General Aviation
Accident Prevention Program

Tips On Winter Flying

FAA Warning/Disclaimer

AIRCRAFT PREPARATION

If your home base is located in a warm climate area, you may not have familiarized yourself with the aircraft manufacturer's recommendations for winterizing your aircraft.  Most mechanical equipment, including aircraft and their components, are designed by manufacturers to operate within certain temperature extremes.  Manufacturers generally can predict their product's performance in temperature extremes and outline precautions to be taken to prevent premature failures.

Baffling and winter covers - Baffles are recommended by some manufacturers to be used in augmented tubes.  Winter fronts and oil cooler covers are also added to some engine installations.  FAA approval is required for installation of these unless the aircraft manufacturer has provided the approval.  When baffles are installed on aircraft, a cylinder head temperature gauge is recommended, particularly if wide temperature differences are to be encountered.

Engine Oil - The oil is extremely important in low temperatures.  Check your aircraft manual for proper weight oil to be used in low temperature ranges.

Oil Breather - The crankcase breather deserves special consideration in cold weather preparation.  A number of engine failures have resulted from a frozen crankcase breather line which caused pressure to build up, sometimes blowing the oil filler cap off or rupturing a case seal, which caused the loss of the oil supply.  The water, which causes the breather line freezing, is a natural byproduct of heating and cooling of engine parts.  When the crankcase vapor cools, it condenses in the breather line subsequently freezing it closed.  Special care is recommended during the preflight to assure that the breather system is free of ice.  If a modification of the system is necessary, be certain that it is an approved change so as to eliminate a possible fire hazard.

Hose Clamps, Hoses, Hydraulic Fittings and Seals - An important phase of cold weather preparation is inspection of all hose lines, flexible tubing, and seals for deterioration.  After replacing all doubtful components, be certain that all clamps and fittings are properly torqued to the manufacturer's specifications for cold weather.

Cabin Heater - Many aircraft are equipped with cabin heater shrouds, which enclose the muffler or portions of the exhaust system.  It is imperative that a thorough inspection of the heater system be made to eliminate the possibility of carbon monoxide entering the cockpit or cabin area.  Each year accident investigations have revealed that carbon monoxide has been a probable cause in accidents that have occurred in cold weather operations.

Control Cables - Because of contraction and expansion caused by temperature changes, control cables should be properly adjusted to compensate for the temperature changes encountered.

Oil Pressure Controlled Propellers - Propeller control difficulties can be encountered due to congealed oil.  The installation of a recirculating oil system for the propeller and feathering system has proved helpful in the extremely cold climates.  Caution should be taken when intentionally feathering propellers for training purposes to assure that the propeller is unfeathered before the oil in the system becomes congealed.

Core of Batteries - Wet cell batteries require some special consideration during cold weather.  It is recommended that they be kept fully charged or removed from the aircraft when parked outside to prevent loss of power caused by cold temperatures and the possibility of freezing.

Wheel wells and Wheel Pants - During thawing conditions, mud and slush can be thrown into wheel wells during taxiing and takeoff.  If frozen during flight, this mud and slush could create landing gear problems.  The practice of recycling the gear after a takeoff in this condition should be used as an emergency procedure only.  The safest method is to avoid these conditions with retractable gear aircraft.  It is recommended that wheel pants installed on fixed gear aircraft be removed to prevent the possibility of frozen substances locking the wheels or brakes.

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