8-45. AUTOPILOT COUPLED APPROACHES.
There are no special preparations required for placing
the aircraft under autopilot control. Refer to Chapter 3
for procedures to be followed for automatic approaches.
Section IV. FLIGHT CHARACTERISTICS
Under certain flight conditions,
prestall buffet may occur before
the stall warning horn sounds.
The RC-12K stall warning system
When operating under conditions
where altitude loss is critical and
stall recovery and aircraft control
is difficult such as at night, IMC
and autopilot operations, the
A prestall warning in the form of light buffeting may be
felt when approaching a stall. An aural warning is also
provided by the warning horn. The warning horn may
begin to sound approximately 5 12 KNOTS above power
off stall speed, depending on aircraft configuration. If
correct stall recovery technique is used, very little
altitude will be lost during the stall recovery. For the
purpose of this section, the term "power on" means that
both engines and propellers of the aircraft are operating
normally and are responsive to pilot control. The term
"power off' means that both engines are operating at idle
power. Landing gear position has no effect on stall
speed. During practice, enter power off stalls from
normal glides. Enter power on stalls by smoothly
increasing pitch attitude to a climb attitude obviously
impossible for the aircraft to maintain, and hold that
attitude until the stall occurs.
Power On Stalls. The power on stall attitude is
very steep and unless this high pitch attitude is
maintained, the aircraft will generally settle or mush
instead of stall. It is difficult to stall the aircraft
inadvertently in any normal maneuver. A light buffet
precedes the stall, and the first indication of approaching
stall is generally a decrease in control effectiveness,
accompanied by a tone from the stall warning horn. The
stall itself is characterized by a rolling tendency if the
aircraft is allowed to yaw. The proper use of rudder will
minimize the tendency to roll. A slight pitching tendency
will develop if the aircraft is held in the stall, resulting
in the nose dropping slightly, then pitching up toward the
horizon; this cycle is repeated until recovery is made.
Control is regained very quickly with little altitude loss,
providing the nose is not lowered excessively. Begin
recovery with forward movement of the control wheel
and a gradual return to level flight. The roll tendency
caused by yaw is more pronounced in power on stalls,
characteristics are not greatly affected by wing flap
position, except that stalling speed is reduced in
proportion to the degree of wing flap extension.
Power Off Stalls. The rolling tendency is
considerably less pronounced in power off stalls (in any
configuration), and is more easily prevented or
corrected by adequate rudder and aileron control,
respectively. The nose will generally drop straight
through with some tendency to pitch up again if
recovery is not made immediately. The Stall Speed
graph (fig. 8-2) shows the indicated power off stall
speeds with aircraft in various configurations. Altitude
loss during a full stall may be as high as 1320 feet.
Accelerated Stalls. The aircraft gives noticeable
stall warning in the form of buffeting when the stall
occurs. The stall warning and buffet can be
demonstrated in turns by applying excessive back
pressure on the control wheel.
Intentional spins are prohibited. If a spin is inadvertently
entered use the following recovery procedure:
Spin demonstrations have not been
conducted. The recovery technique
is based on the best available:
The first three actions should be performed as nearly
simultaneously as possible.
Power levers IDLE.
Apply full rudder opposite the direction of spin