View Full Version : icing
lmlanphere
9th Feb 2001, 00:12
anyone have any info on the rate - if any - of ice accretion in snow (especially wet snow)?
1. What aircraft type are you talking about?
2. Rate of accretion roughly speaking is related to visibility. That's generally how you'll find Flight Manual limitations expressed for falling snow.
3. It's a complex subject......
I've flown in lots of snow. Fluffy snow, sticky snow, wet snow , dry snow ,snow grains, blowing snow, snow in January and snow in June.Snow at zero degrees and snow at minus 25 degrees. Not to say that it can't happen but I have never had it stick to the blades or to any critical part of the aircraft. Generally speaking my only concern with snow is ceiling and visibility.
IHL
ShyTorque
9th Feb 2001, 15:09
As already stated the worst problem is usually the viz reduction. however, you may be already aware that one of the very few helicopters that are truly all weather is the Super Puma, heated blades, special intakes etc et al.
However, a real danger to a helicopter is rain / clear ice which has been known to build up extremely rapidly, is highly "sticky", is very heavy and will change the aerofoil shape of the inner third of your rotor blades as well as goo up your external control runs and unheated transparencies, aerials etc. Thankfully it is rare!
We used to suffer really badly whilst ground taxying in slush. If it was allowed to freeze on the wheels it became:
CHOCK-ICE!
Rotator
9th Feb 2001, 15:13
Most types that I have flown give approval for flight in falling or blowing snow but I'm a bit concerned when you ask about ice accretion. Most multi-engine helo's have, in their limitations section, a statement like "Flight in known icing conditions is prohibited."
If you stick to the Flight Manual clearance it is possible to fly in snow but not when icing conditions may also be present.
Although the aircraft may cope, will you? Be aware of things like white-out in re-circulation near the ground when landing or taking off; navigating difficulties in snow covered ground; instrument flying skills (or lack of) in reduced visibility etc. etc.
Your query may be a technical one but, if you are thinking of flying, approach with great caution.
lmlanphere
9th Feb 2001, 23:45
I guess my question is based on safety more than legality. The limitation 'no flight in known icing conditions' is straightforward, but I wasn't real clear on whether wet snow constituted an icing condition. Thanks for the input above.
Just curious Imlanphere, where abouts are
you going to be flying in snow ??
lmlanphere
11th Feb 2001, 01:19
pacific northwest most likely