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Brake lines and Hydrauli fire

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Ed Anderson

Joined: 10 Jan 2006
Posts: 475

Posted: Fri Dec 21, 2007 5:47 am Post subject: Brake lines and Hydrauli fire

After a ruptured aluminum  brake line (after 340  hours of flying) resulted in runway departure,  a hydraulic fire which  charred tire and wheel pant   - whicht fortunately did not damage  the aircraft, I went with stainless steel braided brake lines with Teflon  liners

  

 I also replace the older brake fluid with the newer  MIL-PRF-83282 D brake fluid which has a much higher flash point  (around 440F).  I then replace the brake rotors with discs twice the  thickness to hold down the temps.

  

 Believe me it is a helpless feeling to have your brake go  to the floor and find you have no effective directional control.  Just had  time to get the engine shut down and used the starter to get the prop horizontal  before going into a ditch off the side of the runway.  Perhaps I should  have considered ground looping - with the remaining good brake, but the thought  did not occur until afterwards.  

  

 Did I mention, its smart to carry a fire extinguisher in  your cockpit?

  

 Ed

  

 Ed Anderson

Rv-6A N494BW Rotary Powered

Matthews,  NC

eanderson(at)carolina.rr.com (eanderson(at)carolina.rr.com)

http://www.andersonee.com

http://members.cox.net/rogersda/rotary/configs.htm#N494BW

http://www.dmack.net/mazda/index.html

  

  

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Ed Anderson
Rv-6A N494BW Rotary Powered
Matthews, NC
eanderson@carolina.rr.com

pitts_pilot(at)bellsouth.
Guest

Posted: Fri Dec 21, 2007 6:21 pm Post subject: Brake lines and Hydrauli fire

Ed Anderson wrote:

  	  Quote: 	
		        DIV { 	MARGIN: 0px }         After a ruptured aluminum  brake line (after 340 hours of flying) resulted in runway departure,  a hydraulic fire which charred tire and wheel pant   - whicht fortunately did not damage the aircraft, I went with stainless steel braided brake lines with Teflon liners

 	
 Sorry ED. I'm not picking on you!!!  Honest!!!   

 Whgere did the hard line break???  At the flare???  Not uncommon.  Happened to me.  My fault.  Using cheap flaring tool (but an AN flare, not a plumbers flare).  Also. clamping the tubing down next to the caliper hinders it's natural movement as the brake pads wear.  another problem area.  Unfortunately, I was aware of the problem (yeah, after I lost a brake on my Pitts but no fire or other damage besides extreme embarrassment cause by doing pirouettes on the runway)    	  Quote: 	
		     I also replace the older brake fluid with the newer MIL-PRF-83282 D brake fluid which has a much higher flash point (around 440F).  I then replace the brake rotors with discs twice the thickness to hold down the temps.

 	
 Thanks for those two tips.  I wasn't aware of either.  Can you give us a part number for the thicker rotors???    	  Quote: 	
		     Believe me it is a helpless feeling to have your brake go to the floor and find you have no effective directional control.

 	
 AMEN!

  	  Quote: 	
		       Just had time to get the engine shut down and used the starter to get the prop horizontal before going into a ditch off the side of the runway.  Perhaps I should have considered ground looping - with the remaining good brake, but the thought did not occur until afterwards. 

   

 	
 Hmmm.  For me, I was mashing both pedals for all I was worth ..... and it came as a surprise to me that the right one was hitting the firewall!   	  Quote: 	
		      

   Did I mention, its smart to carry a fire extinguisher in your cockpit?

 	
 Ya know, I'm rather thick headed (and oblivious to strong hints) ...... but even after two fires up front .... still don't have one.  Both fires were due to my stupidity (hope I don't make more mistakes like that) and on the ground.  Educational experiences I call 'em.

 Linn

 again, do not archive.

 [quote]    

   Ed

    

   Ed Anderson

 Rv-6A N494BW Rotary Powered

 Matthews, NC

   eanderson(at)carolina.rr.com (eanderson(at)carolina.rr.com)

   http://www.andersonee.com

   http://members.cox.net/rogersda/rotary/configs.htm#N494BW

   http://www.dmack.net/mazda/index.html

    

    

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Vanremog(at)aol.com
Guest

Posted: Fri Dec 21, 2007 7:12 pm Post subject: Brake lines and Hydrauli fire

In a message dated 12/21/2007 6:22:21 P.M. Pacific Standard Time,  pitts_pilot(at)bellsouth.net writes:

  	  Quote: 	
		      	  Quote: 	
		       replace the older brake fluid with the newer      MIL-PRF-83282 D brake fluid which has a much higher flash point      (around 440F).  I then replace the brake rotors with discs twice the      thickness to hold down the temps.

	
Thanks for those    two tips.  I wasn't aware of either. 	


 

 ===========================

  

 Search on the MIL-PRF in the archives.  I tried to hip everyone to  this a couple of years back when I did the research and changed  mine.

  

 I believe that several manufacturers have recommended this change for their  fleets but suspect that the old MIL-H-5606 is just too deeply ingrained in the  FBOs for anyone to stock to the better fluid.

  

 BTW, can the thicker Cleveland disc really fit under the old (original  non pressure recovery) wheel pants?

  

  

 N1GV (RV-6A, Flying 872hrs, O-360-A1A, C/S, Silicon  Valley) 



See AOL's top rated recipes and easy ways to stay in shape for winter.

