'Ocassionally the system will push small amounts of
trapped air back to the reservoir creating a low head
pressure on the system. This is especially noticeable
on days with high temperatures. To relieve this
pressure, got to the air pressure valve on the
reservoir and push it in to relieve the pressure. If
this does not work, go to the brake bleeder and crack
it open, allowing a little bit of fluid to drain. The
problem should go away.
Now here is the easy way of bleeding PT brakes. If
the system is empty, service from the bleeder up to
the reservoir. You want to push as much air as
possible into the tank. Don't worry if you don't get
it all. Fill the tank from both sides of the system
until full. Now put some head pressure on the tank,
2# to 5# is ample. Bleed the normal way. The head
pressure alone should be enough to push all air out of
the master cylinder and expander tube. Once this is
done, relieve the air in the tank and the brakes
should be ok. What causes problems? Dirty fluid,
weak seals in the master cylinder, worn out expander
tube and leaking lines are things to look for.
Always, always, always use clean DOT 5 fluid. How do
you know the master cylinder has an internal leak?
The pedal will go to the stop, you bleed as described
above, you get good pedal and after a few minutes, the
pedal drops to the stop again. Replace the seals and
bleed the system. Always, always, always use clean
DOT 5 fluid. Did I say that already??
Mike
--- Robert Lloyd wrote:
> Our PT-26 is back in the air. It took forever to
> get the field
> approval for our Jasco alternator installation, but
> we finally have it.
> We also put on a stainless steel exhaust system from
> Aircraft
> Exhaust Systems of Jumping Branch, West Virginia.
> Thanks
> Jamie and everyone else who gave us advice while we
> were going
> through all of this.
> Now we have a new problem. After a short and
> uneventful
> test flight I turned to go into the hangar and the
> left brake locked. It
> would not budge. When we chocked the other wheel
> and moved
> the tail, the left wheel just skidded. The wheel
> didn't seem to be
> unusually hot. The next morning the wheel was free
> and the brake
> operated normally. The brakes are the original
> expander-tube
> brakes. We had some problems with the left brake
> dragging in the
> past, but we flushed the system and sanded the pucks
> and that
> seemed to take care of it. The wheel bearings have
> been
> inspected and repacked within the last year.
> Does anybody have any ideas?
> Bob
> Lloyd
>
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