Icing Anyone?

[Phil Croucher]

The difference for 206 blades will only be a few degrees, but that will be enough to make a difference - for example, many people don't put blade covers on overnight because they freeze to the blades. Once you've deiced the rest of the machine, and provided the deposit is light and even (gotta watch out for balance), starting the machine then shutting down to check after ten minutes will usually do the trick. Having said that, blades have a high catch efficiency because they are fast and slim as they slice through the air.

 

For those with databanks to fill up it's not only the usual performance (extra weight & drag) and flying controls that can be affected by ice - chunks flying off can hit the tail rotor, and water inside door seals can freeze and stop them opening to let the occupants out if you have to land in a hurry, so be careful!

 

Phil

[45PSI]

Aerodynamic friction heating is biggest at the tips, and smallest at the root, so even if your tips aren't icing your blade roots may be - and they drive the autorevs...

 

Once picked up ice in light fog (unbelievably quickly), and by the time I landed and started the cooldown the exhaust warmed it enough to start shedding. the resulting little bits of ice hitting things near my parking were like bullets... scared the crap out of my poor wrench.

[R22Captain]

Thanks AR.....I'll file that on my C:/ drive

[Guest heli206212]

Wx is crapy for me as well, Does it count as icing if its just wet snow impacted on the nose of the machine and a bit on the wipers? Has anybody ever accumulated ice at or above 0c? Me and another piliot were debating this topic just the other day. I myself have never accumulated ice above about -4c but have had a bit of snow stick to the nose.

Hi Nobul,

 

Flying offshore NL would interest you for icing.

 

The worst temps for icing are generally between 0 and - 10 Cel. You have the visible signs and instrument indications, such as TQ increase. Plus aircraft performance.

 

It is another whole topic in itself. Check out and review TC AIM, CARS, Nav Canada web site, or google it.

 

As to your question, I have heard to stay out of cloud even in temps between 0 and + 5 Cel. Something about Super Cooled water droplets.

 

Take care

[Hazy]

How about turbine blade icing?

 

There is usually a huge flame ahead of them.

 

Seriously, you probably mean the compressor blades. Know your engine anti-icing system. Some systems are pilot initiated, some are not ex. arriel.

 

That being said, be aware that your intake could ice up and give you grief while the engine isn't being iced up.

 

Hrummy

[WTF_was_that]

Tea bagger, what was the flat pitch torque when you landed.

 

Started a jet box, to warm it up. There was light fog and the temp was around freezing. Watched the torque rise from 28% to 35 to 50 in a matter of a minute. Shut the a/c down to find 1cm of ice on the blades. from root to tip. The thickest ice was in middle section. The last 6in of blade may be had half a cm.

 

That was learing experience. I will not repeat.

[Bladestrike]

Tea bagger, what was the flat pitch torque when you landed.

 

Started a jet box, to warm it up. There was light fog and the temp was around freezing. Watched the torque rise from 28% to 35 to 50 in a matter of a minute. Shut the a/c down to find 1cm of ice on the blades. from root to tip. The thickest ice was in middle section. The last 6in of blade may be had half a cm.

 

That was learing experience. I will not repeat.

 

It's only my second winter flying a deiced Super Puma to the platforms 175 miles offshore out of Halifax (flying S61s before that trying desperately to stay out of ice), but I was suprised last week to get a torque rise in cloud at -3 C (that the deice kit quickly rectified when we bothered to turn it on) so ice MAY stick to your blades in the temperatures closer to zero where you wouldn't expect it due to aerodynamic heating. I have picked up abit of ice at 0 right at the cloud tops in a 61, but we just climbed up and didn't notice any torque rise. I can't recall ever picking up ice above 0, and I've been at this for 25 years.

 

I've been suprised in colder temps as well, picked up so much ice taking a shortcut in a S76 many years ago the pitots which are heated couldn't keep up.... -29 C at 9000 feet! I hadn't yet learnt that there can be significant moisture near the cloud tops even in very cold temperatures.

 

One more story....-40 C in Northern Ontario in a 222, departed in clear skies for a medevac 40 miles North. The pickup site was fogged in with that early morning, low-lying fog, so we found a clear area up the road, landed in this confined area and idled for twenty minutes while waiting for and loading the patient. On takeoff I noticed the fog in the trees all around our confined area that I hadn't noticed had formed while waiting, and through about 60 knots the aircraft shuddered then that was it, no noticeable torque rise or visible ice. On landing and shutdown a half hour later, you could see almost an inch of ice on the roots of the blades, and a clear line where the rest had broken off and shed. There was no ice on the airframe whatsoever. We also found a small dent in the tail rotor from the shedding ice.

 

Insidious stuff!

[Bladestrike]

I should add, while I have never picked up ice at temperatures above zero, I have flown into freezing rain at night in temperatures we had thought we're above zero, and picked up significant ice in the time it took to do a 180.

 

We had been flying in temperatures around +1C or +2C in drizzle, but we had obviously flown into some colder air, something to be wary of if warm fronts are around.