DOCUMENT NUMBER:
L500-912.820 ISSUE JUL 20, 2016
AMENDMENT: 00
DATE:
CHAPTERPAGE 319
MAINTENANCE MANUAL STEMME S12
3.4.7 ENGINE CONTROLS AND INSTRUMENTATION
REFER ALSO SECTION 3.2.2
The throttle and choke are operated by Bowden cables, linking the carburetors with the cockpit
levers, which have adjustable friction control. The throttle and choke lever are installed in the
center console between the pilots. The throttle lever has two stops, one for the 100% (max con-
tinuous) power position and one for the 115% (max takeo) power position.
Engine cooling is controlled by the cowl aps, opened and closed by a linkage to the nose-cone
handle. In addition, the cowl ap aperture can be reduced in ve steps by the cowl ap operation
handle on the instrument panel (see section 3.4.3).
Both engine ignition and engine starter are controlled by a key switch. A special feature is a
three-second ignition delay after switching the key to position “START”, to allow the propeller
blades to unfold before engine ignition (see section 3.7.11).
The engine instruments are located on the RH instrument panel.
For positions and function of switches and instruments, refer to section 3.2.2 and 3.7.
3.4.8 FIRE PROTECTION
The engine including exhaust and induction system is isolated from the front, top and rear areas
by rewalls. The rewalls consist of stainless steel sheets (thickness 0.38 mm / 0.015 in).
The insides of the engine cowlings on the LH and RH side of the engine and below the engine
are coated with a re-protective painting (manufacturer: Courtaulds Aerospace). It consists of
three coats of a white re resistant paint (type N 56582/T508) and one coat of clear varnish (type
4232-0303, hardener N39-1327 or N50/2509, thinner N39-3091).
The fuel and oil hoses in the engine compartment are covered by re-protective sleeves.
The re warning system is triggered by two bimetallic temperature sensors above the carburetors.
The re warning is by means of a red warning light (push-to-test function) on the instrument
panel, combined with an acoustic warning tone via the loudspeaker.
3.4.9 ENGINE COWLINGS
COWL FLAPS: REFER TO SECTION 3.4.3
The engine cowling consists of three, (LH, RH and lower) parts. The cowlings are self-supporting
and connected to the fuselage structure forward and aft by means of camlocks.
The LH and RH cowlings are each fastened to the structure by 5 camlocks. Each includes an inlet
cowl ap and air duct assy.
The cooling air duct of the LH cowling maintains a gap of approx. 5 mm / 0.19 in to the radiator
with the cowling installed, to allow for relative motion.
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