2A-27-70: Speed Brake and Ground Spoilers
1. General Description:
The speed brake and ground spoilers use six panels on the upper wing surface to
increase drag and reduce lift allowing the flight crew to increase descent rates
and, on landing, to shorten landing roll and increase braking effectiveness by
quickly transferring aircraft weight to the main landing gear wheels. The three
panels on each wing are hydraulically powered and activated by either manual
command through the SPEED BRAKE handle on the pilot side of the cockpit
center console, or electrically actuated as an automatic selectable feature during
landing. The automatic ground spoilers will also deploy during an aborted takeoff
to reduce aircraft stopping distance.
Hydraulic power for speed brake and ground spoiler actuation is provided by both
the left and right hydraulic systems, with the pressure of each system reduced
from three thousand (3,000) psi to fifteen hundred (1,500) psi by a pressure
control module to prevent structural damage to the aircraft from speed brake
deployment at high airspeeds. Two hydraulic actuators on each wing operate the
spoiler panels in response to manual or electrical control inputs. Each actuator
has tandem pistons, one for each hydraulic system, that move a single actuator
shaft. Failure of one hydraulic system will not effect the actuators - the remaining
system pressure reducer will allow a full three thousand (3,000) psi to the
operational piston to power actuator shaft movement, and the condition will by
annunciated by a blue “Single Speed Brake” advisory Crew Alerting System
(CAS) message. Diagrams of the spoiler system is included in Figure 19and
Figure 20.
The two hydraulic actuators are necessary to provide the multi-purpose operation
of the spoiler system. The two outer spoiler panels on each wing operate in three
(3) modes:
• To assist the ailerons in aircraft roll control
• To actuate as speed brakes
• To actuate as ground spoilers
The single inner spoiler panel on each wing operates as:
• A speed brake
• A ground spoiler
The two hydraulic actuators and the three spoiler panels on each wing are
mechanically linked together; however, the linkage is unidirectional, operating
from the inboard ground spoiler actuator outboard to the flight spoiler actuator. All
speed brake or ground spoiler commands, either manual or electric, are directed
to the ground spoiler actuator that mechanically relays the command to the flight
spoiler actuator. The single direction of the mechanical linkage is necessary in
order for the two outboard spoiler panels of each wing to assist the ailerons
without operating the inboard spoiler panel. The aileron control linkage to the
outer panels is a separate command input that is cumulative to the speed brake
deployment command. For more information regarding the roll assist function of
the outer spoiler panels, see section 2A-27-40: Aileron Roll Control.
Both actuator linkages on each wing have dedicated Rotary Variable
Displacement Transducers (RVDTs) that furnish position information to the
Modular Avionics Units (MAUs). The left ground and flight spoiler actuator
linkages are monitored by RVDTs linked to MAU #1, and both right wing spoiler
RVDTs are monitored by MAU #2. The MAUs share position information with the
OPERATING MANUAL
PRODUCTION AIRCRAFT SYSTEMS2A-27-00
Page 70
August 14/03
To Next Page
Loading...
