Saturday, March 28, 2020

Firewall titanium barrier

I finally got around to installing the titanium firewall barrier that I have been planning.  It was a bit of a chore for several reasons.

  1. Titanium is hard to drill holes into...especially larger holes.  I ended up drilling smaller holes and then using a metal shaving bit in my Dremel tool to get them sized up properly.
  2. I used spray adhesive to adhere both the 1/8" fiberfrax to the stainless steel firewall and then again to stick the titanium to the fiberfrax.  Worked out well except that when you put the two pieces together...they stay...no adjustments.  This caused me to have several slightly misaligned holes.  No big deal but I did have to go back and route the holes in the titanium out a bit to allow the bolts to go through.
  3. Titanium foil is sharp!  No I didn't cut myself ...yet

When all was complete and I had installed most of the firewall mounted components everything looked good.  More importantly in the very unlikely event of a firewall forward fire I will have extra time to get the airplane on the ground before bad things happen.

In addition to the firewall work I also finished trimming up the windshield.  Its now ready to be glued in and then the leading edge fiberglass work completed.

I also spent a ton of time this past couple of weeks working on my wiring diagram.  I've been working on this thing for over two years now but its time to put all the details together into one main drawing.  I think I'm now ready to start fabricating the main avionics wiring harness.

Finally, a while back I had asked Geoff at Aerosport if he would use his nice 3D printer to print up a housing for my autopilot controller.  It came last week so I just had to put it in place to see how it looked.  I may make a few more edits to it before the final install.

One more topic I wanted to record in this blog.  The past few weeks have been rather unusual for me...and probably most of the rest of the world.  We have been dealing with the start of the Covid-19 pandemic.  Right now we have been under an order to remain home except for necessary trips to the grocery store or work if you are in a critical job that can not be done from home.  

Windshield trimmed and ready to be glued in place.

transferred my paper template to the bottom layer of fiberfax for cutting.

I used several pieces of paper all taped together to make a template of my firewall.  I then used this template to mark up both the fiberfrax and the titanium.  It actually worked out pretty good.

Fiberfrax just before it was glued to the firewall

All glued in place except the center recess.  

The final result!  Once the cowling mount flanges are installed I will come back and use the some Firebarrier 2000 to seal up any edges.
Here is a picture of the wiring diagram for this airplane.  Its rather large which makes it hard to see but if you click on the image you will get a better view.  Note that this is only the avionics wiring diagram.  The main power distribution, switches, lighting and assorted smaller systems are not included.

Autopilot controller in the mount that Aerosport printed up for me.  Its not bolted in yet but it fit nicely.


Friday, March 6, 2020

Side windows done

The side windows are done!  At least as far as I am going to take them for now.  As I mentioned earlier there will be some work after the airplane is painted.

I also installed the flap position indicator.  Turns out that was a bit of a challenge simply because I had to use a little geometry to figure out how long the "arm" that attaches to the flap rod needed to be to allow full travel of the flap motor to equal full travel of the 1.2" POS12 sensor.  Turns out that number is 3/8" from the surface of the tubing.  That's a lot less than I thought it would be.

Finally I installed a magnetometer shelf in the top of the tailcone.  This is a kit recently released by Van's and makes the process relatively simple.  It would have been much simpler if I had done it before I installed the top skin...


This is the POS12 flap position sensor mounted on the bulkhead.  The linkage goes down to a small 3/8" tab that is attached to the flap tubing using a simple Adel clamp.  This allowed me to set the angle properly.

Final window during the process of gluing it in place.

Right side windows installed.

I also installed the magnetometer mount in the tunnel overhead.  Originally I was going to install it in the wingtip but this location makes for a much shorter CAN buss run.

Tuesday, February 25, 2020

Forward top skin access panels

This is another of those informational posts.  Tonight I finished installing one of two forward top skin access panels.  I've found during my short 5 years of maintaining my 9A that easy maintenance is the key to successful maintenance.  For example I used quarter turn fasteners all the way around on my cowling including the horizontal split line.  I'm very glad I did that simply because those quarter turn fasteners are much easier to remove than the hings pins.  They don't look quite as clean but I really do like the looks of them. 

Along those lines Van's recently released a kit to install access panels in the forward top skin so that you can gain access to the most forward bay of the instrument panel.  While I don't have much for electronics in those bays I do have two voltage regulators, the GEA 24 engine monitor, and a bunch of wires that pass through to the engine compartment.  All of those items will require some sort of maintenance at some point.  So, I decided to purchase the new kit from Van's and rather than install it in the center bays of top skin, I installed it in the side bay.  This is where the majority of the access will be required and its much easier to reach into this area from a side access even if I have to reach over to the middle bay.

Below are a few pictures of the install process...

Using the tabs provided I clecoed the backing ring to the top of the skin and drew out the two openings to make sure everything would fit nicely. 

Here is the skin with the cutout completed and the backing ring cleco'd in place.

Now I'm getting ready to match drill the screw holes up to the proper size.

After a couple of hours of filing, dimpling, and riveting the backing ring is finally installed.  If you look through the hole you can see where my backup voltage regulator is installed.  Its now much easier to get access to that location.

