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Airplane Flying Handbook
Transition to Multiengine Airplanes
OPERATION OF SYSTEMS

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Airplane Flying Handbook

Preface

Table of Contents

Chapter 1,Introduction to Flight Training
Chapter 2,Ground Operations
Chapter 3,Basic Flight Maneuvers
Chapter 4, Slow Flight, Stalls, and Spins
Chapter 5, Takeoff and Departure Climbs
Chapter 6, Ground Reference Maneuvers
Chapter 7, Airport Traffic Patterns
Chapter 8, Approaches and Landings
Chapter 9, Performance Maneuvers
Chapter 10, Night Operations
Chapter 11,Transition to Complex Airplanes
Chapter 12, Transition to Multiengine Airplanes
Chapter 13,Transition to Tailwheel Airplanes
Chapter 14, Transition to Turbo-propeller Powered Airplanes
Chapter 15,Transition to Jet Powered Airplanes
Chapter 16,Emergency Procedures

Glossary

Index

The aerodynamic forces alone acting upon a windmilling
propeller tend to drive the blades to low pitch,
high r.p.m. Counterweights attached to the shank of
each blade tend to drive the blades to high pitch, low
r.p.m. Inertia, or apparent force called centrifugal force
acting through the counterweights is generally slightly
greater than the aerodynamic forces. Oil pressure from
the propeller governor is used to counteract the counterweights
and drives the blade angles to low pitch,
high r.p.m. A reduct ion in oil pressure causes the r.p.m.
to be reduced from the influence of the counterweights.
[Figure 12-4]

To feather the propeller, the propeller control is
brought fully aft. All oil pressure is dumped from the
governor, and the counterweights drive the propeller
blades towards feather. As centrifugal force acting on
the counterweights decays from decreasing r.p.m.,
additional forces are needed to completely feather the
blades. This additional force comes from either a
spring or high pressure air stored in the propeller
dome, which forces the blades into the feathered position.
The entire process may take up to 10 seconds.

Feathering a propeller only alters blade angle and stops
engine rotation. To completely secure the engine, the
pilot must still turn off the fuel (mixture, electric boost
pump, and fuel selector), ignition, alternator/generator,
and close the cowl flaps. If the airplane is pressurized,
there may also be an air bleed to close for the failed
engine. Some airplanes are equipped with firewall
shutoff valves that secure several of these systems
with a single switch.

Completely securing a failed engine may not be necessary
or even desirable depending upon the failure
mode, altitude, and time available. The position of the
fuel controls, ignition, and alternator/generator
switches of the failed engine has no effect on aircraft
performance. There is always the distinct possibility
of manipulating the incorrect switch under conditions
of haste or pressure.

To unfeather a propeller, the engine must be rotated
so that oil pressure can be generated to move the
propeller blades from the feathered position. The
ignition is turned on prior to engine rotation with the
throttle at low idle and the mixture rich. With the
propeller control in a high r.p.m. position, the starter
is engaged. The engine will begin to windmill, start,
and run as oil pressure moves the blades out of
feather. As the engine starts, the propeller r.p.m.
should be immediately reduced until the engine has
had several minutes to warm up; the pilot should
monitor cylinder head and oil temperatures.

Should the r.p.m. obtained with the starter be insufficient
to unfeather the propeller, an increase in airspeed
from a shallow dive will usually help. In any event, the
AFM/POH procedures should be followed for the
exact unfeathering procedure. Both feathering and
starting a feathered reciprocating engine on the ground
are strongly discouraged by manufacturers due to the
excessive stress and vibrations generated.

Pitch change forces.
Figure 12-4. Pitch change forces.

 

12-4