334 hours on the hobbs - Right Elevator Frame work in Progress

Had to flute and matchdrill the two tip ribs to themselves and to the front spar. This is the first time that I have dealt with two ribs that are butted up against each other. One of them is the tip rib for the end of the elevator, and the other is known as the counter balance rib. Then there is the counter balance skin and the counter balance lead weight. This is one really beefed-up area of the airplane, and I guess it needs to be given the forces that can be applied to this area during flight.

I also drilled out the two holes in the ribs and counterweight for the screws that will attach the weight to the ribs permanently. It's almost impossible to put it on a drill press to ensure a nice straight hole, so I had to free-hand drill this hole through the counter balance skin, the lead weight, and then through the rib flange on the other side, being as careful as possible to keep it straight. If the hole comes out the back side uncentered, the washer and nut may not ahve enough room to sit flat on the rib flange, and that means I would have to order new parts.

Here is the end rib adn the counter balance rib attached to the forward spar for match drilling:

And just in time for Halloween, this assembly looks more like a robot insect from a Tom Selleck Movie with Gene Simmons of KISS fame as the bad guy. I can't remember the name of the movie off hand but perhaps some of you will remember that movie.

And another shot - Here you see the lead weight nicely tucked inside the counter balance skin, up against the tip rib and the counter balance rib flanges. The counter balance rib is on the bottom and cannot be seen in this photo:

It was  a real bitch getting those clecos in place. If you did not take the time to properly flute the ribs and verify that the holes are lined up right it would be even worse, if not impossible to get the holes to line up. This assmebly is a very tight fit. I ended up with everything assembled as shown in the previous photo, and applied as much as force as necessary to get the rear-most holes in the rib to line up, effectively clecoing everything from the rear to the front where the weight is located. Once I got it started the rest of the holes seemed to line up pretty well.

And now for the dreaded hole drilling exercise. They give you two pilot holes to start with on the front of the counter balance skin. If you follow my blog you may remember that I had to prep another counter weight for the rudder not so long ago. The difference between that one and this one, other than the size and shape of the weight, is that the one for the rudder was pre-drilled, so you simply had to enlargen the existing hole a bit. For the elevators all you get is a solid piece of formed lead, and so you have to drill the entire hole through this stuff. You need to start with a lubricant and several drill sizes to step-drill the holes. I had to re-lube the bit often and also had to back out the bit by hand several times as the bit sinks into the lead and can almost imbed itself to the point where it will not move, or worse yet, may break off inside the lead. Luckily none of that happened. I just took my time and tried to drill slowly through the lead so I would not mess up. Note my clamp process as well. I needed to secure the entire assembly because backing the drill bit out took quite a bit of force (I used my Sioux air drill, which does not have a reverse mode on it). I used 3-in-1 oil for the lubricant and it worked just fine. I cleaned off the bits and re-lubed with each pass through the lead.

The plans call for drilling the holes to #12. To get there I started with a #40 and then stepped up using a #30, #28, # 21, #19, and finally the #12 bit. I may take this to a #10 since the screws are the same as the used for the rudder, just a bit longer, and I will need to countersink the lead and dimple the counter balance skin for the screww heads to sit flush with the skin so that they do not interfere with the tip of the horizontal stab after they are assembled.