Removal Of Cross Start Relays; Installation Of Cross Start Relays; Description And Operation Of Battery - Piper Cheyenne IIIA Airplane Maintenance Manual

PIPER AIRCRAFT
PA-42-720 (Advanced Trainer)
MAINTENANCE MANUAL
A. DC Generation (continued)
14. Checking Generator Control Unit (continued)
(c) Turn left starter generator switch to the ON position and turn the right starter generator switch
off. This will transfer the full electrical load to the left starter generator and generator control
unit. The system voltage must remain 28 ± 1 volts.
(d) If the voltage does not remain at 28 ± 1 volts, check the generator and battery, making sure
they are in good condition. Check all circuit connections and all wiring in the starter generator
system for unwanted resistance. Wiring connections should be cleaned and soldered as
necessary. Check voltmeter for accuracy and repeat test. If system voltage still is not within 28
± 1 volts, refer to performance test.
15. Removal of Cross Start Relays
The cross start relays are located under the floorboards, aft of fuselage station 99.00, between the
crew seats.
(a) Determine that electrical power is disconnected (battery and external power).
(b) Remove center avionics console and center floorboards to gain access to the contactors.
(c) Disconnect electrical cables, bus bars and mark to facilitate reinstallation.
(d) Disconnect 20 gauge jumper between contactor coils.
(e) Disconnect annunciator wire (with fuse holder).
(f) Remove screws to contactor and remove unit.
16. Installation of Cross Start Relays
(a) Position contactors on mounting plate and secure with appropriate screws.
(b) Connect annunciator wire, 20 gauge jumper, bus bars and all marked electrical cables to their
appropriate terminals and secure with lockwashers and nuts.
(c) Reconnect battery or external power and perform operational check.
17. Description and Operation of Battery
The nickel cadmium batteries must be kept clean and charged to remain airworthy. Service is
required every 100 hours or 60 days, whichever occurs first. Water consumption is directly
proportional to the overcharge currents experienced. Service frequency depends on operating
conditions.
Important precautions:
WARNING: SERIOUS INJURY CAN RESULT WHEN THE FOLLOWING PROCEDURES FOR
CLEANING OR SERVICING A NICAD BATTERY ARE NOT FOLLOWED.
(a) Remove all metal jewelry, i.e. rings, watch bands, and bracelets. Due to very high current
capabilities, the battery can quickly melt or fuse metal and cause severe burns.
(b) Use only insulated tools. Never use tools previously used on lead acid batteries.
(c) The potassium hydroxide and water battery electrolyte is caustic and can cause severe bums.
Wear protective clothing (rubber gloves, apron, eye protection, etc.) while handling the
electrolyte. If contact occurs, flush immediately with water and neutralize with acetic acid,
vinegar, lemon juice or a 10% solution of boric acid. Flush eyes with water continuously and
contact physician immediately.
(d) Hydrogen and oxygen gases do generate and are highly explosive. Vent these gases to the
outside air when charging. In case of charging indoors with central air conditioning present,
these gases can be circulated via the duct work throughout the building. Outside venting of the
battery service area is mandatory.
(e) ;Make sure all electrical connections are tight and secure to prevent electrical arcs which could
trigger and explosion.
(f) Keep cell vent plugs in place at all times except when inspecting or adjusting electrolyte levels.
EFFECTIVITY:
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24-30-00
Jan 10/90