THIS PAGE IS ONLY AN INCOMPLETE DRAFT. IT REQUIRES ADDITIONAL REVISION.

 

The information for operating the Cessna Citation Mustang in cold weather and icing conditions is sprinkled throughout the AFM, especially 3-151. Cessna also publishes a model-generic Guide to Cold Weather Operations. This page attempts to collect and synthesize the various bits of information.

 

 

The overall temperature envelope is neatly summarized in the AFM figure 2-13, copied above. Within that overall envelope are more specific restrictions listed below.

 

Mustang Temperature Limits

 

Various limits take effect depending on operating temperature. As can be expected, as the ground temperature decreases, greater attention must be made by operator.

 

For simplicity, the temperature listed assumes, unless otherwise noted, that the plane has been cold soaked to that temperature. Cessna defines cold soaking as two hours below -15 C. If the plane is on the ground for just an hour in -30° C Montreal, you can be certain that exposed parts will be cold enough for these limitations to start taking effect.

 

Temperature	Limitation	Reference
22° C	Minimum oil temperature for 5 minutes prior to takeoff	AFM 2-6
10° C	Minimum oil temperature before increasing power to warm engine faster (must be ground idle below 10)	AFM 2-6
	Below this temperature requires visual and tactile wing inspection for frost, ice, snow, slush	AFM 2-19
	(RAT) Engine, windshield anti-ice must be on in visible moisture.	AFM 2-32, 3-148
0° C	Remove EROS crew oxygen masks and all cabin fluids	3-152
-10° C	Battery must be pre-heated prior to start (certain configurations allow battery to be -18 but we suggest a more conservative approach)	AFM 2-4
	Minimum RAT temperature for windmill start	AFM 2-12
-30° C	Minimum temperature for operation of boots	AFM 2-32, 3-144, others
-35° C	Minimum fuel temperature in the wings. No CAS message if this is exceeded. Note that JET B, which has lower limits, is not approved in the Mustang.	AFM 2-14
-40° C	Engine must be pre-heated prior to start	AFM 2-4
	Engine indicating system may take 10 minutes to be usable	AFM 2-4
	Minimum oil temperature	AFM 2-4
	Minimum flap operation temperature	AFM 2-19

 

Flying from Warm Weather to Cold

 

Many planes take their owners to warm destinations and then return to the cold north. A typical flight is going from the Northeast to Florida for a few days and then returning home to below freezing temperatures. In the AFM 2-13, there's this little note:

NOTE

If the ground operating temperature is expected to drop more than 28° C (50° F) or the arrival airfield is expected to be more than than 28° C (50° F) colder than the departure airfield, refer to the Airplane Maintenance Manual for tire servicing.

 

This is a pretty common scenario when flying for Florida to the Northeast in the winter! The Maintenance Manual (and associated tire documentation supplied with the plane) recommend overinflating the tires slightly prior to leave warm weather.

 

Buried on page 43 of the Michelin Tire Care and Service Manual, the recommendation is to increase inflation pressure by 1% for each 5° F temperature drop, but to not exceed the maximum rated loaded tire pressure. On the nosewheel that would mean 130 PSIG and the mains would be 93 PSIG. If the plane will stay in a cold area for longer term, it's recommended to recheck the pressure at least 3 hours after landing or prior to the next flight.  If a plane with underinflated tires comes in a Cessna Service Center, they are obliged to change the tires, which could be expensive compared to a $45 Nitrogen fill.

 

 

Operating Tips in Cold Weather

 

• Turn off boots when on short final. When boots are in operation, the leading edge airfoil changes significantly. This is not an issue while in flight. However in the critical phase of the flare, especially with icing, instability should be minimized. If necessary, the boots can be blown manually a final time prior to landing. Once on short final, the boots should be turned off. In a go-around, if necessary, remember to turn on the boots again.
• Lower flaps at V_fe - 20kts.  If icing is potentially present, deploying flaps 15 at 185 kts could load up the tail. It's safer to wait until there is a bigger margin before loading up the tail. Flaps 15 should be deployed at 165 kts instead of 185 kts.
• Do not trust the "green donut" in icing. In icing conditions, the "green donut" can be off as much as 10 kts compared to the calculated approach speed.  Calculate approach speeds and do not rely on the "green donut".
• Plant it. Minimal flare on a contaminated runway. On any contaminated runway, whether it be wet but especially if it is icy, do not waste precious runway with a soft flare. Plant the plane on the runway, using the trailing link gear as it was designed. Stopping distance is critical. Use full brakes immediately. All the performance books numbers were based on flying the plane onto the runway, not a long gentle flare.