How to really use brakes

[Howard Hughes]

HH, stop showing off about your personal Citation X.

And then I woke up!

[fujii]

It's not just the brakes to consider, it's also the undercarriage. In my bug smasher where the axle is at 90 degrees to the oleo piston, applying the brakes places a turning moment on the links, dowels and bushes causing wear and subsequent uneven tyre wear. Taxi slowly, use brakes lightly, idle before braking and if you have a enough runway there is no need to brake heavily.

[MakeItHappenCaptain]

Here's a good one for PPL and CPL training...

How about bringing the power to idle before stopping non-gearbox equipped aircraft? Have seen several students from other schools claiming they were told only to bring the aircraft (a C172 in both cases) to idle during the runup check. WTF?

Incompetent instructors teaching their own thing?

Does anyone here keep their foot on the accelerator when they stop their car at a red light?

[VH-XXX]

I remember there was a couple of Gazelles at Point Cook a few years back. They used to ride the brakes constantly because they didn't want the Rotax 912 gearboxes chattering at idle. I was told the brakes were cheaper than the gearbox to replace at the time.

[Ultralights]

this thread should be renamed, How to overthink a simple subject such as brake use! simple rules about brakes should be, Dont use the parking brake when
1. refuelling
2. in a hangar.
3. dont lock brakes unless you want square tyres.

[displaced gangster]

Park brake use.

"Leaving a park brake for any length of time pressurises the brake system, is hard on seals and is unreliable. I find it hard to believe any experienced pilot could advocate it"


Don't agree with this opinion. The parking brake system on the types I have flown is precisely that.
If the manufacture didn't intend to use it as a park brake, it would be listed as a limitation in the AFM/POH.
"Hard on seals and unreliable"? The park brake generally pressurises the braking system if this hard on seals what hope has the normal braking system got?

The only circumstances I could think of not setting the park brake would be in freezing conditions or a brake overheat event.

The PIC is obligated to enter any defect or unserviceability in the appropriate documentation.

[LeadSled]

Folks,
Carbon brakes are starting to make an appearance in some high end GA aircraft ( ain't fashion wonderful) and the technique is a 180 degree shift.
You must use them heavily or not at all, no riding the brakes or "light use".

"Light use" causes rapid brake wear with carbon brakes !!

Tootle pip!!

[dubbleyew eight]

"Light use" causes rapid brake wear with carbon brakes !!

so what? you only use brakes as appropriate. wear is something that has to be sorted out in maintenance.

[Captain Nomad]

The other technique that is worth considering, and is perhaps more effective in larger aircraft is that if you are going to use brakes on landing, then it is better (more effective) to use more brake early in the landing roll backing off as you slow down, than to use not much to start with, only perhaps to find you need to apply heavy braking at the end of the roll.

One should also be careful about using heavy breaking before getting full weight on the wheels however. Heavy feet on the brakes before the aircraft weight has settled onto the wheels is a recipe for locked-up wheels and a flat spot at best, or worse, a blown tyre/s and consequential control difficulties on roll-out leading to more problems.

I once had to help remove a light aircraft stranded on the edge of a wide long runway simply because the relatively new CPL blew a tyre trying to make the taxiway exit. It doesn't impress the boss or customers and it simply isn't worth it!

Use the brakes when you need them but like anything mechanical, be mindful of how they work and their limitations and how the manufacturer wants them used.

For prolonged parking I would never trust a park brake on a sloping surface. A physical chock is cheap insurance for brake ineffectiveness due to temperature and system pressure changes.

Don't brake like a taxi driver, keep it smooth - it is another sign of airmanship or lack thereof!

[LeadSled]

so what? you only use brakes as appropriate. wear is something that has to be sorted out in maintenance.

W8
I guess that's the sort of reply I would expect from too many people on this web site. A figurative "What the hell, it's only the boss's money".
Perhaps if I said that that the AFM Operating Requirement is ---- , would you just ignore the AFM??
Tootle pip!!

