Dear Captain Lim,
Let me first say that your site is fantastic! I really do enjoy reading all the articles. I have some questions to ask you.
When an airline orders an aircraft from the manufacturer, where is the painting job done - in the assembly plant or back in the company*s hangar?
How much paint is used? Does the amount of paint affect the overall weight of the aircraft? Are there any regulations for the painting procedure?
If one day, the airline decides to sell or lease its aircraft to another airline, does the new company need to scrape the old paint prior to the new painting? If the old paint weren*t scraped, it would add extra weight to the airplane won*t it? I could imagine that if the old paint weren*t scraped and it is continuously being leased to many airlines; over the times, the outer layer of the aircraft will become *thicker* and weighs more...
When an airline orders a plane, the paintwork is normally done at the manufacturer*s assembly plant. So, if you decide to buy a Boeing 777-200 from the Company, the decorative painting is included in the base price of the airplane.
How much paint is used would depend on the customer*s requirement. If only the upper and lower half of the fuselage, tail and customer markings were considered, it requires about 475 pounds (215 kg) of paint. Without paintwork at the bottom half of the fuselage, then only 330 pounds (150 kg) of paint would be required. To paint a bigger Boeing 747-400, you would require over 90 gallons of paint. That is enough to paint the inside of four family houses! The paint here would weigh around 555 lb (252 kg). Hence, any additional paintwork would add to the overall weight of the plane.
Some airlines prefer a polished airplane as it is lighter and save fuel cost. However, this savings is more than offset by the higher cost of washing, polishing and painting a polished fuselage throughout its service life. I believe there are some regulated procedures in conducting a proper painting job. Thus, to maintain a good image of having cleaner or newer planes, most airlines would repaint their aircraft once in every four years.
When a plane is sold or leased to another company, repainting works would usually be required. Normally, they do not completely strip the paintworks. Instead, they would alternate between complete stripping and merely scuff sanding the existing paint layer and applying a new topcoat.
Generally, airplanes should never carry more than two layers of paint. With more than two layers, operating efficiency drops, inspections become more difficult and corrosion can start under a fresh topcoat.
Yes, excessive paint buildup is a particular concern on aging airplanes.
Hope that answers your many questions.