BEFORE TAKE-OFF.
WARM-UP.
Most of the warm-up will have
been
conducted during taxi, and addi
tional warm-up before take-off should be restricted to the checks out
lined in Section
I.
Since the engine is closely cowled for efficient in-flight
cooling, precautions should
be
taken to avoid overheating on
t:!i
e ground.
MAGNETO CHECK.
The magneto check should be made at
1700
RPM as follows: Move the
ignition switch first to "R" position and note RPM. Then move switch
back to
"BOTH"
position to clear the other set of plugs. Then move
switch to
"L"
position and note RPM. The difference between the two
magnetos operated individually shouldnot be more than
75
RPM.
If
there is a doubt concerning the operation
of
the ignition system, RPM
checks at higher engine speeds will usually confirm whether a deficiency
exists.
An absence of RPM drop may be an indication of faulty grounding of
one side of the ignition system or should be cause for suspicion that the
magneto timing is set in advance of the setting specified.
TAKE-OFF.
POWER CHECKS.
It is important to check full-throttle engine operation early in the take
off run. Any signs of rough engine operation or sluggish engine accelera
tion is good cause for discontinuing the take-off.
If
this occurs, you are
justified in making a thorough full-throttle, static runup before another
take-off is attempted. The engine should run smoothly and turn approxi
mately
2500
to
2600
RPM with carburetor heat off.
Full throttle runups over loose gravel are especially harmful to pro
peller tips. When take-offs must be made over a gravel surface, it is
very important that the throttle be advanced slowly. This allows the air
plane to start rolling before high RPM is developed, and the gravel will
be blown back of the propeller rather than pulled into it. When unavoid-
2-8
