Maintenance Manual STEMME S10-VT
Date of Issue: Jan. 01, 1998
Page 7-21.2
Amendment Nr. 8
Date: Nov. 11, 1999
A4011121_B23.doc
Doc. No. A40-11-121
7.4.10.7 Checking of Pitch Control and Adjusting the Variable Pitch Propeller
The basic setting of the blade-angle is performed by the manufacturer or by a facility or FBO
authorised by the manufacturer to perform major repairs on the variable pitch propeller.
The propeller unit must be positioned in the take-off setting. Check to confirm that the pitch control
mechanism is at the stop in the take-off setting by pressing the half opened propeller blade to the rear
(against the direction of flight), so that the expanding element (15) is completely compressed. No relevant
further movement in the direction of fine pitch should be possible.
Check the propeller pitch angle for take-off with a precision protractor with a nonius scale. Turn the
propeller to an approx. vertical position, place the static arm of the protractor to the lower left on the gear
base-plate, rotate the movable arm to an approx. Vertical position, then rotate the propeller clockwise until
both fork cheeks are in their operating position (see Fig. 3.4.10 c). Lock protractor and read off result. The
setting angle is - 2
30’
5’. The acceptable difference in blade angle settings of both blades is 10’.
Precision adjustment of the propeller pitch (e. g. to achieve correspondence between both propeller
blades) is accomplished by means of two adjustment screws (25). During adjustment, the drive lever is
only set loosely (M5 screw and M8 nut are not fully tightened).
Tighten the M5 bolt and the M8 nut. Tighten the adjustment screw and counter. Check tightening torque of
the M8 nut (20 Nm / 14.7 lbf) with a torque wrench. Re-check the setting angle and secure adjustment
screw with safety lock wire.
Check the pitch control mechanism for ease of operation. Therefor swivel both blades out by 90 against
the fork and then pull on the blades near the tip to the front without using too much force. The blades must
be easily brought into cruise position and, after releasing them, the spring tension must return the blades
to the stop in the take-off position.
Activate the pitch control mechanism
(Master switch “ON”) by pressing the push button at the front
bulkhead for 3 to 4 minutes until the cruise position is reached (fly-weights (19) are forced against the
stop).
Hold the push button (2
nd
person) and check the pitch angle of the propeller blades in the cruise setting
(the method corresponds to measuring the take-off setting). The rated value is 3
54’
10’.
Due to design, after successfully having adjusted the take-off setting, the cruise setting must be within the
permissible limits. If this cannot be achieved, damage or excessive wear may be presumed. In this case,
repair must be performed by the manufacturer or by a facility or an FBO authorised by the manufacturer.
