Cessna Skyhawk 172N Pilot Operating Handbook page 60

SECTION 4
CESSNA
NORMAL PROCEDURES
MODEL 172N
takeoff run. Any sign of rough engine operation or sluggish engine
acceleration is good cause for discontinuing the takeoff.
If
this occurs, you
are justified in making a thorough full-throttle static runup before another
takeoff is attempted. The engine should run smoothly and turn approxi­
mately 2280 to 2400 RPM with carburetor heat off and mixture full rich.
NOTE
Carburetor heat should not be used during takeoff unless
it
is absolutely necessary for obtaining smooth engine accel­
eration.
Full-throttle runups over loose gravel are especially harmful to
propeller tips. When takeoffs must be made over a gravel surface, it is very
important that the throttle be advanced slowly. This allows the airplane to
start rolling before high RPM is developed, and the gravel will be blown
back of the propeller rather than pulled into it. When unavoidable small
dents appear in the propeller blades, they should be immediately corrected
as described in Section 8 under Propeller Care.
Prior to takeoff from fields above 3000 feet elevation, the mixture
should be leaned to give maximum RPM in a full-throttle, static runup.
After full throttle is applied, adjust the throttle friction lock clockwise
to prevent the throttle from creeping back from a maximum power
position. Similar friction lock adjustments should be made as required in
other flight conditions to maintain a fixed throttle setting.
WING FLAP SETTINGS
Normal and short field takeoffs are performed with flaps up. Flap
settings greater than 10° are not approved for takeoff.
Use of 10° flaps is reserved for takeoff from soft or rough fields. Use of
10° flaps allows safe use of approximately 5 KIAS lower takeoff speeds
than with flaps up. The lower speeds result in shortening takeoff distances
up to approximately 100/0. However, this advantage is lost if flaps up
speeds are used, or in high altitude takeoffs at maximum weight where
climb performance would be marginal with 10° flaps. Therefore, use of 10°
flaps is not recommended for takeoff over an obstacle at high altitude in hot
weather.
SHORT FIELD TAKEOFF
If
an obstruction dictates the use of a steep climb angle. after liftoff
accelerate to and climb out at an obstacle clearance speed of 59 KIAS with
flaps retracted. This speed provides the best overall climb speed to clear
4-14
1 July 1978