MOONEY
M20TN - MODEL TYPE-S
SECTION VII
AIRPLANE AND SYSTEM DESCRIPTION
7 -- 21
AIRPLANE FLIGHT MANUAL
ORIGINAL ISSUE -- 04-02-2008
LUBRICATION SYSTEM
Oil Filter -- Full flow oil filter is a throw away filter element with a bypass valve incorporated.
BREATHER FOR CRANKCASE
The crankcase is vented overboard through an air--oil separator to the left tailpipe. The air oil
separator condenses some of the oil vapor and returns the oil back to the crankcase. The tailpipe
slows the vaporization of oil by providing some pressure to the crankcase atmosphere. Proper
maintenance of this system is required to minimize oil consumption.
IGNITION SYSTEM
The TSIO--550--G engine is equipped with pressurized magnetos with impulse couplings on
each magneto.
Power from the engine crankshaft is transmitted through camshaft gear to the magneto drive
gears, which in turn drives the magneto drive couplings. The left magneto incorporates an im-
pulse coupling. As the rubber bushings in the drive gear turns the coupling drive lugs, counter-
weighted latch pawls inside the coupling cover, engage pins on the magneto case and hold back
the latch plate until forced inward by the coupling cover. When the latch plate is released, the
coupling spring spins the magneto shaft through its neutral position and the breaker opens to
produce a high voltage surge in the secondary coil. The spring action permits the latch plate,
magnet and breaker to be delayed through a lag angle of 30 degrees of drive gear rotation during
the engine cranking period. Two lobes on the breaker cam produce two sparks per revolution of
the drive shaft. After engine is running, counter--weights hold the latch pawls away from the stop
pins and the magneto shaft is driven at full advance.
The engine firing order is 1--6--3--2--5--4. Ignition harnesses are connected to the magnetos so
right magneto fires the upper plugs on the right side and lower plugs on the left. The left magneto
fires the upper plugs on the left and lower plugs on the right. The magneto cases, spark plugs,
harnesses and connections are shielded to prevent radio interference.
