Maintenance Manual STEMME S10-VT
Date of Issue: Jan. 01, 1998
Page 7-22
Amendment Nr. 8
Date: Nov. 11, 1999
A4011121_B23.doc
Doc. No. A40-11-121
7.4.10.8 General Aspects of the Electrical Circuit
An expansion element is supplied with an electric power of 50 W through a heating resistor. The supply
period is determined mechanically by an adjustable end-contact. Overheating is prevented by an NTC-
resistor in connection with an electronic control circuit.
Components with a larger power consumption such as landing lights cannot be turned on in the cruise
setting.
Possible radio disruption caused by the slip ring contact is prevented by suppression condensers. The
generator circuit is provided with radio disturbance suppression. In the case of excessive radio disturbance,
the carbon brushes and the slip rings should be cleaned with alcohol and checked for damage.
Carbon brushes worn so that less than 10 mm / 0.39 in. Of length remains within the brush holder
should be replaced
(use only parts supplied by the manufacturer). Remove abrasion dust from slip rings
with alcohol.
The function of the electrical variable pitch propeller can be checked while the engine is shut down using the
push button at the front bulkhead. The master switch must be on.
7.4.10.9 Adjustment of the electrical switch for the take-off setting indicator and stop switch
Remove the lid of the adjusting unit and both lids of the electronic module.
Adjustment of the cruise setting stop switch: the contact screws at both rocker arms should be adjusted in a
way to ensure light pressure (0.2 mm / 0.008 in.) on the stop switch in the closed position. To achieve this,
the propeller should be put in the cruise setting with the push button. Maintaining this setting, the contact
bolts should be adjusted so that the contact screw just is in contact with the contact plate (use an ohmmeter
more than once). Finally secure contact screw.
Adjusting the take-off setting switch: allow the elements to cool down and check if the pitch change
mechanism is at the stop in the take-off setting by pressing the half opened propeller blade to the rear,
completely compressing the expansion element (15). The contact bolt protruding approx. 35 mm / 1.38 in. out
of the switch socket should be adjusted so that there is only light contact between the flat lower surface of the
bolt head and the contact spring (14), fitted at the rocker arm (check with ohmmeter or with the take-off
setting indicator in the cockpit). Then rotate the bolt 1/3 of a revolution (0.2 mm / 0.008 in.) further in (in the
direction of the contact), counter and secure with sealing paint.
Check of the take-off setting indicator: the take-off setting indicator in the cockpit must light up if the propeller
is in the take-off setting. If the propeller is reset by hand in the direction of the cruise setting (pressure should
be applied near the tip of the half unfolded propeller blade, pulling the blade to the front), the take-off setting
indicator must turn off within a small change in angle.
7.4.10.10 Dynamic Balancing
After repairing or replacing parts or carrying out maintenance on the propeller, which put the dynamic
balancing at risk (e.g. replacing or repairing the propeller blades, replacing the propeller forks, replacing the
blade coupling parts)
, the propeller must be dynamically balanced, as laid down in Manufacturer’s Instruction
A17-10AP-V/2-E (see Appendix A).
The dynamic balancing must be recorded in Appendix C of this Maintenance Manual.
