The Challenger assembly process varies greatly based on what kit you order, and what options you add. For example, a part 103 kit with sail cloth wings is much quicker and easier to build than an XL-65. In any case, your Challenger kit will arrive with the fuselage all framed up, and the controls installed. The wing panels and tail components are also all framed up. All of these components are built in a jig at the factory to ensure that they are exactly straight, and also saves a lot of time for the builder. With Challenger, you have the option to order the kit in sections. The factory refers to this as “Kit by Sect.” With the “kit by sect” option normally the tail is shipped first, then the wings, then the fuselage, but you can order them in what ever order you want. While this may be helpful from a budget or space standpoint, it will add to the shipping expense considerably. There is a manual included with the kit that is very detailed and gives you step by step instructions on how to assemble the airframe. It would be helpful to read the manual entirely before starting on the assembly process. If you would like, the manual can be sent ahead in paper or PDF so that you can start reading while your kit is in production at the factory. There are also many other resources available to you for information and are listed in our “Resources” section, and of course, you local dealer is here to help anytime you have a question. (Keep in mind when purchasing a kit, the dealer you purchase it from is your go-to person for help during the build process.) At Heavenbound Aviation we also provide builders assistance if you would like us to complete certain steps of the build process. Please contact us for more information on that. In either case, one of the first things you should do is call the EAA and get an experimental aircraft registration kit and begin that process. Remember, you are dealing with the federal government, nothing happens fast! You don’t want to end up with an airplane that is ready to fly and then have to wait for months for the FAA to get their paperwork completed.
Once you get started on you assembly you will find that it is actually pretty simple, and a lot of fun. There are lots of holes to drill and lots of rivets to pull, but nothing complicated. Some of the tasks that are very time consuming are the instrument panel and electrical wiring, depending on the complexity of it, and the covering process. The fabric process is not complicated and regardless of which process you use, a complete manual is available that give you step by step instructions. It does require a lot of attention to detail however, and does take some time. But once again, it is a lot of fun.
Once your kit arrives, the first thing to do is to inspect all of the boxes and make sure there is no shipping damage. It is also a good idea to go through the packing list and make sure everything is there. The factory sends along a packing list that not only lists everything shipped with the kit, but also what box it is in. This is very helpful.
The first step we like to do when building a Challenger is to acid etch the airframe and then epoxy primer it. This will not only make the airframe look nice, but will protect it from corrosion for the long haul. Once the primer is dry we begin construction process. Now we can accomplish tasks such as temporarily installing the nose cone, and nose gear, setting up the tail hinges and struts, and installing a few fabric formers. Then we can install the fuel plumbing and electrical components. We can build the instrument panel and wire it as well as build and install the main wiring harness. At this point it is recommended to build the doors if you have them. It is preferable to do this before covering to avoid any damage to the fabric as you are fitting and building the doors. There is an article in our “Resources” section that will greatly assist you in this process. You can leave the lexan on the doors a little oversize and do the final trim when the airplane is complete. The windshield can be installed at this point as well, but the top will need to be left long until final assembly so it can be trimmed to fit the gap cover. Once we are satisfied with all of those things, we are ready to start the covering process on the fuselage.
The first step in the covering process is to install felt on the airframe anywhere that the fabric will come in contact with a rough surface. The purpose of the felt is two fold. One is to protect the fabric, and the other is for appearance. When fabric is very near or touching something rough such as a gusset plate it will either be glued to it, showing that rough look through the fabric, or if it is not glued to it, the air in flight will cause the fabric to rub on that spot and eventually wear through. If we glue a piece of felt over that spot, the fabric will now have a nice smooth look to it, and the felt will protect it from wear. Proper felt placement is critical to having a nice looking, long lasting finish on your airplane. Once the felt is all in place we can cover the airframe with fabric. Once the airframe is covered and the fabric has been shrunk with heat, the next step is to apply reinforcement tapes. These tapes are simply strips of fabric with pinked edges that are glued onto the main fabric. The purpose of these tapes is to protect fabric edges and to provide additional strength in high stress areas. Once the tapes are on, you are ready for the first coat of UV protection. Depending on the process you are using, that may be brushed on, or sprayed on. There will be several coats of UV protection, with some sanding and ironing tape edges along the way. After that comes the top coat. At that point the fuselage is ready for final assembly. Don’t forget along the way to prep and paint the gap cover and wheel pants if you have them! It’s much easier to do them while you are painting the wings or fuselage rather than go through the whole paint process again.
The wing construction is very simple as well. The wing panels are built at the factory in a jig. If you are using wing sails on your wings this process will go very quickly. First you will temporarily install the ailerons, being careful to get the hinge locations just right, then remove them. Then, your wing sails will simply slide on the wing panels and then ribs are installed into them. The ailerons will require the conventional aircraft fabric an paint process. If you are using conventional aircraft fabric on the wings you will need to drill the holes for the fabric rivets on the top of all the ribs, and drill all of the rib gussets. Then the ribs are installed with rivets. If boxing the wing tips, this is done now, as well as some sheet metal at the wing root. If you have wing tanks and lower ribs such as an XL-65, there will be a few additional steps for that. Once your wings are ready to cover, the process is essentially the same as covering the fuselage. The location of felt varies from one builder to the next, but we like to cover the entire leading edge with felt. Some builders choose to use a metal leading edge wrap on the wings. If that is the case, we would cover the entire leading edge wrap with felt. While this does add some weight, it will look much nicer.
Once the wings are complete you will be ready for final assembly. The key to final assembly is to check and recheck every nut and bolt, every cotter pin, every safety wire! One thing we do now if we complete a final assembly on a customers aircraft it to take pictures of every cotter pin and turnbuckle safety wire and document that in our records. (Another safety tip, along the way we like to tie a bright pink ribbon around anything that is a critical item that must be completed later to help us remember.) If you purchase your kit from us we would be happy to inspect if for you at this point to make sure it is ready to fly. (we can inspect it any point along the way too if you need us too) Also, for our customers we will gladly test fly it for you as well as provide primary or transition flight training if needed.
While this is certainly not an exhaustive guide to assembly, hopefully it gives you a good overview of what the process entails, and that it is not an overwhelming feat, but a fun process! And remember, should you choose to buy a kit from us, we are here for you to answer questions, or even complete parts of the build process for you if you like. Please contact us for more information.