force of the blades. In this case, the plug B is removed
and installed in passage C of the governor. This permits
governor oil pressure to be directed to the rear of the
cylinder, to decrease pitch. Oil pressure is directed to the
forward side of the cylinder to increase pitch. See figure
b. Installation. The following general procedures
are for governor installation:
(1) Remove all portions of old gasket from
(2) Remove nicks and burrs on governor base
and mounting pad with a fine stone, Federal Specification
SS-S-736, prior to installation.
(3) Install a new gasket every time a governor
(4) Torque mount nuts in accordance with
applicable aircraft maintenance manual.
(5) Retorque mount nuts after the first 15
minutes engine runup.
c. Rigging. The following general procedures are
for rigging the propeller governor. Refer to the applicable
maintenance manual for specific instructions.
Engine operation shall be performed by
authorized personnel only.
(1) Start engine.
(2) Perform engine run-up check With PROP
lever in the full forward position, adjust power lever until
propeller rpm stabilizes at high rpm.
(3) Next, retard PROP lever to the minimum
Adjust governor when rpm settings are not
d. Operation Checks. At the time of propeller
governor, or engine installation, the following
steps are normally taken to ensure that the
power plant will obtain takeoff rpm:
(1) During ground runup, move the throttle to
takeoff position and note the resultant rpm and manifold
(2) If the rpm obtained is higher or lower than
the takeoff rpm prescribed in the instructions of the
manufacturer, reset the adjustable stop, as shown in
figure 2-11, on the governor until the prescribed rpm is
2-15. Propeller Icing. Ice formation on a propeller
blade, in effect produces a distorted blade airfoil section
which causes a loss in propeller efficiency. Generally, ice
collects unsymmetrically on a propeller blade and
produces propeller unbalance and destructive vibration.
Icing types, anti-icing, and deicing are explained in the
a. Icing Types. The types of icing are glaze or
clear, rime, and glime or mixed. Each type is described
in the following paragraphs.
(1) Glaze ice. Glaze (or clear) ice is hard,
glossy, and heavy. This type of ice forms when, after
initial impact, the remaining liquid portion of the raindrop
flows out over the surface freezing as a smooth sheet of
(2) Rime ice. Rime ice has an irregular shape
and rough surface. It is brittle and frost-like and lighter
than glaze ice. Rime ice forms when raindrops are small.
The liquid portion remaining after initial impact freezes
rapidly before the drop has time to spread. The small
frozen droplets trap air between them giving the ice a
white, frosty appearance.
(3) Glime ice. Glime (or mixed) ice is a
mixture of glaze and rime ice. Glime ice is a hard, rough
mixture which can form rapidly. Glime ice forms when
raindrops vary in size or when liquid drops are mixed with
snow or ice particles.
b. Anti-lcing. Propeller anti-icing is normally
accomplished by spraying anti-icing fluid over the leading
edge of the propeller. The fluid is pumped from the fluid
tank through small tubes that open just outside the
propeller hub as shown in figure 2-12. The centrifugal
force of the spinning propeller spreads the fluid over the
leading edge of the blades.
Change 2 2-17