Holding the Brakes

L

LighterThanAir

Guest
Bringing this here before taking it anywhere else. CFI shrugged it off the one time I've mentioned it.

I am very small and... apparently not strong enough to hold the brakes myself for more than a few minutes at a time. I start shaking badly at around five. Tower cleared me for takeoff in the nick of time this one day after a long hold-short. Both my flight school and airport are increasingly busy, so it's getting hard to schedule/depart during a lull and avoid the lines. I'm dealing with a fleet of old birds with busted parking brakes, but am open to switching planes if there's a chance one is less mushy.

I've got a feeling that *certain organizations* may not smile upon the contraptions I've snuck onto the plane to help hold the pedals. So, anyone got any ideas (workout routines accepted)? This is such a dumb reason to not solo...
 
LighterThanAir said:
FI shrugged it off the one time I've mentioned it.
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You brought up a concern you have about safety, and a legitimate personal limitation that you've identified, and your CFI didn't take it seriously? That doesn't sit right with me.

Do the parking brakes help at least? Meaning, do you still have to hold the brakes all the way down when the parking brake is engaged?

Also, maybe consider some calf exercises to strengthen those muscles? (It is those muscles that are engaged during braking, correct?)
 
Hmmm. I’ve never had to apply a lot of pressure to hold the plane in place at 1000rpm and I generally don’t rely on the parking brake to do the job for me…easy way to forget it’s on when you can finally apply power.

If the seat is fully forward and you have trouble manipulating the controls, consider a back cushion, but that puts you even closer to the yoke, which creates it’s own considerations from a safety standpoint.

Pedal extensions of some sort would be the best answer, but using temporary things to manipulate the toe brakes really opens to the opportunity for blocking the pedals at a really inopportune time as you taxi, turn, apply power and add right rudder.
 
Baked Potato said:
You brought up a concern you have about safety, and a legitimate personal limitation that you've identified, and your CFI didn't take it seriously? That doesn't sit right with me.

Do the parking brakes help at least? Meaning, do you still have to hold the brakes all the way down when the parking brake is engaged?

Also, maybe consider some calf exercises to strengthen those muscles? (It is those muscles that are engaged during braking, correct?)
Click to expand...
The parking brake is completely inop. Hanging out by the wiresXD
 
1) find a better plane to rent. Broken parking brake mechanisms are not normal and should not be tolerated
2) it takes only a very light touch of the brake to keep a typical aircraft from moving at 1000rpm. My plane actually takes a little throttle (1200rpm or so) to get it to move from a dead stop. If you can't hold the plane at idle, you're going to have a very hard time with short field operations. My guess is you're pushing too hard and wearing yourself out.
3) Cherokees have a hand operated hydraulic parking brake that might be easier for you to deal with. The cessna setup (which I assume you're flying because you mention a cable) is a little clunky imo.
 
TCABM said:
Hmmm. I’ve never had to apply a lot of pressure to hold the plane in place at 1000rpm and I generally don’t rely on the parking brake to do the job for me…easy way to forget it’s on when you can finally apply power.

If the seat is fully forward and you have trouble manipulating the controls, consider a back cushion, but that puts you even closer to the yoke, which creates it’s own considerations from a safety standpoint.

Pedal extensions of some sort would be the best answer, but using temporary things to manipulate the toe brakes really opens to the opportunity for blocking the pedals at a really inopportune time as you taxi, turn, apply power and add right rudder.
Click to expand...
Interesting! I'll look into extensions and a back cushion. Have just been using a seat cushion so far.
 
If the parking brake is busted, what else in that airplane is busted? I'd find a better school.

Now. Are those brakes bled properly? Are they bottoming out? More bad maintenance. Is the engine set to idle at 1000 RPM? That violates the FAA-Approved service manual. I would also bet that the brake discs are worn to below minimum thickness, resulting in brake fade. If the brake linings are worn past limits, their brass rivets are riding on the disc, taking braking pressure off the lining. Brass doesn't hold the airplane still too well.

WE looked after the airplanes for a local school. They had a short student, so they bought a set of pedal extenders STC'd for the Cessna, but we had to install and remove them every flight and make log entries. That gets expensive. They don't just clip on; they have clamps held by screws. They can't take a chance on them coming loose in flight and tangling everything up.

