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"

In article .com,
"Jay Honeck" wrote:

[snip]
Or should I keep blaming Mary
for riding the (right) brake?

If you didn't say it, I was going to. In fact, as soon as I knew it
was a brake problem, I knew it would be blamed on Mary...

:-)

--
Bob Noel
(let's face it, lawyers won't like ANY sign...)

You just know that brake had been lightly engaged since you last
worked on it, Jay. Did the airplane tend to go to the side when you
were at low speed?

Had take off runs gotten just a little bit longer? A little more P
torque, things like that, sending subtle messages?



On Mar 8, 6:29 pm, "Jay Honeck" wrote:
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 N56993www.AlexisParkInn.com
"Your Aviation Destination"

"Jay Honeck" wrote in message
oups.com...
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

I'm by no means an expert, but as I was reading this, I was thinking of
possible causes and came up with this possibility.
In my training a/c, full throttle requires some right rudder to keep her
straight. I'm assuming your a/c does this too. Is it possible that when you
are applying this right rudder, you're also inadvertently applying the right
brake at the same time? I'm also assuming your a/c has toe brakes. As you
can see, I know very little about a/c mechanics, but this seemed feasible to
me.
Oz/Crash Lander

Ouch...

This is one of those stories that makes me glad that I didn't spend
the extra money (and lost useful load) to install Toe-Brakes in 61J...

Yes it was odd... for the first 5 minutes of taxiing.

After seeing two of my old club's planes go through a set of pads per
100 hour inspection (one of them having a similar catastrophic right
(I believe) break failure... only during a landing... only a VERY good
instructor prevented a ground-loop). And then hear stories like this
from a very experienced pilot no-less...

I can't say I miss them.

"Jay Honeck" wrote in message
oups.com...
...
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...

Your first problem is that you drive decent cars. If you always drove junk,
you would know that step 1 for _any_ puddle is to stick a finger in it to
see what it is - water, oil, etc. Touch, color, and smell will nearly always
identify the fluid. One rarely has to resort to taste.

...
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.

Disk brakes rely on rotor runout to push the pads back just a bit do you
don't have the pads in constant contact. If the new O ring was a bit on the
tight side, and the piston was sticking (the O ring could have worked like a
spring) then the pad would drag all the time the wheel was turning and wear
out quite quickly.

Your second problem is that you fly too much. Airplanes sitting in the
hanger don't wear out.

...
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?

Hard, brake locked, turns won't wear the inside pads - they are locked. No
movement, no wear.

Anyone know if it's possible for a brake to hang up and not release,
resulting in advanced wear like this?

As noted above.

Or should I keep blaming Mary
for riding the (right) brake?

That is likely to work as well as me denying that I snore at night.

Your third problem is that your wife (like most) is smarter than you and
blaming her generally backfires.

--
Geoff
The Sea Hawk at Wow Way d0t Com
remove spaces and make the obvious substitutions to reply by mail
When immigration is outlawed, only outlaws will immigrate.

Didn't you just have an annual? When I had my 182, while camping at
Johnson Creek, I was landing at McCall, Idaho and had the same thing
happen. No left brake, all the fluid squirted past the window on
landing. Luckily there was a shop on the field. We taxiied up and
asked if he could fix it. He said not til tomorrow, he had to catch up
on his paperwork. You're ****tin' me I thought. So we called the guy
in Cascade, just down the lake from McCall. He said fly it over. So we
did, paying more attention to wind direction than normal. We left the
plane with him, took his car and went and got something to eat. $50 and
a short new section of brake line and we were on our way.




Jay Honeck wrote:
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.

Capt. Geoffrey Thorpe wrote:
"Jay Honeck" wrote in message
oups.com...

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.

Disk brakes rely on rotor runout to push the pads back just a bit do you
don't have the pads in constant contact. If the new O ring was a bit on the
tight side, and the piston was sticking (the O ring could have worked like a
spring) then the pad would drag all the time the wheel was turning and wear
out quite quickly.

Actually, disk brakes are designed such that the deformation of the
seals causes the pads to slightly retract when pressure is released. I
suspect that the seals on Jay's brakes had hardened to the point that
they didn't deform when the brakes were applied and thus could not
"spring back" to pull back the pads.

Rotor run-out will certainly help push the pads back in, but that isn't
how they are designed to operate. Disk brakes will work just fine even
if the rotor is completely true with no run-out.


Matt

In article .com,
"Jay Honeck" wrote:

Or should I keep blaming Mary for riding the (right) brake?

That was going to be my suggestion. ;-))

"Jay Honeck" wrote
Or should I keep blaming Mary
for riding the (right) brake?

You haven't been reading that suicide thread again have you? From how I
think Mary's been feeling, I think I'd blame ANYTHING or ANYBODY BUT Mary!
lol

Sorry about the brake deal. Things like that suck almost as bad as having
them happen "on the road".

Jim