point, you should use a voltage and continuity check to
Depot Maintenance
confirm the specific cause of the problem.
Depot maintenance is normally based at a shore
In the preceding sections of this TRAMAN, you
facility. This level of maintenance involves the repair or
have read about the design, control systems, and basic
disposition of components, modules, or assemblies that
maintenance you will encounter in your duties and
are sealed or require major overhaul. Depot
responsibilities aboard an LCAC. Now, let's look at the
maintenance also consists of repair procedures that are
propulsion system of another type of landing craft, the
not available at the enhanced organizational level and
patrol combatant missile (hydrofoil) or PHM.
those that are not cost effective at the lower levels.
Specialized Repair Facility
PATROL COMBATANT MISSILE
(HYDROFOIL)
Specialized repair facility maintenance is normally
The PHM is an advanced design, fast, highly
accomplished at a shore facility that has the specialized
maneuverable, foilborne warship. The mission of the
c a p a b i l i t i e s required for specific parts that need
P H M is to operate offensively against hostile,
maintenance actions beyond the scope provided by the
heavy-surface combatants and other surface craft and to
depot maintenance level.
conduct surveillance operations, such as screening
N o w that we have talked about the different
coastal convoys or amphibious forces in the arrival and
m a i n t e n a n c e levels, let's look at some of the
departure areas. This small, fast, and versatile ship
troubleshooting procedures you may need in
provides the Navy with high-speed support capabilities.
maintaining the LCAC control equipment and systems.
The basic design of the PHM is shown in figure
7-18. This design offers the stability and ride comfort
TROUBLESHOOTING
PROCEDURES
normally limited to much larger ships at a much lower
In troubleshooting the components and systems of
cost. It also offers the high maneuverability and speed
the LCAC, you will use the basic troubleshooting
associated with smaller vessels. Its propulsion system
methodology we discussed earlier in this TRAMAN.
consists of both a foilborne and hullborne system. This
Sometimes, system analysis will allow you to go
combination design offers the advantages of a diesel
directly to a specific faulty component or cable. When
engine in its economical, long-range cruising and
y o u need to use a more comprehensive process,
close-in, low-speed twin-engine maneuvering ability
however, the half-split method of troubleshooting will
and those of a lightweight GTE in its immediate,
provide you with the most logical approach to fault
h i g h - s p e e d foilborne capabilities. Its maximum
isolation.
hullborne range is greater than 1,200 nautical miles with
a maximum speed of 11 knots. While the craft's takeoff
To perform the half-split method of fault isolation,
speed is dependent on the loading, sea state, and power
you should first pick a circuit midpoint on a specific
settings of its controls, its maximum foilborne speed is
wiring diagram. Your ability to gain access to this
greater than 40 knots with a maximum cruising range of
midpoint should be the determining factor. By taking a
greater than 500 nautical miles.
signal measurement at the midpoint, you will be able to
determine which half of the circuit is defective. After
As we discuss the PHM, we will provide you with
you determine a midpoint, refer to the wiring diagram
a general description of the physical and functional
to identify the signal level or range required. If the signal
characteristics of its propulsion systems and controlling
is correct at the midpoint, then the defective part or
stations. The basic control system includes the systems,
circuit lies somewhere between that point and the end
controls, and equipment needed for direction, speed, and
of the circuit. If the signal made at the midpoint is not
o t h e r maneuvering operations. Its propulsion and
correct, the problem lies somewhere between that point
auxiliary systems include the following six subsystems:
and the point at which the signal starts. Your next step
Main propulsion (foilborne) subsystem
1
✎
is to continue to use the half-split method on the part of
the original circuit you have found to be defective.
2 Main propulsion (hullborne) subsystem
✎
You should continue this process until you can
3 Power train subsystem
✎
isolate the defective part or area. In the last stage of the
4
Automatic control subsystem
✎
half-split method, you should be able to isolate the fault
Electrical subsystem (ship's service power unit)
5
to a specific component or part of the circuit. At this
✎
7-19
