Bad timing...

As is apparent from my other recent thread, we're planning to fly to
Texas Sunday afternoon. Well, today was a beautiful day here in Iowa,
and we agreed to fly a good friend to a nearby airport, where he was
supposed to pick up his new (to him) Cessna 172, and take his biennial
flight review.

We spent the morning snaking wires for the kids' new DVD players --
the price for a good quality display has FINALLY dropped to $79.95 (at
Radio Shack, of all places), so we bought two -- and generally enjoyed
bumming around the hangar. We were able to clean the windshield for
the first time in over a month, and basically removed a winter's-worth
of debris from the plane.

Gum wrappers, pencil stubs, dead batteries, they all came out, and we
probably gained 3 pounds of useful load by the time we were finished.

During the preflight I spotted a wet mark under the right wheel pant.
Pointing this out to Mary, we both figured that it was the slush and
ice from inside the wheel pant melting in the 40-degree sunshine. We
had heard an "ice ball" bouncing around in the wheel pant after our
last landing, so I "hmph'd" and moved on...

Our friend arrived, and we got into the sun-warmed airplane. What is
it about a leather interior baking in the sun that just smells SO
good? Combined with a little gas on the fuel tester, that odor just
screams *airplane* in so many ways... God help me, I love it.

We taxied out to the hold-short line, I applied the brakes, and we
immediately began a pyrhouette to the left. The right brake pedal
went completely to the floor -- nothing at all. Pumping did nothing,
either -- so we taxied back in.

This brake had done this once before, when an O-ring had failed,
causing the brake fluid to dump overboard. At the time, we debated
buying a new brake cylinder housing, because the inside where the O-
ring fits wasn't pristine, leading to speculation that it may have
been cutting the rubber O-ring over time. However, my A&P had said
the failed ring was old, and had been able to insert a new O-ring
without difficulty, so he pronounced it "serviceable" and we'd been
flying it that way ever since.

It was looking like that decision was coming back to haunt us, as I
gingerly taxied back to my A&P's shop. But we wouldn't know till he
took a look.

Luckily, he was able to drop everything and have a look. Brake fluid
was dumping everywhere as I removed the wheel pant (the most God-awful
job on earth, with a zillion easily strippable screws, a couple of
inaccessible nuts, and a lot of places to bang your head), and we all
climbed under the wing for a look.

To our surprise, the brake assembly itself loose. We had virtually NO
brake pads left, and -- without pads -- the backing plates can come
far enough out to allow the cylinder to come completely out, resulting
in a complete loss of fluid.

The metal-on-metal braking had apparently been going on for some time,
because the disk rotor was warped and scored. It was toast, our
flight with our friend was scrubbed, and we would need some new parts.

Strangely, we had changed that O-ring maybe six months ago, and the
pads were fine, then, so we now have a mystery. How did the brake
pads wear completely away so fast? To be safe, we removed the OTHER
wheel pant (more screws, nuts, banged heads) and inspected the left
brakes, and they are fine. Tons of pad left in them.

So, we've ordered the parts to be shipped overnight from Spruce, and
they should be here tomorrow. We *should* still be able to depart for
Texas on Sunday, with luck. And I guess we should say that this was
actually GOOD timing, because this could just as easily have happened
in Fredericksburg, far from home.

But we're still wondering what/how this happened, especially since the
ONLY time we lock the brakes to make a turn is at our hangar, and that
would be a hard LEFT turn. We NEVER turn hard right, so why should
that brake wear so quickly?

Anyone know if it's possible for a brake to hang up and not release,
resulting in advanced wear like this? Or should I keep blaming Mary
for riding the (right) brake?

:-)
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"