The last time I was in the RV-6, it was on fire. *That was 12/26/2019 about seven hours and three beers ago.
I headed out west to the Lake Michigan coastal airport of Frankfort to fly the RV a couple weeks ago. *There was a small, dried puddle of something around the right wheel pant and the right brake pedal was mush. *The right line from the master was visibly white, and empty to the reservoir. *I removed the right pant and inspected the caliper and brakes in place. *Line and fitting were dry - the caliper had fresh 5606 drops dangling, the pads were wet and there was 5606 mud in the bottom of the wheel pant. *But no real culprit at this point. *I clipped the safety wire and plucked the caliper thinking the piston o-ring must be misbehaving.
Incidentally, the return from annual inspection was the last flight, and more than a month ago, where we had installed new tires, tubes, etc., and packed wheel bearings. *At the time, the left brake pads looked new, with the right showing slight wear, but definitely serviceable.
Back to the shop a week ago, an inspection of the cleaned brake assembly showed absolutely no signs of wear on the piston, nor the bore of the caliper. *The original o-ring had no visible defects, or stiffness, but it was likely 20 years old. *While I was at it with a new o-ring, just for good measure, I installed new brake pads at the shop then took the clean, fresh package out to install in today's 50+ degree balmy weather. *With the hangar door open, the bright sun lighted my workspace and warmed the recently-frigid wrenches and pliers to the bone. *The classical music station (keeping the mice out, because mice have no class) still played Holiday music; even the day after. *Bing, and Nat. *I was loving life.
We know that our phones will answer any question on the spot. *This would be a good time to take a micrometer to the brake disc, and compare to minimum thickness from Cleveland's specs. *The mic in the box was metric, but translated to .175-ish on a couple spot checks with min. spec for the 500x5 in the .160's. *Installed, the pad-to-disc clearances looked like a new installation.
I gas-ragged the 5606 mud (dirt and hydraulic fluid) from the belly of the right pant, pumped new brake fluid into the right bleeder, tested the right pedal until rock-firm while letting the volatile blue 100LL flash off before final installation of the pant. *Many brake cycles, no leaks, so on went the pant.
Now, back to the phone for a reminder of the Cleveland brake lining conditioning sequence... Oh yes, taxi 1500 feet with engine at 1700 rpm and brake(s) applied. *Stop. *Let cool 3 minutes, then test the brake-hold at a full power run-up. *If it holds, go fly. *If not, repeat process.
So that I did. *Sort of. *The frisky wind on the 15-33 runway was 200-240 at 12G22, so I thought maybe I'd just break-in the brake today instead of fly. *AWOS was showing an enticing downward trend of wind however, and I was being tempted to fly as I taxied in the stiff-ish left crosswind. *Dragging the right brake for the prescribed 1500 feet I couldn't hold 1700 rpm. *That's nearly take-off power in an RV-6 with a 160hp Lycoming 320. *Sub-1400 rpm *was getting me there just fine. *And largely because I was only breaking one brake in, (the right) as the left pads were fine, remember? *Everything was splendid. *The right brake was holding my taxi straight in the stiff left crosswind. *And braking was firm and effective. *I probably *ran an extra 500 feet to the run-up area with the break in procedure to generate glazing heat because of the cold.
When I finally slowed, then stopped at the runway end I could, not surprisingly, smell a little heat from the right brake side. *Then maybe a glimpse of smoke? *Or was that my imagination? *Nah, couldn't be that hot. *Then, at this stopped position the right brake pedal suddenly went limp. *#*!$$@. *Now what's going on? *And I'm 3000 feet down the runway from the barn. *Well, the now-right crosswind was a blessing having no right brake, I was able to idle very slowly, cautiously and carefully back to the hangar-ish. *All left turns, and all very slowly, and deliberately, because once the tailwheel unlocks, any asymmetrical braking situation, as in this case, makes this plane spin about aimlessly like a dazed housefly. *I was actually wondering about my insurance coverage as I straddled this delicate situation.
I did seem to get an occasional whiff of heat on the way back, but certainly no additional heat could be generated by the now-dead right brake.
I taxied to within 50 feet of the hangar before I ran out of directional wind benefit, and it's maneuvering luck. *I stopped, and now saw another puff of smoke. *Or not? *Could it be? Fuel off! mixture lean! electrical off! *key off! I hopped out and rounded the beak only to see the right wheel pant of my favorite airplane burning like yesterday's Christmas hardwood in great-nephew Kenny's home-heating fireplace. *I mean really burning, and right under the wing tank. *Yes, very momentarily, but there was again denial on my part. *Then an immediate *sprint to the hangar looking for something wet - yet not frozen. *Nothing in the wash bucket... Windex won't be adequate... WD40? *McGuiars won't ever put a shine on this again... the 5 gallon can of 100LL avgas sure ain't gonna help this situation!
"You idiot. *You have a fire extinguisher in here somewhere." And there it was., by the door, where it's supposed to be. *Dated, but there. *I grabbed the extinguisher, pulling the pin as I sprinted to the burning airplane. *You know, an extinguisher about 4" in diameter and 18" tall isn't quite adequate to put out a wheel pant, and now, tire-fire. *In retrospect, I wish I had choreographed this moment ahead of time to include time for a quick photo, or video, or selfie of this persistent, olympic torch. So a sprint back to the hangar for the bucket hoping the frost-faucet at the terminal building is working. Then a sprint back to the rekindled campfire with five gallons of water. *Boom! went the new $350.00 tire and tube combo with the five-gallon surgical douse of cold water. *And it wasn't out yet. *So, another sprint to the terminal building and another wet five, which got things under control. *Then one more, walking this time in disbelief of what just happened, and what nearly happened.
Well, with a little neighborly help, Richard, the Airport Manager, and another neighbor were able to help get the right gear on a dolly and back into my hangar before dark. *I still have a plane, but also a boatload of redundant, needless work.
The way that fire-retardant 5606 hydraulic fluid and fiberglass combo burned has me re-thinking the aluminum vs. composite construction world. *My wheel pant was very difficult to extinguish, and turned into a literal dishrag that I simply ripped from the mounts before dollying.
What a day. *Now, I need to think about *the root cause of this event. The quick answer may be that there are times "to go the extra mile" but riding the brakes on break-in, or ever, ain't one of 'em. *Funny, it could even happen in a fiberglass sailplane with no fuel aboard. *Some have disc brakes, and of course, that flame-retardant 5606. Dang, I always felt safer with no gas aboard. Does that even make sense?
Happy New Year.