I looked at the 172L, M and N POH equipment lists. The park brake is not mentioned at all, so we don't know if it's legally required. But the attitude of the school is a dangerous one.
 
I used to have this problem. It stemmed from me being young and not having enough juice in my legs to hold the brakes for very long. Sounds funny, but it’s true. It’s no longer a problem obviously, but I can see how it could be for some.

A couple tips - make sure you’re actually holding the brakes and not part of the rudder pedal ie., just pressing the very top part of the pedals to get the most braking action. Secondly, I used to rent from a place that had an airplane with a broken parking brake that seemingly never got fixed. I left there and haven’t looked back. If they’re deferring something that simple, what else are they deferring?
 
kgruber said:
Why are you idling @ 1000 RPM?
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Are you suggesting the OP should idle at less than 1000RPM?

I don't know what plane they're flying, but my Cherokee POH says (note the last two sentences):
1705449817291.png
 
Dan Thomas said:
I looked at the 172L, M and N POH equipment lists. The park brake is not mentioned at all, so we don't know if it's legally required. But the attitude of the school is a dangerous one.
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Not required, but if it's inop, it needs to be properly deactivated and placarded and a log entry made IAW 91.213. Judging by the OP's statement of "hanging out by the wires", I'm just guessing it's not properly deactivated and placarded.

I agree with your assessment of the school's attitude.
 
Jim_R said:
Are you suggesting the OP should idle at less than 1000RPM?

I don't know what plane they're flying, but my Cherokee POH says (note the last two sentences):
View attachment 124447
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From the Cessna 1977 172 service manual:

1705451575041.png

1705451629508.png


None of that Cherokee stuff applies to idling while taxiing. The manufacturer specifies 600+/-25 RPM for idle, and that's where it should be most of the time when on the ground. At 1000 you have to drag the brakes, burning out brake linings, discs, and even tires, all expensive stuff, and that braking also pulls the nose lower so that the prop picks up stones and other hard debris, chewing up the prop.

Too many instructors jump to too many false conclusions from stuff like the POH statement. And instructors are often so convinced of their rightness that they won't listen to mechanics. It takes much longer to become a mechanic than it does from zero time up to CPL and instructor. Four years for the mechanic, in Canada. He's the one that gets to find and fix the terrific damage from poor airmanship.

And from the Cherokee service manual:

1705452393316.png
 
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Jim_R said:
Are you suggesting the OP should idle at less than 1000RPM?

I don't know what plane they're flying, but my Cherokee POH says (note the last two sentences):
View attachment 124447
Click to expand...


Doesn't your Cherokee have a mixture control? Lean aggressively on the ground to avoid plug fouling; idling at 1200rpm is silly.
 
Pedal extensions would probably help, but as mentioned above are difficult to install and remove for each flight. Instead, have you considered different shoes?

1705455607778.jpeg
 
Idling at 1000 isn't a bad idea if you run leaded fuel.

Lead Fouling | Preventing Lead Fouling in Aircraft | Shell Global

This article discusses lead fouling, what causes it and the most efficient way to prevent it in aviation engines. Read the full details here.
www.shell.com www.shell.com

If holding a 152 at 1000 rpm is fatiguing, something is wrong. I can't imagine that it should take more than a few ounces of force.
 
LighterThanAir said:
I've got a feeling that *certain organizations* may not smile upon the contraptions I've snuck onto the plane to help hold the pedals.
Click to expand...
Certain organizations frown on such things because such things have killed people. Do not attach anything unapproved to the controls. Worse, do not use anything loose in the aircraft that could jam the controls.

Pull the engine back to idle, lean the mixture, lay off the brakes, do some calf raises. If it's an issue that you really can't reach the brakes, how do you operate the rudder?
 
From lycoming service letter l192b:

Avoid prolonged closed throttle idle engine speed operation (when possible). At engine speeds from 1000
to 1200 RPM, the spark plug core temperatures
are hot enough to activate the lead scavenging
agents contained in the fuel which retards the for-
mation of the lead salt deposits on the spark plugs and exhaust valve stems.

