Step 13.5, Hanging the engine

I've been trying to run a just-in-time airplane factory.  Just-in-time is, as expected, the concept that the purchased materials for a product to be built are not warehoused at the factory, but instead are brought to the factory at the last possible second before assembly.  Thus increasing efficiency and lowering costs.  It seems like I may have jumped the gun on purchasing my engine as it has been sitting in my factory for well over a year.  Thus decreasing efficiency and increasing my costs. That's how I roll.

And so, the time has finally come to mount my IOX370.  Previously, I had the engine on an engine stand where I attached the vibration isolators to the tubular steel dynafocal engine mount.  The dynafocal mount is designed in such a way as to transmit less vibration from the engine through to the fuselage.

To mount the engine, I needed to drill the holes from the engine mount to the firewall.  I had previously drilled through the firewall to mount the fuselage to the rotisserie, but I used a smaller diameter bolt for that so that when the time came to mount the engine, the larger engine bolt holes would (hopefully) be drilled through the same holes.  But if there were some misalignment with the engine mount, the larger mount holes will overlap the smaller holes previously drilled.  Using the dynafocal mount itself as a drill guide, the six holes are enlarged to 3/8 inches. 

The mounting order that I used is different from the Van's aircraft recommendation.  They have you fix the engine mount to the fuselage first, then hang the engine.  I suspected that hanging the engine on the mount to be the more difficult challenge so elected to do that first.  

Slip the front landing gear into place.

The front landing gear is held in place with a single bolt.

With the front landing gear secured, I moved on to torquing down the engine mount bolts.  Each of the six are secured with a castle nut and cotter pin.

Move the engine hoist out of the way and Ta Da!  My airplane is on its gear with an engine.

I'm very happy to have finally reached this milestone.  It is a curious fact that it was much easier to hang the engine than it was to install the landing gear.  Go figure.

Step 13.4, Main gear

With the majority of the painting done I can finally get on to some more interesting stuff eventually leading to the hanging of the engine.  My first task with my newly painted fuselage is to get it off of the rotisserie.  Here's a picture from way back showing the rotisserie:

Removing the fuselage is much simpler to to say than it was to accomplish.  My first thought was to move it on to some saw horses, but that would require two moves -- the second being from the saw horses on to the main landing gear.  Being naturally thrifty when it comes to expending physical effort, I think one move sounds better since two moves will take longer. And let's not kid ourselves, my very presence in the same room as my just painted fuselage puts it at significant risk for some kind of damage.

First up, installing the left gear.  Using the rotisserie, I roll the fuselage over allowing easy access to the left landing gear mount.  The left gear slides right in with firm pressure and a little grease in the socket. Then I let that side down until the wheel is resting on the floor.  This is where the trouble starts.

I have a great deal of difficulty wiggling the rotisserie off of the fuselage. The contributing factors were: The shop was hot and I was in a hurry because we were about to go out to lunch. However, the proximal cause I identified as binding on the forward rotisserie bearing. The binding was caused by the off axis angle that the fuselage makes relative to the rotisserie when the fuselage is made to slip past the tail end of the rotisserie for assembly or disassembly.  This was a shortcoming of my rotisserie design that I discovered when I first put the fuselage on the infernal contraption.  If there ever is a version 2.0 of the rotisserie, it will have a removable bearing top at the front and back that would allow the fuselage to be lowered straight down, thus preventing many bad thoughts.

Getting in a big ass hurry is a time honored tradition for me and a recipe for disaster. Although I was vaguely aware of this at the time, I still had an acute case of get it done-itis, which of course trumps rational thinking.  No need to prolong the suspense any further... Nothing bad happened.  The rotisserie was unbelievably stubborn, but I was eventually able to get it out from under the plane, but not before getting grease all over me, the rotisserie, and the landing gear.  I kept touching the rotisserie bearing which is greasy while looking for a hand hold to pull. Why I couldn't remember not to do that I don't know, but I had to stop and wash my hands about 5 times during the process which only elevated my level of aggravation.

With the rotisserie out, I could lift the fuselage up onto a jack that I placed under the right side main spar.  I was thinking the whole time that the jack was not exactly stable and that if it slipped, it would punch a 4" hole right through the passenger side floor.  It was not unreasonable to be thinking that this was a real possibility because I could see it slipping a little as I was vigorously wiggling the right landing gear back and forth while trying to force it upwards into its socket.  Back and forth, up and down, I was applying a great deal of pressure to no avail.

I find my patience with others greatly compromised when I'm preoccupied by a mechanical contrivance with a flair for noncooperation.  I'm sure the gentle reader will agree that when a thing that must fit, doesn't, it's extremely maddening. At this point I'm out of breath from trying to force the gear and I've only made about 1/2" of progress into the gear socket.

