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.

"EridanMan" wrote in message
ps.com...
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.


I have had a right break failure in a piper with toe brakes also right brake
stuck upon applying them.

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.


I have had a right break failure in a piper with toe brakes also right
brake
stuck upon applying them.


This makes me just a little curious.

Is the handbrake on a Piper (without toe brakes) mechanical or hydraulic?

My reason for asking is that, if hydraulic, the same culd happen with the
handbrake--although the possiblility of inadvertantly dragging the right
brake while applying rudder would be eliminated.

Peter

Yes its hydraulic (Single Cylinder)... so yes, it could definitely
still fail.

The whole system is much simpler (And lighter, by about 8 lbs) than
the toe-brake system though, and according to my mechanic at least,
its basically bullet-proof...

This is simply according to him - but apparently fried right wheels/
brakes are a reasonably common (especially on Grummans and training
aircraft)... he attributes it simply to the subconscious dragging on
takeoff/taxi... At the very least, the right pads wear faster than the
left on most planes he looks at, even with experienced pilots.

The only planes he doesn't see it on are the few that don't have toe
brakes. That was enough for me... (Disclaimer, I am a young, low-time
pilot with ABSOLUTELY no experience in this matter, other than I
learned in a few toe-brake planes before I bought 61J, and I adapted
to no toe-brakes in about 5 minutes...)

I do tend to trust the opinion of a mechanic who tells me not to give
him money for things though...

-Scott

Yes its hydraulic (Single Cylinder)... so yes, it could definitely
still fail.

The whole system is much simpler (And lighter, by about 8 lbs) than
the toe-brake system though, and according to my mechanic at least,
its basically bullet-proof...

This is simply according to him - but apparently fried right wheels/
brakes are a reasonably common (especially on Grummans and training
aircraft)... he attributes it simply to the subconscious dragging on
takeoff/taxi... At the very least, the right pads wear faster than the
left on most planes he looks at, even with experienced pilots.

The only planes he doesn't see it on are the few that don't have toe
brakes. That was enough for me... (Disclaimer, I am a young, low-time
pilot with ABSOLUTELY no experience in this matter, other than I
learned in a few toe-brake planes before I bought 61J, and I adapted
to no toe-brakes in about 5 minutes...)

I do tend to trust the opinion of a mechanic who tells me not to give
him money for things though...

-Scott


Thanks.

Eight pounds is quite a weight saving, especially since Pipers have very
positive nose wheel steering, so the toe brakes provide only dedundancy. My
personal prejudice favors the greatest theoretical redundancy, meaning nose
wheel steering plus toe brakes, but I don't have the experience either--so
it is just opinion, and worth slightly less than you paid for it.

BTW, the Gruman Cheetah and Tiger models, and many of the newer training
aircraft, have castoring nosewheels--so steering is accomplished by
differential braking until the rudder becomes effective. That should cause
them to have faster right side brake wear than Cessna trainers, which have
spring steering which allows the nose wheel to lock straight ahead in flight
and which can become a little problematic; especially if the nose strut and
the springs are not maintained.

Peter

On 2007-03-10, Peter Dohm wrote:
This makes me just a little curious.

Is the handbrake on a Piper (without toe brakes) mechanical or hydraulic?

I presume you're meaning on aircraft like the TriPacer which has the
hand brake, but no toe brakes.

In the TriPacer, a cable goes from the hand brake, around a few pulleys,
and ultimately it ends up under the pilot's seat. Under the pilot's seat
(and I'm not joking) you will find a Piper Cub heel brake, with a hole
in the back of the heel brake, where the cable connects.

The heel brake is hydraulic and applies both wheel brakes
simultaneously. The diaphragm has a habit of splitting just when you
really need the brakes, leaving you with nothing!

--
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