Service Letter No. 192 B

Supersedes Service Letter No. L192A January 19, 1988 Models Affected To all Owners and Operators of Lycoming Aircraft Engines. In many cases spark plug fouling resulting from the tetraethyl lead (TEL) in aviation fuels can be reduced or eliminated by proper operating techniques.
www.lycoming.com www.lycoming.com
 
kgruber said:
It is ridiculous to idle at 1200 RPM. I have thousands of hours flying piston engines, mostly on floats. If you idle a float plane at 1200 RPM you destroy the prop.
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We're not talking about DC-3s, 737s, or float planes, so I'm not sure why it's relevant to bring up any of those planes' unique idling considerations.

Dan Thomas said:
None of that Cherokee stuff applies to idling while taxiing.
Click to expand...

Nor does the OP's question. They're talking about holding prior to takeoff.

Half Fast said:
Doesn't your Cherokee have a mixture control? Lean aggressively on the ground to avoid plug fouling; idling at 1200rpm is silly.
Click to expand...

I don't idle at 1200. But I also don't use the OEM plugs. I used to use the extended nose variants, and now use fine wires...and yes, I do run very lean on the ground too. But we're talking about the OP's plane/techniques, not mine.

kgruber's question was, "Why do you idle at 1000RPM?" Apparently the answer is, "Because the flight school policy specifies that." You guys can now direct your critiques to the flight school instead of me.
 
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I guess I'm getting old, but back in the day you just assumed that parking brakes could not be trusted on a rental.

I'd be more worried about mushy brake pedals. That is a safety issue. It should not take Sumo wrestler leg strength to hold an aircraft at idle or fast idle. Even at 1800 RPM runup, no more than light to moderate pressure should be required.
 
Ed Haywood said:
I guess I'm getting old, but back in the day you just assumed that parking brakes could not be trusted on a rental.
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Wait. Is that what that handle is for?

There are three things I was taught (and teach) to never trust in a piston plane: heater, parking brake, gas gauges.

To the OP:
If they don't give a crap about their equipment, such as fixing an obviously inop parking brake, then why should you give a crap about fouling their plugs?
 
LighterThanAir said:
Interesting! I'll look into extensions and a back cushion. Have just been using a seat cushion so far.
Click to expand...
A back cushion can be very effective. Most seats are angled slightly up from back to front so, in addition to moving you closer, it can also move you higher. And give you extra back support comfort.

I know pilots who use them. I sometimes recommend them to people I fly with. Some to get higher. Some to get closer. Some for comfort. I use one in one of the airplanes I fly just because the seat back leans a little further back than I like in the full upright position.

But I share the same concern as others about brakes that can’t hold the airplane at 1000 RPM with very light pressure or take extraordinary effort at runup power.
 
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Ed Haywood said:
I guess I'm getting old, but back in the day you just assumed that parking brakes could not be trusted on a rental.
Click to expand...
I’m getting old too but have flown airplanes in which the hand brake was the only brake. No toe brakes either side. One was this past week. Older Cherokee.
 
Why not insist that the brakes work correctly? You might really need them some day.
 
When I had a plane with marginal brakes I would sometimes taxi off the pavement onto the grass while it warmed up, much less likely to roll that way. Stopping with the wheels right on a crack in the pavement can help, too.
 
LighterThanAir said:
Bringing this here before taking it anywhere else. CFI shrugged it off the one time I've mentioned it.

I am very small and... apparently not strong enough to hold the brakes myself for more than a few minutes at a time. I start shaking badly at around five. Tower cleared me for takeoff in the nick of time this one day after a long hold-short. Both my flight school and airport are increasingly busy, so it's getting hard to schedule/depart during a lull and avoid the lines. I'm dealing with a fleet of old birds with busted parking brakes, but am open to switching planes if there's a chance one is less mushy.

I've got a feeling that *certain organizations* may not smile upon the contraptions I've snuck onto the plane to help hold the pedals. So, anyone got any ideas (workout routines accepted)? This is such a dumb reason to not solo...
Click to expand...
What are the “…contraptions I've snuck onto the plane to help hold the pedals…”
 
Jim_R said:
We're not talking about DC-3s, 737s, or float planes, so I'm not sure why it's relevant to bring up any of those planes' unique idling considerations.



