Turbocharger System; Ignition System; Fuel System - Continental Motors TSIO-520-BE Maintenance And Operator's Manual

3-6 TURBOCHARGER SYSTEM
The function of the turbocharger system is to maintain a desired manifold pressure at a given throttle
setting, regardless of varying conditions of ambient air temperature and pressure.
The complete turbocharger system consists of two turbines and compressor assemblies, wastegate
assembly, a sloped pressure controller, two sonic venturi, and necessary hose, linkage and ducting required
for a functional installation.
(2) sonic venturis permit the restricted flow of compressor air for aircraft cabin pressurization. When air flow
through the unit reaches approximately 5 pounds per minute each, it becomes critical; that is, 5 pounds per
minute each is the maximum flow the sonic venturi will permit regardless of pressure at the inlet. When air
from the sonic venturis is not used for cabin pressurization, the air is bled into the nacelle.
3-7 IGNITION SYSTEM
Conventual twin ignition is provided by two magnetos. The left magneto fires the 1-3-5 lower and 2-4-6 upper
spark plugs, while the right magneto fires the 1-3-5 upper and 2-4-6 lower spark plugs.
Torque from the engine crankshaft is transmitted to the camshaft gear, driving the camshaft and propeller
governor gears on the opposite end. The idler gear assembly is also driven by torque from the crankshaft
which drives the magneto drive gears. The magneto drive gear incorporates rubber bushings that engage
the magneto impulse coupling. As the rubber bushings in the drive gear turns the coupling drive lugs,
counterweighted latch pawls, inside the coupling cover, engage a pin on the magneto case and hold back
the latch plate until it is forced inward by the coupling cover. When the latch plate is released, the coupling
spring spins the magneto shaft through its neutral position and the breaker opens to produce a high voltage
surge in the secondary coil. The spring action permits the latch plate, magneto and breaker to be delayed
through a lag angle of 30 degrees to drive gear rotation during the engine cranking period. Two stop pins
in the case and two lobes on the breaker cam produce two sparks per revolution of the drive shaft. After
the engine is started, counterweights hold the latch pawls clear of the stop pins and the magnet shaft is
driven in full advance.
3-8 FUEL SYSTEM
The fuel injection system is of the multi-nozzle, continuous-flow type which controls fuel flow to match engine
requirements. Any change in air throttle position, engine speed, deck pressure, or a combination of these
causes changes in fuel pressure in the correct relation to the engine requirements. As fuel flow is directly
proportional to metered fuel pressure, settings can be predetermined and fuel consumption can be
accurately predicted and controlled.
The continuous-flow system permits the use of a typical rotary vane pump with integral relief valve. With the
system there is no need for an intricate mechanism for timing injection to the engine.
The fuel pump is a two stage, vane-type of advanced design which has improved vapor suppression
characteristics and performs well at high altitude and at low inlet conditions. It is driven directly by the engine
and its flow rate depends on engine RPM. An aneroid unit is incorporated as an integral part of the pump
and functions to increase pump output during high manifold pressure operation. The fuel pump forces liquid
fuel into the fuel-metering control assembly.
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