[Ultralights]

W8
I guess that's the sort of reply I would expect from too many people on this web site. A figurative "What the hell, it's only the boss's money".
Perhaps if I said that that the AFM Operating Requirement is ---- , would you just ignore the AFM??
Tootle pip!!

As an aircraft owner, i have no problem with using the brakes as required, brake pads are cheap!
as an owner, i always leave brakes OFF in a hangar, last thing i want is someone else going through my aircraft to unlock the park brake to move it. and i hate coming to the airport to find my aircraft parked in behind a temporary visitor, who has locked their aircraft, and left the park brake ON, and parked everyone else in. some owners wil get a tug and pull said aircraft out of the way, park brake on or not. also, helps with access if there is a fire. Brakes off refuelling, for same reason.

as for when the engines running. use as required.. even my aircraft at idle power will have you at 20 kts taxi speed if you dont keep on the brakes.

[A Squared]

Originally Posted by Aussie Bob

Leaving a park brake for any length of time pressurises the brake system, is hard on seals

Well, yes, of course it "pressurizes" the system. That's how brakes work. With pressure. If there wasn't any pressure, there wouldn't be any brakes. And engaging the parking brake is no more "hard on the seals" than using the brakes, it doesn't apply any more hydraulic pressure to the seals.

[Capt Fathom]

A Squared, stop encouraging them.

Everyone knows how brakes work..... Don't they?

[A Squared]

Originally Posted by Capt Fathom

Everyone knows how brakes work..... Don't they?

Dunno. Aussie Bob seems not to, or is that some sort of obtuse comedy act I'm not following?

[Tu.114]

At the flight school I attended, the parking brake was only used when the aircraft was attended. At all other times, it was chocks and most importantly chains attached to a solid concrete foundation on the other end to keep the aircraft in place.

[Aussie Bob]

Dunno. Aussie Bob seems not to, or is that some sort of obtuse comedy act I'm not following?

You blokes may have the benifit of operating late model aircraft, my career has gravitated towards ****ters. I stand by what I said.

Stretching a thin wire downwards to pressurise an old braking system is ok short term. Long term, I prefer chocks and an unpressurised brake system.

Well, yes, of course it "pressurizes" the system. That's how brakes work. With pressure. If there wasn't any pressure, there wouldn't be any brakes. And engaging the parking brake is no more "hard on the seals" than using the brakes, it doesn't apply any more hydraulic pressure to the seals.

Sage words indeed from a bloke who lacks understanding of how a hydraulic system wears. No doubt your nervous when geographically displaced from the local Woolworths store. Of course it is impossible for fluid to leak past a worn brake piston.

You can teach a monkey how how to ride a bike until the chain falls off.

[A Squared]

Originally Posted by Aussie Bob

You blokes may have the benifit of operating late model aircraft, my career has gravitated towards ****ters.

and

Originally Posted by Aussie Bob

No doubt your nervous when geographically displaced from the local Woolworths store.

I'm laughing out loud at this stuff. Really? All of this is essentially argument ad hominem: In other words, “I am right because of who I am and who you are”. Most people recognize the fallacy of this sort of "reasoning". If you have to rely on statements of who you are and derogatory claims about the other person to bolster your argument, that's usually a sign that your argument isn't all that strong.

Having said that and recognizing the irrelevancy of that method, I will play along briefly as you seem to find that sort of information compelling.

I own, and maintain myself, an airplane built in 1953.
I've flown and instructed in a number of airplanes built in the 1940's.
I also own and am in the process of rebuilding myself, an airplane based on a 1940's era design.
I have been employed in a GA maintenance shop, wrenching on light aircraft of various vintages.

As far as the geographical displacement, aside from being completely irrelevant to the operation of GA brakes, perhaps on reflection you can recognize the futility of employing such a silly argument on a forum populated by international pilots?

