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flap extension until closer to the runway. VYSE is still
the minimum airspeed to maintain.
On final approach, a normal, 3° glidepath to a landing
is desirable. VASI or other vertical path lighting aids
should be utilized if available. Slightly steeper
approaches may be acceptable. However, a long, flat,
low approach should be avoided. Large, sudden power
applications or reductions should also be avoided.
Maintain VYSE until the landing is assured, then slow
to 1.3 VSO or the AFM/POH recommended speed. The
final flap setting may be delayed until the landing is
assured, or the airplane may be landed with partial
flaps.
The airplane should remain in trim throughout. The
pilot must be prepared, however, for a rudder trim
change as the power of the operating engine is reduced
to idle in the roundout just prior to touchdown. With
drag from only one windmilling propeller, the airplane
will tend to float more than on a two-engine approach.
Precise airspeed control therefore is essential, especially
when landing on a short, wet and/or slippery surface.
Some pilots favor resetting the rudder trim to neutral
on final and compensating for yaw by holding rudder
pressure for the remainder of the approach. This eliminates
the rudder trim change close to the ground as
Ch 12.qxd 5/7/04 9:55 AM Page 12-22
the throttle is closed during the roundout for landing.
This technique eliminates the need for groping for the
rudder trim and manipulating it to neutral during final
approach, which many pilots find to be highly distracting.
AFM/POH recommendations or personal
preference should be used.
Single-engine go-arounds must be avoided. As a practical
matter in single-engine approaches, once the airplane
is on final approach with landing gear and flaps
extended, it is committed to land. If not on the intended
runway, then on another runway, a taxiway, or grassy
infield. The light-twin does not have the performance
to climb on one engine with landing gear and flaps
extended. Considerable altitude will be lost while
maintaining VYSE and retracting landing gear and
flaps. Losses of 500 feet or more are not unusual. If the
landing gear has been lowered with an alternate means
of extension, retraction may not be possible, virtually
negating any climb capability.
ENGINE INOPERATIVE
FLIGHT PRINCIPLES
Best single-engine climb performance is obtained at
VYSE with maximum available power and minimum
drag. After the flaps and landing gear have been
retracted and the propeller of the failed engine feathered,
a key element in best climb performance is
minimizing sideslip.
With a single-engine airplane or a multiengine airplane
with both engines operative, sideslip is eliminated
when the ball of the turn and bank instrument is centered.
This is a condition of zero sideslip, and the
airplane is presenting its smallest possible profile to
the relative wind. As a result, drag is at its minimum.
Pilots know this as coordinated flight.
In a multiengine airplane with an inoperative engine,
the centered ball is no longer the indicator of zero
sideslip due to asymmetrical thrust. In fact, there is no
instrument at all that will directly tell the pilot the
flight conditions for zero sideslip. In the absence of a
yaw string, minimizing sideslip is a matter of placing
the airplane at a predetermined bank angle and ball
position. The AFM/POH performance charts for single-
engine flight were determined at zero sideslip. If
this performance is even to be approximated, the zero
sideslip technique must be utilized.
There are two different control inputs that can be used
to counteract the asymmetrical thrust of a failed
engine: (1) yaw from the rudder, and (2) the horizontal
component of lift that results from bank with the
ailerons. Used individually, neither is correct. Used
together in the proper combination, zero sideslip and
best climb performance are achieved.
Three different scenarios of airplane control inputs are
presented below. Neither of the first two is correct.
They are presented to illustrate the reasons for the zero
sideslip approach to best climb performance.
1. Engine inoperative flight with wings level and
ball centered requires large rudder input towards
the operative engine. [Figure 12-16] The result is
a moderate sideslip towards the inoperative
engine. Climb performance will be reduced by
the moderate sideslip. With wings level, VMC will
be significantly higher than published as there is
no horizontal component of lift available to help
　
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