SECTION 4
PA-28-181, ARCHER III NORMAL PROCEDURES
4.27 CRUISING
The cruising speed of the ARCHER III is determined by many factors,
including power setting, altitude, temperature, loading and equipment
installed in the airplane.
The normal maximum cruising power is 75% of the rated horsepower of
the engine. Airspeeds which may be obtained at various altitudes and power
settings can be determined from the performance graphs provided by
Section 5.
Use of the mixture control in cruising flight reduces fuel consumption
significantly, especially at higher altitudes. The mixture should be leaned
during cruising operation above 5000 ft. altitude and at pilot’s discretion at
lower altitudes when 75% power or less is being used. If any doubt exists as to
the amount of power being used, the mixture should be in the full RICH
position for all operations under 5000 feet.
To lean the mixture, disengage the lock and pull the mixture control
back.
Best economy mixture is obtained by slowly leaning the mixture until
engine operation becomes rough or until engine power rapidly diminishes.
When either condition occurs, enrich the mixture sufficiently to obtain an
evenly firing engine. Some engine power and airspeed must be sacrificed to
gain a best economy mixture setting.
Best power mixture is obtained by gradually leaning the mixture until
either the tachometer or the airspeed indicator reading peaks.
If the airplane is equipped with the optional exhaust gas temperature
(EGT) gauge, a more accurate means of leaning is available to the pilot. Best
economy mixture is obtained by moving the mixture control aft until peak
EGT is reached. Best power mixture is obtained by leaning to peak EGT and
then enrichening until the EGT is 100F. rich of the peak value. Under some
conditions of altitude and throttle position, the engine may exhibit
roughness before peak EGT is reached. If this occurs, the EGT
corresponding to the onset of engine roughness should be used as the peak
reference value.
Always remember that the electric fuel pump should be turned ON
before switching tanks, and should be left on for a short period thereafter. In
order to keep the airplane in best lateral trim during cruising flight the fuel
should be used alternately from each tank. It is recommended that one tank
be used for one hour after takeoff, then the other tank be used for two hours;
then return to the first tank, which will have approximately one and one half
hours of fuel remaining if the tanks were full at takeoff. The second tank will
contain approximately one half hour of fuel. Do not run tanks completely
dry in flight. The electric fuel pump should be normally OFF so that any
ISSUED: JULY 12, 1995 REPORT: VB-1611
4-23
SECTION 4
PA-28-181, ARCHER III NORMAL PROCEDURES
4.27 CRUISING
The cruising speed of the ARCHER III is determined by many factors,
including power setting, altitude, temperature, loading and equipment
installed in the airplane.
The normal maximum cruising power is 75% of the rated horsepower of
the engine. Airspeeds which may be obtained at various altitudes and power
settings can be determined from the performance graphs provided by
Section 5.
Use of the mixture control in cruising flight reduces fuel consumption
significantly, especially at higher altitudes. The mixture should be leaned
during cruising operation above 5000 ft. altitude and at pilot’s discretion at
lower altitudes when 75% power or less is being used. If any doubt exists as to
the amount of power being used, the mixture should be in the full RICH
position for all operations under 5000 feet.
To lean the mixture, disengage the lock and pull the mixture control
back.
Best economy mixture is obtained by slowly leaning the mixture until
engine operation becomes rough or until engine power rapidly diminishes.
When either condition occurs, enrich the mixture sufficiently to obtain an
evenly firing engine. Some engine power and airspeed must be sacrificed to
gain a best economy mixture setting.
Best power mixture is obtained by gradually leaning the mixture until
either the tachometer or the airspeed indicator reading peaks.
If the airplane is equipped with the optional exhaust gas temperature
(EGT) gauge, a more accurate means of leaning is available to the pilot. Best
economy mixture is obtained by moving the mixture control aft until peak
EGT is reached. Best power mixture is obtained by leaning to peak EGT and
then enrichening until the EGT is 100F. rich of the peak value. Under some
conditions of altitude and throttle position, the engine may exhibit
roughness before peak EGT is reached. If this occurs, the EGT
corresponding to the onset of engine roughness should be used as the peak
reference value.
Always remember that the electric fuel pump should be turned ON
before switching tanks, and should be left on for a short period thereafter. In
order to keep the airplane in best lateral trim during cruising flight the fuel
should be used alternately from each tank. It is recommended that one tank
be used for one hour after takeoff, then the other tank be used for two hours;
then return to the first tank, which will have approximately one and one half
hours of fuel remaining if the tanks were full at takeoff. The second tank will
contain approximately one half hour of fuel. Do not run tanks completely
dry in flight. The electric fuel pump should be normally OFF so that any
ISSUED: JULY 12, 1995 REPORT: VB-1611
4-23
REVISED: FEBRUARY 5, 2010
REVISED: FEBRUARY 5, 2010
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