Aircraft Painting – Strip & Prep

A successful aircraft paint job begins with the surface preparation. A new aircraft from the OEM needs only to be lightly sanded and cleaned prior to receiving the primer-filler coat. Some rivets may need to slightly shaved if they don’t properly sit flush to the skin. Temporary seals need to be cut out and removed while others need to be covered with tape. The quality of skin work varies and can be flushed with body fill, however over time this putty can crack loose so use it very sparingly or none at all.

Repainting an existing aircraft first shall require the stripping of the old paint. This will first be dictated on the shop’s location and its use of chemical strippers. The Environmental Protection Agency (EPA) in the US has regulated the use of toxic strippers that contain methylene chloride. Older facilities can still use these strippers but must contain the waste in drums and have it removed by collection systems. Newer facilities or some that has changed for environmental concern, now use synthetic polymer beads and high pressure air systems that simply blast away the old paint without penetrating the aluminum skin. This technique is similar to sand blasting where a pressurized gun blows beads against the airframe at about 40 PSI. The beads, dust and paint is removed in a prep-area and then the surface is lightly sanded as required and cleaned for priming and painting.

The use of bead blasting also has its advantages where chemical etchants can get between aluminum panels and rivets where the OEM has sealed theses seems where Alodine was used to prevent corrosion. Strippers can also affect the coatings and anodized finishes of fasteners and rivets. It would be a good idea to consult with the OEM by speaking to your local in-field, service representative before you strip you aircraft.

Once the paint has been removed, inspect the surface carefully to be sure all of the old paint has been removed and that there is no residue, oils or hydrologic fluids on the skin surface. Also dust or dirt needs to be wiped off as any of these contaminants under the primed or final paint finish will affect the longevity and durability of the final painted surface. All of the foil and paper protection from the stripping process now needs to be removed and replaced with new protection to begin the paint process staring with the primer coat.

Composite Interior Components

One of the first interiors I worked in was a GII completed at Atlantic Aviation in the mid-seventies. The cabinet sub-structure was made of marine plywood, wood screws and aluminum angles. At the same time, DuPont was further developing the woven fire proof fabric known as Nomex into structural material. It did not have the integrity that DuPont was seeking, but when the panel was combined with a honey comb interior and impregnated with Phenolic resin, it became rigid and very light weight. In the early eighties, Nomex panel became the aviation industry standard for sub-structure that could be manufactured into cabinets and formed into headliners and the like.

Parallel to the development of the Nomex panel was the enhanced development of aluminum honeycomb panels. Both of these types of panels at that time were very costly, but the benefit of weight savings could not be ignored by cabinet shops and completion centers. DuPont went even further than Nomex as a fire proof material with the development of Kevlar. This petroleum based fiber was then developed for the military in the eighties when the matrix woven fabric was then impregnated with low viscosity resin it was found to be bullet proof. This material it was so low in weight and high in tensile strength, that it could not be ignored for numerous uses that include body amour, building construction and aircraft airframe manufacturing as well.

Nomex Burn Samples

Today all three of these panel materials are commonly used in the manufacture of business jet interiors. Depending on the location of application they can be used alone or combined to create complex components. Panels are now cut on Computer Numeric Controlled (CNC) Routers that allow one skin to remain intact so a five sectioned panel can be bent into a single drawer without being cut. Panels are glued together with pins, injected with epoxy and the edges are filled with structural putty.

Delrons

Once formed or built, these panels can be secured to the aircraft structure with shock mounted brackets known as isolators. These attachments are fastened to the Nomex components with inserts called Delron’s that can be secured with screws that won’t crush the composite panel.



It is good to be able to inspect cabinets and components in rough form before they are covered in wood veneer or fabric. Edges of wet units like galleys and vanities need to have the composite edge filled and sealed so water cannot penetrate the panel. Corners and edges that have been filled with putty should be inspected to insure that the fill is adequate and won’t crack loose. By giving components the once over, it will guarantee that the finish material adheres properly especially wood veneer that can delaminate once that cabin pressurizes in operation.      

