Warner Engine Handbook:

Starting and Normal Operation

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Section V - Starting and Normal Operation

1. General

Consult the airplane or engine specifications for fuel and oil grades and requirements, limitations of crankshaft speeds, power, temperatures, pressures, and other operating conditions. Do not exceed these limitations.

2. Pre-Flight Inspection

a. Inspection prior to starting engine for first time after installation

1. Check the magneto ground wires to make sure that they are properly connected to the magnetos and engine crankcase or airplane fuselage. See that all connecting wires are in good condition. Inspect the connections and insulation carefully.

2. Check all bolts and nuts on the engine and mounting ring to see that they are tightened properly and securely locked.

3. Check the propeller and hub for tightness and proper safetying.

4. Check for proper connection of the oil pressure gauge, tachometer, cable thermometers and thermocouples, if provided.

5. Check the priming system, if installed, to see that it is in proper working condition.

6. Check throttle and mixture controls for full travel and proper connection.

7. Try gas cocks. Check all fuel and oil lines for tight connections and freedom from constrictions.

b. Before each flight, check the following:

1. Fill the oil tank to the proper level with the recommended grade of oil.

2. Fill the gasoline tanks with the specified grade or gasoline.

3. Operate the throttle and mixture controls to see that they function normally over their entire range.

c. Immediately before starting, make certain that the ignition system switch is in the "off" position, pull the propeller through by hand for at least three complete revolutions. If the propeller turns harder than it should, remove the spark plugs on the bottom cylinders and check to see if liquid is present. If liquid is found, continue working up the engine pulling plugs until dry cylinders are found.


The rods may be bent or broken if the engine is started with excessive oil or fuel in the cylinders. It is therefore urgently recommended that all operators take steps to have engines pulled through three complete revolutions by hand before they are started.

3. Starting the Engine


If the engine has been in storage and is being started for the first time then the procedure given in the section on stored engines must be followed.

a. Hand Starting

(1) Place spark in the fully advanced position. When starting a hot engine the spark should be retarded slightly to avoid kick back.

(2) Place the ignition switch in the "off" position.

(3) Turn the gasoline shut-off valve to the "on" position.

(4) Open and close the throttle rapidly several times. This will place a charge of gasoline into the induction housing by means of the accelerator pump within the carburetor.

(5) Turn the propeller several times with the throttle fully closed.

(6) Place the ignition switch on "contact" and throw the propeller quickly through compression. If the engine does not start, consult the section on "Engine Troubles".

b. Starting With Electric Starter

(1) Use the same sequence as in 3a except retard the spark approximately two thirds.

(2) Allow the engine to gain momentum before turning the ignition switch on. This will prevent possible kick-back against the starter.

4. Cold Weather Starting

In extremely cold weather, unless the airplane is equipped with an oil dilution system, the oil should be preheated.

5. Warm-Up

a. Aircraft engines will always be warmed up on the ground until proper lubrication and engine operation for the take-off and flight are assured.

b. After the engine is started, do not allow it to run at a speed greater than 800 R.P.M. until the oil thermometer indicates a rise in temperature. The thermometer will indicate a different temperature according to the type cowling installed as well as the manner in which the thermometer is installed. The proper running temperature should be determined by experience on the various installations.

c. When free flowing oils are used, safe operation of the engine under take-off conditions and cruising may be obtained when the oil temperature indicator hand begins to show a rise in temperature.

d. If the oil gauge does not show pressure within one-half minute the engine should be shut down and the cause of the trouble located.

e. Short bursts of speeds not to exceed maximum permissible ground R.P.M. and not to be maintained for periods in excess of 20 to 30 seconds may be used during warm-up period to check instruments and controls on the ground after the oil temperature gauge shows a definite increase indicating the circulation of the oil and also the oil pressure is two thirds of the minimum full power oil pressure. Maximum permissible ground R.P.M. will be that specified for "Minimum Cruising" in the specific operating instructions.

f. The magnetos may be checked by switching to one magneto at a time and checking for a loss in R.P.M. Normal loss in R.P.M. while running on one magneto should not exceed 1OO R.P.M. It is important to switch back to "both" after testing one magneto to make sure that the engine has picked up the lost R.P.M. before testing the other magneto.

g. Adjust the carburetor air heat to the hot position if atmospheric conditions are conducive to ice formation.

6. Taxiing

a.  Hot Weather

1. The mixture control must be in the full-rich position.

2. The carburetor air heat must be in the coldest position.

b. Cold Weather

When engine and oil temperatures are subnormal prolonged ground operation is permitted, provided normal engine temperatures are maintained and the engine speed is increased periodically to scavenge the cylinders of accumulated exhaust gases and oil.

7. Take-Off and Climb

a. The mixture control must be in the full-rich position.

b. The spark control should be in the full-advance position.

c. Do not start the take-off with cylinder head temperature above 203 F. or below 104 F.

d. Manifold pressures must be reduced on take-off and climb to prevent detonation and resultant engine failure when abnormally high temperatures exist.

e. Always set carburetor air heat in the cold position during take-off unless severe atmospheric ice is present, such as ice or snow. Before changing the carburetor air heat, richen mixture, if not already rich.

f. Take-off will be accomplished at full-throttle.

8. Flight

a. When flying, the spark control should always be in the full advanced position.

b. After take-off, the throttle control should be set at the desired Cruise R.P.M.

c. It is not recommended that the mixture control be used below an elevation of 5,000 feet, and at such time as it is used, it should be used to give the best running condition of the engine, rather than in an attempt to save gasoline. An excessively lean mixture will cause overheating of the cylinders.

d. The R.P.M., oil temperature And the oil pressure give the most satisfactory indication of the engine's performance. If any of these appear irregular, the engine should be throttled and if the cause cannot be eliminated, a landing should be made to investigate and remove the trouble.

