I have one in my Citabria, and although I do use it, its a pain in the ass. I have to get into the plane to depress the pedals to set it and release it. It would be nice to be able to set and release it by reaching in after pushing the plane around. But this way its very hard to accidentally set the brake while flying and land with it on...

David

A Scout is very tall (for me) with 31" tires. Therefore, on a slope the parking brake must be used before exiting. But, they are extremely dangerous if deployed at the wrong time.

Yay (with strong reservations and concerns).

Yay

Ten or eleven of us parked on petroleum point at one time had me shitting bricks. If one airplane started to roll, several others were going to be in a bad way.

Have it on my Champ, wish I had them on the J-3.

A parking brake valve is a convenience.

But mine, probably due to my lack of knowledge o. It's operation, caused a ground loop. Is cost me some fabric, welding, wingtip, engine inspection, new prop and two new gear legs, struts, etc. had the gear not collapsed, there would've been much more damage.

I got all the repairs don't in time for the JC fly in a few years back, but still did not know I had a problem with the brake valve, and landing was much more difficult than I remembered from before the incident.

A couple of weeks later, while taxiing out, the L brake locked. Another long story here, but no damage, just a lot of work to get the aircraft back to the hangar.

My brake valve is now safety wired open and labeled inop. It is easy to drop a chock from the seated position in the BH.

I would like one for the convenience, but the risk it too great for my pocket book.

The ramp in Saltillo, Coahuila, Mexico has just enough of a grade that your plane will start to roll while you clear customs if you don't lock the brakes (or have a makeshift chock). Ask me how I know...

http://leftbase.com/?p=1046

Having hand propped a Luscombe with mechanical brakes and no parking brake, (Even the J4 has one!) I can tell you, I won't go without one again.

If you are swinging a 88" prop on an 0-540 I don't suppose it matters much. So think about being on a dry lake bed someplace with no help and a dead battery. There you go. I'm sure some folks would tell you that you deserved it for letting the battery go dead but I certainly don't see it that way.

Oso Loco wrote:A parking brake valve is a convenience.

But mine, probably due to my lack of knowledge o. It's operation

Crazy Bear, what kind of actuation device were you using on your valve? Cable?

Zzz wrote:

Oso Loco wrote:A parking brake valve is a convenience.

But mine, probably due to my lack of knowledge o. It's operation

Crazy Bear, what kind of actuation device were you using? Cable?

What kind of valve are (were) you using??

For the Grove valve (which is all I know), I'd have said it's impossible to lock just one side.

Sincerely sorry to hear about your bad experience. I think damaging a plane is a lot more traumatic with homebuilt, than a factory model.

It is disconnected on my Stinson, I do have a comment to make on them however. There used to be a company called MICO LOCK you could install them on any vehicle with hydraulic brakes. They worked well, you just flipped the lever and stomped the brake pedal. The problem showed up when the temperature would rise a bit. A good tight brake system would lock up so that it could not be released, if the temp increase was enough it would burst a line or slave cylinder. For short time use they were great, for anything longer than a few minutes they could be a real problem. In a plane with separate master cylinders this could create some interesting problems. You might get one side to let go and not the other and go in circles or if it got set after takeoff just a tiny bit and warmed up you might land with one brake locked.
On my plane the old master cyls bypass enough I would never have a lock up issue but could sure have a one side dragging problem.

Z,

Good job breaking the code. Anyone who knows me knows I'm not that crazy!

The valve was activated by a AS cable. It is a Matco valve.

Here is what I learned from George Happ, the owner of Matco after the fact (BTW, they are located on my home field-KBTF):

It is critical that the valve lever be all the way on, or all the way off. Anything in between is no mans land and it could be on, off, or even one wheel on, etc.

The procedure for use it to set the valve on, and then release, or depress and release the pedals-they are one way valves.

The brake line closest to to the lever can engage first if the lever is in no mans land.

Picture the valve mounted on the firewall with the lever on one side. If the lever is parallel pointing from up to the firewall to a 45* angle away from the firewall it is ON. If it is in the opposite position up to 45*'it is OFF. So the 90* in between is no mans land. Clearly mine was set right on the edge of no mans land and ON as I now know the left brake was locking up from time to time, possibly after heavy braking such as run up etc.

I never used the P Brake until my first trip to Big Creek, about a month prior to the fire. I now believe I had a latent problem from that day until the time it lockers while taxiing, after the loop and all the fun with that. (Ask me what else happened at Big Creek that day.......)

As an aside, I was heavy the day of the accident with 4 adults, some much larger than me. The incident was at Elko; we were going over to watch Black Rock's first flight. Fortunately his flight went very well but seeing my plane on its belly may have scarred him for life!!!!!!

Cal

I have one on my S6 and I've used it a couple of times. I'm glad I have it. Mine is a simple valve. Push the brakes on, pull the control out. To release the brake, just push the control back in. Simple and light weight.