Upholstery Leather

Leather seat covering has been a favorite finish material that is easy to maintain and conveys luxury in business jet aircraft. It passes the burn test requirements easily and can be custom dyed to match any interior. Typically upholstery grade leather comes from European cows where barbed wire is not used in fences that can cause scratches and scars on the animal’s hide. There are also specialty leathers and hides that come from deer, ostrich, crocodiles, stingrays and sharks as well.

The initial process in tanning leather starts where the hides or “crusts” are then cleaned and pickled to remove the hair, soften and cure the material. This prevents the hides from drying out or decomposing over time. When the hide comes out of this process it has a grey blue finish and the crust is known as a “wet blue” and is now ready for tanning.

There are several types of tanning processes which include natural or vegetable tanning, aniline and semi-aniline dying and synthetic tanning that creates unique finish effects. Vegetable tanned leather has a very natural look as it uses dyes made from vegetables, tree barks and plant matter to give warm colors such a tans and browns. Aniline tanning uses a wider array of pigments that create vivid colors this type then has a protective wax coating applied to give it a glossy finish. This type is the most widely used in aircraft seating as it wears well, looks good consistently and needs little maintenance.

Upholstery grade leather is quite different than fashion grade material. There are four main catoagories of upholster leather, full grain, top grain, split and corrected. Full grain leather uses all layers of the hide; it is thick and sometimes difficult to upholstery with but will wear best over time. Top grain and spilt are hides that have been separated using only the top of the hide or the bottom which can give different effects in grain or suede finish. Corrected leather is a lower quality material grained pattern is embossed which takes away from the natural beauty of the animal. This type is lower in cost but will not last long and where out in heavily rubbed areas like arm rests.

If given the opportunity, inspect each hide prior to upholstery. Look for thin spots, scars, scratches, blemishes, pin holes and rub marks. Select the best sections for the seat panels and back panels. Less desirable sections can be used in the non-visible areas of the bucket and cushions. Ask the shop to provide you with a rub test if possible. Testing machines known as the Taber Abrasion Test is provide from some leather suppliers. The high the number of rubs that the leather can withstand, the longer the seat will wear during operation.

   

Next Gen IFE

Walk up to the Gulfstream 650 with an I-Phone in your pocket and the aircraft asks if you would like to download the cabin control app. The “I” world is changing around us at speeds even computers can’t keep up with. So is In-Flight Entertainment known as IFE and Cabin Management Systems or CMS. Seamless connectivity that allows the passenger to move from home to office to aircraft without missing any voice or data has been around for a few years. Now with the app revolution, it goes one step beyond to cabin controls and entertainment selected from your device.

Not only does this mean lower cost IFE and CMS equipment, it also cuts the weight of having excessive monitors, DVD players and source equipment on board. In the cabin WIFI environment, these devices can “live stream” TV, Audio and Video directly to passengers hand held devices and portable pads. It also eliminates large switch panels located on side ledges and cabinets as well as many sub-control units buried in or under furniture.  

It starts with a Broad Band connection, typically operating over an Inmarsat SATComm System connected to a cabin distribution unit or server over a secure WIFI connection. Then by adding a SAT-TV connection or an Audio/Video on Demand System passengers can watch TV or movies by tapping on screen.

Sound simple, almost; there are numerous types of systems. Before you jump into one, find out the cost per minute of the service. These rates can vary but constant live streaming over long flights can come with high monthly bills. If you are upgrading and existing system, work with you modification center to select a system that will be compatible with your aircraft’s CMS/IFE backbone and the aircraft’s antenna.

Once you have created this “in-flight hot spot”, passengers can connect and control all cabin functions. This cuts down significantly on the miles or wires used in a traditional cabin management system. Weight is also cut significantly and these hand held devices are inexpensive and can be stored anywhere in the cabin. Intuitive Graphic User Interfaces or GUI’s, help the passenger access and control the system with little help from cabin crew.