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  #1  
Old 08-27-2012, 07:59 AM
N8RV's Avatar
N8RV N8RV is offline
 
Join Date: Mar 2005
Location: Elkhart, Indiana
Posts: 1,186
Default Check your brake fluid levels!

Confession time. Ignorance bit me in the butt (pretty typical), but nothing was bruised but my ego.

When the RV-1 was on the Barnstorming Tour of the Midwest, I landed at Toledo, OH, to meet Bob Mills and The One. Upon landing and rollout, I discovered that my tailwheel didn't lock. I had to use differential braking while taxiing to the ramp.

As I contemplated borrowing someone's hangar and tools to service the tailwheel, I jostled it a bit and the wheel locked OK. We took off, landed back home without incident and I reminded myself to service the tailwheel ASAP.

I had no issues for the next 10 hours or so. Tailwheel was locking perfectly, so I figured I'd just wait until condition inspection time and do it then. That is the moment when a little voice should start saying, "Stupid ... stupid ... stupid ..."

Last week, I took Smokey up for a local flight just for fun. Came back to land and, as the tailwheel came down, started an immediate departure of the runway to the right. I immediately knew that the tailwheel wasn't locking, so I pushed on the left brake to straighten out, but to no avail. I was no longer a pilot but a passenger.

I missed the runway lights, careened into the grass and came to a stop. The tailwheel locking pin was stuck again, but of more concern was that I had no brakes.

As I taxied to the hangar, I realized that I had brakes, but not much. Far more pedal resistance on the right than on the left.

I pulled the tailwheel and disassembled, cleaned, deburred and regreased it. Works like a charm now. However, checking the brakes was another story.

When I checked the brake pads last year, I still had significant pad thickness left, so decided that I'd change them this year. I pulled the left wheel pant and found that I still had decent brake pads. Hmmm... so, I pulled the baggage compartment floor to see how the brake fluid levels were (I have the kind with the master cylinders and reservoirs mounted to the brake pedals). I pulled the plugs and found NO brake fluid!

I was quite surprised, as I hadn't noticed any brake fluid puddles on the hangar floor, none in the cockpit and no leaks when I did condition inspections the last two years. I just assumed that, being in a "closed system" like that, there's no place for the fluid to go and that the level really didn't need to be checked. Wrong.

I still can't explain where three years' worth of brake fluid went, but I topped off the right one in the reservoir because I still had firm pressure, and drained the left system and refilled it from the bottom. I now have solid brakes again.

So, if you're assuming that your brake fluid reservoir is full because it was when you filled it and you haven't seen any leaks anywhere, you might want to check the fluid level to be sure. It's a good item to have on your annual condition inspection list.
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Don McNamara
Peoria, AZ

Builder: RV-8 "Smokey"
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  #2  
Old 08-27-2012, 09:12 AM
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TomVal TomVal is offline
 
Join Date: Dec 2007
Location: SC & CA
Posts: 907
Default

Don,

Part of my pre-landing check is to apply the brakes checking for firmness of the pedals. If not firm, at least you are prepared to make a landing with one or both brakes inop.

Regards,
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Tom Valenzia
RV8 (Sold)
RV12 Jabiru 2200 Powered (Sold)
Dues contributor since 2007

Learn from the mistakes of others. You won't live long enough to make all of them yourself...Anonymous
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  #3  
Old 08-27-2012, 10:31 AM
rwhittier rwhittier is offline
 
Join Date: Oct 2006
Location: Glendale, AZ
Posts: 256
Default Brake fluid goes down with use...

Don,

Glad no one was hurt and no damage done.

Over time as you use the brakes the pads wear (duh, obvious I know) and the calipers pucks have to extend out further to engage the brakes. This requires more brake fluid for the pucks to reach out there. We have really small brake fluid reservoirs and this can consume most of your available reserve fluid.

You don't have to have a leak to need to add fluid. I always check my brake fluid every oil change. And I often have to add a small amount.

Good reminder of why.

Quote:
Originally Posted by N8RV View Post
I pulled the plugs and found NO brake fluid!

I was quite surprised, as I hadn't noticed any brake fluid puddles on the hangar floor, none in the cockpit and no leaks when I did condition inspections the last two years. I just assumed that, being in a "closed system" like that, there's no place for the fluid to go and that the level really didn't need to be checked. Wrong.

I still can't explain where three years' worth of brake fluid went, but I topped off the right one in the reservoir because I still had firm pressure, and drained the left system and refilled it from the bottom. I now have solid brakes again.

