Chapter 11. Safety, Ground Operations, & Servicing
Ground Movement of Aircraft
Engine Starting and Operation
The following instructions cover the starting procedures
for reciprocating, turboprop, turbofan, and
auxiliary power units (APU). These procedures are
presented only as a general guide for familiarization
with typical procedures and methods. Detailed instructions
for starting a specific type of engine can be found
in the manufacturer’s instruction book.
Before starting an aircraft engine:
- Position the aircraft to head into the prevailing
wind to ensure adequate airflow over the engine
for cooling purposes.
- Make sure that no property damage or personal
injury will occur from the propeller blast or jet
exhaust.
- If external electrical power is used for starting,
ensure that it can be removed safely and it is
sufficient for the total starting sequence.
- During any and all starting procedures, a “fireguard"
equipped with a suitable fire extinguisher shall be
stationed in an appropriate place. A fireguard is
someone familiar with aircraft starting procedures.
The fire extinguisher should be a CO2 extinguisher
of at least 5-pound capacity. The appropriate place
is adjacent to the outboard side of the engine,
in view of the pilot, and also where he or she
can observe the engine/aircraft for indication of
starting problems.
- If the aircraft is turbine engine powered, the area in
front of the jet inlet must be kept clear of personnel,
property, and/or debris (FOD).
- These “before starting" procedures apply to all
aircraft powerplants.
- Follow manufacturer’s checklists for start procedures
and shutdown procedures.
Reciprocating Engines
The following procedures are typical of those used to
start reciprocating engines. There are, however, wide
variations in the procedures for the many reciprocating
engines. No attempt should be made to use the
methods presented here for actually starting an engine.
Instead, always refer to the procedures contained in the
applicable manufacturer’s instructions.
Reciprocating engines are capable of starting in fairly
low temperatures without the use of engine heating
or oil dilution, depending on the grade of oil used.
The various covers (wing, tail, cockpit, wheel, and so
forth) protecting the aircraft must be removed before
attempting to turn the engine. External sources of
electrical power should be used when starting engines
equipped with electric starters, if possible or needed.
This eliminates an excessive burden on the aircraft
battery. All unnecessary electrical equipment should
be left off until the generators are furnishing electrical
power to the aircraft power bus.
Before starting a radial engine that has been shut down
for more than 30 minutes, check the ignition switch
for off; turn the propeller three or four complete revolutions
by hand to detect a hydraulic lock, if one is
present. Any liquid present in a cylinder is indicated
by the abnormal effort required to rotate the propeller,
or by the propeller stopping abruptly during rotation.
Never use force to turn the propeller when a hydraulic
lock is detected. Sufficient force can be exerted on the
crankshaft to bend or break a connecting rod if a lock
is present.
To eliminate a lock, remove either the front or rear
spark plug from the lower cylinders and pull the propeller
through. Never attempt to clear the hydraulic
lock by pulling the propeller through in the direction
opposite to normal rotation. This tends to inject the
liquid from the cylinder into the intake pipe. The
liquid will be drawn back into the cylinder with the
possibility of complete or partial lock occurring on
the subsequent start.
To start the engine, proceed as follows:
- Turn the auxiliary fuel pump on, if aircraft is so
equipped.
- Place the mixture control to the position recommended
for the engine and carburetor combination
being started. As a general rule, the mixture
control should be in the “idle cut-off" position
for fuel injection and in the “full rich" position
for float-type carburetors. Many light aircraft are
equipped with a mixture control pull rod which has
no detent intermediate positions. When such controls
are pushed in flush with the instrument panel,
the mixture is set in the “full rich" position. Conversely,
when the control rod is pulled all the way
out, the carburetor is in the “idle cut-off" or “full
lean" position. The operator can select unmarked
intermediate positions between these two extremes
to achieve any desired mixture setting.
- Open the throttle to a position that will provide
1,000 to 1,200 rpm (approximately 1/8 to 1/2 inch
from the “closed" position).
- Leave the pre-heat or alternate air (carburetor air)
control in the “cold" position to prevent damage
and fire in case of backfire. These auxiliary heating
devices should be used after the engine warms up.
They improve fuel vaporization, prevent fouling of
the spark plugs, ice formation, and eliminate icing
in the induction system.
- Move the primer switch to “on" intermittently
(press to prime by pushing in on the ignition switch
during the starting cycle), or prime with one to
three strokes of priming pump, depending on how
the aircraft is equipped. The colder the weather,
the more priming will be needed.
- Energize the starter after the propeller has made
at least two complete revolutions, and turn the
ignition switch on. On engines equipped with an
induction vibrator (shower of sparks, magneto
incorporates a retard breaker assembly), turn the
switch to the “both" position and energize the
starter by turning the switch to the “start" position.
After the engine starts, release the starter switch
to the “both" position. When starting an engine
that uses an impulse coupling magneto, turn the
ignition switch to the “left" position. Place the
start switch to the “start" position; when the engine
starts, release the start switch. Do not crank the
engine continuously with the starter for more than
1 minute. Allow a 3- to 5-minute period for cooling
the starter (starter duty cycle) between successive
attempts. Otherwise, the starter may be burned out
due to overheating.
- After the engine is operating smoothly, move the
mixture control to the “full rich" position if started
in the “idle cutoff" position. Carbureted engines
will already be in the rich mixture position. Check
for oil pressure.
Instruments for monitoring the engine during operation
include a tachometer for rpm, manifold pressure
gauge, oil pressure gauge, oil temperature gauge, cylinder
head temperature gauge, exhaust gas temperature
gauge and fuel flow gauge.
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