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Airplane Flying Handbook
Transition to Multiengine Airplanes
ENGINE INOPERATIVE LOSS OF DIRECTIONAL CONTROL

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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

While maintaining entry heading, the pitch attitude is
slowly increased to decelerate at a rate of 1 knot per
second (no faster). As the airplane slows and control
effectivity decays, the increasing yawing tendency
should be counteracted with additional rudder pressure.
Aileron displacement will also increase in order
to maintain 5° of bank. An airspeed is soon reached
where full right rudder travel and a 5° right bank can
no longer counteract the asymmetrical thrust, and the
airplane will begin to yaw uncontrollably to the left.

The moment the pilot first recognizes the uncontrollable
yaw, or experiences any symptom associated
with a stall, the operating engine throttle should be
sufficiently retarded to stop the yaw as the pitch
attitude is decreased. Recovery is made with a minimum
loss of altitude to straight flight on the entry heading at
Vsse or Vyse, before setting symmetrical power. The
recovery should not be attempted by increasing power
on the windmilling engine alone.

To keep the foregoing description simple, there were
several important background details that were not
covered. The rudder pressure during the demonstration
can be quite high. In certification, 150 pounds of force
is permitted before the limiting factor becomes rudder
pressure, not rudder travel. Most twins will run out of
rudder travel long before 150 pounds of pressure is
required. Still, it will seem considerable.

Maintaining altitude is not a criterion in accomplishing
this maneuver. This is a demonstration of
controllability, not performance. Many airplanes will
lose (or gain) altitude during the demonstration. Begin
the maneuver at an altitude sufficient to allow completion
by 3,000 feet AGL.

As discussed earlier, with normally aspirated engines,
VMC decreases with altitude. Stalling speed (Vs),
however, remains the same. Except for a few models,
published Vmc is almost always higher than Vs. At
sea level, there is usually a margin of several knots
between VMC and VS, but the margin decreases with
altitude, and at some altitude, Vmc and Vs are the
same. [Figure 12-21]

Should a stall occur while the airplane is under asymmetrical
power, particularly high asymmetrical power,
a spin entry is likely. The yawing moment induced
from asymmetrical thrust is little different from that
induced by full rudder in an intentional spin in the
appropriate model of single-engine airplane. In this
case, however, the airplane will depart controlled
flight in the direction of the idle engine, not in the
direction of the applied rudder. Twins are not required
to demonstrate recoveries from spins, and their spin
recovery characteristics are generally very poor.

Graph depicting relationship of VMC to VS.
Figure 12-21. Graph depicting relationship of Vmc to Vs.

Where Vs is encountered at or before Vmc, the departure
from controlled flight may be quite sudden, with
strong yawing and rolling tendencies to the inverted
position, and a spin entry. Therefore, during a Vmc
demonstration, if there are any symptoms of an
impending stall such as a stall warning light or horn,
airframe or elevator buffet, or rapid decay in control
effectiveness, the maneuver should be terminated
immediately, the angle of attack reduced as the throttle
is retarded, and the airplane returned to the entry
airspeed. It should be noted that if the pilots are
wearing headsets, the sound of a stall warning horn
will tend to be masked.

The Vmc demonstration only shows the earliest onset
of a loss of directional control. It is not a loss of control
of the airplane when performed in accordance with
the foregoing procedures. A stalled condition should
never be allowed to develop. Stalls should never be
performed with asymmetrical thrust and the Vmc
demonstration should never be allowed to degrade into
a single-engine stall. A Vmc demonstration that is
allowed to degrade into a single-engine stall with high
asymmetrical thrust is very likely to result in a loss of
control of the airplane.

An actual demonstration of Vmc may not be possible
under certain conditions of density altitude, or with
airplanes whose Vmc is equal to or less than Vs. Under
those circumstances, as a training technique, a demonstration
of Vmc may be safely conducted by artificially
limiting rudder travel to simulate maximum available
rudder. Limiting rudder travel should be accomplished
at a speed well above Vs (approximately 20 knots).

 

12-30