Below are some general rules to go by for winter ops for our club airplanes:
32 DEGREES: If the current temperature is less than 32°F, or the average temperature over the past 24 hours is less than 32°, then you should put heat on the airplane for at least an hour before flight. Put in the engine pre-heaters, make sure you have a blanket on the cowling and cowl plugs installed to keep in the warmth.
25 DEGREES: If the current temperature is less than 25°F, or the average temperature over the past 24 hours is less than 25°, then you'll need more time. Depending on the type of heater it will be anywhere from 2 - 12. When in doubt have heat on it for at least 12 hours. No Champ solo flights. Explanation below.
15 DEGREES: If the current temperature is less than 15°F, or the average temperature over the past 24 hours is less than 15°, then I'd rather not have the airplanes flown. It's much harder on the airplane than it's worth. There are just too many parts on an airplane that need heat. It's hard on gyros, it's hard on just about everything. We simply don't charge enough per hour to have to replace or repair things from operating below this temperature. The exception would be an airplane that is kept inside a heated hangar. If you're on a trip and the temps are forecast to be below freezing, then plan to rent a hangar.
COCKPIT HEATERS: Please warm up the cockpit! We have heaters to put inside the cockpit prior to your flight. Sure, it makes your flight more comfortable, but it's really all about warming up the radios and instruments! BE CAREFUL WITH THOSE COCKPIT HEATERS! Check on them every so often and *don't leave them on all night or unattended*.
STARTING: Please do not crank and crank and crank on an airplane starter. They are not like cars. If it doesn't start with just a few turns of the prop (4-5) then please quit cranking, because you don't have the right combination of fuel/air. (Probably not enough fuel). If you have tried repeatedly without luck, STOP before you run the battery down. If you're new to winter ops then get with an instructor and have him/her show you the ropes on the specific plane you’re in.
RUN-UP: Make sure you give the airplane enough time for the oil temp to get into the bottom of the green arc before you do your run-up. This may take some time in the colder temps. Lean the mixture, run it up around 1200 RPM or so, and wait for the oil temp to warm up enough to start moving into the green. This could take ten minutes.
Be careful pulling the airplanes out of the hangars when there is frost, snow or ice! Easy to fall and hurt yourself!