Yay for brake locking system.
It is important to adjust the cable, spring and pushrod lock mechanism correctly, and to be sure the resevoir plug is reinserted properly on the Maule system. If this is done, the lock feature is a great advantage.
To double check prior to landings in G U M P S, U for Undercarriage tells the pilot to check the brakes for not being locked. Depress pedals twice in case you inadvertantly lock them on first press.

Fool proof system.

Being able to lock up only wheel is a great feature of the Matco type valves, it can be very handy in off airport situations

Oso Loco and I have the same valves/setup in our bearhawks. After talking to him and having my own reservations about the way it worked mine has been rendered useless.

Thanks oso,

Russ

I've used parking brake to keep airplane from rolling away in high winds when trying to fuel solo at self serve and no chocks in sight. Handy. I say yay.

I learned a very expensive lesson with parking brakes as well, but in my case it was a very different lesson. The short version ; stopped on a sand bar on a cold morning, kicked back in the front seat eating munchies, I slid my feet back and under the seat. Kinda like sitting indian style. With big clunky boots on this locks the parking brakes on a cub. Prior to this I rarely used the parking brakes and always relied on chalks, so I rarely really checked them prior to a departure. Ended up getting out and hanging around for quite a while, which was long enough for the brake brake fluid to get warmed up enough to pressurize the system some. The surface was sandy enough to mask the partially locked brakes, but they were locked enough to necessitate an abort. Aborting a T/O roll in a cub with the tail already in the air and the brakes inadvertently set is costly

another example;
A few summers ago a very well known experimental was running around with a few very well known north westerners, they were playing on glaciers and at some the pilot of the experimental locked the parking brake on the slopped ice. Even on 35's the T/O with locked brakes was a non event. Upon returning to the lodge, where there was no ice, the experimental A/C did a somersault on landing. It made it's way back to the lower 48 in a shipping container to fly again someday

Both myself and the experimental pilot still use parking brakes today. Our mistakes were genuinely ours, and while I can't speak for the other gent I can certainly say that in my case what I learned from my brake problem was that failing to properly use and understand our equipment does not constitute a failure on the equipments side. Since then I have set the parking brake in everything I fly, every time I park, unless prudence dictates otherwise. In any case I treat every plane I intend to move as if the brake was set prior to movement. Furthermore, since levers can be manipulated in flight, I also treat every landing as though the brakes have been set for the duration. To the poster who said GUMPS, BINGO. But don't just sing out a nemonic , do something about it, check and touch the gas lever, touch the brakes and gear, etc..

I find parking brakes far more valuable of a tool to leave off any airplane. They contribute less weight to an airplane than anything else that is so handy when you really need it. For me removing a valuable tool does not constitute a solution, and if the tool was poor in design I would prefer to seek a better thought out design. On a standard A/W cert. this might prove to be a challenge, but as an experimental there should be no reason to not build a system that works as you see fit.

FWIW, the Thrush I fly every night has the same Scott valves as my cub, and they get locked every time I return to the pad. This is an average of 20 times a night. We routinely get out of the airplanes to check mixes, maps, pee, eat, etc... During this time the airplane is normally getting hot loaded and / or fueled. Leaving a running A/C without parking brakes would be a no-no. This is in feathered Pratts, some would argue that leaving any running Garret is a no-no, I won't comment on that here.
I suspect this is far more cycles on the valves than the typical G/A airplane, but with standard maintenance they do just fine and do not exhibit any bad behaviors.

More food for thought...

Thanks for the thoughts, everyone. I didn't realize parking valves were so widely used.

I suppose half the battle is finding a good actuation device. I've seen so many push/pull cables like the ones used on cabin air or mixture working themselves out that a more positive one would be a must-have for brakes.

Chocks are certainly safer, unless you're alone on any significant slope.

It is difficult to find a "chock" large enough for big bushwheels. The last time I really needed a parking brake was when we were all on that hillside in Nevada that is in Terry's Avitar. I taxied up behind everyone and stopped. It was a good thing Z, that you were with me and could hop out and search for some big enough rocks while I sat on the brakes. I don't use the brake in the Maule, but this thread has made me realize how handy one would be. You need a Cinder Block to stop a 35'' bushwheel on any kind of slope or wind........even then, at low pressure these big tires absorb about anything in their way. Even after we got the Maule chocked on that hill, I kept having visions of it rolling down the hill and taking out 3-4 other airplanes on the way while I hiked around.

For all the convo about improvised chocks: carry your tools in one of those triangular shaped bucket boss bags or similar. Same cross section and mass as a truck chock, if you fill it with tools, etc.
-DP

Zzz wrote:I suppose half the battle is finding a good actuation device. I've seen so many push/pull cables like the ones used on cabin air or mixture working themselves out that a more positive one would be a must-have for brakes.
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Look no further:
http://www.aircraftspruce.com/catalog/appages/a700.php