Installation & Operation Manual
O-360 and IO-360 Series Engines
© March 2004 Superior Air Parts Inc. Chapter 6 • Normal Operating Procedures
6
E. Pre-Takeoff Ground Check
Table 6-5 • Fixed Wing – Pre-Takeoff Ground Check
1. Warm-up as stated above in Table 6-3
2. Mixture control "Full Rich", check oil pressure and oil temperature.
3. Propeller Check - Cycle the propeller through its complete operating range to check operation
and return to full low pitch position. Full feathering check on a twin engine aircraft on the ground
is not recommended, but the feathering action can be checked by running the engine between
1000-1500 RPM, then momentarily pull the propeller control into the feathering position. Do not
allow the RPM to drop more than 500 RPM.
4. Magneto Check - Factors other than the ignition system affect magneto drop. Some factors
include load-power output and mixture strength. Make the magneto check in accordance with the
following procedures:
CAUTION: ABSENCE OF RPM DROP WHEN CHECKING MAGNETOS MAY INDICATE A MALFUNCTION IN THE
IGNITION CIRCUIT. SHOULD THE PROPELLER BE MOVED BY HAND (AS DURING PREFLIGHT) THE ENGINE MAY
START AND CAUSE INJURY TO PERSONNEL. THIS TYPE OF MALFUNCTION SHOULD BE CORRECTED PRIOR
TO CONTINUED OPERATION OF THE ENGINE.
CAUTION: DO NOT UNDERESTIMATE THE IMPORTANCE OF PRE-TAKEOFF MAGNETO CHECK. WHEN
OPERATING ON SINGLE IGNITION, SOME RPM DROP SHOULD BE NOTED. NORMAL INDICATIONS ARE 25 – 75
RPM DROP AND SLIGHT ENGINE ROUGHNESS AS EACH MAGNETO IS SWITCHED OFF. AN RPM DROP IN
EXCESS OF 150 RPM MAY INDICATE A FAULTY MAGNETO OR FOULED SPARK PLUGS.
4A. Controllable pitch propeller - Check for ignition problems with propeller in "Low Pitch, High
RPM", and set the throttle to approximately 1700 RPM.
A. Move propeller governor control toward low RPM position and observe tachometer. Engine
speed should decrease to minimum governing speed (200-300 RPM drop). Return governor
control to high speed position. Repeat this procedure two or three times to circulate warm oil
into the propeller hub.
B. Where applicable, move propeller control to “feather” position. Observe for 300 RPM drop
below minimum governing RPM, then return control to “full increase” RPM position.
4B. Fixed pitch propeller - Aircraft that are equipped with fixed pitch propellers may check
magneto drop-off with engine operating at approximately 1700 RPM.
5. Check magnetos: Move the ignition switch first to “R” position and note engine RPM, then
move switch back to “BOTH” position to clear the other set of spark plugs. Move the switch to “L”
position and note RPM. The difference between the two magnetos operated individually should
not differ more than 25-75 RPM with a maximum drop for either magneto of 150 RPM. Slight
engine roughness is expected during this test. However, excessive roughness may indicate
spark plug fouling or other ignition system problem.
Note: Minor spark plug fouling can usually be cleared with magnetos on and holding throttle at
2200 RPM.
6. Mixture – Move toward idle cutoff until RPM peaks and hold for ten seconds. Return mixture to
full rich.
