Figure 6-4.-LCAC operator station command module.
modulated by P4 air from the combustor. The function
indicating devices for engine pressure, temperature,
of the air bleed system is to provide a margin for
and speed. Visual indications of engine sequencing,
compressor surge. This function protects the engine
EGT, speed, and lubrication conditions are provided
while it is accelerating to maximum power. The air is
on the command station instrument and control panel
vented overboard through ports in a screened flange
and on the modular control box assembly modules.
in the assembly.
The modular control box assembly is a solid-state
LCAC CONTROL SYSTEMS
modular unit encased in a splashproof enclosure. This
In the following paragraphs, we will describe the
assembly contains the system power supply,
basic physical and functional characteristics of the
temperature monitor, GP speed monitor, PT speed
LCAC control systems. The LCAC control systems
monitor, engine sequence, malfunction monitor, fuel
include all the systems and controls the operator
control, isolation analog, and utility panel modules.
needs to maneuver the craft. Maneuvering an LCAC
basically consists of controlling the craft's direction,
During the start cycle, a maximum current drain
speed, and cushion.
of approximately 10 amperes at 24 V dc is required.
This current requirement is reduced to approximately
The LCAC control systems are divided into the
6 amperes after the start sequence is completed.
AIR SYSTEM. We will discuss the TF40B air
1. Steering control system
system in terms of its major sections and general
Air Starter System. The starter is mounted on
3. Lift fan control system
a pad on the accessory gearbox module in the power
output section. Air enters the inlet housing module
4. AVCO Lycoming TF40B engine control system
through ports on each side of the inlet housing
assembly. The inlet air is then powered by 37 to 46
psi through the air start valve and directed to the
6. Rate of turn system
The compressed air then flows through the air
diffuser assembly and into the combustion chamber.
7. Outside air temperature system
After the engine has started, a control switch
terminates starter operation. For a more detailed
8. Speed/sideslip indicator
discussion of these components, refer to the specific
technical manual for this system.
These subsystems are controlled by the operator in
the LCAC operator station command module or the
Air Bleed System. The air bleed system consists
operator in the engineer control station. Figure 6-4
of an air bleed valve assembly that is located on the
shows the physical arrangement of a typical LCAC
air bleed manifold housing. The air bleed manifold
housing is located on the combustor housing
assembly. The air bleed valve is spring loaded. It is