prefixed to the digital display will be removed. All
event data is still available for playback until the data is
erased. The display will be prefixed with an "E" again
on the next power up cycle if the old data has not been
erased or if another event is recorded.
Pressing the EXCEEDENCE ERASE switch
for 0.2 seconds or longer will cause all
events to be erased from non-volatile
memory. There are not provisions for
erasing individual events.
The Propeller Speed Tachometers are each
protected by 1.0-ampere circuit breakers located on
the pilots left subpanel and placarded PROP RPM #1
Section VII. UTILITY SYSTEMS
2-59. DEFROSTING SYSTEM.
a. Description. The defrosting system is an
integral part of the heating and ventilation system.
The system consists of two warm air outlets connected
by ducts to the heating system. One outlet is just
below the pilot's windshield and the other is below the
copilot's windshield. A push-pull control, placarded
DEFROST AIR, on the pilot's subpanel, Figures 2-6
and 2-8, manually controls airflow to the windshield.
When pulled out, defrosting air is ducted to the
windshield. As the control is pushed in, there is a
corresponding decrease in airflow.
b. Automatic Operation.
1. Vent blower switches As required.
2. Cabin Air Mode switch AUTO.
3. Cabin Air Temp control As required.
4. Cabin air, copilot air, pilot air, and defrost
air controls As required.
c. Manual Operation.
1. Pilot air, copilot air In.
2. Cabin air and defrost air controls Out.
3. Cabin air mode switch MAN HEAT.
4. Cold air outlets As required.
5. Cabin air manual temp switch As
2-60. SURFACE DEICER SYSTEM.
a. Description. Ice accumulation is removed
from each inboard and outboard wing leading edge,
and both horizontal stabilizers by the flexing of deicer
boots which are pneumatically actuated. Engine bleed
air, from the engine compressor, is used to supply air
pressure to inflate the deicer boots, and to supply
vacuum, through the ejector system, for boot hold
down during flight. A pressure regulator protects the
system from over inflation. When the system is not in
operation, a distributor valve applies vacuum to the
boots for hold-down.
(1) Deice boots are intended to remove ice
after it has formed rather than prevent its formation.
For the most effective deicing operation, allow at least
1/2 inch of ice on the boots to form before attempting
ice removal. Very thin ice may crack and cling to the
boots instead of shedding.
Never cycle the system rapidly, this may
cause the ice to accumulate outside the
contour of the inflated boots and prevent
(2) A three position switch on the overhead
control panel, placarded DEICE MANUAL / OFF /
SINGLE CYCLE AUTO, C D T1 and DEICE
MANUAL SINGLE CYCLE AUTO T2 controls the
deicing operation. The switch is spring loaded to
return to the off position from SINGLE CYCLE AUTO
or MANUAL. When the SINGLE CYCLE AUTO
position is selected, the distributor valve opens to
inflate the wing boots. After an inflation period of
approximately 6 seconds, an electronic timer switches
the distributor to deflate the wing boots and a 4-
second inflation begins in the horizontal stabilizer
boots. When these boots have inflated and deflated,
the cycle is complete.
(3) If the switch is held in the MANUAL
position, the boots will inflate simultaneously and
remain inflated until the switch is released. The switch
will return to the off position when released. After the
cycle, the boots will remain in the vacuum hold down
condition until again actuated by the switch.