Installation & Operation Manual
O-360 and IO-360 Series Engines
4 Chapter 3 • Aircraft / Engine
© March 2004 Superior Air Parts Inc. Integration Considerations
3. FUEL SYSTEM
The fuel system design can significantly effect
both performance and longevity of an aircraft
engine installation. In addition to the obvious
performance aspects, fuel systems that limit the
fuel supply can promote engine detonation and
vapor lock. Un-damped and extreme pressure
pulsations can cause malfunction of the fuel
metering systems.
A. Fuel System Requirements and Filtration
Superior Vantage Engines are supplied with
positive displacement fuel pumps that are
directly driven by the engine. These pumps are
designed to provide the appropriate flow and
pressure to the fuel metering devices according
to their requirements. The aircraft fuel system
should be capable of providing at least twice the
maximum engine fuel flow requirements to
minimize the potential for vapor formation. The
fuel flow requirements are defined in Table 1 of
the Model Specification Data.
The flow of fuel must be vapor free, water free
and filtered to be free of foreign objects or
debris. The foreign object filter requirements are
defined in Table 2 of the Model Specification
Data.
B. General Fuel System Design
The aircraft fuel system should be designed so
flow restrictions do not occur in the piping
system. Flow restrictions in this context refer to
system conditions such as sharp radius bends,
abrupt changes in pipe diameter (larger or
smaller), tee and other fittings, valves, etc. In
addition to limiting maximum fuel flow, flow
restrictions increase the potential for vapor
formation. Vapor formation, if extreme can
cause engine stoppage due to lack of fuel.
Vapor formation in a minimal degree can cause
lean operation of the engine that can lead to
improper operation, service ceiling restrictions or
engine detonation under certain conditions.
Note:
When running fuel lines for use with
unleaded fuel, do not use 90° fittings. Instead,
use large radius bends to reduce the likelihood
of vapor lock. Also, try to locate the fuel boost
pump as close to the fuel tank as possible.
Periodically inspect non-metallic fuel system
components for degradation.
Aircraft boost pumps (non-engine driven) may
be used to supplement fuel flow to the engine
driven fuel pump, prevent vapor lock and aid in
priming of fuel injected systems. The maximum
inlet pressure allowable at the engine driven fuel
pump is defined in Table 3 of the Model
Specification Data. Although the use of aircraft
boost pumps are not required for engine
operation (other than priming of fuel injection
systems), Superior Air Parts recommends their
use as a backup to the engine driven fuel pump
and as an aid in preventing vapor lock,
particularly when using motor gasoline. The fuel
system should be designed such that the
minimum acceptable fuel pressure is available to
the engine driven fuel pump at all times without
the use of an aircraft boost pump. The minimum
acceptable fuel pressure is defined in Table 3 of
the Model Specification Data. In addition, the
fuel system should be capable of providing at
least 150% the maximum required flow of fuel to
the engine driven fuel pump without the need for
an aircraft boost pump. (See Table 1 of the
Model Specification Data.)
Fuel tanks should be vented to the atmosphere
to prevent vacuum formation in the fuel tanks. If
un-vented, the pressure in the fuel tank (as fuel
is consumed) can reduce to the point that the
pressure available at the pump inlet is below the
cavitation limit of the pump. In this case,
cavitation can occur and engine stoppage due to
fuel starvation is possible.
Superior Air Parts recommends the use of fuel
flow meters as an aid to the pilot for proper
engine management. Two types of fuel flow
meters are available for use in such systems;
those that indicate flow based upon sensed
pressure and those that sense flow directly.
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