B-2 Windows Get Quicker Fixes Thanks to SIBR Program

  • Published
  • By Shane Juhl
  • Materials and Manufacturing
WRIGHT-PATTERSON AIR FORCE BASE, Ohio --  A Small Business Innovation Research (SBIR) program between the Air Force Research Laboratory and Physical Optics Corporation has introduced a method for repairing scratched indium tin oxide (ITO) coatings on aircraft canopies. The Laser-Assisted Coating Repair (LACR) will be performed during regular ground maintenance operations.

The LACR process repairs damaged canopies with a transparent conductive material. The handheld LACR unit will be able to repair B-2 transparency (windshield and side window) geometries without removal of the aircraft from the field, and with minimal preparation time for the damaged surface and surrounding areas. The resulting technology provides modern and improved maintenance procedures, greatly simplified logistics for critical repair processes, and cost savings, while keeping valuable Air Force systems mission-ready.

In operation, conductive metal oxide coatings on aircraft canopy windshields and lamp housings perform several functions, including absorption of light that makes it difficult to see instruments and resistive heating for de-icing to remove condensation that solidifies during high-altitude and cold-weather flights. During the lifetime of the ITO coating, scratches and nicks develop and it begins to degrade. Current repair processes are temporary, time consuming and labor intensive; they reduce visibility in the repaired area and tend to chip or peel off.

When the size of the damaged area increases beyond an acceptable level, the entire coating must be replaced, costing money and increasing downtime. Currently, this repair process includes the removal of the entire canopy and shipment to specialized facilities wherein the coating is stripped and reapplied in large vacuum chambers. Although this approach successfully returns windshield and side windows in pristine condition, it also requires several weeks or months to complete, during which time the aircraft is out of commission.

The LACR process includes a method of ITO deposition that can be performed under ambient conditions without removing damaged fixtures and that can be applied during routine repair of irregular scratches and nicks that occur during flight missions. Support equipment, such as the laser source and power supply, operate on standard AC power and require minimal maintenance, with the exception of the occasional replacement of cooling water for stable operation of the laser source.

During this SBIR Phase II effort, Physical Optics defined the architecture of the repair process, optimized the processing parameters, and packaged the necessary optoelectronics in a handheld device that is comfortable and allows for repair of surfaces with extreme curvature. The Phase II unit weights 1.5 pounds and is coupled to the laser source, power supply, and cooling system, allowing sufficient mobility for reaching damaged portions of the canopy. Based on feedback from Air Force and B-2 officials, the LACR process shows considerable promise for improving current repair techniques. The SBIR team is currently tailoring the prototype in order to increase its technology readiness level and to prepare Physical Optics Corporation to become the vendor of this repair unit.