1. COLD WEATHER OPERATIONS Navy Flying Club Safety Brief October 12, 2004

2. Cold Weather Operations – Pre-flight Planning When the temperature is less than 25 deg F, preheat should be applied to engine Insufficient heat causes hard starting, abnormal wear to internal engine parts, reduced engine performance, and shortened TBO Plugs can ice-up during start attempt due to condensation and freezing of water vapor

3. Exercise special caution regarding any possible water contamination of fuel - water can freeze in fuel line; drain tanks and sump Check engine breather tube! Moisture frozen in end of breather tube can lead to loss of engine oil Check fuel selector valve for freedom of movement; statistics document cases of frozen selector Cold Weather Operations – Fuel Considerations

4. Amount of priming must be increased as air becomes colder and more dense However, do not overprime! This can lead to engine fire Throttle position should be slightly closer to idle position, on start-up, because of colder, more dense air Cold Weather Operations – Engine Priming

5. General rule for engine starters: after three, 10-second periods of operation, with a pause between each, a five minute cooling period is required Failure to observe this can lead to starter overheating and damage/failure Cold Weather Operations – Engine Startup

6. After start, do not idle below 1000 RPM - Cold temperatures increase probability of lead fouling of plugs During flight, exercise constant speed props every 30 minutes to prevent congealing of oil in prop dome Don’t run fuel tank nearly dry before switching tanks; selector valve may have frozen Cold Weather Operations – Engine Startup

7. Allow extra time for oil to warm up after startup. In the T-34, because of it’s 12 quart sump, 15 minutes at idle may be required to bring oil to minimum operating temperature Avoid power-off descents - engine should not be “shock cooled”; cylinder head temperature change should not exceed 50 degrees F per minute Cold Weather Operations – Engine Startup & Operation

8. Plan descents earlier Reduce power gradually Maintain power throughout descent Keep fuel/air mixture leaned during descent Cold Weather Operations – Flight Considerations

9. Cold Weather Operations – Frost, Snow & Ice FAR 91.527 Operating in icing conditions. (a) No pilot may takeoff an airplane that has- (1)Frost, snow, or ice adhering to any propeller, windshield, or power plant installation or to an airspeed, altimeter, rate of climb, or flight attitude instrument system; (3)Any frost adhering to the wings or stabilizing or control surfaces, unless that frost, has been polished to make it smooth.

10. Cold Weather Operations – Frost, Snow & Ice Assuming that a thin coating of frost or ice is of no consequence, or that snow will blow off during takeoff is to ‘court disaster’! Frost/snow/ice on wing and tail surfaces during takeoff has been a contributing factor in a number of well-publicized aircraft accidents

11. Cold Weather Operations – Frost, Snow & Ice – All frost/snow/ice should be removed before attempting flight For frost or ice, place aircraft in heated hangar, if possible (be sure water doesn’t run into control surfaces & re-freeze when aircraft is brought outside again) If no hangar is available, face aircraft control surfaces towards the sun to utilize/maximize radiation heating

12. Cold Weather Operations – Frost, Snow & Ice For snow, brush off (don’t count on snow blowing off during takeoff roll!) Note: Sometimes frost adheres to surfaces below snow covering Alcohol, glycol or other ice-removal chemicals can be used Exercise extra care when warm aircraft has been pulled from hangar and left out in snow conditions

13. Cold Weather Operations – Frost, Snow & Ice Following snow conditions, be extra careful on pre-flight to check: Inside pitot tube Static opening Fuel vents Heater intake Carburetor intake Trim tabs and controls Wheel wells

14. Cold Weather Operations – Frost, Snow & Ice “Unseen Frost” – Same conditions which cause frost formation on external surfaces can cause internal problems – Moisture in fuel tanks can freeze (good reason for topping tanks after flight) and can cause blockage of fuel flow to engine

15. Cold Weather Operations – Frost, Snow & Ice Every year, there are between 30 and 40 accidents involving icing, approximately half of which are fatal Many pilots underestimate rate of ice accumulation and its effect on aircraft performance If aircraft has enough ice to be unable to hold altitude, chances of making it safely to on-airport landing are poor

16. Cold Weather Operations – Frost, Snow & Ice Typically, even small buildup of ice can cause 30% reduction in maximum coefficient of lift, decreasing the stall angle-of-attack Drag builds up, and if it exceeds max. thrust (full throttle), leads to descent, whether desired or not! Thrust also lost due to ice accumulation on propeller

17. Cold Weather Operations – Frost, Snow & Ice First place ice accumulates is small-radius or sharp-edged surfaces (fuel vent, temp. probe, etc) Small leading edge on tail surfaces make them more efficient collectors of ice (almost twice as fast as wing ice accumulation); tail may reach stall angle-of-attack before wing becomes problem

18. Cold Weather Operations – Frost, Snow & Ice Since horizontal tail produces “down” lift, stall results in tail going up, and aircraft nose pitching down Flap deflection increases downwash on tail, leading to higher (more negative) angle-of- attack, and earlier stall, if tail is iced

19. Cold Weather Operations – Summary Allow extra time for pre-flight planning, aircraft preparation and engine warm-up Understand the effects that frost, snow and ice have on an aircraft When flying in cold weather, keep in mind the impact that the temperature has on the aircraft and plan maneuvers accordingly Avoid flight in/through visible moisture Fly Safe!!

20. QUESTIONS?