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Brake failure (A safety issue)

T

Ted Radclyffe

Active Member
Not wishing to open a huge discussion again but I have just had an experience which could have been a safety issue.
On the down wind leg, I felt that the right brake was perhaps spongy....no, it was OK on the second push!
On landing I felt it best to roll through to the last taxiway rather than hard braking perhaps there could be a problem.....no it seemed OK this time.

I taxied to the bowser for fuel and used the right brake to spin round infront of the bowser. No right brake!

With the wind the way it was, I was able to limp to my parking bay and check the callipers and pipe work only to find that the aluminium pipe had work hardened and cracked at the flare on the AN calliper fitting. There was plenty of brake fluid on the disk and tyre.

It could have been my own faulty workmanship on the flaring but I don't feel that this is the case. Regardless, I am now in the process of putting braided flexible hoses between the brake callipers and the aluminium tubes down the legs.

The only reason I post this is because I had ignored the previous discussions on the topic to my peril. It could have been a dramatic safety issue if I had used hard braking on the landing.

My advice would be to consider using hoses between the leg and the calliper during construction rather than getting caught later.

Ted.
RV6A (About 100 landings)
 
If it failed after 100 landings, I'm guessing faulty flare. Flares are difficult, just because there are very few information sources which give you good flaring instructions and give a clear standard of what to look for in a good flare.

I've seen several certified aircraft with flared aluminum tubing brake lines that are doing very well after almost 30 years.
 
Good post, Ted... Good Idea to check those aluminum lines close at inspection time for sure..
I caught one that was just about to wear through in a spot due to it rubbing on the edge of the wheel pant mount... If the tube is bent with a nice strain relef coil a the end, don't think it should be a problem..However, the braded hose idea can't hurt
Sheldon
 
True, but cert. doesn't use 3003

Kyle Boatright said:
If it failed after 100 landings, I'm guessing faulty flare. Flares are difficult, just because there are very few information sources which give you good flaring instructions and give a clear standard of what to look for in a good flare.

I've seen several certified aircraft with flared aluminum tubing brake lines that are doing very well after almost 30 years.
Click to expand...

That's true, but certified planes use 5052, not cheapo 3003 like Van's puts in the kits. It's very difficult to get a good flare in 3003 because it's too soft. Then, when the flare leaks, you tighten the nut until it quits. But 3003 is so soft that you can squash it paper thin just by over-tightening the nut.

Ask me how I know. I had exactly the same type of failure as Ted, with my first passenger in the plane.

Replacing part of the system with flex hose is not going to help if there is still 3003 tubing with bad flares in the system. I say rip it all out and replace it with 5052.
 
How to test it

My plane is four years old, so just to be sure they're still putting 3003 in the kit, you might test it before you order new tubing.

Just make a flare in a scrap piece, put an AN fitting on it and clamp it down in your shop vise. Then tighten the nut as hard as you can. Don't worry about stripping it -- unless you use a cheater bar, you're probably not strong enough. Remove the nut and take a look at the flare. If it's the cheap stuff, it will be thin enough to break off with your fingers. If it's 5052, it will look the same as before.
 
Great test. I like your certainty of results. I'm almost inclined to go out and try it just for fun :). Thanks for sharing.

jonbakerok said:
My plane is four years old, so just to be sure they're still putting 3003 in the kit, you might test it before you order new tubing.

Just make a flare in a scrap piece, put an AN fitting on it and clamp it down in your shop vise. Then tighten the nut as hard as you can. Don't worry about stripping it -- unless you use a cheater bar, you're probably not strong enough. Remove the nut and take a look at the flare. If it's the cheap stuff, it will be thin enough to break off with your fingers. If it's 5052, it will look the same as before.
Click to expand...
 
No 5052 at Vans...

jonbakerok said:
My plane is four years old, so just to be sure they're still putting 3003 in the kit, you might test it before you order new tubing.

Just make a flare in a scrap piece, put an AN fitting on it and clamp it down in your shop vise. Then tighten the nut as hard as you can. Don't worry about stripping it -- unless you use a cheater bar, you're probably not strong enough. Remove the nut and take a look at the flare. If it's the cheap stuff, it will be thin enough to break off with your fingers. If it's 5052, it will look the same as before.
Click to expand...

Vans web site does not list any 5052 in the material section of the Web Store or in "the list".

I got new brake lines for my Tiger (similar setup to the -6A), and the 5052 tubing is a lot stiffer, and it seems like they also used a thicker wall tubing as well. It looks like they used the 0.049 wall stuff...

gil in Tucson
 
5052

Gil: Where did you get your 5052? I don't know what the tubing on our Pitts S-2A is but it has held up well for 25 years. Bill
 
Came pre-bent...

