GRUMMAN AMERICAN
FOR TRAINING USE ONLY – SECTION 4
MODEL GA-7/COUGAR
NORMAL PROCEDURES
4-23
Issued: April 10, 1978
COLD WEATHER OPERATION
STARTING
When starting in extremely cold weather, use of an external preheat and an external power source is
recommended to reduce severity of load on the electrical system and engines.
WARNING
WHEN PULLING A PROPELLER THROUGH BY HAND, TREAT IT AS IF THE IGNITION
WAS ON. A BROKEN OR LOOSE GROUND WIRE ON EITHER MAGNETO COULD
CAUSE THE ENGINE TO FIRE.
Propellers should be pulled through several complete revolutions by hand to loosen oil.
Starting procedures in cold weather are the same as for normal starting except that more priming may be
required.
WARM-UP
During cold weather operations, no indication will be apparent on the oil temperature gauge prior to takeoff if
outside air temperatures are very cold. After a suitable warm-up period (2 to 5 minutes at 1000 RPM), accelerate
the engine several times to higher engine RPM. If the engine accelerates smoothly and the oil pressure remains
normal and steady, the airplane is ready for takeoff.
IN FLIGHT
ENGINE ROUGHNESS
Engine roughness is usually due to carburetor icing, and may be accompanied by a slight loss of airspeed or
altitude. If too much ice is allowed to accumulate, restoration of full power may not be possible. Prompt action is
required.
1.
Carburetor Heat – On. Power will decrease slightly and roughness will increase. Wait for a decrease in
engine roughness or an increase in power. If no change in approximately one minute, return carburetor
heat to OFF. If engine is still rough, try the following steps:
2.
Mixture Control – Adjust for a maximum smoothness. Engine will run rough if too rich or too lean.
3.
Auxiliary Fuel Pumps – On.
4.
Fuel Selector – Change to cross feed to see if fuel contamination is the problem.
5.
Engine Gauges – Check for abnormal readings. If any gauge reading is abnormal, proceed as follows:
a.
Magneto Switches – Check, one at a time, then both ON. If operation is satisfactory on either
magneto, proceed on that magneto at reduced power, with mixture full rich, to a landing at the
first available airport.
If engine roughness persists, prepare for a precautionary landing at pilot’s discretion.
