Where did it go?

Steve Barnes · #1 08-06-2010, 09:43 PM

I got in on the passenger side of my plane the other day and pushed the brake pedals. Both R and L went totally to the floor even after I pumped many times. The pilots side worked perfectly. Further investigation showed that my reservoir was dry. I know that I was remiss about checking the fluid the last two inspections, but with no leaks I didn't feel a need too. I am positive that I didn't have a leak, because it makes a sticky mess like dried syrup (I have experience with this on my last plane). So, WHERE DID IT GO? All I can think of it that the plastic lines expanded and took some of the volume, or it evaporated out the the breather cap. Neither one of these seem feasable to me though. Again there is no evidence of leakage in the cockpit, FWF or around the wheel pants. Any ideas?

Steve Barnes "The Builders Coach"

instructor_bill · #2 08-06-2010, 11:06 PM

since your fluid supply to the feed side of the master cylinders in the pilot's circuit is uncompromised, the fluid must have leaked out the pax circuit emptying the reservoir.

You sure the evidence of the leak is not hiding in the carpet under the pax master cylinders? (assuming you have carpet)

Steve, still need to set up a meeting with you. You coming to petaluma any time soon? I'm off until wednesday.

gasman · #3 08-07-2010, 01:20 AM

Steve, did you install larger brakes?
If so, check your pads. They are probably ready to be changed. As the pads wear thin, the pistons move out and more fluid is needed to fill that space................

Warren

Steve Barnes · #4 08-07-2010, 02:10 AM

Bill,I don't have any carpet, just floor, but good guess. How about Sunday to look at your plane. Steve 972-3582

Warren, good call on fluid transfer from reservior to slave cylinder. However brakes are half worn and have in the past been worn further, with out current symptoms.

Steve

ao.frog · #5 08-07-2010, 03:12 AM

Hi.

I need to refill the brake-reservoir rutinely due to aerobatics, even though I have the "flip-valve" on it.

If you lately have flown more aerobatics than normal, maybe that could be the sollution? (assuming you have an aerobatic RV)

Steve Barnes · #6 08-08-2010, 12:15 AM

I never fly inverted. My engine is not set up for it, but good idea.

steve

turbo · #7 08-08-2010, 07:50 PM

it go for 2 to 3 years without checking? you may need a thorough inspection at this time. planes have a way of talking to you.

rwhittier · #8 08-08-2010, 08:23 PM

The pucks in the calipers have to reach further out, which takes fluid. Our reservoirs are not very large. I bet most of it went not out the system but to the calipers to fill in for brake wear.

I check my fluid reservoir whenever I change the oil.

Quote:

Originally Posted by Steve Barnes

I got in on the passenger side of my plane the other day and pushed the brake pedals. Both R and L went totally to the floor even after I pumped many times. The pilots side worked perfectly. Further investigation showed that my reservoir was dry. I know that I was remiss about checking the fluid the last two inspections, but with no leaks I didn't feel a need too. I am positive that I didn't have a leak, because it makes a sticky mess like dried syrup (I have experience with this on my last plane). So, WHERE DID IT GO? All I can think of it that the plastic lines expanded and took some of the volume, or it evaporated out the the breather cap. Neither one of these seem feasable to me though. Again there is no evidence of leakage in the cockpit, FWF or around the wheel pants. Any ideas?

Steve Barnes "The Builders Coach"

339A · #9 08-08-2010, 08:57 PM

My reservoir fluid drained once and the only reason I finally noticed it was when I saw it dripping on the floor from the firewall stiffener angle. I have insulating foam on the firewall. The leak was coming from the nylon fitting that screws into the back of the reservoir. The fluid made its way out the threads and just got soaked up by the foam.

This was after 500 hours or so. Tightened it up two turns its been fine ever since. It seems as though the nylon fitting must have shrunk some over time? It was tight originally and didn't leak for a couple years.