Cessna Annual and Tailcone Part 2

Cessna Repair

A tad bit off the subject of the RV-10, however it's relevant to the education process of building a plane in general.  December means its time for the annual inspection on my second favorite project plane, a 1977 Cessna 172N 180 HP conversion... for reference here's a before and after picture....

Before

After

Being a certified plane, and since I'm not an A&P I obviously didn't do much of the work.  Things like engine overhaul, exterior paint, sportsman STOL, new windscreen, avionics, etc were all done by professionals.  However, I was able to redo the entire interior including some STCs and in the end it's a fantastic clean little plane.  She is also 40 years old that went from flying about 10 hours a year to over 150 hours over the last year.  So things are going to break.

I've remained fairly involved in the maintenance of the plane over the last year so no surprise to the A&P that I wanted to be involved this year on the annual.  A lot of my contribution consists of doing small tasks, ordering parts, helping hold various tools or doing the grunt work. I find similar with the plane build I'm continually learning which is always a good thing. In fact, as an owner/pilot it's incredibly important to be involved with your aircraft.  Especially when it's something that carries your family and friends around in the sky.

On this year's annual there are some minor repairs, some new parts that were ordered and some items to keep an eye on.  On the lower cowl there were a number of rivets that have worked their way loose and in several spots fell completely out. One thing about having a fresh paint job is the loose or failing rivets are easily noticed.  I decided to use my new-found knowledge, tools and Vans rivets to see if I could fix it.  I had meant to take some action pictures showing the process, but it literally took me all of 10 mins.

• Cleco'd the empty holes
• Drill out loose rivets
• Clean holes with #40 reamer bit, ScotchBrite, Acetone and compressed air
• Rivet with gun and bucking bar... proper sized rivet is determined using gauge.
• A&P inspects and is amazed at your structural mechanic skills!

Sorry for the dirty cowl....

That was all there was to it and I enjoyed putting my newly developed building skills to practical use on my current bird.

Tailcone

Now onto the RV-10 build. I had been looking forward to the tail cone for quite some time.  While the other parts are extremely cool, nothing beats looking down the end of the tail cone in all it's shiny gloriousness.

Pretty!

Getting to the above picture though took both time and patience as well as learning a few lessons on the way.  Here are a few things that I learned;

• Cleco Management - I had ordered 300 3/32 (Silver) clecos at the start of this project.  Never really ran into any type of shortage issue until I got to the tail.  You have to start getting rather crafty in harvesting clecos from completed areas... take too much and you can't ensure alignment... don't take enough and you can't complete tasks.  My process was to start removing from the bottom then work to the sides.
• 3/32 vs #40, 1/8 vs #30 bit - I was under the incorrect assumption that these were synonymous with each other.  I for whatever reason thought when the plans were telling you to use a 3/32 that that meant use a #40.  After a discussion on VAF my ignorance was pointed out and I was able to correct it.  The reason you drill once with a 3/32 and then again with a #40 is because this is done when you're overlapping two skins.  So 3/32 will get the first skin cleco'd in and the final drill with the #40 ensures a snug fit.

Following the plans from where I was last posting I had to make some very large longerons.  Now I had to reorder one of these because I inadvertently cut a bracket out of the long piece.  No excuse just overlooked, $14 for the part $25 for shipping.. easy fix.  I guess a good rule of thumb is really double triple check the large or long parts before you cut, drill or otherwise defile these.. because shipping them is expensive.  Working with the piece was fairly simple, just required you to cut to length, put a few notches in them and then hammer a bend in it.  The bend correlates to a change in curvature of the skin.

Now comes the action!  You start clecoing the frame ribs to the base of the tail.  Lacking saw horses I tried several methods of working with the pieces.

This was the winner in the end.

This process consists of a lot of match drilling and clecoing, using this many clecos in the beginning you'll start to realize fairly quick that you're going to run out... unless you bought maybe 500 of them. The jframe pieces you made start going in and you start attaching the sides as well.  No major issue just again time consuming and you really need to pay attention to the lines you drew on the pieces to ensure they line up correctly.

Reminds me of a canoe

After the sides and ribs are attached you finish up attaching the aft end tail assemblies you made previously.  It is very important that these are somewhat level.  If they're not then you probably have something misaligned and you'll want to fix that later.  This level is cool, but these are cooler.  I actually picked one of the Smart Tool level but it didn't come till after I took this picture.  I did go back and I learned the piece was off by 3 10ths of a degree... my bench is off by 1.4 degrees and my floor is off by 4 10ths of a degree, but I think that's by design.  I found myself walking through my house checking various services for levelness....

Hard to tell in the picture but this part is you make some more brackets and attach them to the bell-crank ribs.  Not to give it away but as you can tell by the perfectly countersunk holes this will end up being an access panel for this area.

After you have some rigidity to the tail you are able to put the rest of the aft piece in place.  This includes match drilling to 3/32  the longerons to the side skins.  It's extremely snug when you do this and your hand will be in some pain afterwards from pushing in the clecos.

It all goes together very nicely, however don't forget to put the small skin piece under the tail tie down area.  For whatever reason I missed this and didn't discover it until I was looking over the plans in bed and immediately went to the garage and corrected it.  Nothing major because I hadn't match drilled it yet and it didn't affect the leveling at all.

You get to a point on the tail cone assembly where you can't work on it sitting on a work bench anymore.  Unless I suppose you're freakishly tall which in that case you might not fit in the plane when it's completed anyhow.  I'm not a fan of just setting stuff on my garage floor so I took the container my replacement HS spar came in and re-purposed it to a little platform along with some scrap ply wood.

Setting the tail on the platform allowed me to work through and attach the top skins, match drill and final drill everything together.  It becomes a little challenging to match drill the stiffeners solo so it helps to have an extra set of hands come either drive the drill or align the line in the holes.  In the end you have a pretty cool piece.

Not looking forward to taking this all apart....