The Tail Boom Repair - Part 1

The time has come to start work on repairing the fuselage.

I started to cut away the damaged glass to determine how much of tail boom will need to be replaced.   

The aft section had a split under seam to the tail wheel fairing. The pneumatic tubing and antenna COAX were also damaged.

After assessing the damage, and cutting away the broken material, I removed the broken pushrods and sent them to the shop for repair.

The underside of the fuselage was mostly scraped up, and doesn’t look like any major repairs will be needed. 

The top of fuselage had some superficial cracks along the seam, which will require further investigation.

After cleaning out the dirt and debris, I left the most complete side intact, though the glass will need to be cut away after I get the broken plane on the assembly-alignment jig .  

A test fit of the broken boom to ensure the proper length. 

The repaired pushed rods are back. The shop did a great job repairing them.   

Here is what the broken elevator pushrod looked like before,

And here they are repaired… The shorter one is the push rod for the vertical stabilizer.

Now comes the time to make the tail boom skin mold. Robert let borrow his project PIK-20B to make the molds from. The unfortunate thing about this plane is that all of the paint was scraped off with a grinder, so it is uneven in spots, but for the most part it’s useable.

My first step in making the mold was to find the center seam line. A laser line was a good tool for that task.   

Next, tape and plastic were used to mask the mold halves.  

The surface was prepped with PVA and wax, then a layer of tooling gelcoat was applied, followed by several layers of fiberglass, starting with a 6oz ply followed by a 10 oz, 18 oz roving and 6 oz chopped glass.

After the molds were completed, the alignment jig was constructed. I used 2x4’s, although steel tubing would be the preferred material.

  

Here is the completed jig with the broken PIK secured to it.

A special note
After placing the wreck on the jig: I found out that the one I used to make the Jig was 2" longer than mine. Some where in production, they made changes to the design. And down the line, at least 38 airframes between Roberts and mine, they shortened the fuselage. This changed the boom shape slightly, and of course, it would have been in the area that was broken

I have looked at 4 PIK-20's and found changes in the design and materials used. They were not identical, which surprised me, since they were supposed to be the same model!

The first repairs were to the aft portion of the tail boom. The underside seam was split wide open. Robert recommended the use of clecos to hold the seam closed when I re-bond the surfaces. So, after cleaning and roughing up the surface, I re-bonded the seam with epoxy paste.

After the epoxy cured, I prepped the surface, filled the cleco hole with epoxy-flock paste and laid in 2 ply's of 92125 to strengthen the seam.

After the layers cured, I sanded the surface and used bondo filler to even out the seam depression.

After sanding down the bondo to even out the curve, a final layer of 90070 was used to strengthen the filler.

Now the biggest step of this project, making the fuselage tail boom skins. The mold was prepped and treated with PVA and wax, and then a thin layer of white gelcoat was applied followed by the application of the 5 layers of glass that makes up the fuselage skin. I used the layup scheduled provided by the manufacturer.

Finally, after 24 hours of curing, I popped the skin out of the mold, and required little cleanup.

The post cure will follow after the repairs are completed.

And the last repair was to the aft bulkhead. There was a split in the side. I anchored it to a flat surface and patched the crack with glass and flock paste.

  

So this concludes Part 1 on the tail boom repair.

 

The Horror of the Horizontal Stabilizer.

As I have stated, there were some parts I can no longer find for the PIK. I knew there would be a challenge doing the repairs on this plan, since there is no support services out there that cater to the PIK glider needs.

After making the damage assessment, I found that there were a few parts I needed to complete the repairs. The T-mount for the vertical stabilizer which aligns and hold the horizontal in place, a couple of push rods, a bearing mount for the horizontal stabilizer, and the elevator.

As mentioned in the earlier post, the many attempts to locate parts were a total bust. My connection at the airport did not have parts, or the ability to fabricate the parts based on the drawings. But I was given the name of a machine shop that fabricated MIL spec parts, so I approached them with a set of drawings from PIK provided by the Finnish Transportation Dept.

Upon review of the drawings, and advice from my AP-IA, the first part fabrication was improved on and approved.

The first part to be recreated was the T-alignment mount for the tail.

The drawing spec’s a folded and welded structure, ...

.. but as the wrecked piece indicated, the hollow piece is easy to bend.

The machine shop used the spec's from the drawing, including the type steel used, and created a CNC duplicate part. Since we plan on changing the type certification to experimental, the replacement part (lower right) was acceptable and is just like the newer ones used on gliders today.

It was just a tad thinner, due to the available material thickness, but since the part mounts aft of the tail support wall, the horizontal stabilizer aligns perfectly, and fits snugly!

