Here\'s what\'s happening. Aircraft with hyd pressure applied by aux pump.
Parking brake released, normal brakes selected, anti skid on and foot pedals
depressed to hold brakes, The left forward anti skid valve will occasionally
release brake pressure on the left forward brake dropping pressure to zero
and then restores it back to 1800 psi. The other brakes drop just slightly.
The control box, left anti skid control valve and the left forward
transducer have all been replaced, having no affect. Wiring has all been
shook down and visually checked. Aircraft had been flying fine days prior,
came back with a brakes dragging write up, hyd shop bled brakes, ran follow
on maint per tech data, signed it off. Went to fly aircraft, while on spot
running to depart jumped forward. All checks above have been done with aux
pump no engines running. The left forward brake releases, However if the
parking brake is set, anti skid turned off or emergency brakes selected,,,
it does not happen. I have printed out the Lockheed Service News for the
Anti skid system, which has been no help.
Looking for any input...