So, what exactly am I patting myself on the back for this weekend? Well, it is in response to my incredibly astute (if not financially efficacious) decision to keep Papa's annual inspection in the month of March, rather than move it two months further downstream to May as I legally could have. As in just about anything related to flying, it really comes down to weather management. There's nothing worse than a disassembled airplane right in the heart of flying season. As we all know, March comes in like a lion and out like a lamb, except when it doesn't. There's nothing lamb-like about the weather on this, the last weekend of March. In fact, this is the first time I think I've ever heard a weather phenomenon referred to as a "vigorous cold front." Cold fronts are never that fun, but "vigorous??" Oh my! That can't be good!
You may remember that one of the things I found during the inspection last week was a worn pair of brake pads on the right side. The left side was not as worn, but I decided to replace both sides this weekend. The aforementioned weather having left me no options other than to either stay home and make a nuisance of myself or go the hangar and do something productive, the choice was obvious. But, finding that making a nuisance of myself was not nearly as gratifying as I had hoped it would be, I ended up invoking option two.
Changing the brake pads is actually a very simple job, and I'm surprised that it isn't included in the list of things that store-bought airplane owners are permitted to do to their own airplanes as listed in Appendix A of Part 43 of the Federal Aviation Regulations. According to the regs, they're allowed to remove and replace safety wire and cotter pins, replace tires, and repack wheel bearings. Nothing is mentioned about the brakes. You have to remove at least one side of the brake calipers to get the wheel off to perform any of the allowable things listed above, so I'm not clear on the reasoning behind prohibiting the replacement of the pads as long as the calipers are off. It's really a quite simple operation, and interestingly does not even require the removal of the wheels.
With regards to safety wire and cotter pins, I should mention that the regulation specifically states the an airplane owner is permitted to "replace defective safety wire or cotter keys," so this may introduce a little bit of a Catch-22 unless there is no stipulation against the owner, you know, being the entity that rendered the safety wire or cotter pin defective in the first place. So as is usual with the FARs, the real rule is determined by enforcement cases rather than clear, unambiguous writing. Ambiguously crafted FARs are one of the crosses we bear as owners and pilots.
In any event, that kind of thing is moot for me since my airplane falls under the auspices of a much friendlier set of regulations. Section 1 of Part 43, paragraph (b) states that "This part does not apply to any aircraft for which an experimental airworthiness certificate has been issued, unless a different kind of airworthiness certificate had previously been issued for that aircraft." While that's not entirely a get-out-jail-free card, it is a get-out-of-paying-for-simple-work clause. And one of the simplest jobs on the airplane is replacing brake pads.
If you follow that advice, the first step should be easy. You'll be happy to know that the second step is just as easy, albeit maybe a little bit shady in a strictly legal sense as detailed in my in-depth legal analysis above.
As you are removing the bolts, you will notice that the caliper feels loose, and you may be tempted to get all panicky and try to tighten it up. Don't panic; it's supposed to feel like that.
Once the outside pad is removed, you can slide the remaining part of the caliper assembly off of the slide pins to remove the other pad. This should be done with great delicacy if your airplane, like mine, has rigid brake fluid lines.
Once both of the pads are off, it is time to use the brake pad removal tool that you spent so much time looking for in the first step. In preparation for the rivet removal, take off all three of the pieces/parts that you installed if you are using my patented storage method.
Put the tool in a vise and clamp it down. Place the brake pad into the 'C' part of the tool with the smushed up part of the rivets facing up. Slowly screw down the threaded rod until the pointy bit is nicely centered and seated on the rivet. Slowly screw down the threaded rod while holding the pad in place. The idea is to use the pointy part to push the old rivet out.
Once both pads are removed, or if you are a linear thinker and prefer to dress in a one-sock-one-shoe process rather than a two-socks-then-two-shoes manner, you need to reconfigure the tool for putting the new rivets in the new pads.
Line up the new pads on the caliper halves and drop new rivets down into the recessed holes in the pads. I put all three rivets in rather that doing them one at a time to ensure that I don't rivet a pad in crooked and find that I can't get the other rivets in. This is a bit tricky, though, because the pad has to be turned over to fit it into the tool. This can (and often does) result in anywhere between one and three rivets falling out. As you can surely imagine, this is not a desirable turn of events since rivets, much like the disparate parts of the brake tool, are absolute masters of camouflage. They look all bright and shiny and you'd think they'd be easy to find, but take my word for this: you do not want to drop them.
I usually start with pressing the center rivet. This lets me contort my fingers such that they are holding the other two rivets in place. What you're trying to do is get the bottom part of the tool to fit up into the recessed hole at the bottom of the pad while you screw down the conical thingy to press the rivet into place. I could write a thousand words about this, but I think these pictures might show it better:
Voilá! Snug them down tight, but not too tight. (Hey, I know that's ambiguous and arbitrary guidance, but I was reading Federal Regs just a few paragraphs ago - it's contagious!):
Now it's simply a matter of replacing the brake pieces back to where you found them.
And, of course, replacing the defective safety wire:
See? This was a lot easier than jacking the plane, rendering safety wire and cotter pins defective, removing the wheel, deflating the tire, splitting the wheel, removing, cleaning, and repacking the wheel bearings, and reassembling the whole mess. (In other words, the very things that the FAA has deigned to allow store-bought airplane owners to legally do by themselves.)
I know this to be true because I did all of that other stuff yesterday too. The brake work takes about half an hour per side. The removal and repacking of the bearings took at least an hour per side. I simply cannot understand why Part 43 allows one but not the other.
See what I mean?