Bill Dicus said:
Gil: Where did you get your 5052? I don't know what the tubing on our Pitts S-2A is but it has held up well for 25 years. Bill
Click to expand...

It came pre-bent (lots of bends in this case near the wing root) from the Grumman main supplier Fletchair in TX.

...But Aircraft Spruce has 5052-0 tubing listed on their web site. I bought a short length a while ago for a C-210 owner, and I noticed they shipped it straight, rather than coiled. The C-210 also used 3/16 in it's brake system rather and the 1/4 we use....

gil in Tucson
 
jonbakerok said:
That's true, but certified planes use 5052, not cheapo 3003 like Van's puts in the kits. It's very difficult to get a good flare in 3003 because it's too soft. Then, when the flare leaks, you tighten the nut until it quits. But 3003 is so soft that you can squash it paper thin just by over-tightening the nut.

Ask me how I know. I had exactly the same type of failure as Ted, with my first passenger in the plane.

Replacing part of the system with flex hose is not going to help if there is still 3003 tubing with bad flares in the system. I say rip it all out and replace it with 5052.
Click to expand...

I'm with Jon on this. I discovered that even using a good Imperial Eastman tubing bender, I could inflict nasty gouges in the 3003 if I tried to make two 90 degree or greater bends very close together. I used the 3003 to make patterns as practice for the final 5052 lines. The rated pressure of 5052 is double that of 3003.
I even used it for the fuel system, because I'm concerned about possible damage to the lines inside the cabin. Everything inside the cockpit will get bumped and banged around over the life of your ship. I believe in doing it right the first time.
I got my 5052 from ACS. The 5052 is a joy to work with. It bends nicer and the job, cosmetically turns out much better.
Charlie Kuss
 
Shipping 5052

chaskuss said:
......
I got my 5052 from ACS. The 5052 is a joy to work with. It bends nicer and the job, cosmetically turns out much better.
Charlie Kuss
Click to expand...

Charlie... how do they ship long lengths? Can it be coiled?

gil in Tucson
 
ACS straps the 5052 to a piece of wood and the ship in a lony rectangular section box. Or so they did with mine. No you cant bend the 5052 in a coil and easily get it straight again so dont try it .

Another trick with 5052 is to cut it only with a pipe cutter. Completly deburr and polish the cuts. Put some thick oil on the flaring end and tool, and then flare.
The resultant flare is a thing of beauty [non builders wouldnt understand]

Also if a bend cant be done with a pipe bender, fill the tube with any dry and fine sand. Compact it nicely and block the ends . You can then bend it by hand or over a pipe or whatever you need without kinking it.

I dont see the 3003 being a issue, but compared to 5052 it just doesnt come close.

EJ.
 
I used to bend 5052 brake lines (1/4") by hand without the sand trick, as long as you're not trying to make tight turns, it's easy to bend.
 
It can be coiled

az_gila said:
Charlie... how do they ship long lengths? Can it be coiled?

gil in Tucson
Click to expand...

When I ordered mine from ACS, they asked if I would mind if they coiled it, which they did. I didn't have any trouble straightening it out. Obviously, you have to be careful about it, but I actually thought it was easier to uncoil than 3003. It came out straighter.
 
ACS shipment of 5052-0 tubing

az_gila said:
Charlie... how do they ship long lengths? Can it be coiled?

gil in Tucson
Click to expand...

Gil
Sorry for the long delay in responding. I don't think I looked at this thread after I commented until today. (I was searching for an old post I'd made regarding 5052-0)
ACS shipped my 5052-0 tubing by taping it (fiberglass reinforced packing tape) to a 6 foot length of wood lathing. This was then inserted into a slim cardboard box. The wood prevented the tubing from being kinked or bent during shipment. This method protected the tubing yet keeps the shipping cost down.
Charlie Kuss
 
Lets take a different approach to this.... Brakes are for mistakes. Most pilots grosssly over use brakes. This is a pet pieve of mine. I rountinely bitch at pilot certificate applicants at all levels including ATP about abusing brakes.

Brakes fail, and a brake failure, in an RV, is not and, should not be an emergency. The Rocket has upside down master cylinders like an RV-4 and they are nearly impossible to bleed out completely. I routinely fly at 16K, 17,K and FL 180 and the smallest bubble in the world will become very large at FL 180 and you have a flat brake on landing. I have landed numerous times with one brake and taxied in with it. Neither is a big deal, even in a significant crosswind.

