Installing the doubler kit is not difficult in itself. Rather than a cumbersome complex fuselage support, all that is necessary is a simple floor jack under the hull to take the weight off the wings. Typically, simply jack the hull up so that the wing strut is fully extended, but the tire is still holding only the weight of the wing. You can adjust that slightly such that the bolts will slide in and out easily. NEVER have more than three bolts removed at any one time from either the lower or upper attach fitting. When driving the bolts either in or out make sure to use a soft (brass or equiv) hammer. We do NOT recommend "screwing" the bolts out or in. In fact if you try "screwing" the new Aerofab (unplated) bolts in, you will end up galling the bolts and the wing fitting, destroying the bolt and possibly the wing fitting as well. The Airtech bolts are cad plated.

Rather than use the rivets supplied for attaching the straps to the back side of the spar, use NAS 6603-14 bolts (NAS 6603-15 for Renegade wings). Use an 11/64" drill and a 0.1875" (carbide tip) reamer to line ream and finish the holes for the NAS-6603 bolts. They should fit snugly. Whenever inserting a new, or even a used bolt into the attach fitting make absolutely sure the hole is clean and free from debris. Lubricate the bolts with some sort of anti seize grease such as moly di sulfide or spark plug anti seize. We have found that the holes drilled in the steel strap in the Aerofab kit are not exactly the same spacing as the holes in the wing fitting on the aircraft. The misalignment is only a few Thousandths, but with such a close tolerance bolt, the alignment is not perfect. It is permissible to clean out the holes with a 0.375" or 0.4375" hand reamer as applicable, but NOT under power. Finally, do not over torque any of the bolts. Nothing is in tension here, only in shear, so the only function of the nut is to hold the bolt in place. Many people have stripped either the 3/8" nuts or the 3/16" nuts. The bolt lengths are adequate in the AirTech kits, but in the Aerofab kits they are really too short, and you may not be able to use proper washers under the nuts or bolt heads. It is more important to get sufficient thread into the nylon locking portion of the nut.

If you are using the Aerofab kit, make sure that the aluminum filler piece DOES NOT interfere with the flange of the first rib of the wing structure. If the rib is a "Little" closer than average, then the filler plate is too long and will not lay flat against the spar web. The Airtech kit has a beveled end to take care of this problem, and if you use the Aerofab kit, go ahead and grind a small bevel on the end of the filler plate to make sure it clears the web flange.

We find that the instructions with the Airtech kit are easier to follow and are clearer. When drilling the reinforcement plates we locate the holes in the filler plate from the aircraft, and then transfer the holes (undersize) from the filler plate to the hardened reinforcement plate on the bench (Drill press). Some people have tried to drill the holes on the aircraft, and that does not work very well due to the pressure etc. required to drill the hardened material. We use an 11/64 carbide drill, but a good cobalt HSS drill will work if you go slow enough. The strap is about 40C Rockwell so it is pretty tough.

We have gotten the labor time down to ten hours per aircraft and charge a flat rate of $500 to install the kit. However we have now done about 50 kits, so that time is a result of experience. For a first time endeavor, if your mech takes about 16 hours he has done a good job.