Piper Aircraft Corporation Malibu Mirage PA-46-350P, Airplane Maintenance Manual

Page: 417 / 1956

PAGE 1
Feb 28/07 2H19
24-30-00
PIPER AIRCRAFT, INC.
PA-46-350P, MALIBU MIRAGE
MAINTENANCE MANUAL
DC GENERATION
1. Alternator System (Refer to Figure 1)
The PA-46-350P uses a dual 70-amp ( S/N’s 4636001 thru 4636131 ) or 75-amp ( S/N’s 4636132 and up )
alternator system, consisting of two belt driven alternators that feed their individual positive outputs to
the main bus through separate 60-amp (
S/N’s 4636001 thru 4636131 ) or 80-amp ( S/N’s 4636132 and
up ) main bus circuit breakers. Shunts in each alternator output feed total current flow to the respective
ammeter. Each ammeter circuit is protected by two 5-amp fuses.
2. Main Electrical Bus
Operational check of bus isolation diodes
A. Turn on external or battery power.
B. Check to see that landing gear indication circuit breaker is in.
C. Check to see that gear position lights are on.
D. Pull one of the Main circuit breakers. The gear position lights should remain on.
E. Reset the Main circuit breaker that was pulled in Step D. Pull the other Main circuit breaker. The
gear position lights should remain on.
F. If gear position lights are inoperative when either Main circuit breaker is pulled, troubleshoot the
Main electrical bus system.
3. Avionics Bus
A separate avionics bus is provided. This bus is powered through a main bus tie and controlled by the
avionics master switch.
4. Voltage Regulation and Control
WARNING: USE ONLY AN INSULATED SCREWDRIVER TO MAKE THIS ADJUSTMENT.
Voltage regulation and control is provided for both alternators by Lamar solid-state alternator control
units that regulate voltage through control of field voltage and automatic overvoltage protection. The only
adjustment is the voltage adjust potentiometer located under the removable cover plug.
System voltage should be set at 28.5 Vdc maximum. Should an overvoltage condition occur, the unit can
be reset by cycling the alternator switch “OFF’’ and back to “ON’’. The Lamar alternator low output sensor
will activate the alternator output warning lamp on the annunciator panel. If an overvoltage trip occurs,
an alternator is switched off or an abnormally low voltage exists due to a faulty system.
5. Troubleshooting
See Chart 1.
A simple in-aircraft check can be made to determine if an alternator warning light illumination is caused
by either a low voltage or an overvoltage condition. Turn both alternator switches “OFF’’ and then back
“ON’’ again, one at a time. If the alternator annunciator(s) extinguish(es), the system(s) can be
considered normal and can be verified so by the ammeter indication. In any case, either alternator
system output can be read on the appropriate ammeter.
NOTE: Illumination of the alternator warning annunciator at low engine idle speeds, with high electrical
loads on the systems, may occur and are considered normal, especially if the battery is
requiring a heavy charge. Under such conditions, the annunciator will extinguish at an
increased rpm, as the battery charge returns to normal and the electrical load is reduced.
6. Distribution
See Figure 1.