Cessna 402C - Page 90

SECTION 4
NORMAL PROCEDURES
(AMPLIFIED PROCEDURES)
b~"402C
MODEL
c. Oxygen Flow Indicator - Check Flow. (Indicator Toward Mask
Indicates Proper Flow).
d. Disconnect hose coupling when not in use.
10. Trim Tabs - ADJUST.
Normal cruising requires between 50% and 70% of maximum normal operating
power. The mani fo ld pressure and RPM sett i ngs requ ired to obtain these
powers at various altitudes and outside air temperatures can be determined
I with your cruise computer. A maximum cruising power of (29.5 inches Hg.
manifold pressure and 2450 RPM or 30.3 inches Hg. manifold pressure and
2300 RPM) may be used if desired. Various percent powers can be obtained
with a number of combinations of manifold pressure, engine speed, altitude
and outside air temperature. For a given throttle setting, select the
lowest engine speed in the green arc range that will give smooth engine
operation without evidence of laboring.
,.-----!CAUTION!-----......,
The use of 30.3 inches Hg. manifold pressure (narrow
green
arc on the manifold pressure gage) is re-
stricted to the 2200 to 2300 RPM range only.
The use of lower power settings and the selection of cruise altitude on
the basis of the most favorable wind conditions ,are significant factors
that should be considered on every trip to reduce fuel consumption. Addi-
tional range can be achieved when operating at select power combinations,
see Figure 5-20, by leaning to peak exhaust gas temperature (EGT) for Best
Economy mixture. This setting results in an airspeed loss of 4 KTAS and
range
increase of 8% compared to the Recommended Lean mixture. Do not lean
to the extent that engine roughness or excessive speed loss occurs •
....------ICAUTION\----- .....
Operation at Best Economy mixture is not recommended
until oil consumption stabilizes or during the first
50 hours of operation. The purpose of this interval
of operation at higher power levels (65% to 75% of
maximum normal operations power) is to insure proper
seating of the rings and is applicable to new
engines, and engines in service following cylinder
replacement or top overhaul of one or more cylin-
ders.
When leaning, accompl ish the procedure as precisely as possible. A
little extra effort in setting the mixtures will yield significant divi-
dends.
I
For normal cruise conditions, your cruise computer should be utilized to
set the fuel flows. The cruise computer is based On indicated OAT, there-
fore, the ram ri se does not have to be subtracted. The crui se computer is
marked with two fuel flow scales. These scales are provided to insure that
you can obtain the maximum perfonnance and utilization from your airplane.
The inner fuel flow scale (marked Recommended Lean) should be utilized for
all nonnal 'cruise performance. Data shown in Section 5 are based on
Recommended Lean mixture. The outer fuel flow scale (marked Best Power)
will provide maximum speed for a given power setting. The speed will be
approximately two knots greater than the speed with Recommended Lean mix-
Iture.
1 November 1979