So, if you're assuming that your brake fluid reservoir is full because it was when you filled it and you haven't seen any leaks anywhere, you might want to check the fluid level to be sure. It's a good item to have on your annual condition inspection list.
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RV7A Quick Build, Tip Up
N1MY Reserved - Canopy finished - Wings mated, Engine hung, electrical 95%
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  #4  
Old 08-27-2012, 01:00 PM
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Neal@F14 Neal@F14 is offline
 
Join Date: Aug 2007
Location: Wichita Falls, TX
Posts: 2,182
Default

Yikes!

Glad to hear you didn't bend any sheetmetal on your off-road excursion.

Back when I was having issues with the tailwheel not locking on the RV-8, I ordered a new rocket link arm and a new pin from Flyboy Accessories, and Vince emailed me a PDF that showed how to cut the notch into the arm a little deeper, and to put more of a blunt, almost squared-off nose on the pin with the edges radiused just enough to round them a wee bit, rather than the almost half-round semicircle shape of the stock pin. I carved the original arm's slot a little deeper with a rat-tail file and re-shaped the nose of the pin on the scotchbrite wheel and put the reworked old parts back on, and they've been locking perfectly since then. The new parts are still in the envelope, unused.

My RV-6 has a firewall-mounted brake reservoir with translucent plastic tubing running to all the master cylinders on both sets of pedals. One good feature of that is, it makes it easy to visually check the level just by looking down and seeing the red fluid in the lines. A bad feature is that every one of those nylon hose fittings everywhere in the system very slowly oozes hydraulic fluid a teeny-tiny amount, needing to be wiped off about once every few weeks before it seeps enough to drip onto the carpet, and of course, there's a need to add fluid to the reservoir which means pulling the top cowl off
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Airplaneless once again...
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  #5  
Old 08-27-2012, 02:12 PM
Rupester Rupester is offline
 
Join Date: Dec 2005
Location: Mahomet, Illinois
Posts: 2,195
Default Great post ...

...thanks much. Until now, I was thinking like you ... if there's no fluid on the hangar floor or on the A/C floor, there can't be any leaks. This is a great item to add to weekly/monthly maintenance checks.
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Terry Ruprecht
RV-9A Tip-up; IO-320 D2A
S. James cowl/plenum
(Dues paid thru Nov '18)
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  #6  
Old 08-27-2012, 03:23 PM
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N8RV N8RV is offline
 
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Location: Elkhart, Indiana
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Quote:
Originally Posted by Rupester View Post
...thanks much. Until now, I was thinking like you ... if there's no fluid on the hangar floor or on the A/C floor, there can't be any leaks. This is a great item to add to weekly/monthly maintenance checks.
That's exactly why I posted it.

I was supposed to go to a picnic at a friend's private strip that weekend. Had I not gone flying and had my little excursion into the weeds at our home field, I might have experienced that little off-runway adventure right into a line of parked planes!

Sometimes we discover things that need to be passed on so that embarassing (and dangerous!) moments like that can be avoided by others.

Glad you found it helpful.
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Don McNamara
Peoria, AZ

Builder: RV-8 "Smokey"
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  #7  
Old 08-27-2012, 03:37 PM
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Rick_A Rick_A is offline
 
Join Date: Oct 2005
Location: Jacksonville, FL
Posts: 1,572
Default I check at every oil change

I check mine brake fluid at every oil change. There was a period when I had to keeping adding fluid, but I never saw evidence of a leak.

Eventually, I found the leak around the threads of the fitting that screws into the brake master cylinder on 1 pedal. The fluid had absorbed in the the carpet - which is why I never saw where the fluid was going. (Yes, I did have to replace the carpet)
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Jacksonville, FL
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  #8  
Old 08-27-2012, 05:10 PM
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tkatc tkatc is offline
 
Join Date: Nov 2007
Location: NJ
Posts: 1,747
Default

Thanks for posting. I bet things like this happen all the time (some with worse results) but for whatever reason, people don't post it. The "Air Force" cannot learn from mistakes if people don't post them.

Swallow your pride and help your community!
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Bought my flying -7A
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  #9  
Old 08-27-2012, 06:20 PM
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panhandler1956 panhandler1956 is offline
 
Join Date: Jun 2006
Location: Ohio
Posts: 1,686
Default

Good post Don! You probably saved a few folks, myself included, from some dings.
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Brent Owens
EAA Chapter 9 Tech Counselor/Flight Advisor
Columbus, OH
RV-8 'Contrary Mary' flying
N784DE S/N #82614

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  #10  
Old 08-27-2012, 09:09 PM
Frank Smidler Frank Smidler is offline
 
Join Date: Feb 2005
Location: Stoughton, WI
Posts: 491
Default Watch it when you replace your pads

Don,

When you replace your pads you will have to push the brake caliper piston in which will push fluid back into the reservoir. If they are full when you do this it will overflow.
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Frank Smidler
N96FS, RV-6
Flying 1/11/09
1085 hr
2WI6 Stoughton, WI
Formally of Lafayette, IN
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