Icing

Definition:

Icing conditions can exist when the Outside Air Temperature (OAT) is +5°C or less and visible moisture is present (visible moisture can appear as cloud, fog, mist, drizzle, rain, hail, snow, sleet, slush, spray or ice crystals).

Limitations:

The Seneca V ice protection system is designed for operation in light to moderate icing conditions.

Flight in the following conditions is prohibited and must be avoided:

  • Severe icing conditions
  • Freezing rain
  • Freezing drizzle
  • Supercooled liquid water
  • Ice crystals

If any of these conditions are encountered, use of the autopilot is prohibited and the pilot should be prepared to divert the flight promptly, by changing course and/or altitude, if hazardous ice accumulations occur.

Seneca V Icing Equipment:

The Seneca V is equipped with the following icing equipment:

Use of Icing Equipment

After Engine start.  On a cold day the Cabin Heating may be switched on after the engines have been started, but if not required on the ground, the CABIN HEAT and DEFROST switches should be selected ON in the climb as the OAT reduces through +5°C.

Before Take-Off.  If icing conditions exist on the ground, the PROP HEAT switch should be selected ON at the appropriate point during the Before Take-Off checks.  The ALT AIR must be OFF for take-off due to performance reasons, so if ice is seen to be forming on the wings before take-off, do NOT take-off!  At night, switch on the ICE LIGHT to ensure that the wings can be inspected and use a torch if necessary.

On the Runway.  When cleared for take-off, always toggle the PITOT STALL WARN HEAT switch to the ON position and ensure that the warning caption extinguishes. Start the timer as you do so to ensure that the system is not switched on for more than 3 minutes prior to starting the take-off run.

During the Climb.  The OAT must be checked passing 1000 ft in the climb and every 1000 ft thereafter.  As the OAT reduces to +5°C:

  • Select the PROP HEAT switch ON
  • Select the CABIN HEAT and DEFROST switches ON

Once the OAT is at or below +5°C, check (by asking the examiner if wearing a visor) for any signs of ice formation on the aircraft surfaces; if ice is forming:

  • Select the WSHLD HEAT switch ON
  • Select the ALT AIR to ON
  • Activate the SURF DEICE function if more than 1/4 inch (0.7 cm) of ice has built up on the wing leading edges.
  • Be prepared to select the Alternate Static Source should pressure instruments indicate errors. If the altimeters fail, remember that GPS with SBAS enabled will indicate a Geodetic altitude (available on the AUX – GPS STATUS page) accurate to about +/- 13 ft.

At the Top Of Climb, and during the Cruise.  

If the OAT is at or below +5°C confirm that:

  • The PROP HEAT switch is ON
  • The CABIN HEAT and DEFROST switches are ON

Check (by asking the examiner if wearing a visor) for any signs of ice formation on the aircraft surfaces; if ice is forming:

  • Select the WSHLD HEAT switch ON
  • Select the ALT AIR to ON
  • Activate the SURF DEICE function if more than 1/4 inch (0.7 cm) of ice has built up on the wing leading edges.
  • Be prepared to select the Alternate Static Source should pressure instruments indicate errors. If the altimeters fail, remember that GPS with SBAS enabled will indicate a Geodetic altitude (available on the AUX – GPS STATUS page) accurate to about +/- 13 ft

If ice has stopped forming on the aircraft surfaces:

  • Select the WSHLD HEAT switch OFF
  • Select the ALT AIR to OFF

During the Descent.  Check the OAT when passing every 1000ft during the descent. When the OAT increases above +5°C:

  • Select the PROP HEAT switch to OFF
  • Confirm or select the WSHLD HEAT switch to OFF
  • Confirm or select the ALT AIR to OFF
  • The CABIN HEAT and DEFROST switches may;
    • Remain ON or;
    • Select CABIN HEAT to OFF (central position) and DEFROST to OFF

After Landing. During the After Landing checks:

  • Confirm or select the PROP HEAT switch to OFF
  • Confirm or select the WSHLD HEAT switch to OFF
  • Confirm or select the ALT AIR to OFF
  • The CABIN HEAT and DEFROST switches may
    • Remain ON or;
    • Remain OFF or;
    • Select CABIN HEAT to FAN and DEFROST to OFF

When Closing Down.  When shutting down the engines:

  • The CABIN HEAT and DEFROST switches:
    • Remain OFF or;
    • Select CABIN HEAT to FAN, then after 2 minutes to OFF, and DEFROST to OFF.