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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

OPERATION OF SYSTEMS

This section will deal with systems that are generally
found on multiengine airplanes. Multiengine airplanes
share many features with complex single-engine airplanes.
There are certain systems and features covered
here, however, that are generally unique to airplanes
with two or more engines.

PROPELLERS
The propellers of the multiengine airplane may outwardly
appear to be identical in operation to the
constant-speed propellers of many single-engine
airplanes, but this is not the case. The propellers of
multiengine airplanes are featherable, to minimize
drag in the event of an engine failure. Depending
upon single-engine performance, this feature often
permits continued flight to a suitable airport following
an engine failure. To feather a propeller is to stop
engine rotation with the propeller blades streamlined
with the airplane's relative wind, thus to minimize
drag. [Figure 12-2]

Feathering is necessary because of the change in parasite
drag with propeller blade angle. [Figure 12-3]
When the propeller blade angle is in the feathered
position, the change in parasite drag is at a minimum
and, in the case of a typical multiengine airplane, the
added parasite drag from a single feathered propeller
is a relatively small contribution to the airplane total
drag.

At the smaller blade angles near the flat pitch position,
the drag added by the propeller is very large. At these
small blade angles, the propeller windmilling at high
r.p.m. can create such a tremendous amount of drag that
the airplane may be uncontrollable. The propeller windmilling
at high speed in the low range of blade angles
can produce an increase in parasite drag which may be
as great as the parasite drag of the basic airplane.

As a review, the constant-speed propellers on almost
all single-engine airplanes are of the non-feathering,
oil-pressure-to-increase-pitch design. In this design,
increased oil pressure from the propeller governor
drives the blade angle towards high pitch, low r.p.m.

In contrast, the constant-speed propellers installed
on most multiengine airplanes are full feathering,
counterweighted, oil-pressure-to-decrease-pitch
designs. In this design, increased oil pressure from the
propeller governor drives the blade angle towards low
pitch, high r.p.m.—away from the feather blade angle.
In effect, the only thing that keeps these propellers
from feathering is a constant supply of high pressure
engine oil. This is a necessity to enable propeller feathering
in the event of a loss of oil pressure or a propeller
governor failure.

Feathered propeller.
Figure 12-2. Feathered propeller.

Propeller drag contribution.
Figure 12-3. Propeller drag contribution.

 

12-3