Cessna 208B - Overspeed Governor Test Switch

CESSNA SECTION 7
MODEL 2088 (675 SHP) AIRPLANE AND SYSTEMS DESCRIPTION
PROPELLER (Continued)
Reversed propeller pitch is available for decreasing ground roll during
landing. To accomplish reverse pitch, the power lever is retarded
beyond IDLE and well into the BETA range. Maximum reverse power is
accomplished by retarding the power lever to the MAX REVERSE
position which increases power output from the gas generator and
positions the propeller blades at full reverse pitch. An externally
grooved feedback ring is provided with the propeller.
Motion of the feedback ring is proportional to propeller blade angle, and
is picked up by a carbon block running in the feedback ring. The
relationship between the axial position of the feedback ring and the
propeller blade angle is used to maintain control of blade angle from
idle to full reverse.
CAUTION
OVERSPEED GOVERNOR TEST SWITCH
An overspeed governor test switch is located on the left side of the
instrument panel. The switch is the push-to-test type and is used to test
the propeller overspeed governor during engine run-up. The switch,
when depressed, actuates a solenoid on the propeller overspeed
governor which restricts propeller RPM when the power lever is
advanced. To check for proper operation of the overspeed governor,
during engine run-up, depress the press-to-test switch and advance the
power lever until propeller RPM stabilizes; propeller RPM should not
exceed
1750 +I- 60 RPM.
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- I Revision 23
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U.S. 7-69