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aerobubba(at)earthlink.ne
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Posted: Sat Dec 22, 2007 4:33 am Post subject: Brake lines and Hydrauli fire

Hi Again, Ed!



 	  Quote: 	
		  Just had time to 

get the engine shut down and used the starter to get the prop horizontal 

before going into a ditch off the side of the runway. 


	


Wow- quick thinking.  Sometimes the force is with you.  I was going to go

the Teflon route for the brake line loop to the caliper, but it's been

suggested that there is a threat of brake temps melting the Teflon in the

braided line.  Does anyone have any hard evidence, numbers, or anecdotal

info to this effect?



 	  Quote: 	
		  Did I mention, its smart to carry a fire extinguisher in your cockpit?

 
	


Thanks for reminding me to get that on the do list.



glen matejcek

aerobubba(at)earthlink.net

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Ed Anderson

Joined: 10 Jan 2006
Posts: 475

Posted: Sat Dec 22, 2007 6:58 am Post subject: Brake lines and Hydrauli fire

Hi Linn,

  

 Actually, I was surprised at the location of the break in  the line, myself.  I would have though the flare would be the most likely  place. All flares were made with aircraft quality 37deg flaring  tools.  

  

  But, in my case, a chunk of the line blew out, about  1/2 the circumference of the tube and about 1" long - simply blew the side wall  out of the tube back about 3" from the Flare.   I'll try to post some  photos in the photo section of the list.

  

 I suspect that I may have work harden the tube in that  area by trying to get the loop around the axis correct - or it could have  possibly been nicked or otherwise damaged.  However, after thinking about  it, I decided that having a length of aluminum tubing which does not have the  best fatigue life designed to flex as the calipers moved in and out was not the  best approach.  Yes, I know, hundreds of folks have used it with no problem  - that not withstanding, aluminum tubing fatigues fairly easily and I decided to  eliminate it in my brake lines.

   

  

 The Cleveland part number for the thicker rotors  is  164-09900.  I purchased an equivalent  pair from Chief  Aircraft  made by RAPPCO part number RA164-09900.   Aircraft Spruce sells the complete  199-93 kit  which when I  checked  will cost you around $300 for basically 2 rotor discs, some shims,  the brake linings and some labels to put on your wheels.upgrade  kit.

  

 I purchased the two rotors from chief for $140 for the  pair.  Be advised you will need a 1/8" spacer to fit between the two  caliper pieces to accommodate the thicker disc - Cleveland wanted $85  EACH for a 1/8" thick piece of aluminum with two holes  drilled in it - the spacer.  I made mine out of 6061T6 aluminum I had  laying around.  Took me about 45 minutes as you need to shape the inner  side of the spacer so it matches the curve of the disc.

  

 Everything will fit inside the old (pre-pressure recovery)  wheel pants, but you will probably need to remake your wheel pant bracket -  I made new ones out of SS sheet - the old ones might work, but you have to space  it out further from the wheel due to the thicker rotor and then the wheelpant  attachment screws hole may not line up with the bracket nutplates.  You  will need to make new bracket spacers and add 1/8" to the length of those  aluminum tube spacers that stand the brackets off of the wheel.   

  

 The brakes feel much firmer, I get no brake fade even  under heavy braking and I have not smelled any indication that the brakes are  getting as hot as they once did.  Theoretically having twice as much metal  to absorb the heat, the temps should be lower.

  

 Hope this helps

  

 Ed

  

  

  

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Ed Anderson
Rv-6A N494BW Rotary Powered
Matthews, NC
eanderson@carolina.rr.com

Ed Anderson

Joined: 10 Jan 2006
Posts: 475

Posted: Sat Dec 22, 2007 7:03 am Post subject: Brake lines and Hydrauli fire

Yes, I had to buy the new stuff by the gallon - enough to last  me for a decade {:>).  Have not found any at local FBOs who carry  it.  Apparently the need for the new higher flash point was driven my  Military need for less flammable brake fluid - so I read.

  

 Yes, the thicker rotors will fit under the old (pre-pressure  recovery) wheelpants.  However, I had to redo my wheelpant brackets and add  1/8" to the three aluminum tube bracket spacers.

  

 Ed

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Ed Anderson
Rv-6A N494BW Rotary Powered
Matthews, NC
eanderson@carolina.rr.com

Ed Anderson

Joined: 10 Jan 2006
Posts: 475

Posted: Sat Dec 22, 2007 7:07 am Post subject: Brake lines and Hydrauli fire

Hi Glen,



Well, I didn't think to try ground looping with the one good brake - it may 

not have worked out too well with a nose wheel aircraft - I can just picture 

it pitching over in a sharp turn.   Perhaps the fact,  I had just installed 

a new $1500 propeller might have had some influence on the decision process 

{:>).  .



The brake lines with Teflon lining are standard use brake lines.  I have 

found that having stainless steel braid around any hose liner material seems 

to do a good job of holding the temps down.  Not to say it couldn't happen. 

My view is the stainless steel Teflon lines are less likely to give you an 

immediate and catastrophic failure - I believe that leaks would develop and 

you would get some indication (mushy peddle?)  of a problem before the leak 

got large enough to preclude braking.  But, that is just speculation on my 

part.



Yes, get that fire extinguisher - that way you will never need it.



Ed

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Ed Anderson
Rv-6A N494BW Rotary Powered
Matthews, NC
eanderson@carolina.rr.com

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