Wed Aug 19 2020

Brake pedals

I'm still going through the instructions to complete items in prior sections that have tasks left incomplete. One item I want to do soon is to install the elevator trim cable. Since that is going to require routing down through the tailcone, I decided to clean the airplane. I vacuumed and wiped out all the dust and dirt that I could. Unfortunately, the nearby wildfires were depositing ash throughout the day, so I imagine it's going to need additional vacuuming. No pics of the cleaning, sorry.

After cleaning, I figured out a way to debur the holes I drilled yesterday for the crotch strap. I made this little deburring tool from an old wood screw. The screw head is about 3/8" diameter, so it's large enough to debur the 5/16" holes. I cut the shank short enough to fit (barely) down between the two brackets.

After fitting the custom deburring tool in between the brackets, I used a phillips screwdriver to debur the forward bracket.

After that, I turned the deburring tool around and gripped the stubby little shank in a drill to deburr the aft bracket.

Looks good!

Since I'm checking unfinished items off the list, I decided to assemble the brake pedals and drill the hole where the master cylinders attach. It seems that when I countersunk these holes, I went a bit too deep.

So, I made up (actually modified an existing one) a custom squeezer die. The head of the die has a 100 degree chamfer around...slightly smaller in diameter than the head of an AN426 rivet.

Here's how it will fit into the countersink.

It took some care to keep that custom squeezer die centered on the rivet heads, but that worked great. Here are the brake pedals.

I retrieved the rudder pedals from their storage location and put them in position in in the plane. However, it quickly became clear that it was going to be a challenge to instal the pivot bolts while leaning over the side of the fuselage.

After taking the rudder pedals back out, it became apparent that one of the reasons for the difficulty installing the brake pedal pivot bolts is because the welded on tabs are not square. Grr.

Quickly resolved with some pliers and a bit of prying.

I was thinking that the mounting of pedals the way Van's instructs (using a short bolt on each side) wasn't a great way to do it. It would be way stronger if those two short bolts were replaced with a single, long bolt that spanned the full width of the pedal. So, I measured how wide the tabs were spaced (5 3/8" from outside to outside) in order to spec the correct length of bolt. I went to Genuine Aircraft Hardware's website...they have lots of technical information. Turns out that for a 5 3/8" grip length, I need a AN3-56 bolt. By this time, I was experiencing a sense of Deja-vu. Had I already thought this through, and perhaps even ordered these?

I did a search of my e-mail for AN3-56 and found that, indeed, I had ordered four of these bolts EXACTLY ELEVEN YEARS AGO!

Two takeaways:

  1. Well, that's one helluva coincidence.
  2. Fuck, seriously?!?! Eleven years?!?! And I haven't finished this thing yet?!?! Arg!

Here's a photo of two of the four brake pedals with the long bolts. By this time, it was about 104 F in the garage shop, and the smoke was really bad, so I decided to knock off for the day. I'll try to get the holes drilled where the master cylinders attach tomorrow.