4-13
Virus SW 121
Pilot Operating Handbook
POH-121-00-40-001
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PAGE
SECTION 4
NORMAL PROCEDURES
4.4.5 BEFORE TAKEOFF
During cold weather operations, the engine should be properly warmed up
before takeo. In most cases this is accomplished when the oil temperature
has reached at least 50° C. In warm or hot weather, precautions should be
taken to avoid overheating during prolonged ground engine operation. Ad-
ditionally, long periods of idling may cause fouled spark plugs.
WARNING! Do not takeo with frost, ice, snow, or other contamination on
the fuselage, wing, stabilizers, and control surfaces.
ENGINE TEST
1 Brakes Hold
2 Doors Latched
3 Choke Verify closed
4 Throttle Lever 4000 RPM
5 Alternator Check value and warning light
6 Voltage Check value
7 Ignition Switch RIGHT, note RPM, then BOTH
8 Ignition Switch LEFT, note RPM, then BOTH
WARNING: RPM drop must not exceed 300 RPM for either ‘’magneto’’
and the dierence in drop should not exceed 150 RPM.
9 Propeller lever
Cycle lever 3 times,
observe RPM drop
10 Propeller lever Full forward
11 Throttle lever Set to just above idle
NOTE: RPM drop must not exceed 300 RPM for either ‘’magneto’’ and the
dierence in drop should not exceed 150 RPM If there is doubt concerning
operation of the ignition system, RPM checks at higher engine speeds will
usually confirm whether a deficiency exists. An absence of RPM drop may in-
dicate faulty grounding of one side of the ignition system or magneto timing
set in advance of the specified setting.
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