STEMME S12 User Manual

DOCUMENT NUMBER:
L500-912.820 ISSUE JUL 20, 2016
AMENDMENT: 00
DATE: 
CHAPTERPAGE 736
MAINTENANCE MANUAL STEMME S12
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 capacitors.
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
pushing the test 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) against 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 and check several times). Finally, secure
contact screw.
Adjusting the take-o setting switch: allow the elements to cool down and check that the pitch
change mechanism is at the stop in the take-o setting by pressing the half opened propeller
blade to the rear, completely compressing the expansion element (15). The contact bolt protrud-
ing approx. 35 mm / 1.38 in out of the switch socket should be adjusted so that there is only light
contact between the at lower surface of the bolt head and the contact spring (14), tted at
the rocker arm (check with ohmmeter or with the take-o 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),
secure with lock nut and secure with sealing paint.
Check of the take-o setting indicator: the take-o setting indicator in the cockpit must illuminate
when the propeller is in the take-o setting. If the propeller is moved 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 forward), the take-o setting indicator must extinguish within a small change
in angle.

STEMME S12 Specifications

General

Brand	STEMME
Model	S12
Category	Aircrafts
Language	English