Service and Repair Manual

AN 01-25CN-2

PARAGRAPH 6

up. During the filling operation, operate the landing gfar twice by hand and three or four times by power and operate the flaps several times, always taking care that the reserve tank is kept full.

  (c) Any air in the system will be returned to the reserve tank and there vented overboard.

  (d) If the system still shows signs of air after the filling operation, it may be necessary to disconnect the hydraulic lines at the tail wheel retracting strut and bleed the system at that point.

  (e) Do not replace the filler cap until the filling operation is completed.

(3) INSTALLATION AND DISASSEMBLY.

  (a) TO REMOVE THE MOTOR DRIVEN PUMP.-This pump is accessible through the baggage compartment door, and may be removed as a unit by disconnecting the hydraulic lines and electric wires and removing the motor pump unit mounting bolts.

  (b) TO REMOVE THE HYDRAULIC HAND PUMP.-The hand pump may be removed from the floor of the cockpit by disconnecting all hydraulic lines and removing the four hold-down,bolts.

  (c) TO REMOVE THE HYDRAULIC CON. TROL VALVE.

  1. Disconnect the two hydraulic lines at the bottom of the unit, one on the inboard side and three at the top.

  2. Remove the four bolts holding the control valve onto the mounting casting and remove the valve from the airplane.

  (d) TO DISASSEMBLE THE HYDRAULIC CONTROL VALVE (See Fig. 102 and 103).

  1. Place the control valve in a vise with aluminum covered jaws and secure the valve in the vise at the four attachment bosses. Remove the cotter pins and nuts from the two camshaft bolts.

  2. Push the bolts back beyond the valve cover and remove the cover from the valve body.

  3. Puff the bolts and the segment completely out of the camshafts and lift the camshafts from the valve body.

  4. Remove the retainer spring on top of the valve body and pull the followers out of the valve. It is very important that the followers and gaskets, including the shims, be kept together and in order, so that they may be replaced in the same order in the valve body upon installation.

  5. Remove the gaskets and shims from the valve and place them with the correct followers.

  6. Release the valve body from the vise, turn it upside down, and replace it in the vise. Next, remove the eight snap rings locking the retainers in the valve body. Use either a snap ring wrench or a small pair of pliers.

  7. After the rings are all removed, engage the ends of the retainers with a pair of pliers and pull the retainers free of the valve body. When removing the retainers, exercise extreme care not to damage the rubber cups by fouling them in the snap ring grooves inside the valve body.

  8. The valve springs may now be removed from the valve body with a light pair of pliers. Be very careful not to score the valve cylinder surface with the pliers or springs.

  9. Remove the valve body from the vise, turn it upside down, and insert it into the vise. Pull the cotter pins from the valve nuts. Remove the valve body from the vise.

  10. To facilitate the removal of the valve nuts it is suggested that a tool be made up to engage the slotted ends of the valves in order to keep the valves from turning with the nuts. Such a tool can be easily fashioned from a piece of tubing that may be inserted into the valve cylinders. Saw a slot in the diameter of one end of the tube 1/4 inch deep and cut a piece of 1/4-inch steel band the length 'of the diameter of the tube. Insert the steel band into the slot on the tube and anchor the steel into the slot -with solder. Grind the end of the bar down to be sure that no sharp edges of the steel band protrude beyond the circumference of the tube to score the valve cylinder surfaces when installed.

  11. Line up all the slots in the ends of the valves to parallel each other so that the valve slots can be quickly engaged by the special tube wrench.

  12. Insert the tube in the vise with the special end up to engage the valve slots and retain the valves while the nuts are turned off.