MOONEY INTERNATIONAL CORPORATION
M20V SERVICE AND MAINTENANCE MANUAL
Page
Date
18
MAR 2017
Rev Date
24- 34- 00 - POWER PLANT CIRCUITS
1. Starter - Ignition Circuit. The starter- ignition switch
has five positions: OFF, R (right), L (left), BOTH, and
START. In the OFF position both magnetos are
grounded. At the R position the left magneto is
grounded. At the L position the right magneto is
grounded. At the BOTH position both magnetos are
HOT and the ignition system is ON. Turning the ignition
switch to start and pushing IN, closes the starter sole-
noid, engages the starter and allows the impulse cou-
pling to automatically retard magneto until the engine is
also at its retard firing position. The spring action of the
impulse coupling is then released to spin the rotating
magnet and produce the spark to fire the engine. After
engine starts, the impulse coupling flyweights do not
engage due to centrifugal action. The coupling then
acts as a straight drive and the magneto fires at the nor-
mal firing position of the engine. The starter- ignition
switch is spring loaded to return from START to the
BOTH position, when released.
-WARNING-
Do not turn the propeller when the magnetos
are not grounded. Ground the magneto
points before removing switch wires or elec-
trical connectors. All spark plug leads can be
removed as an alternate safety measure.
-CAUTION-
Do not operate starter in excess of 15 seconds
or re- engage starter without allowing it time to
cool.
A. LOW BATTERY STARTING PROCEDURE.
A battery that has been discharged to the point
where it will not turn the engine over but has sufficient
power remaining for other equipment; should NOT
have the engine jump started with another power
source for two major reasons:
(1) The discharged aircraft battery is not airwor-
thy because it will not have the necessary reserve ca-
pacity required to operate the aircraft electrical system
and avionics in the event of failure of the charging sys-
tem during flight.
(2) Active material on the positive plate expands
when the battery is discharged and the fast recharge
from the higher potential source, battery, alternator,
rectifier, etc., will severely damage the battery. A slow
charge is recommended prior to flight.
-CAUTION-
When either battery voltage is low, inspec-
tion should be conducted to determine con-
dition of battery and/or reason for battery
being low. Replacement or servicing of bat-
teries is essential and charging for at least
one hour shou ld be done before engine is
started. Batteries must be serviceable and IT
IS RECOMMENDED THAT BATTERIES BE
FULLY CHARGED TO OPERATE AIRCRAFT.
Electrical components may also be damaged
if aircraft is operated when batteries are low.
The M20V has a second battery that may be selected
as the primary battery for a particular flight. The battery
not being utilized will be recharged by a trickle charge
from the aircraft alternator’s charging system, if no
more then 10 amps are required to charge the battery.
-WARNING-
If more then 10 amps are required to trickle
charge the battery, the circuit breaker will pop.
There is no indication to the pilot if this occurs.
Therefore, if only one battery is discharged to the point
that it will not start the engine the other battery may be
selected and the flight continued.
2. Oil and Cylinder Head Temperature Gauge Cir-
cuits. Both the oil and cylinder head temperature are
displayed on the G1000 screen. The oil temperature
gauge circuit has a resistance bulb in the oil cooler
adapter adjacent to the vern- a- therm valve. Changes
in resistance caused by changes in oil temperature al-
ter current flow rate, thereby varying the magnetic field
in the indicator coils.
3. The oil pressure instrument circuit contains an
electrical instrument and a transducer which varies re-
sistance with pressure.
24- 35- 00 - LIGHTING CIRCUITS
1.
Navigation light combination switch/circuit
breaker turns wing tip and tail navigation lights ON.
Should a short occur, the combination switch/circuit
breaker will automatically trip to the OFF position.
The glareshield and panel lights are also turned on
when this switch is ON. Control dimming of either
glareshield or panel lights with momentary switches
on lower console.
2. Select and push split switches to turn desired
set of
left or right landing and taxi lights located in the
wing’s leading edge
. Push switches OFF to turn
desired set of lights off. Lights should be operated
only for short time periods while not in flight to pre-
cludeoverheatingoflamps.Overloadprotectionis
achieved by circuit breakers in panel.
24-34-00
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