Piper ARCHER III Pilot Operating Handbook page 188

SECTION7
DESCRIPTION & OPERATION
7.7 INDUCTION SYSTEM
The induction system incorporates an Avstar RSA-SAD I type fuel injector.
The injector is based on the principle of differential pressure, which balances
air pressure against fuel pressure. The regulated fuel pressure established by the
servo valve when applied across a fuel control (jett i ng system) makes the fuel
flow proportional to airflow. Fuel pressure regulation by the servo valve causes a
minimal drop in fuel pressure throughout the metering system. Metering pressure
is maintained above most vapor forming conditions while fuel inlet pressure is
low enough to allow use of a diaphragm pump. The servo system feature also
checks vapor lock and associated starting problems.
The fuel injection servo meters fuel tlow proportionally with airflow and
maintains the mixture as manually set for all engine speeds. The fuel flow divider
receives metered fuel and distributes fuel to each cylinder fuel nozzle.
The induction airbox assembly contains a valve that can open and allow
airflow into the engine in the event of blockage of the primary induction air
source. The air provided through the alternate air source is heated, which will
also provide induction system icing protection. As this alternate air source is not
filtered, the primary air source should always be used for takeoff.
Control of the alternate air valve is through a lever located to the right of the
engine control lever quadrant.
The pilot should read and follow the procedures recommended in the
engine Operator's Manual for this engine, in order to obtain maximum engine
efficiency and time between engine overhauls.
7.9 ENGINE CONTROLS
Engine controls consist of a throttle control and a mixture control lever.
These controls are located on the control quadrant on the lower center of the
instrument panel (Figure 7-1) accessible by the pilot and the copilot. The control
cables are teflon-lined to reduce friction and binding.
The throttle lever is used to adjust engine RPM. The mixture control lever
is used to adjust the air to fuel ratio. The engine is shut down by the placing the
mixture control lever in the full lean position. See Section 4 of this handbook for
proper leaning procedure.
REPORT: VB-2749
7-2
PA-28-181, ARCHER ill
ISSUED: December 22, 2017
REVISED: March 9, 2021
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