The next repair was to the bearing mount that was broken of during the crash. After removing bearing from the center rib in the stabilizer, I notice that the mounting tabs were torn from the bolt socket.

I had to have a new mount made,


... so back to the machine shop with drawings in hand. They used the original socket, but welded new tabs to the stem. And with a new bearing, we are ready to install it back into the stabilizer!

The mount was painted with chromate and DCC to protect it from oxidation.

With a cleaned out and enlarge opening, I bolted the support mount back on the center rib.

I then created a cover plate using the material from the other wrecked PIK (you will see me doing this a lot over the next months).

The plug was glued in using epoxy paste and taped down till it was cured.

The nest step was to scarf off the old glass around the plug to re-glass the repair.

The glass will be applied per the repair manual, then to the paint shop.

The Flap Control

The first major repair task was to clean up parts, and fabricate new ones to replace the un-repairable parts. I tried to call and email people that I was told once serviced the PIK's, and might have parts, but after several attempts to contact the individuals, I was unable to reach them. I contacted other glider repair stations, and the answers to the availability of parts was the same,... NO. If I cannot get replacement parts, this project will come to a screeching halt!

I spoke with a few pilots and the local repair station, and found there were a couple of machine shops in town that could address the repair of metal parts, and possibly fabricate new parts matching the drawings of parts I received from the Finish Transportation Dept.

With that question put to bed, I decided to tackle the flap control, since this mechanism was partially corroded.

After removing the control from the fuselage, I photographed the control, and then disassembled the mechanism

During the disassembly of the handle, I noticed that there was a crack in the plastic grip due to being worn through over the years of use. As mentioned in a earlier post, replacement parts are virtually unattainable. So, I had a local machine shop at the airport make me a new one out of  aluminum.



After cleaning up the parts, I was unable to get the scale toothed bar re-chromed, I repainted the bar and handle with DCC auto polyurethane, and the reassembled the flap control.

I also painted the back side of the disc gray to aid in keeping the parts cool when in the sun.

The pin hole inside ring of the disc was scratched up, so I buffed off the black coating and polished the exposed aluminum.













The finished flap control looks good as new!






Next, the horizontal stabilizer!

What's the damage Doc?

I just posted an update on what was going on over the past several months, and now I would start filling you in on what I have in store .

So, here is what we are looking at in regards to repairing the glider. It's ugly, but doable.


The main wing damage is to the left outer wing and on the wing tip.

The right wing has some minor dings on the leading edge and a couple of small punctures in the skin.

The left aileron was crushed in the center and torn apart at the center hinge line.

The fuselage boom was broken off, and split on the bottom seam line to the tail wheel well.


The push rod for the elevator, will need to be repaired or replaced.

All tubes and the antenna coax will need to be repaired or replaced.













The belly was scrapped up including the damage to the gear doors, which will need to be replaced

The horizontal stabilizer had small hole in the top skin, but the bearing was broken off and the mount was bent and partially pulled out. I cut an opening in the skin to remove the mount for repair

The elevator push rod and t-mount were bent beyond repair


I would mention something about the condition of the elevator, that is, the elevator was folded and torn in so many places, that it was a total loss and will need to be re-fabricated.

The canopy was scratched and had a few minor break near the screw holes for the sliding window rails. I started the repairs and polishing of the plexie.

The worse part were the hinges. They were cut off at the time of the accident, My guess, the emergency release was rusted in place.

I know that many of these issues were mentioned earlier, but I needed to restate them, because the repair work has started!

Where has the time Gone?

I cannot believe where the time has gone!

We finished my Libelle 201B at the end of May, and over the summer, when the weather was good, did some flying.

I also spent a great deal of time selling model kits from my personal collect to clean out the garage to make room for repairing the glider.

I have also had a difficult time finding replacement parts for the PIK-20B and there were no usable parts from the other wreck.


Now that the cold is setting in here in New Mexico, I will be working in the chilly garage. The goal is to have the repairs completed by spring. The finishing and replacement instruments will be another story, and will come as I can afford it!.

Update - Summer

Not much to report as of today.

I have been working on another project, which has cut into my time on working on this plane.

For now, I can state this; after going over the wreck of the PIK-20D, I found that it will be a total write off. The damage to the fiberglass skins were too extensive. The metal parts seem to be all that is salvageable, with the exception of the hardware in the vertical stabilizer connecting to the horizontal stabilizer, and airbrake on the right wing.

If all goes well, I will be starting the repair assessment and the mold construction in about a month.

Later!