Secondary Flight Controls Of The Aircraft
The secondary flight controls are
very vital for controlling the aircraft during when airborne, the secondary
flight controls are also required to aid take-off to aid lift the large tonne
weight aircraft into the air. Additionally, the secondary flight control aids
effective manoeuvring of the aircraft through it's flight path. The speed of
operation of the secondary flight control does not have a immediate effect as the
motor vehicle steering wheel. Some controls may take up to 30 seconds for its operation. example of the secondary flight control is the flaps, slats amongst others.
Flaps: The flaps is a vital secondary flight control mechanism, they are located on the trailing edge
of the wing and are moved in the upward and downward direction. The secondary
flight control known as flaps also has the capability of remaining in the
middle to complete the chord line. When this is secondary flight control is in
use, the wing shape is modified to achieve lift and to reduce the aircraft
stalling speed (speed at which aircraft loses its speed) during low airspeed
operation. It has a lever in the cockpit the pilot make use of for its
operation. It takes 38 seconds for the trailing edge flaps to fully extend. In
the analysis of the flaps in the mechanical control room, there are two (2)
system reservoirs and a standby reservoir to aid hydraulics for its operation. The
trailing edge flaps are operated hydraulically or electrically, if there is a
hydraulic system failure the flaps maybe operated electrically with the aid of
ultimate flap extension mechanism. The power drive unit is responsible for the
flaps extension or retraction. It converts hydraulic power into mechanical
force to operate the flaps. When the flaps lever is moved, there is an input
sent to the leading edge flaps and slats. There is an indicator for leading
edge flaps and slats in the in the cockpit located below the trailing edge flap
indicator to indicate how they are often used. The green indicator or light
comes on when all the leading edge flaps and slats are fully extended. The leading
edge flaps indicator indicates when the flap is not in the supposed position.
Slats: Slats are secondary flight control which also are movable
and are located at the leading edge of the wing to change the wing shape to
achieve extra lift. They are used to reduce the aircraft stalling speed during
low air speed and high angle of attack operation. The slat aids to smoothen the airflow
in the upper surface of the wing. The slat is vital because when the aircraft is
about to stall, it’s the leading edge of the wing that stalls first. They are
located there so as the initial phase of the stall the aileron will provide a
roll control.
Spoilers: They are also
secondary flight control which functions contrary to the flaps. They are
located on the upper surface of the wing and are extended upward for the
purpose of disrupting the airflow that aids to generate lift. When they are
extended they create drag to aid descend rate. On ground taxing, the spoilers
aids to reduce the speed at which the aircraft touches down during landing
which is a few knot higher than the speed at which it would have taken of. For
this reason spoilers are deployed to destroy the excess lift and aids the landing
gear to have good adherance to the runway. There are leading edge flaps and
slat as well as trailing edge flaps and slats.
Elevator Trim tab: They are
secondary flight controls located at the trailing edge of the elevator. Its
functions is similar to the operation of flaps. But they function
simultaneously. When both elevator trim tab faces upward, there is a lowering
of the tail section and its aids the nose pitch up, when the trim tab of the
elevator faces downward is, its aids the nose down. It’s controlled by a wheel
in the cockpit which you trim up and down in variation.
There are few protection mechanisms for the
protection of secondary flight controls. Which includes the flaps and slat
namely:
Flap load relief mechanism: it works for the trailing edge flap for
the purpose of relieving load of the flap. When I mean load, I refer to weight
of the flaps. When the trailing edge load relief is active the flaps load
relief light indicates.
Leading edge automatic slat function: it moves leading edge flaps
to the fully extended position.
Others includes;
Asymetry and skew detection mechanism
Uncommended motion detection
Trailing edge alternate flap extension
Without the secondary flight control, its going to be difficult to fly the aircraft in any condition. for effective function of each of the control, they have to be maintained and checked always as a pre start routine before flight.
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