Exhaust Ring Installation; Engine Conditioning Hints; Ignition - Thrush Aircraft S2R-R1340 Maintenance Manual

THRUSH AIRCRAFT, INC – MODEL S2R-R1340

EXHAUST RING INSTALLATION

To install exhaust ring, proceed as
follows:
A. Inspect cylinder exhaust port studs
for cleanliness
condition. Replace as required.
B. With the clamp assembly on the
smooth end,
segments to the cylinder exhaust
ports, leave nuts loose to facilitate
installation of remaining segments.
Work progressively around engine
until all segments are in place and
properly aligned. After all segments
are in place and properly aligned,
torque all clamp and flange nuts in
accordance with Table 2-3, Section
2.
C. Install carburetor hot air muff.

ENGINE CONDITIONING HINTS

IGNITION

Proper operation of the engine ignition
system is necessary for efficient engine
performance and long life. Although the
ignition system will not require frequent
attention, it is important to recognize and
know how to correct ignition problems to
eliminate the adverse effect on operating
economy and flight safety.
Spark plugs require the majority of
ignition problems. Normal erosion of the
plug electrodes, caused by continuous
firing of the plugs, requires periodic plug
replacement. However, spark plug life
will be reduced drastically by extended
ground operation of the engine or
operating the engine on an excessively
rich idle mixture. Proper adjustment of
the idle mixture will assure longer spark
4-24
AIRCRAFT MAINTENANCE MANUAL
and general
install individual
plug life. Improper magneto timing, faulty
magneto points, or fouled spark plugs
may be the cause of an engine rpm drop
when switching from both to single
magneto. It is easy to determine if an
ignition problem is caused by the plugs
or the magneto by close observation of
the engine rpm variations during the
magneto check. As the speed of the
engine increases
compression increases and makes it
more difficult for the spark plug to fire;
therefore, an rpm drop caused by
magneto malfunction or timing will not
follow a change in engine speed with the
same consistency as faulty spark plugs.
If the magneto drop is excessive in either
the L or R position, manually lean and
operate the engine approximately 30
seconds.
This technique will increase combustion
temperature, and may clear excess oil
and fuel from spark plug electrodes.
Return mixture to FULL RICH position
and recheck magneto drop in L and R
positions.
Repetitious fouling of the spark plugs in a
particular cylinder is indicative of ignition
breakdown or low compression.
The difference between the two causes,
and consequently a clue to what is
causing the trouble, can usually be
obtained by comparing engine manifold
pressures and rate of rpm drop when
operating on a single magneto.
compression is characterized
variation in manifold pressure, slower
rpm drop during magneto check and
rough idling.
the cylinder
Low
by a
Effective: 01/01/2008