Why planes are repainted so often

• Commercial airplanes are repainted as often as every seven to 10 years.
• It can cost airlines hundreds of thousands of dollars each time.
• We outline the process for repainting airplanes and explain why it is so vital for safety.

Following is a transcript of the video.

Narrator: Over the course of a 20- to 30-year life span, commercial planes are completely repainted as often as every seven to 10 years, depending on the size, accumulated flight time, and the climate of the plane's route. The process typically involves stripping away the old paint for a thorough inspection before applying anywhere from 600 to 1,200 pounds of new paint, based on the size of the plane. And it's estimated that repainting a large Boeing 777 can cost $100,000 to $200,000 each time. On top of that, for larger planes, the process can take two weeks, meaning airlines take a financial hit every time a plane in their fleet needs a touch-up. So, why are commercial airplanes repainted so often? And what justifies the cost?

Corrosion from the elements can be a big risk during a plane's lifetime. Over the course of many flights, dust, oil, grease, water, battery acid, and other pollutants slowly strip away at the paint, leaving areas unprotected. When unprotected metal comes into contact with oxygen in the atmosphere, it leads to corrosion. Without a protective layer over the metal of a plane, harmful UV rays are able to penetrate the aircraft, or worse, sustained stress corrosion could cause integral components like propellers or landing gears to fail. That's why on top of routine inspections, planes come here, to Roswell, New Mexico, where a crew of only eight people work around the clock to prep, strip, and repaint a Boeing 737 from nose to tail in just eight days.

The first step in the repainting process is to strip away all of the paint. After covering windows and other sensitive areas to avoid damage, workers sand down logos by hand and apply a heavy paint thinner that melts the paint away overnight. With the paint removed, the corrosion becomes much easier to detect. During this inspection, it's vital that workers identify any areas of concern. If plane maintenance is neglected, corrosion and metal fatigue could lead to a major accident.

Like Aloha Airlines flight 243, when a poorly maintained Boeing 737 burst midair, leaving a massive 18-foot hole in the fuselage. The National Transportation Safety Board reported the probable cause was that the Aloha Airlines maintenance program failed to "detect the presence of significant disbonding and fatigue damage" on the 19-year-old plane. But the key to stopping corrosion isn't to catch mistakes, it's to be proactive. That's why a greenish-yellow compound containing zinc chromate is sprayed to cover the plane's bare aluminum body. The chemical compound slows down the process of corrosion and prevents harmful UV rays from penetrating through the cabin.

Once corrosion has been addressed, aircraft are painted with a high-volume, low-pressure spray system. For an average Boeing 737, over 33,300 square feet need to be covered, with each layer being only 0.12 millimeters thick. All of that paint adds 1,300 to 2,200 pounds of weight to the aircraft, which is why only two very thin layers of white paint are typically applied, to provide a sufficient finish without adding too much weight.

Additionally, planes are typically painted light shades, like white or gray, to reflect heat from the sun. To finish the process, a clear coat adds another layer of UV protection, but this varies from airline to airline. It's a constant balance between safety and efficiency. For example, by removing the mica layer previously used when painting its Boeing 737-800s, American Airlines saves nearly 300,000 gallons of fuel annually.

Repainting airplanes is also an opportunity for airlines to distinguish themselves from competitors. Various stencils and colors are used to paint expressive liveries, like the KLM Royal Dutch Airlines, which paints the front half of its 777s a bright orange to represent the Dutch flag. Plane liveries are one of the biggest marketing tools used in the airline industry. They are quite literally flying billboards, which is why airlines work tirelessly to maintain a consistent brand image of safety, efficiency, and comfort across the entire fleet.