Saturday, October 13, 2012

Flaperon Hinge Bearings Completed – Rear Spars Started

Assembly began on the flaperon hinge bearings by clecoing the components together and squeezing the two AN426 flush rivets first while the tip of the hinge bearing assembly was in a vice to aid in  keeping the ends together during riveting. Once the two AN426 rivets were flush riveted, the squeezer's sets were changed out for AN470 rivets and those rivets were squeezed using a random pattern to help prevent warpage.
                                                        Completed flaperon hinge bearing assemblies.

The flaperon hinge bearings will be attached to the wing’s rear spar along with a doubler plate that looks a lot like a large tuning fork. The rear spar doubler plates were quite bowed from the stamping process and required a little “fine tuning” so to speak.
                                                          Rear spar doubler plates before straightening.

Not having a press on hand, decided to use a piece of PVC pipe to aid in rolling the curve out of the doubler plates by using downward pressure while rolling the metal back and forth over the pipe. I thought that a better choice than pounding on the metal with a soft hammer. It took a little time to get the doubler plates close to being flat, but they look much better now.
   Rolling the rear spar doubler plates over a PVC pipe to remove the bend in the metal from the stamping process.
                         Rear spar doubler plates after straightening … not perfect, but much straighter than they were.

With the exception of the ribs, the rear spar is the last major component left to work on before the actual wing assembly begins. Each rear spar receives one of the doubler plates, a flaperon hinge and a short tip attach angle. In addition, because DOG Aviation is using flush rivets to attach the skins to the wings, the rear spars will need to be dimpled. The spar thickness is .032 inches which is far too thin to be machine countersunk for 1/8” rivets.

Preparations on the rear spars consisted of filing down all the burrs left from the shearing process then using the 1”Scotch-brite wheel to smooth the edges down followed by a quick rubbing with the 3M foam abrasive pad. Both spars are now ready for dimpling and there are lots and lots of holes to convert into craters.
                      Smoothing down the edges on the left rear spar with a 1” Scotch-brite wheel on an air grinder.