In aviation as in fashion and the movies, good looks count. This is why aircraft paint jobs need to look as perfect as possible; be they adorning a Beechcraft Bonanza or an Airbus A380.
The actual task of painting aircraft is extremely time-consuming and complex. This is why "we request our customers give us 30 days to paint their aircraft," says Chuck Siehr. He is the regional group sales manager for the northern United States and Canada, at Landmark Aviation in Springfield, IL. "Painting an aircraft properly is both a science and an art form, requiring skilled and patient technicians."
So how do the pros do it, and what can you learn from them? Here's what AMT learned from talking to Siehr and Jim Burress, general manager of Dean Baldwin Painting in Roswell, NM.
Preparing the canvas
In aviation painting, the aircraft serves as the canvas, and what a canvas it can be! Even the smallest aircraft has hard-to-reach places to spray-paint; requiring the use of special platforms. In the case of large aircraft like the B747, these platforms can be a few stories in height.
But size is just the beginning. Whatever their size, aircraft all contain parts that aren't meant to be painted. This requires technicians to cover them using specialized barrier materials, including paper, mylars, and tapes. In the case of a Boeing 777-200LR, for instance, the nacelles on each of its two GE90-110B1 turbofans have diameters measuring 11.25 feet across. That's a lot of paper and tape!
The masking process becomes doubly important when an aircraft is being repainted. This is because the aircraft is stripped of its existing paint job before the new livery is applied. Not only does this ensure better adhesion to the airframe, and a chance to look for telltale signs of corrosion on the aircraft's stripped skin, but it also helps keep weight down, thus fuel costs down. According to Boeing, a complete fuselage and tail paint job on a 747-400 weighs 555 pounds.
Meanwhile, even brand-new airframes require masking and surface preparation before paint is applied. Specifically, the skin is chemically etched using phosphoric acid, to "roughen up" the surface and give the paint something to stick to.
Acrylic urethane and polyester urethane paints are the options when it comes to painting aircraft. According to Chuck Siehr, it is "the polyurethanes" that are the most popular: "They come in two parts that are mixed just before application, which interact chemically with each other in a process called polymerization to provide a hard, durable finish."
Aviation paint providers include Pratt and Lambert, Sherwin-Williams, PRC Desoto (PPG), Akzo Nobel, and Axon. Jet Glo and Acry Glo by Sherwin-Williams are two popular brands. Typically, one coat of corrosion primer is laid down followed by two to three successive coats of paint; then any decorative striping and clear coat are applied. High-end business jet paint requirements go a step further, requiring a sanding surfacer to be applied after the corrosion primer.
Paint selection is where the most serious errors occur in aviation, says Jim Burress. "Manufacturers take the time to specify which brands and types of paints work best with their aircraft," he tells AMT. "Unfortunately, some paint shops have a 'What, Me Worry?' attitude that results in them not checking the aircraft's manual before spraying begins. Ideally, you should be trying to produce a paint job as good as or better than the factory's as possible, to give customers the best appearance and longest wear. That's why you should always go to the manual first and use the product specified or an equivalent product that meets the manufacturer's specifications."
"Dry film thicknesses of each paint layer as directed by the coatings manufacturer must be strictly adhered to by the aircraft refinisher for corrosion resistance, long-term durability, and gloss retention," says Richard Giles, technical services representative, Sherwin-Williams Aerospace. "Typical primer thickness is 1 mil and topcoat thickness is 3 mils and greater."
Axon Products was established in the mid 1990s and is located in Greenville, S.C., in the Southeastern United States. Axon Products principal operating partners have been introducing high-end niche...