Aircraft windshields, casings and windows.
Repairs are more manageable when they are repairs to plastic windshields, housings and windows in non-pressurized aircraft. Replace or repair plastic windows in pressurized aircraft according to the manufacturer’s recommendations. When aircraft acrylic windshields and side windows are damaged, they are usually replaced unless the damage is minor and repair is not in sight. Windshield repair usually requires a lot of work. Spare parts are readily available, so replacement is usually more economical than repair. From this you can understand that the design of ground support equipment has been looking for a solution for the renovation of airplane acrylic windows for a long time.
Sometimes the windshield may crack and safety is not impaired. In that case, repairs can be made by stopping the ends of the crack by drilling with a #30 drill bit (1/8 inch) to avoid stress concentrations that cause the crack to continue. Drill a series of number 40 holes one-half inch from the edge of the crack, about one-half inch apart, and thread brass safety wire through these holes and seal with clear silicone to make them waterproof. Diamond cutting heads have also been developed to cut and remove cracks.
Temporary repairs are also possible. One way to make a temporary fix is to stop-drill the ends of the crack and then drill 27 holes about an inch apart into the crack. Use AN515-6 screws and AN365-632 nuts with AN960-6 washers on both sides of the plastic. This holds the crack together and prevents breakage until the windshield can be properly repaired or replaced.
Design of ground support equipment.
Permanent repairs with a special purpose diamond cutting head machine are now possible. Aircraft windshields or side windows with small cracks that only affect appearance and not airworthiness can be repaired by first finishing by drilling the ends of the crack with a #30 or 1/8 inch drill bit. Then fill the crack with a hypodermic syringe and needle with a polymerizing cement such as PS-30 or Weld-On 40 and allow capillary action to completely fill the crack. Soak the end of the 1/8 inch acrylic rod in the cement to form a pad and insert it into the stop drilled hole. Let the patch dry for about 30 minutes and then cut the rod flush with the sheet.
Polishing and finishing can be done in the following way. It is possible to remove scratches and repair marks from acrylic plastic with certain restrictions. Grinding, which may adversely affect the optical properties of the plastic and distort the pilot’s vision, should be avoided.
If there are scratches or repair marks in the area to be sanded, they can be removed by sanding first. Use 320 or 400 grit sandpaper wrapped around a felt or rubber pad.
Use circular rubbing motions, light pressure and a mild liquid soap solution as a lubricant. After sanding, rinse the surface thoroughly with running water. Then continue to lightly sand using 500 grit paper. Continue to move to a higher grit paper and sand and rinse until all sanding or repair marks are removed. After using the forest sandpaper, use sanding compound and sand in a circular motion to remove all sanding marks.
Acrylic windshield restoration.
Acrylic windshield repair can be finished nicely and airplane windows can be cleaned by washing them with mild soap and running water. Rub the surface with your bare hands in a stream of water. Follow the same procedure but with soap and water. After the soap and dirt have been rinsed off, dry the surface with a soft, clean cloth or cloth and polish it with a windshield cleaner specially approved for use on clear aircraft plastics. These cleaning agents can be purchased at aircraft maintenance shops.
A thin wax coating fills all possible small scratches and forms raindrops that are easily blown away by the wind.
Acrylic windshield cover.
Acrylic windshields are often referred to as “lifetime” windshields to distinguish them from windshields made of the much shorter acetate material. However, airplane acrylic windshields also need to be protected from the elements.
When an airplane is parked in direct sunlight, the windshield absorbs heat and actually gets hotter than the inside of the airplane or the outside air. The sun gets very hot inside a closed airplane, and this heat is also absorbed by the plastic windshield.
To protect against this damage, it is wise to keep the aircraft in a hangar. If this is not possible, there should be some kind of shade so that the sun does not come into direct contact with the windshield. Some aircraft owners use a close-fitting, opaque, reflective cover over the windshield. In many cases, this has done more harm than good. This cover can absorb moisture from the air and release harmful fumes, and if it comes in contact with the surface of the plastic, it can cause cracking or small cracks in the windshield. Another danger of using such a cover is that sand can explode under the cover and scratch the plastic.