Aircraft Transparencies Optical quality inspection is one of the most important phases of the aircraft transparency production process. The principal objective of multiple inspections is to avoid numerous negative effects that may be caused by the optical characteristics of transparencies that are not in compliance with the standards established for a given aircraft. High quality requirements are essential particularly in military aviation, since poor-quality transparencies may result in sighting errors, inadequate perception of the target and aircraft maneuvering, pilot’s fatigue, etc.
Factors that may affect transparency quality appear at the very beginning of the transparency production process, regardless of the level of its modernity. The problem is that it is almost impossible to make acrylic/polycarbonate sheets – used for making transparencies – of completely uniform thickness, even in the case of sheets belonging to the same batch. Another important factor (which most affects the quality of transparencies) are changes in the thickness of the transparency caused by thermoforming in a mould. Subsequent non-uniform polishing of the transparency’s external surface, installation of the transparency into the canopy frame, and installation of the canopy on the aircraft are additional negative parameters that can modify optical characteristics of a transparency.
The method most often used to measure the degree of optical distortion in a transparency utilizes a photographic procedure. Usually, that method is based on international standards (e.g. ASTM) and/or internal company procedures developed from those standards. Data thus obtained are mainly processed manually or, at best, by using the most rudimentary functionalities of commercially available image processing software. Whichever method is used, a key problem in traditional optical quality inspection is that the obtained data are highly susceptible to subjective interpretation by the quality inspector and the end user (i. e. the pilot).