Cessna 402C Pilot Operating Handbook page 91

(AMPLIFIED PROCEDURES)
SECTION 4
NORMAL PROCEDURES
The cowl flaps should be adjusted to maintain the cylinder head tempera-
ture within the normal operating range (green arc).
Best propeller
synchroph~sing
is obtained by making the final adjustment
of the propeller controls in a DECREASE RPM direction. Manually synchro-
nize the propellers as closely as possible and tighten the quadrant fric-
tion lock securely. Position the synchrophaser switch to PHASE. The
phasing knob should then be adjusted until the desired sound and vibration
characteristics are obtained. This setting will vary from flight to
flight. If non-synchronized operation occurs during long cruise flights,
manually re-synchronize the propeller controls as closely as possible and
synchronized operation should reoccur. Securely tighten the quadrant
friction lock, then adjust the phasing knob as desired.
On long cruise flights, where the slaved governor Can eventually operate
near either end of its operating range, it may be necessary to periodically
select the OFF position, reset the propeller controls and reengage the
synchrophaser.
For flight in an icing environment, refer to the Alternate Induction Air
paragraphs in this section and other sections dealing with flight in an
icing environment.
DESCENT
1. Fuel Selectors - Left Engine - LEFT MAIN (Feel For Oetent).
Right Engine - RIGHT MAIN (Feel For Oetent).
2. Auxiliary Fuel Pumps - ON.
3. Power - AS REQUIRED to maintain engine temperatures in the green.
4. Mixtures - ADJUST for smooth operation with gradual enrichment as
altitude is lost.
5. Propeller Synchrophaser - AS REQUIRED (Optional System).
6. Cowl Flaps - CLOSE.
7. Altimeter - SET.
Descents should be initiated far enough in advance of estimated landing
to allow a gradual rate of descent at cruise speed. It should be at
approximately 500 fpm for passenger comfort, using enough power to ,keep the
engines warm. This will prevent undesirable low cylinder head temperatures
caused by low power settings at cruise speed. The optimum engine speed in
a descent is usually the lowest one in the RPM green arc range that will
allow cylinder head temperatures to remain in the recommended operating
range.
The combination of high pressure altitudes and above-standard tempera-
tures has a significant effect on engine operation. Power output at any
manifold pressure or power setting will be lower at high ambient tempera-
tures than under standard atmospheric conditions. As temperatures
increase, a constant fuel flow rate will result in a progressively richer
mixture.
When operating at high altitudes and/or high ambient temperatures.
careful attention should be paid to proper leaning of the mixture for both
fuel economy and engine performance. This is especially important during
prolonged low-power or idle-power operation. Overly rich mixtures during a
long idle-power descent from cruising altitude could result in loss of
power. During low-power operations. mixtures should always be leaned for
smooth operation.
1 November 1979
4-21