So Carol has had about enough of my ever increasing state of agitation, and heads back up to the house.  I am still in a hurry, but I decide to take time out to just sit down and study the geometry of the gear leg. Why is it so much more difficult than the left gear?  I make some small adjustments to the jack allowing me to get a better angle on the gear. I find nothing at all to give me any confidence whatsoever that my next assault on the summit would be any more fruitful.  Never-the-less, I decide that I would make one more big push and then go to lunch. Three or four more minutes of really hard effort and it finally capitulated to my will.  Ahh-ha, ha, ha. (crazed maniacal laughter).  It was a fustercluck to be sure, but I had my airplane sitting on its main gear for the first time.  

And the reason for all of the mechanical intransigence?  Paint.  When the gear was fully seated, it was apparent from looking at the open end of the gear socket (inside the cockpit), that it had peeled a very thin layer of paint from the inside of the socket tube as it was pushed through.  I thought I had the tubes blocked off for painting, but some paint must have gotten in there anyway. 

So here it is on the gear for the first time.  Note to self:  That black rotisserie spindle is very greasy.

Step 13.3, Painting the Fuselage

In early 2010, long before I even began the RV-7A project, I was planing to paint it.  The design of my paint booth depended on the size of my airplane's fuselage.  And the size of my shop depended in part on the size of the paint booth.  It is a really good feeling to finally be at this point now and I am pleasantly surprised to find that the fuselage which is the largest single piece that I will have to paint on this project, just fits.

There were minor dings that were hammered flat and some that needed filling and when that was complete the fuselage was rolled into the booth for primer.

After priming the fuselage was rolled back out for sanding and another round of minor body work.

And then the real fun begins.  Laying out the stripes.  

To lay out the stripes I wanted to first make a paper template so that I could be sure that the stripes would be identical of both sides of the aircraft.  To make the template, I taped some paper down along the length of the fuselage and then went to work adapting my paint scheme drawing to the full sized aircraft.  I went to a lot trouble calculating angles from my drawing, finding tangents at selected points along the curve and then transferring those points to the template in an effort to replicate the drawing exactly at full size.

The big problem with this approach is that it doesn't take into account that the transformation from drawing to fuselage is a transform from 2D to 3D.  Although when viewed exactly straight on from the side the resulting stripes did look like the drawing, there were certain angles that were aesthetically challenged.

In the end, I did a lot of adjustment by eye, as it were, to get the flowing shape I was initially going for.  Once the template was complete the fine-line tape is applied to the fuselage along the edge of the paper, recreating the shape of the stripe.  Flipping the paper over gets the same stripe on the other side of the plane.

Here a stick is employed to hold the rudder cables out away from the fuselage during the painting process.

The first stripe pained is the silver stripe.  The photo below is after the stripe has been painted and the re-taping process is underway.

The stripe is taped off and cover with masking allowing the blue stripe to be completed.  Once both stripes are done the white can be laid down.  Here Carol is preparing the masking for the blue stripe.

Finally, the white goes on and the fuselage is done:

Now, I start the whole process over on the vertical stabilizer and rudder:

There is still a lot of work to do on the paint; the cowling, the wheel pants, and the landing gear fairings, for example.  But the vast majority of the hard work on the painting is done.  The remaining pieces are manageable in size and should not be a major time sink like the fuselage and wings were.

Before I take the fuselage off of the rotisserie, I'll attach the four antennas that go beneath the plane (2 COMM, 1 Transponder, and 1 ADS-B IN).  That leaves 3 antennas to attach on the top side, but I'll save that for later.

Step 13.2, Horizontal Stabilizer, SB

Vans aircraft announced a Service Bulletin a while back that applies to my plane.  The SB requires recurring inspection of a section of the main spar of the horizontal stabilizer that has been shown to develop cracks on some aircraft over time .  This is not a particularly worrisome development -- GA airplanes get these types of service bulletins or ADs (Air worthiness Directives) all the time.

What is a Service Bulletin and how does it differ from an AD?  SB are maintenance recommendations from a manufacturer and do not carry the force of law.  Air worthiness Directives are mandatory compliance issues that come from the FAA.  An AD may reference an SB in which case the SB does become mandatory.  Even though an SB may not be mandatory, it is probably not a good idea to just ignore them.

That Vans Aircraft has responded with the SB and provided a retrofit kit is a good thing and shows that the company is safety conscious and is proactive in maintaining their good reputation. The SB states that the retrofit kit is not required until cracks have developed. As a preventative measure, I have decided to implement the fix anyway since the horizontal stabilizer is not yet on the plane and has not been painted.  There will never be a more convenient time to do the work so I might as well do it now even though it will delay my completion date a few days.

The first step is to disassemble the center section.  This means removing the inside ribs and the attachment flanges.  There are a lot of rivets in here.  The last time I worked on this piece was in early 2012.  I always hoped that I would be get to fly the plane a little before I started tearing it apart.

The rivets attaching the inside ribs are removed.

