MAULE MX-7-420 TURBO-PROP, Руководство по обслуживанию

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MAULE AEROSPACE TECHNOLOGY, INC.
MAINTENANCE MANUAL
FOR
MX-7-420
32
Rev. A
The fuel lines should be checked for cracks and chafing every 100 hours or annually
and the external fuel filter should be cleaned at the same time. The auxiliary tank transfer
pump strainers should be cleaned at the same interval. This is done by removing the pump
bottom with a 5/8” wrench. The pump is on the rear spar, inboard of the auxiliary tank, and
the bottom is exposed.
ELECTRICAL SYSTEM
The electrical system is a 28 volt, 100 amp, direct current, single wire circuit using the air-
plane structure as a ground return to the battery. All wiring in the airplane is fabricated into
harnesses which are groups of related wires tied together. Most of the harnesses originate
at circuit breakers on the main bus (center of instrument panel) and terminate at the load
(light, pump motor, etc.) A wiring diagram is shown at the end of this manual.
CAUTION: Addition(s) of electrical equipment must not cause the total load to exceed
100 amperes.
BATTERY:
A lead plate type storage battery rated at 24 volts is installed in the battery box on right
side of firewall. The battery supplies current for the airplane electrical system when the mas-
ter switch is in the “ON” position only.
The battery is the sealed type or the manifold vented type, with the base being integrally
vented. Tubes attached to the case vent the battery to the fuselage bottom. Battery caps
should be kept tight to prevent electrolyte spillage. If spillage does occur, the affected area
should be cleaned with a liberal application of an acid neutralizing solution such as baking
soda and water. The vent tube must be properly routed through the fuselage bottom as bat-
tery acid will destroy the fabric.
Some batteries are sealed recombinant design which do not require the external vent
tube.
This battery is considered fully charged at a hydrometer specific gravity reading of
1.265. A low charge would be 1.225 or lower. Operating with a low charge will shorten the
life of battery and can be prevented by recharging are operating with electrical equipment
turned off until the battery has been sufficiently recharged.
GENERATOR CONTROL SYSTEM:
Overvoltage protection is incorporated in the generator control unit which will latch off
regulator output after an overvoltage event. Reset of latch off caused by either overvoltage
or shorten output is accomplished by momentary turn off of supply voltage, i.e., to reset to
ON.