115/200-volt, three-phase ac, and 28-volt dc
and weight. They are designed for the utmost
power. The electrical power controls are located
maneuverability and mobility. On shore stations,
on two panels at the right side of the operator's
these units may be mobile or they maybe mounted
compartment. The propulsion control and engine
on trailers and require towing. There are many
instruments are on the control panel forward of
types of MEPPs in use. The type used depends
the steering wheel.
upon the type of aircraft to be serviced.
The power plant uses two electronic gover-
MEPPs, especially the self-propelled type, are
nors--the engine governor assembly and the drive-
high on the list of SE involved in ground accidents
control module governor assembly. The engine
with aircraft. In addition to the hazards of driving
governor assembly monitors the output frequency
or towing MEPPs with cables still plugged into
of the ac generator and controls the engine speed.
the aircraft, there is the possibility of damage to
Speed control is achieved by the governor-
the aircraft's electrical or electronic systems due
controlled torque motor, which adjusts the engine
to improper electrical operation. High voltage is
internal fuel control. The drive-control module
certainly a hazard in the use of all MEPPs.
governor assembly controls the torque motor by
Although protective insulation and covers provide
the position of the accelerator pedal when the
protection, malfunctions or improper operation
START/DRIVE SERVICE POWER is in the
can create electrical shock hazards.
START/DRIVE position. The accelerator pedal
uses a variable resistor, not mechanical linkage.
NC-2A Power Plant
One of the primary hazards of this MEPP is
the unusual driving characteristic. The rear wheel
The NC-2A is a self-propelled MEPP. See
steering puts the maneuvering part of the vehicle
figure 3-3. It is designed primarily for use aboard
behind you. It takes lots of practice to become
aircraft carriers. This unit is powered by a three-
familiar with rear-wheel steering, and you should
cylinder, two-cycle, series 53 Detroit diesel engine
be totally familiar with it before maneuvering
governed at 2,550 rpm. The NC-2A is front-wheel
close to aircraft on the flight line.
driven and steered by the rear wheels. The steering
is similar to that of a forklift, and is highly
maneuverable in congested areas. The unit has a
NC-8A Power Plant
turning radius of approximately 11 feet. The front
wheels are driven by a variable-speed, reversible,
The NC-8A is a mobile, self-propelled unit
28-volt dc electric motor. It is capable of
used for servicing and starting rotary- and
propelling the unit up to 14 mph on level terrain.
fixed-wing aircraft. See figure 3-4. This MEPP
The diesel engine drives the generators through
is used primarily aboard shore stations. It is
a speed-increasing transmission to produce a
powered by a four-cylinder, two-cycle, diesel
engine controlled by an electrohydraulic governor.
This unit has one dual-purpose generator
capable of supplying both ac and dc power
simultaneously. It consists of a dc generator and
a synchronous alternator enclosed in one housing.
Figure 3-4.-NC-8A mobile electric power plant (MEPP).
Figure 3.3.-NC-2A mobile electric power plant (MEPP).
3-4