Nor does the OP's question. They're talking about holding prior to takeoff.



I don't idle at 1200. But I also don't use the OEM plugs. I used to use the extended nose variants, and now use fine wires...and yes, I do run very lean on the ground too. But we're talking about the OP's plane/techniques, not mine.

kgruber's question was, "Why do you idle at 1000RPM?" Apparently the answer is, "Because the flight school policy specifies that." You guys can now direct your critiques to the flight school instead of me.
Click to expand...
I don't know why you abuse your airplanes, but idling at 1200 RPM and dragging your brakes is stupid. It would help if you had some dual from a knowledgeable instructor.
 
I'm neither an A&P/IA nor do I run a flight school, but brake work is cheaper than engine work, so procedures that mitigate lead accumulation on an engine that's already prone to morning sickness seem like a good idea to me.
 
LighterThanAir said:
The parking brake is completely inop. Hanging out by the wiresXD
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Have your instructor give you a lesson in Minimum Equipment. You are going to need to know it for you checkride anyway.
This should cover...
What equipment may be inoperative?
What procedures must be followed for inoperative equipment. Note there is a difference between inoperative and just working poorly. 152 parking brakes never were thought to be very reliable.

Short answer is a 152 with an inoperative parking brake it is legally not airworthy.
If an examiner notices this during a check ride the, the check at a minimum will be discontinued, at worst the applicant would fail to meet the standards which I think is more likely.
An Examiner might not notice this, since no one uses parking brakes in a 152. But if you require it and it is obviously broken, that will be an issue.

I agree with other posts, a 152 at 800-1000 rpm idle should require only the lightest touch, if any brake.
if you need to, you can idle slower, the engine just doesn't run as smoothly at a lower RPM.
It might be the tach is not accurate, this fairly common and they tend to read low so when it says it is idling at 1000 rpm it might really be at 1300 RPM
There is a cool Iphone RPM app that frequently does a quite good job checking the RPM, using the microphone.
1705505319747.png


Brian
CFIIG/ASE
 
Wow. Blown away by the amount of conversation here. Thank you, everyone, for the insight so far! And jokes. Just gotta laugh at stuff like this sometimes...
 
brcase said:
Short answer is a 152 with an inoperative parking brake it is legally not airworthy.
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Watch out for the "well, it's not in [unmentionable mnemonic about burning red fruit], so you are good to go."

Actual quote from a CFI about a different piece of required equipment.
 
Jim K said:
Avoid prolonged closed throttle idle engine speed operation (when possible).
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The key word there is "prolonged." I never had problem with plug fouling in the flight school airplanes, and we taught the students to use the minimum power to keep taxiing at the right speed. We did not drag brakes, and if someone did, it was corrected. 35,000 hours or so while I was there. I sometimes had to change brake discs early when someone dragged the brakes. The linings are metallic, and they will tend to locally fuse (weld) to the disc when they get hot, and that raises burrs on the disc that eats up the lining real quick.

"Prolonged" would mean maybe 20 minutes taxiing or waiting for takeoff. The right thing to do there is to lean that engine, not run it up to 1000 or 1200 for a long time. That introduces cooling concerns.
GeorgeC said:
I'm neither an A&P/IA nor do I run a flight school, but brake work is cheaper than engine work, so procedures that mitigate lead accumulation on an engine that's already prone to morning sickness seem like a good idea to me.
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But propeller replacement is not cheaper than brake work, and taxiing around at 1000 RPM sucks up rocks and broken concrete and the like, chewing up that prop and necessitating dressing of the blades. There's only so much that can be removed before a blade goes beyond minimum width or thickness, and now a new prop is in order. Thousands of bucks for that.

Moreover, cooling concerns rise when the engine is "idled" too fast and the airplane is hardly moving, or not moving at all. That shortens engine life a lot more than plug fouling. As above, just lean the engine to minimize fouling, and use the extended-electrode plugs in any engine that they're approved for.
 
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