Icing procedures VS NASA
 

Hi,

I'm studying up for a possible interview, and have been watching a NASA video on icing for Corp and Regional pilots/aircraft. Their recommendations seem to conflict with traditional thought on when and how many/much to cycle the boots. They recommend cycling often and that modern boots do not create ice bridging. Since I don't have this experience, can I get some real life wisdom here.

Thanks,

577nitro-

The AFM should have the procedure in section 5 for the particular aircraft...

Are you talking about ice bridging?

It's kind of a defunct procedure. First sign of ice blow the boots.

someone once told me that the whole ice bridging myth came from an old movie and it just kinda snowballed from there. We are told to turn the boots on at +5 and visible moisture and leave em on for 15 min after leaving the conditions

I've been flying a King Air for 4 years and have watched that NASA video many, many times. Beech / Raytheon / Hawker, what ever it is they call themselves this year, recommends waiting for 1/2 inch of ice to build up before you cycle the boots. If you cycle the boots four times (get two inches of build up) then the recommendation is to immediately exit the icing environment. Here is the trick. How do you determine the difference between 1/2 and 1/4 and 1 inch of ice? You guestimate based on things attached to the leading edge of the wing (stall stips, recognition light guards, etc). From what I've been told, many modern T-Props have boots that continuously cycle when you turn them on. Mine don't; they inflate and then deflate until you hit the switch again. I will say that if you hit the boots with too little ice on them, not all will pop off. In my experience, it is best to wait for a build up.

Take that NASA video to heart when it comes to tail plane icing. If you make a configuration change and things start going very bad, undo what you just did. That means keeping your hand on the flap selector until they are fully down and the aircraft is reacting normally.

One last thing. Be careful of rapid decents and level-offs with ice on the wing. Something crazy happened to me about two weeks ago, I think it was an ice induced accelerated stall because I was doing 145knots leveling off from a 2000fpm decent in a King Air, in ICM, 4000 feet above the ground, during the seconds between when I asked for the de-ice boots to be popped and the other pilot hit the switch. Scared the daylights out of me.

Happy Flying

I'm on the brasilia, and I've been in some very nice icing situations. I have seen bridging a couple of times (luckily we weren't in icing for a long period of time), but it was brought on by cycling the boots too early in clear icing conditions. Not to say it happens all of the time, but I'm sure all of the stars need to be aligned for it to happen. Like Clue said, you gotta watch the tailplane icing close (just because the leading edges don't have much, doesn't mean the tail is clear too). I usually base the boot actuation off of the current accumulation. I've never have issues with airspeed decay, maybe the occasional prop imbalance (due to the stellar prop deice system *sarcasm*) but it's worked well for me. The FAA's done more tests than I have so take this info with a grain of salt.

What are these boots you speak of :D I'd better study up for the Brasilia - teach me and I will listen LoL

They look exactly like the moon boots that Napoleon Dynamite wears in his movie. You velcro them around the back, great traction on the bottom, with a shnazzy glimmer in the mid morning winter sun!