Defroster System; Ventilating System - Cessna 177 SERIES Service Manual

14-7. DEFROSTER SYSTEM. lators mounted in the overhead console, two adjust-
able ventilators mounted in the aft wing root areas
14-8. DESCRIPTION. The defrosting system is com- and flexible ducting connecting the system.
prised of a duct across the aft side of the firewall, a
defroster outlet, mounted on the left side of the cowl
14-14. OPERATION. Ram air received from scoops
deck immediately aft of the windshield, a control
mounted in the inboard leading edges of the wings is
knob on the instrument panel and flexible ducting con-
ducted to small plenum chambers, located at each
necting the system. wing root rib.
From the plenum chambers the air is
routed to the pilot and copilot overhead console out-
14-9. OPERATION. Air from the duct across the lets and to the rear seat outlets. On some aircraft
aft side of the firewall flows through a flexible duct
the quantity of air flowing through the outlets is con-
to the defroster outlet. The defroster control oper- trolled by means of a geared-type control, actuated by
ates a damper in the firewall duct outlet to regulate
rotating a knob at each outlet position. (Refer to fig-
the amount of air deflected across the inside surface ure 14-2, sheet 1.) On other aircraft the quantity of
of the windshield. The temperature and volume of air is controlled by means of a 360 degree manually-
this air is controlled by the settings of the cabin operated swiveling valve which can be turned to in-
heating system control. crease, decrease and direct the flow of air wherever
desired. (Refer to figure 14-2, sheets 2 and 3.)
14-10. TROUBLE SHOOTING. Since the defrosting
system depends on proper operation of the heating 14-15. TROUBLE SHOOTING. Most of the oper-
systems. refer to paragraph 14-5 for trouble shoot-
ational troubles in the ventilating system are caused
ing the heating and defrosting systems.
by sticking or binding air valves and their controls
or damaged air ducting. In most cases, air valves
14-11. REMOVAL, REPAIR AND INSTALLATION. or controls can be freed by proper lubrication. Dam-
Figure 14-1 illustrates the defrosting system and aged or broken parts should be repaired or replaced.
may be used as a guide for removal, installation and When checking rigging of controls, ensure valves
repair of defroster system components.
Burned, respond freely to control movement, that they move
frayed or crushed hose should be replaced with new in the correct direction and that they move through
hose, cut to length and installed in the original rout-
their full range of travel and seal properly.
ing. Trim hose winding shorter than the hose to I
allow clamps to be fitted. A defective defroster out- 14-16. REMOVAL, REPAIR AND INSTALLATION.
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let must be repaired or replaced. Figure 14-2 illustrates the ventilating system and
may be used as a guide for removal, installation
14-12. VENTILATING SYSTEM. and repair of the ventilating system components.
Frayed or crushed hose should be replaced with new
i4-13. DESCRIPTION. The ventilating system is
hose, cut to length and installed in the original rout-
comprised of an airscoop mounted in the inboard ing. Trim hose winding shorter than the hose to
leading edge of each wing, a small plenum chamber allow clamps to be fitted. Defective air valves must
mounted at each wing root rib, two adjustable venti- be repaired or replaced.
Check for proper operation
of valves and controls after repair or replacement.
SHOP NOTES:
14-6 Change 7