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Field-Level Transparency Inspection System



OBJECTIVE: Develop a field-level capability to inspect windscreen (canopy) coatings to take measurements of the electro-static discharge layer under polycarbonate or acrylic materials. Tool must provide a reliable and accurate assessment of the performance of the discharge layer to the user. The technology must be applicable over curved surfaces in a highly physically constrained area. 

DESCRIPTION: The current field-level transparency inspection is based upon a human visual inspection. This process is limited in that the eyeball cannot reliably detect the inception of damage which typically manifests as a pinhole (~0.01 in the protective coating. Identifying such defects early in their manifestation is critical in maintaining the proper performance in order to take corrective actions before more damage occurs. Therefore a requirement exists to provide a capability to inspect these coatings on the transparencies in the field. This will ensure that all defects are accurately detected early to minimize the extent of the required repair. Aircraft transparency systems (canopies, windscreens, etc.) incorporate shielding layers that require inspection during manufacturing and throughout the life of the aircraft to ensure proper performance is achieved and maintained. Current inspections are conducted manually, are very time consuming, and do not cover 100% of the transparency surface. Once transparencies are fielded, they are subject to damage as a result of bird strikes, weather events, precipitation, static discharge, environmental exposure, and even routine maintenance activities. When transparency damages compromise the shielding layers, the damage must be characterized to assess the impact to system performance and determine the proper course of action. Depending on the system impact, the transparency may be removed and replaced or repaired. Currently, a field inspection capability to assess transparency performance throughout its life and accurately characterize defects, damages, and repairs does not exist. This results in unknown transparency performance and increases removal and replacement rates, increasing program cost and maintenance. Therefore, a requirement exists to develop a lightweight field-level probe that can be used in limited physical constraints, the technology must be readily adaptable to take measurements in a physically constrained area on a highly curved surface. Sensor system must be able to take measurements of the electro-static discharge defect (as small as ~0.01 under a topcoat that is applied over a thick substrate such as polycarbonate or acrylic materials. Capability must be either man-portable (objective of no more than 5 lbs and threshold of no more than 7 lbs) or able to be attached to an autonomous delivery system. Rigorous technology demonstrations using representative targets shall be performed. To that end, correlations between current baseline systems and the new technologies shall be carried out. Specifically, an optimized hardware and software system solution to provide capability to a 5-level maintainer or technician that is reliable, repeatable, and easy to use. This strategy is centered on developing a robust tool with advanced algorithms and processing for production, depot and field maintenance crews that only require entry-level user training and knowledge to be successfully used and operated. New equipment and technology shall comply with CE/ATEX certifications for use around a fueled aircraft, and integrate with existing aircraft health assessment systems. System must also be ruggedized for use in an operational environment including exposure to light dust, moisture, humidity, low and high temperatures, and salt fog conditions. In-depth investigations shall be conducted to create confidence on new approaches and methods. These in-depth validation and verification activities shall address user requirements including but not limited to human safety, reliability, operator fatigue, reparability, and robustness of the equipment to survive in a high tempo maintenance environment. 

PHASE I: Demonstrate the feasibility of the prototype sensor system in a laboratory environment on relevant transparency material system. Any prototype sensor design must meet field-level requirements for a maintainer in the field, to include Class 1/Div 2, ergonomic and safety requirements. The Government will not provide any GFE during the Phase I. 

PHASE II: Building on Phase I demonstrated feasibility, the Phase II task will be to optimize the technology to advance the TRL/MRL. The Phase II prototype will be required to be demonstrated on a relevant transparency system in an operational environment. Spiral development will require development and feedback of usability of the sensor to meet field-level requirements for sensor ergonomics, software user interface, data analysis and processing. The Government will provide relevant GFE during the Phase II. 

PHASE III: Determine a commercialization plan to demonstrate the technology for other applications or commercialize the product for other platforms and customers. 


1: Michel Mardiguian, EMI Troubleshooting Techniques, McGraw-Hill, 1999.

2: L.F. Chen et al., Microwave Electronics: Measurement and Materials Characterization, Wiley, 2004.

KEYWORDS: Transparency Inspection, Nondestructive Evaluation, Field-level Inspection 


Juan Calzada (RXCA) 

(937) 255-9761 

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