We are well into fall and winter seems to be fast approaching, I am ever reminded by all the holiday décor already up around town. For the majority of us, baring you lucky few down south, we will notice drops in temperature and for many areas across the United States temperatures can drop well below freezing. With freezing conditions come additional weather hazards like frost, ice, and snow to name a few. Often times, new pilots overlook the fact that cold weather can also affect the aircraft itself, specifically aircraft systems. When an aircraft has been exposed to cold for any length of time, extra care should be taken when preparing the aircraft for flight. Your Pilots Operating Handbook (POH) or Information Manual will often list specifics for cold weather operations.
Some of the aircraft systems affected by cold weather include the engine, oil, fuel, and electrical systems. At low temperatures, changes occur in the viscosity of engine oil, batteries can lose a high percentage of their effectiveness and drain quicker, instruments and warning lights can stick in the pushed position when “pushed to test.” Therefore, preheating the engines, as well as the cockpit, before starting is advisable in low temperatures. The pilot should also be aware that at extremely low temperatures, the engine can develop more than rated takeoff power even though the manifold pressure (MAP) and RPM readings are normal.
Over-priming is a frequent cause of difficult starting in cold weather because oil is washed off the cylinder walls and poor compression results. Many POHs will outline different procedures and checklists for cold weather starting.
During cold weather preflight operations, be sure to check the oil breather lines. The vapors caused by combustion may condense, then freeze, clogging these lines.
Since most aircraft heaters work by using the engine to heat outside air, a pilot should frequently inspect a manifold type heating system to minimize the possibility of hazardous exhaust gases leaking into the cockpit.
In addition to your standard aircraft checklist, there are often many additional tasks that need to be followed for cold weather operations. You need to adjust and allow yourself extra time in your pre-flight to make sure everything is accomplished to allow for a safe flight.
Here are a few questions to test your knowledge on the material covered above.
1. During preflight in cold weather, crankcase breather lines should receive special attention because they are susceptible to being clogged by
A. congealed oil from the crankcase.
B. moisture from the outside air which has frozen.
C. ice from crankcase vapors that have condensed and subsequently frozen.
2. Which is true regarding preheating an aircraft during cold weather operations?
A. The cabin area as well as the engine should be preheated.
B. The cabin area should not be preheated with portable heaters.
C. Hot air should be blown directly at the engine through the air intakes.
3. Frequent inspections should be made of aircraft exhaust manifold-type heating systems to minimize the possibility of
A. exhaust gases leaking into the cockpit.
B. a power loss due to back pressure in the exhaust system.
C. a cold-running engine due to the heat withdrawn by the heater.
