9. Check that system components perform
reverses the action of both blades. The mechanical
smoothly with no erratic operation and blade reversing
locking device is provided to hold the blades in the
is synchronized. Blade rotation must be 75 degrees.
parked position when the needle valve is closed.
The wiper blades must not touch the center post, travel
NOTE: Do not operate the windshield wiper
into the parking area, or short cycle during high-speed
blades on a dry windshield.
operation.
Maintenance of the windshield wiper system
10. Reduce speed of blade operation, and manually
consists mainly of operational checks, removal and
stall each wiper separately. While the blade is stalled,
installation of components, and troubleshooting.
the opposite blade should operate smoothly.
11. Park the blades by slowing down the cycling
The operational check should be performed
speed to permit blades to move into the park position
according to the following procedures:
before they reverse.
1. Provide a supply of water on the outside
NOTE: Parking area is the area between the bottom
surface of the panels when the wiper blades are in
edge of the glass and the break in the contour of the
motion.
fuselage. To adjust the blades, loosen the blade
2. Check for a wiper arm force of 7 to 10 pounds
attaching screw and rotate blade. One serration is
on the windshield (at the blade attachment).
approximately 5 degrees of rotation. If it is not possible
3. Connect external electrical power supply.
to install within the parking area, install the arm
4. Energize hydraulic power system No. 1 ac
outboard with the blades as close to the parking area as
pumps.
possible, then remove the arm and adapter. Looking
5. Slowly open the windshield wiper speed
down on the arm, carefully remove the adapter and
control needle valve.
rotate it one serration counterclockwise with respect to
6. Blades must move from parked position and
the arm, and then reinstall the adapter in the arm. This
begin to cycle between 100 to 300 strokes per minute.
will permit the arm to be installed approximately 1.25
7. Open instrument panel to gain access to
inches closer to the parking area. If the blade is still
window units. Bleed air from units as they cycle by
parked on the glass, repeat the above procedure. Final
cracking the B-nuts on the tubing at each end of the
adjustment must leave slots in the adapter and arm
window units. Allow fluid to bleed into existing drip
approximately in line to permit proper clamping action
pans until it is evident that all air has been removed.
of the arm and adapter to the shaft of the window unit.
8. Check that no hydraulic fluid leak is visible on
Figure 15-18 illustrates a windshield wiper unit.
the system tubing, connections, or at any component.
Figure 15-18.--Windshield wiper unit.
15-20
