MAINTENANCE MANUAL
Page 71-20
Effectivity: All
Edition 2 | Rev. 1
AIR INTAKES
1. DESCRIPTION AND OPERATION
A. Original engine cowlings
The lower part of engine cowling is provided with the air inlets.
The two upper holes in the lower part of engine cowling serve as an air inlet for cylinder cooling
(A, Fig. 71–5). The central hole, below the hole for the propeller flange, serves as an air inlet for
the liquid cooler (B, Fig. 71–5). The NACA inlet in the middle of the lower part of engine cowling
serves as an inlet of cooling air into the oil cooler (C, Fig. 71–5). The NACA inlet on the right
side of the lower part of engine cowling serves as an air offtake for the engine air intake (D, Fig.
71–5).
B. New engine cowlings
The upper and lower part of engine cowling is provided with the air inlets, that serve as an air
inlet for cylinder cooling (A, Fig. 71–5). The central hole serves as an air inlet for the liquid
cooler (B, Fig. 71–5). The NACA inlet in the middle of the lower part of engine cowling serves
as an inlet of cooling air into the oil cooler (C, Fig. 71–5). The NACA inlet on the right side of the
lower part of engine cowling serves as an air offtake for the engine air intake (D, Fig. 71–5).
The air from the airbox enters into the air intake necks of carburettors. The airbox of a cylindrical
shape and is equipped with the flanges for connection to the carburettors, inlet necks for cold and hot
air and with the regulation flaps located in the inlet necks. The inlet of cold air is designed as the
NACA inlet (D, Fig. 71–5). The air flows from the NACA inlet through the air filter via the hose into the
airbox.
The inlet of hot air serves for carburettor preheating under the conditions specified in the POH of
Sportstar RTC airplane, Chapter 4.
The air entering the exchanger on the exhaust pipe muffler is heated here and then the air flows
through the hose into the neck for hot air intake located on the airbox. The inlet neck of the airbox are
provided with the regulation flaps. These regulation flaps allow setting the optimum ratio of hot and
cold air for carburettor preheating. The regulation flap are of a rotary type and the protruding parts of
small shafts are provided with the levers that are mutually connected by the pull-rod. The leverage is
provided with the return spring. The spring pulls the leverage of flaps to the fully opened preheating.
The right lever (inlet of hot air) is connected with the bowden string of the control. The basic setting is
a fully opened flap in the cold air inlet. By pulling the CARBURET. PREHEAT. controller on the middle
panel, the flap in the supply of cold air is being closed and simultaneously the flap in the supply of hot
air is being opened. The heated air prevents from inlet neck freezing of the carburettor, but at the
same time it reduces the engine power.
To Next Page
Loading...