The horizontal stabilizer main spar is that thin piece of sheet metal in the foreground.  The area of concern are the four rounded notches right at the edge of the skins,  This is, evidently, a high stress area, which is why the notches are placed there in the first place.  The theory behind the notches is that the slow curvature of the inside edge of the notch would allow the stress to flow around this area rather than build up at a single point, resulting in crack formation. 

The theory has worked on most planes, but a few have developed cracks which led to the service bulletin.

The retro fit kit further beefs up this intersection with doubler plates on each side.

The doublers are clecoed in place prior to riveting

This is the front mostly riveted.

And the rear with the doublers visible.

Now the ribs are re-installed.

The final step is to complete the painting.

Horizontal stabilizer service bulletin (and painting) complete!

Step 13.1, more painting

Sand, sand, primer, sand, sand, base, base, base, sand, clear, sand, sand, buff. done.  Ok, good, now on to the next piece.  Obviously it's needless to say, but painting is a slow, messy, and often very tedious business.  I comfort myself in the knowledge that I'm saving big bucks here  -- enough to buy fuel for about 5 years worth of flying (assuming the average GA pilot flies about 50 hrs/yr). I plan to fly more than that, but who knows.

After the primer is sanded down to #800, the masking for the stripes begins.  Here the wing tips are masked and ready for the first stripe.  I don't know if this is the most efficient method or not, but I start with the gray stripe.  The when that is on and dry enough, I peel the tape up and re-apply it over the gray, but on the other side of the line so I can mask off the just painted stripe.

Then the blue is applied and re-masked for the white.  Here is Carol preparing the tape for the blue stripe.

Finally after all of the base colors are on there are two coats of clear applied over the top.

On to the next thing.  Carol sanding primer on the left wing.

Here I'm applying 3-M fine line tape to follow paper templates for the stripes.

Here is a wing in the blue stripe phase.

Wing tips and wing after clear coat in the paint booth.  I think the flash must have been off.  I don't think it was really that dark in there.

So at this point, I've done no color sanding or buffing because that can wait. Indefinitely, I think, because there will always be something more fun to do.  I've completed about 1/2 of the painting now with just one really big item, the fuselage to go.  Of course there are numerous smaller items such as the cowling,  the vertical stabilizer, rudder, wheel pants, and fairings to go... 

Step 13.0, Time out for a disaster

Gravity sucks.  Yes, it is the weakest of the four fundamental forces, but it still manages to wreak havoc on a macro scale.  While preparing to spray the epoxy primer on the right elevator I somehow caused it to fall off of the hook and slam on to the concrete floor.  Can we say with the telephoto lens of hindsight that its position on the hook was precarious and replete with gravitational potential? Yes, if we must. And since I was holding the other end of the elevator at the time, a far too honest assessment might conclude that I had something to do with the accident. However, we should not fail to toss a wary eye at gravity itself, lest it escape blame entirely.

Did that just happen?  I just stood there in stunned disbelief while my brain worked feverishly to assemble the appropriate profane response.  Fortunately, I had the forethought to stockpile a great reserve of emergency profanity for just such an occasion.  Logistically though, it's not such an easy thing to do. That is, to launch in an instant, the mother of all swear storms that common sense demands.  In a second or two my paralysis fades and I spring into verbal action.  At least that is what I thought would happen.  But I find that I am unable to form intelligible words as I attempt to unload my entire arsenal at the same time.  That ever so small portion of the profane artistry which finally makes it past my vocal cords intact is just one tiny, weeny, almost imperceptible, "shit." All the while, in in my mind, I keep seeing the Hindenburg going up.  Over and over.  Oh, the humanity!  

Now the moment has past and I move on to survey the damage. It seems that the aluminum carnage stops at the first rib tip and there is no sign of bending anywhere except at the inside corner as shown. My first thought is that I will have to build a new elevator or at least re-skin it.  I really did not like the thought of re-skinning because removing rivets often causes as much damage as the original problem.  Since the elevator is small, it might be better to just make a new one.

Then I think, not yet accepting the stark reality of the situation, that perhaps I could just unbend the corner using a screw driver and some pliers.  Well, I had nothing to lose so I gave it a go:

As expected it cracked in several places as the folded metal was pulled out.  It was pretty clear that this was not going to work, so I moved on to plan C.

My next idea was to cut off the corner and replace it with fiberglass.  The photo above shows the cutting process already begun.

Here is the elevator with the corner cut off and the edges smoothed.

The next step is to build a foam core for the corner and epoxy it in place.

Then build up the corner with fiberglass.

And sand it down smoothly feathered into the aluminum.

So I end up with a fiber glass tip and a few hours wasted, but the fix is very strong and virtually invisible.  At least from the top or bottom.  From the end the plug is visible, but I don't think it's obvious what kind of horrors went on there.  It's kind of like some scar you carry from childhood that you laugh about now, but was just short of amusing at the time.

So next time I'll continue with more painting and, hopefully, fewer mishaps.