held Fuel Tanks Using a Portable Hand-Held

Nd: YAG Laser SystemNd: YAG Laser System

Norman J. OlsonPacific Northwest National Laboratory

Richland, Washington 99352

Mitchell WoolGeneral Lasertronics Corporation

San Jose, California 95112

2005 CTMA Symposium – Tacoma, WAApril 18-21, 2005

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The ProblemThe Problem

> 300 A-10 Aircraft in ServiceCenter Wing Fuel Tank Cells Have Fasteners Covered with Sealant (Primer Coating Elsewhere)Sealant in Fuel Tanks Needs to be Removed for NDE and/or RepairSealant Removal from Center Wing Tanks is Tedious and ExpensiveNeed a Less-Expensive, Faster Alternative

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The ProblemThe Problem

Current Technology is Hand Scraping Difficult and Slow Incomplete Cleaning is Highly

Likely Damage to Substrate is Likely

Laser Coating Removal Offers Potential Minimal Experience in

Confined Spaces Many Unanswered Questions

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Demonstration Objectives Demonstration Objectives and Requirementsand Requirements

A portable Nd: YAG laser that can remove sealant more economically than current methods,A hand-held delivery system that is capable of removing all sealant in the center wing section,A hand-held delivery system that is easy and safe to use,A system that has the potential to remove only sealant and not primer (color recognition), andA system that has reasonable reliability so that it will be operational for long periods of time without maintenance.

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Target for DemonstrationTarget for Demonstration

A-10 SPO Sent Retired Center Wing Fuel Tank Section to General Lasertronics Corporation Facilities in San Jose, CADemo Wing Section Had Eight (8) Access Ports to Fuel Cells There Were Approximately 600 Fasteners Covered with Sealant in Each of the Eight (8) Fuel CellsAccess Ports Barely Large Enough for Operator Cell

Opening

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Attributes Needed to Meet Requirements Attributes Needed to Meet Requirements for A-10 Center Wing Tankfor A-10 Center Wing Tank

Portability and reliability – DP Nd: YAG laser Compact hand-held end effector that can operate in confined space – GLC SBIR designAbility to see target area even if there are obstacles in line of sightMeet laser safety and environmental issuesTWO-dimensional automated beam scanning to eliminate substrate damage potential and to ensure complete and systematic coating removalColor recognition – potential to selectively remove sealant without disturbing other coatings

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200 and 500 Watt Demonstrations Using 200 and 500 Watt Demonstrations Using GLC-Developed SystemsGLC-Developed Systems

200 watt , 13 kHz, Nd: YAG Lamp-Pumped, Q-Switched System was Used for the Demo Conducted 9/21/2004 US Laser 406Q laser

500 watt, 10 kHz, Nd: YAG, Diode-Pumped, Q-Switched System was Used for the Demo Conducted 12/9-10/2004 Cutting Edge Optronics Laser:

Northrop-GrummanOperator Uses Video Display if Line-of-Sight Obstructions Exist

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GLC Confined Space Tool GLC Confined Space Tool for Laser Coating Removalfor Laser Coating Removal

End Effector Consists of: Laser Aperture Two-Dimensional Scanning 25 cfm Air Blow from

Aperture Cooling Clear Work Area

Video Camera Optical Fiber Umbilical

Cell Waste Evacuation Separate 300 CFM Purge Remove Ablated Debris Remove Sealant Vapors Maintain Good Visibility

Camera

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Demonstration ResultsDemonstration Results

Sealant Removed from Equivalent Fastener 200 watt in ~ 1 Minute 500 watt in < ½ Minute

Estimate of Labor for Entire Center Wing Fuel Tank GLC Laser Tool Using the

500 watt System

One 8 Hour Shift

Conventional Scraping Has never been fully

completed >> 800 work hours

24 Equivalent Fasteners

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Demonstration ResultsDemonstration Results

Color Recognition Potential Demonstrated on Automated System to Remove Coatings from Other AircraftColor Recognition Previously Demonstrated with a GLC Hand-Held Delivery Tool

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Demonstration Objectives MetDemonstration Objectives Met

A portable Nd: YAG laser can easily remove sealant more economically than current scraping methodsA hand-held delivery system could be configured to remove all sealant in the center wing sectionWith minimal operator training, a hand-held laser delivery system is easy and safe to useThe system could be configured to remove only sealant and not primer by implementing existing color-dependent sensing technology and automated laser firing controlsThe system has reasonable reliability so that it will be operational for long periods of time without maintenance.

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SafetySafety

Requirements Filtered (Clear) Glasses Worn by Operators Work Area Secured the Same as a Welding Area No Other Personal Protective Equipment Needed

Recommendations Two Operators in Work Area

Improve Productivity by Maximizing Trigger Time Keep Work Area Clear of Unauthorized Personnel

Could Enclose Work Area with Filtered Glass

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Recommendation for NCMS/Recommendation for NCMS/CTMA ProjectCTMA Project

Implement System at Hill AFB Build hand-held laser system for test, evaluation, and

subsequent installation Develop laser system operating parameters to ensure

sealant removal without 2024-T3 Al substrate damage Systematic exposure over a range of laser conditions Collect metallographic and SEM information and relate to

mechanical test data over statistically significant data sets Develop end-effector attachments for easier access to all

fasteners within A-10Project Funding ~ $1500K, including cost-sharing