Maintenance Manual STEMME S10-VT
Date of Issue: Jan. 01, 1998
Page 3-40
Amendment Nr. 14
Date: Nov. 30. 2007
A4011121_B23.doc
Doc. No. A40-11-121
Auxiliary Fuel Pump Switch
:
The auxiliary fuel pump switch is installed on the switch plate in the centre instrument panel. In position ON, it
closes the circuits of the aux pumps selected by the Fuel Selector Switch. At the same time, position ON
energises the green status light (ref. to section 3.7.9), indicating operation of the aux fuel pumps.
Fuel Selector Switch
:
The Fuel Selector Switch is a two level switch controlling both, main and aux pumps. It has the positions
"LEFT", "BOTH" and "RIGHT" and connects the respective main pumps to the internal generator and the
respective aux pumps to the Engine Bus 3VV.
Electric Master Switch
:
When the Master Switch (two levels) is selected ON, the main relay is activated, connecting Battery Bus
(1VV) to Main Bus (2VV). The second level of the Master Switch connects the additional battery (if
installed) to the Main Avionic Bus (4VV-1). If the engine is running and the external generator energises
the Generator Bus (5VV), this connects the additional battery and the Main Avionic Bus (4VV-1) to the
Main Bus (2VV). These functions are for position UP of the Avionic/Battery switch. This logic is realised
with three relays. The electric Master Switch is installed on the switch plate on the centre instrument
panel.
External Generator Switch
:
With this switch, the external generator is connected or disconnected to the a/c electric system. Generator
output and exciter coil are simultaneously engaged by two relays. With the Generator Switch the control
circuits of the two relays are activated simultaneously. The Generator Switch is in series with the dome
locking limit switch, so the generator can only be connected in powered-configuration and is deselected
automatically in glider-configuration.
Engine-Backup Switch
:
The Engine-Backup switch is installed on the switch plate in centre instrument panel. With this switch, the
engine master limit switch can be bypassed in case of malfunction of the engine starter due to malfunction
of the engine master limit switch. The engine master limit switch is operated by the propeller-dome lever
and connects the engine bus to the main bus in the open and locked propeller dome position. If the engine
instruments do not indicate after opening and locking the propeller dome, a malfunction of the engine
master limit switch is probably the reason. In this case, the Engine Bus can be connected directly to the
Main Bus by switching the Engine-
Backup switch „ON“.
The Engine-Backup switch is protected by a black safety plate against unintended operation.
TCU Emergency Switch
The TCU Emergency Switch is installed on the switch plate in the centre instrument panel to switch off the
wastegate actuator in case of a TCU malfunction.
(Refe
r to "Maintenance Manual (Heavy Maintenance) for ROTAX Engine Types ROTAX 912 and 914 Series”,
section 76)
If the turbocharger-wastegate, controlled by TCU and actuated by a servo actuator, starts oscillating, a stable
operation normally can be restored by switching the TCU Emergency Switch to its upper position,
separating the servo motor from the TCU, and a few seconds later re-connect TCU and servo by
switching the TCU Emergency Switch back to the lower position. After separation of TCU and servo, the
servo actuator maintains in the last position prior to operating the switch. After re-connecting TCU and
servo, the TCU performs a self-test and after that normally operates properly.
The TCU Emergency Switch is protected by a red safety plate against unintended operation.
Engine Master Limit Switch
:
The Engine Master Limit Switch is a micro switch, controlled by the propeller dome handle. It is installed at
the drive shaft tunnel below the centre instrument panel and is actuated by the control rod of the handle.
The Engine Master Limit Switch has two levels. One level is to select the control circuit of a relay, which
connects the Engine Bus 3VV and the Main Bus 2VV. The second level switches the control circuit of the
generator relay. This design ensures that, when locking or unlocking the propeller-dome handle, the
generator relay and the Engine Bus are switched simultaneously.