9. Landing

a. General.  Landing operation includes the operation of the engine preparatory to landing and after landing.

b. Before landing, the mixture control should always be placed in the full rich position to prevent the stalling of the engine, due to an exceptionally lean condition on reaching the lower altitudes.

c. From cruising condition, slowly close throttle to 1,000 R.P.M.

d. If the airplane must execute a prolonged glide to reach the ground, keep turning the engine under partial throttle so as to retard rapid cooling of the engine.

e. Periodic low R.P.M. bursts of the engine will insure clean cylinders and a warm engine ready for instantaneous emergency application of power.

10. Stopping The Engine

a. The correct method of stopping the engines will reduce time in stopping, reduce backfire, and also prevent overheating of tightly baffled engines.

b. Set mixture control at full rich.

c. Set the throttle for normal idling of 400 to 600 R.P.M. and let the engine run with nose cowls fully opened until the engine has cooled appreciably below cruising temperature.

d. After obtaining the proper temperature, the R.P.M. should be increased to 1,000 to 1,100 R.P.M. for one-half minute in order to permit scavenging of the crankcase oil.

e. Cut the ignition switch. As the propeller slows down and with the ignition switch off, slowly move the throttle to the full open position.

f. Allow the throttle to remain in its open position after stopping the engine, as this lessens the likelihood of accidental starting while the engine is hot.

11. Mixture Control Operation

a. Definitions Of Settings Applicable To Manual Control

(1) "Full-Rich" is the setting of the mixture control lever in the position giving maximum fuel flow.

(2) "Best Power" or "Maximum Power" is the setting of the mixture control level which, with a given fixed throttle setting, results in the maximum engine R.P.M. at the leanest fuel flow; i.e., further leaning to the mixture would cause a decrease in engine R.P.M.

(3) "Rich Best Power" is the setting of the mixture control lever which, with a given fixed throttle setting, results in the maximum engine R.P.M. at the richest fuel flow.

(4) "Smooth Operation" is obtained by setting the mixture control lever for "Best Power" and then enriching the mixture until the engine speed drops 20 to 30 R.P.M.

(5) "Maximum Economy" is obtained by adjusting for "Best Power" and then leaning the mixture to obtain a decrease in engine speed of 40 to 50 R.P.M.

b. The mixture control should never be used without a full understanding of its effect on the engine and a knowledge of the general conditions under which the engine is operating.

c. It is possible to ruin an engine in a few minutes by improper use of the mixture control, as too lean a mixture will rapidly overheat the engine.

d. When using the mixture control, the cylinder temperatures must be carefully checked to prevent overheating.

e. The mixture control is set at a "full rich" position for take-off and landing.

f. Above 5000 feet the mixture control is adjusted for smooth operation.

12. Carburetor Air Heat Control

a. The function of the carburetor air heat is to prevent or eliminate the formation of ice in the induction system. The formation of ice restricts the carburetor air flow and results in loss of power.

b. Induction system icing consists of one or both of the following: Atmospheric ice is ice formed from water already in the atmosphere as ice, snow or liquid water, while fuel evaporation ice is that formed from moisture vapor present in the air and is due to the cooling effect of the fuel evaporating in the air after it is introduced into the air stream at the carburetor.

c. Formation of Ice In Induction System

(1) Normally, the formation of ice may be indicated by either a gradual loss of R.P.M. or a reduction in manifold pressure, or perhaps a combination of the two, without changing the throttle setting or the altitude of flight. Under most conditions the formation of ice is relatively slow, and the pilot may be able to maintain constant R.P.M. by slowly and continuously advancing the throttle.

(2) In extreme cases, the formation of ice may be so rapid and the loss or power so abrupt that the prompt use of the carburetor air heat is necessary to prevent total loss of power.

d. Operation Under Icing Conditions

(1) GENERAL Use full carburetor air heat under icing conditions with precipitation near the freezing point to insure ice elimination. Then maintain a temperature between 86 and 95 F. measured with a carburetor air mixture thermometer.


If these temperatures cannot be maintained, place control in full "cold" position.



It will be necessary to readjust the mixture control whenever the carburetor air heat control setting is changed.

(2) STARTING  Carburetor air heaters will always be in full "cold" position to eliminate heater valve damage due to backfire.

(3) GROUND RUNNING. Ordinarily the carburetor heat will be in the "cold" position. However, during icing conditions the instructions in (1) above will followed during extended ground operation and just before take-off.

(4) TAKE-OFF Carburetor air heat will not be used during take-off. Under icing conditions, carburetor air heat will be used immediately before take-off, to insure that all ice is removed from the induction system. Immediately after take-off when power is reduced, carburetor heat will be adjusted to maintain the temperatures in (1) when icing conditions are indicated.

(5) CRUISING When cruising under severe icing conditions, at least 75 per cent engine power will be used and the mixture control will be set on the rich side of best power. At the same time it is advisable to seek a more favorable altitude where precipitation can be avoided and where the temperature is farther from the freezing range.

(6) LANDING Carburetor heat control will be in the "hot" position when in a long glide before landing. but will be in the "cold" position immediately prior to the landing approach so as to have full power available.

13. Run Out On Unleaded Fuel

a. If engine is to be shut down over 48 hours, it should be operated at 40 to 50 per cent of normal rated R.P.M. for 15 minutes on the propeller load with 73 octane unleaded fuel. This is necessary to avoid corrosion caused by tetra-ethyl lead.

b. Before shutting off engine, run it between 700 and 800 R.P.M. long enough to permit the cylinders to come to a maximum temperature of 250 F. Then turn the ignition switch to the "off" position.

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