Piper Cherokee Six 300 Information Manual page 75

CHEROKEE SIX - 3OO
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 feet altitude and at pilot's discretion at lower altitudes when 7 57o 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 rnixture, disengage lockr and pull the mixture control until the engine
becomes rough, indicating that the lean mixture limit has been reached in the leaner cylinders.
Then enrich the mixture by pushing the control towards the instrument panel until engine
operation becomes smooth. The fuel flow meter will give a close approximation of the fuel
being consumed.
If the airplane is equipped with the optional exhaust gas temperature (EGT) gauge, a more
accurate means of leaning is available to the pilot. Fbr this procedure, refer to the
"Avco-Lycoming Operator's Manual."
ln order to keep the airplane in best lateral trim during cruise flight, the fuel should be
used alternately from each main tank, and when these are nearly exhausted, from each tip tank.
It is recommended that one main tank be used for one hour after takeoff, the other main tank
used until nearly exhausted, then retum to the first main tank. When nearly exhausted, turn to
one tip tank and alternate at one-half hour intervals to maintain lateral trim.
The following listing contains, as a reminder, a few of the more highly recommended fuel
operation procedures:
l. Fuel quantity should be visually checked in all fuel tanks before entering the aircraft.
2. After using the undeneat quick drain, it should be checked from outside the aircraft
to make sure it has closed completely, and is not leaking.
3. Takeoff should be mide on the tank with the highest quantity of fuel to assure best
fuel flow, and this tank selected before or immediately after starting in order to allow
fuel flow to be adequately established before takeoff. The tank with the highest
quantity of fuel strould be selected for landing.
Fuel tank selection at low altitude is not recommended, since little recovery time is
available in the event of an elTor in tank selection. When switching tanks, make sure
that the selector drops into a detent, and is lined up with the desired tank.
The electric fuel pump should be turned on before switching tanks, and should be left
on for a short period thereafter.
To preclude making a hasty selection, and to provide continuity of flow, the selector
should be changed to another tank before fuel is exhausted from the tank in use.
Operation of the engine driven fuel pump should be checked while taxiing or during
pretakeoff engine run up by switching off the electric fuel pump and observing fuel
pressure.
During cruise, the electric fuel pump should be in the off position so that any
malfunction of the engine driven fuel pump is immediately apparent.
If signs of fubl starvation should occur at any tirne during flight, fuel exhaustion
should be suspected, at which time the fuel selector should be immediately positioned
to a full tank and the electric fuel pump switched to the on position,
When the seventh seat is used, all weight in excess of 3l 12 pounds must be in fuel
weight only. Fill tip tanks first and use fuel from main tanks first.
*Serial nos. 7540001 and up
OPERATING INSTRUCTIONS
REVISED: JUNE 20.1974
4.
5.
6 .
7.
8 .
9 .
10 .
7-7