Engine A/I selection and FADEC
 

Hi everybody,
I used to fly with non-FADEC Engines and always I had been told to switch on/off the Engine anti ice one by one and with a delay enough to check the engine parameters to be stabilize because the change in the bleed configuration.
When I moved to A320 I could see quite a lot of colleagues switching them without any precaution and even both at the same time (using two fingers).

Is it because the FADEC is taking care of it? Is it still a good idea to do it one by one or I am getting to old? :{

Probably differs with engine type. With my "Rollers" we switch them on one at a time. If the first one stops we know not to switch the second one on! :}

Many newer airplanes have auto icing detection systems that automatically turn on engine anti-ice, and it does the same thing to all engines at the same time. Hasn't been an issue.

One thing you need to watch out for with manual anti-ice - if you don't turn it on 'right away' and allow ice accumulation on the inlet, turning anti-ice on can result in a sudden large ice shed that can cause problems. For that scenario, I'd still recommend the 'one engine at a time' to make sure you're not making things worse...

if you turned one on at a time and you got a boom and vibration, what are you going to do with the other engine ?

Obviously that would depend on the exact circumstances, but if turning on anti-ice causes an engine to surge and quit, you might want to consider seeing if you can get it restarted before moving on to the next engine...:rolleyes:

FADEC or not, anytime one is making a massive change on the demand of any system it is prudent to do so with kindness to the machine.

Ya don't say?! I doubt that Loma was asking a question... ;)

In normal flight configuration, the bleed systems are independent, so the demands on the system are no different whether you turn them off individually or simultaneously. It's really a philosophical question then. I have heard of 2-finger oopses, such as switching off both gens instead of turning on both packs...

I think it has to do with new generation of engines that are not easily destabilised and very reliable relight function. First generation 747 engines used to flame out if throttled back for descent at high altitude so they had throttle restrictor bar.