So, now can we dispense with the ridiculous “I am right because I have XXX experience and you are wrong because you do not” arguments.??? Maybe we could discuss the actual operation of brake systems, as that is the topic at hand here. Deal? OK, moving right along …

Originally Posted by Aussie Bob

Sage words indeed from a bloke who lacks understanding of how a hydraulic system wears. ... Of course it is impossible for fluid to leak past a worn brake piston.

Actually, I understand hydraulic systems fairly well. I certainly don't claim to know it all, but you're unlikely to convince me that you know something I don't, merely by claiming I “lack understanding” without explaining what you believe I don't understand. As far as fluid leaking past a worn brake piston, I never claimed anything of the sort, go back and re-read my words. It simply ain't there. If that's your basis for claiming I lack understanding, you miss badly on the point. Yes, seals can leak. And in a high pressure system, a leak past an o-ring can shred the o-ring, I've seen it happen. But that's a high pressure powered system; we're not talking about high pressure hydraulic systems, we're talking about low pressure unboosted systems such as found in light aircraft. A leak past an o-ring in a low pressure system isn't going to damage the o-ring any more than the existing damage or wear which is causing the leak. An o-ring in a brake piston wears because of friction as it moves within the cylinder, not because fluid is seeping past it. Besides, even *if* we were to agree that a fluid leak *causes* o-ring wear (not that I'm conceding the point) why would it cause any *more* wear to set the parking brake than it would to actuate the brakes normally with the pedals to slow or stop the airplane? Seriously, that's not a rhetorical question. I really would like to hear you explain why you apparently think that setting a parking brake is harder on/causes more wear/whatever to the o-rings, than actuating the brakes normally with the pedals. I'd also be interested to hear you explain why you apparently believe that leaving the parking brake set for some length of time causes any *more* pressure to be applied to the brakes than applying the brakes with the pedals. (reference your statement in your first post on this thread) Or if that's not what you meant, maybe you can explain what you did mean.

Perhaps you can do that without trying to claim superior experience, pretending I've said things that I haven't said, calling me a monkey, or the like.

Originally Posted by Aussie Bob

Stretching a thin wire downwards to pressurise an old braking system is ok short term.

If you're referring to a Cessna parking brake system or similar, it's far better to pressurize the brakes by pressing the pedals, then gently but firmly pulling out the parking brake handle to snug up the system and hold the pedals, rather than applying pressure by yanking out on the parking brake handle. For the same pressure applied to the brakes, it places a lot less stress on the rather flimsy structure supporting the parking brake handle and pulleys.

[Aussie Bob]

I'm laughing out loud at this stuff.

That was the intent.

Let's take the case of an aging Cessna. When the park brake is left applied, the hydraulic system is left pressurised. 24 hours later the park brake has minimal effect. The fluid has obviously leaked somewhere. Would I trust it? No. In a percentage of cases the fluid will be a couple of drips on the ground. Before the maintenance release has expires I am out on the tarmac replenishing the fluid via the bleed nipple so the aircraft has brakes again.

Let's take hydraulic systems in general. It is recommended by most in the industry to leave a hydraulic system unpressurised when not in use. Why is this?

There is very little point in further argument, I recommend chocks. Trust your park brake at your peril. The one in my personal aircraft works flawlessly, this does not mean I leave it for weeks on end in a pressurised state, it is my belief that this is not good for the system. No proof sorry. Park your own aircraft how you like.

[A Squared]

For the record, I have not advocated long term use of the parking brake. I agree that it is not secure as it likely to bleed down and release. I'm just disagreeing with your claim that doing so will damage the brake system.

[Aussie Bob]

Perhaps it won't hurt but consider this: If the system is unpressurised for the time you fly, say 100 hours per annum and pressurised heavily by a ham fisted pilot the rest of the year (8660 hours) wouldn't ib be highly likely that the seals would memorise the position they are most often in, which is distorted somewhat by pressure? Dunno, I guess we are splitting straws and enough has been said. Merry Christmas.