Extra EA-500/Icing

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General

The Extra500 includes an icing model meaning that under the correct atmospheric conditions, ice will form on the aircraft. Without the proper counter measures, you will run into problems quickly.

Recognizing icing

There is no ice warning device on the Extra500. Therefore you must keep an eye on the outside air temperature (on the IFD, left centre of the PFD screen). If it is freezing and you have 'visible moisture' (clouds, fog etc) ice might form. In that case keep a close eye on the wing nose!

Effects

In general there are 4 effects:

1. Aerodynamic
2. Engine operation
3. Systems
4. Visibility

Aerodynamic effects

The most predominant is the increase of drag. Of course, this will slow down the aircraft, but the effect mostly feared is the decreased climb speed. Usually you will want to climb through the icing to get to cruise altitude. In severe icing this might be a problem, also because of the reduced engine performance (see below).

The second effect is a significantly increased stall speed. Up to 10 knots higher.

The third effect is Ice Contaminated Tail Stall (ICTS). If there is ice on the horizontal stabilizer it stalls much earlier. This is especially dangerous when there is a high downward aerodynamic load on the tail. This is usually the case with flaps extended. When in icing or afterwards, it is best not to fully extend the flaps. When the horizontal tail stalls you will experience and almost unrecoverable pitch down moment.

The aileron effectiveness is also reduced when the outer wing has icing on it.

The last effect is the propeller. Ice reduces the efficiency and causes a cockpit vibration (propeller unbalance).

Engine operation

The engine air inlet is very sensitive to icing. It can stall or ice up in which case the engine will go out. Therefore the first thing to do is to activate the engine anti-icing. It is the RH Bowden cable in the middle console. Activation will increase the TOT, so when you are flying at the TOT limit, make sure to reduce power a bit. As mentioned before, in combination with aerodynamic effects you might find yourself in a problematic situation, so take care...

Systems

The pitot tubes may ice up which results in a false airspeed indication. This is valid for the stall warner as well. When iced up, it will not give a stall warning anymore.

Visibility

The windshield might ice up, reducing your forward view.

Counter measures

As can be seen the effects of icing are not to be underestimated. Therefore the Extra500 has several de- and anti-ice systems.

1. As already mentioned, the engine inlet has an anti-ice system. Activated by the RH Bowden cable in the middle console and indicated to be working in the annuciator panel by the green light: INTAKE HEAT.
2. The pitot tubes are protected by their electrical heating. There are 2 switches, one for the LH pitot tube and another for the RH. The stall warner heating is activated by the R-PITOT switch. The annunciator panel has 5 lights to indicate when the pitot/static/stall heating is not working. Normally these systems are always switched on (but Weight On Wheels will keep them from overheating on the ground).
3. The pilot windshield has a heating in it which can be used to clear a small portion of the window. It has a controller that keeps the windshield temperature between 20 and 40 degC. When heating, WINDSHIELD HEAT ON lights up green.
4. The aerodynamic surfaces are protected by pneumatic boots. When activated, the boots are inflated for 6 seconds (indicated by BOOTS green light), shedding the ice formed on the surface nose. They are inflated every minute and there are 2 cycles, one for the wing inboard boots and the other for the wing outboard and empenage boots.
5. The propeller has electric boots which are activated by the PROP switch. Proper function is indicated on the propeller ammeter in the LH upper corner of the instrument panel.