I have flown airplanes that are very difficult to control without brakes. The Beech 18 without a brake is a handful. Landing a Beech with one brake requires landing with the dead brake on the upwind side, and taxiing in is difficult if not impossible.

But an RV with a single brake is just not a problem, and should not be, the brakes should be used for little more than stopping the airplane, and holding the airplane for runup. Use less brakes!!!!

Stepping off the soapbox.
Doug Rozendaal
 
jonbakerok said:
When I ordered mine from ACS, they asked if I would mind if they coiled it, which they did. I didn't have any trouble straightening it out. Obviously, you have to be careful about it, but I actually thought it was easier to uncoil than 3003. It came out straighter.
Click to expand...

Jon, I hope they did not send you 3003.
 
For Taildraggers Only?

B25Flyer said:
Lets take a different approach to this.... Brakes are for mistakes. Most pilots grosssly over use brakes........

........But an RV with a single brake is just not a problem, and should not be, the brakes should be used for little more than stopping the airplane, and holding the airplane for runup. Use less brakes!!!!

Stepping off the soapbox.
Doug Rozendaal
Click to expand...

Doug- While I agree with the basic premise of using brakes sparingly, I am assuming that your comments are for Tail Dragger RV's, which have TW steering??? If one brake failed on a Nose Wheel RV, then all turns would have to be in one direction, away from the failed brake. IMHO, steering an "A" model with one brake would be a chore.

What say you?
 
I can taxi our 6A without using the brakes for turning ... you can use just rudder and quick engine pluses to stree an A model.


FYI we had a flare fail around 400 hours inside the firewall side.
 
Flare failure inside the firewall side?

n468ac said:
I can taxi our 6A without using the brakes for turning ... you can use just rudder and quick engine pluses to steer an A model.


FYI we had a flare fail around 400 hours inside the firewall side.
Click to expand...

"we had a flare fail around 400 hours inside the firewall side?"

What do you mean? What flare (brake?, fuel?). I am building an RV-7A I would like to know more about the flare failure. The brake lines in the cockpit and on the inside of the firewall are "static" and don't move about like the brake lines on the gear legs. A flare failure inside the cockpit would be rather concerning.

Please explain more.

Thanks,

Paul
 
PCHunt said:
Doug- While I agree with the basic premise of using brakes sparingly, I am assuming that your comments are for Tail Dragger RV's, which have TW steering??? If one brake failed on a Nose Wheel RV, then all turns would have to be in one direction, away from the failed brake. IMHO, steering an "A" model with one brake would be a chore.

What say you?
Click to expand...

I've met Doug, and I'm not 100% sure he's ever sat in a nosewheel airplane, except possibly as a passenger in an airliner. He may not recognized this issue.

Remember to be gentle to noobs :)
 
flyeyes said:
I've met Doug, and I'm not 100% sure he's ever sat in a nosewheel airplane, except possibly as a passenger in an airliner. He may not recognized this issue.
Click to expand...

I've definitely seen Doug flying a B-25 which is a nosewheel. By that time, the aircraft manufactures and the US Army Air Corp, had realized that the nosewheel configuration had definite advantages... :D

L.Adamson
 
Flair on firewall side?

Christofer,

I do not have one single flare on the firewall side! What line was it that failed?

Regards, Tonny.
 
L.Adamson said:
I've definitely seen Doug flying a B-25 which is a nosewheel. By that time, the aircraft manufactures and the US Army Air Corp, had realized that the nosewheel configuration had definite advantages... :D

L.Adamson
Click to expand...

Point taken.

However, the B-25 is a twin, so you can steer with the throttles, which is cheating ;-)
 
L.Adamson said:
I've definitely seen Doug flying a B-25 which is a nosewheel. By that time, the aircraft manufactures and the US Army Air Corp, had realized that the nosewheel configuration had definite advantages... :D

L.Adamson
Click to expand...

A brake failure in the B-25 is a major emergency. Because of that, each main wheel has two brake packs, and there is a normal and emergency system to actuate them. There are however some failures that could take both systems, but I hope I never, ever, have to experience a total brake failure on one or both sides. It would be a pretty bad day. And some **** fine airmanship, plus some good luck, would be required to keep from bending metal. I would look for the longest widest runway I could find with lots of smooth grass on both sides. NO Ditches, NO Buildings and NO taxiing traffic!!!!

With regard to the RV Nose dragger issue, you have just added another item to the long list of reasons to build and fly T/W RVs ;)

Tailwinds,
Doug Roznedaal

BTW, In the interest of full disclosure, I do have a B-55 Baron with 550's but I try to fly it in the clouds or the dark so nobody sees me....:rolleyes:
 
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