(c) CABIN AIR handle Pull.
(d) Cabin adjustable outlets Full open.
(e) CABIN TEMP SEL switch Full clock-
1. Heater function switch OFF.
After heating and ventilating system has been
stopped with the generator(s) ON, the blower
will continue to operate until the temperature
within the heater combustion chamber is be-
2. Wait two minutes before turning generator(s)
8-4-5. Alternate Operation Heating and Ventila-
The following paragraphs describe heating and ventilat-
ing system failure modes.
8-4-6. Vibrator Contact Failure.
The heater may be equipped with either a solid state
vibrator or an electromechanical vibrator. The electrome-
chanical vibrator may experience vibrator contact failure,
which will result in failure of the heater to operate. Heat-
ers equipped with electromechanical vibrators are identi-
fied by a rotary selector switch on the heater junction box.
The electromechanical vibrator is equipped with two sep-
arate sets of contacts designated NORMAL and RE-
SERVE. Upon failure of the normal contacts, the reserve
set may be brought into operation by placing the switch
on the junction box to RESERVE. The junction box is on
the ignition unit next to the heater.
8-4-7. Heater Overheat Condition.
If the HEATER HOT caution illuminates, proceed as fol-
The heater function switch shall remain
ON while performing steps a. through c.
a. Wait two minutes for cool down.
b. HTR START switch Press.
c. HEATER HOT caution Monitor. The HEATER
HOT caution light will not extinguish until combustion
chamber temperature is below 177_C and HTR START
switch is pressed.
8-4-8. Engine Starting.
No special cold weather start procedures are
8-4-9. Warmup and Ground Tests.
Allow the engine and transmission oil pressures and tem-
peratures to stabilize prior to takeoff. This will require
several minutes of operation at FLT.
To prevent unnecessary scratches, allow electrical wind-
shield heating to completely soften frost, snow, or ice
before using the windshield wipers.
Difficulty will be encountered when taxiing on ice and
snow covered surfaces where braking action is poor.
Taxiing on the aft gear (front wheels off the ground) is
recommended; however, caution should be taken be-
cause of the poor visibility resulting from blowing snow.
No unusual problems are associated with either the hov-
ering, rolling, or vertical type takeoffs other than the ef-
fects of blowing snow and slippery surfaces. Depending
on the weight of snow and ice accumulated on or in the
fuselage, takeoff and overall performance can be seri-
8-4-12. During Flight.
Initial hovering with cold hydraulic fluid may produce in-
sensitive control inputs. Hovering above 10 feet (aft
wheel clearance) is recommended under these condi-
tions until operation is normal. With AFCS on, light pitch
and roll oscillations can be expected during the first 10 or
20 minutes of flight
No unusual problems are encountered during a descent.
Use windshield heat if necessary.
8-4-14. Landing in Snow.
Landing in loose snow from a hover presents the unusual
problem of low visibility caused by blowing snow. This
helicopter does not produce this effect to any greater
extent than other helicopters; however caution should be
exercised during this type landing.
8-4-15. After Landing.
Maneuvering the helicopter into a slippery parking area
may be difficult to accomplish and towing may be neces-
sary. Taxiing on the aft gear should not be used to posi-
tion the helicopter among other parked aircraft.
8-4-16. Engine Shutdown.
No unusual problems are encountered during engine
shutdown as long as the procedures in Section II are