Same hole but looking forward to where my firewall penetration for the wiring bundle will be.

And finally I screwed the cover in place.  I still need to trim the lower edge of the cover down a bit before paint but overall the kit fits well and I've spent about 4 hours working on an access panel that will provide me many hours of maintenance simplicity.

Monday, February 24, 2020

Window installation procedure -Silpruf method

I've been working through the side and door windows using the Silpruf method I mentioned in my last post.  I really like how its turning out so I thought I would document the process in a little more detail in case I want to use this in the future.  If somebody else is reading this I highly recommend you watch the video's at least once and then feel free to use the checklist I created below.

First, you need a few items.

  • SCS2000 Silpruf in the color you prefer.  I used black and will probably use 2 tubes for all 5 windows.
  • Popsicle sticks.  I cut these into thirds to act as "slats" to help hold the window flush with the cabin top.
  • rubber gloves...lots of rubber gloves.
  • plastic squeegee.  Cut into about a 1" edge size.
  • dry erase markers.  Thin edge and best get a few.  I bought a 4 pack on Amazon.
  • Permatex Ultra black RTV (black because I was using black Silpruf)
  • 1/4" masking tape.  (couldn't find the link to what I purchased)

Checklist

To Do Trim window with a 3/16" gap between edge of glass and recess wall
To Do Sand top edge of glass to form 1/16" rounded edge. 
To Do Sand edge of glass with 300 grit to make a defect free edge
To Do Drill cleco holes in recess to support window in opening.  Approximately every 4-5"
To Do Install window and mark inside edge surface of window where the recess wall ends (with erasable marker.)
To Do Remove window and place outside face down on a white towel.
To Do Apply 1 layer of tape about 1/8"-3/16" from inside edge of line just created.  This is done with 1" tape or larger.
To Do Apply first layer of 1/4" masking  tape such that it leaves the line  fully visible.
To Do Write a small number 2 on the top end of the tape.
To Do Wipe dry erase line off of window with damp cloth. 
To Do Apply second layer of 1/4" masking  tape such that it covers the outside edge of the first layer of 1/4" masking tape by about 1/16".  Mark the end of this tape with a number 1.
To Do Sand inside surface of the window where it will be glued to the frame.  This helps the Silpruf adhere.
To Do Tape the outside surface of the window and back cut to form nice edges.  2" tape is good for this step.
To Do Glue small Silpruf standoffs at each cleco hole (using ultra black RTV)
To Do Apply a layer of Silpruf to the exposed inside edge of the window.
To Do Remove 1/4" masking tape marked with a #1.
To Do Let sit for 24 hours.
To Do Fit window to recess by trimming the Silpruf standoffs until window is flush with exterior surface.  Trimming the Silpruf standoffs with an angle cut seems to work well here.
To Do Tape the outside edge of the window recess such that the exterior surface and the wall of the recess are covered.
To Do Tape the inside edge of the window recess and back cut the tape to provide a smooth edge 
To Do Ensure all exposed areas that might get Silpruf on them are protected with tape or paper.
To Do Drill out cleco holes if inside tape covered any of them.
To Do Apply a thin layer of Silpruf to edge of window that was revealed when tape #1 was removed.
To Do Apply generous bead of Silpruf to the window recess.
To Do Install and cleco window with clean wood straps.
To Do Using small squeegee clean the excess Silpruf from both sides of the window.  Leave the 3/16" gap empty for now.
To Do Remove tape marked #2.
To Do Remove cleco's one at a time pulling up the tape that protects the Cabin top.  Clean out under the wood slat, install clean slat and then reinstall the cleco.  Do this for all cleco's.
To Do Let sit for at least 48 hours before removing cleco's.

Here are a few pictures of the process.  Some of these have already been posted on this blog.

Trimming window to fit recess opening.  Note the 3/16" gap around the edge of the window.

Fitting window with Popsicle stick pieces to keep it flush with the surface of the cabin top.

Small Silpruf standoffs glued to the cabin top at each cleco hole using Permatex Ultra black RTV.

Outside edge of window taped off and back cut flush with the window edge.  Its actually not flush because I held the razor at an angle so that the 1/16" rounded top edge would not be covered.

Inside surface of window with all three layers of tape as well as the gluing surface sanded with 120 grit for adhesion purposes.

Last layer of tape with the #1 annotated on the end that I will use to pull the tape up.

Outside surface taped and fiberglass protection.  As noted in my blog post I need to add more protection to the top edge as I found my hand touching the fiberglass during the clean up.  

Window installed after applying a generous bead of Silpruf and then cleaning out the excess squeeze out.  In this picture I have also completed the step where the cabin protection tape layer has been removed and the Popsicle sticks replaced.

Inside edge after cleanup/smoothing and tape #2 removal.  I could have removed the green tape as well here but I left it in place so that the Silpruf would dry and it would be less messy to remove.
Final look of window after 2 days of cure time.  Note the nice clean lines on the inside edge of the window.  The outside edge with the 3/16" gap looks messy now but after paint is applied I will come back and fill this gap in with a fresh batch of Silpruf.