Icing in R/W Aircraft

[SASless]

One real scare in serious icing conditions and you will be solidly in UM's Fan Club!

I pair the classic Fog and Icing as being two of the Rules I obey blindly.

Temp and Dew Point within 2-3 Degrees, nil to light wind, any kind of condensation nuclei....Tea Time.

Forecast or Actual Icing Conditions forecast.....VFR flight only and upon encountering icing....Tea Time.

I once used Radar to find the Columbia River Gorge as we were headed down at full power and Vy Airspeed.....fortunately the weather improved and we broke out of cloud below the tops of the ridges.

If you encounter Freezing Rain.....there is warmer air above you. How high is the 64 Dollar question.

[sycamore]

M-H Driver, if you can look back at `rotorheads around the World,views from the cockpit(not video),page 15 /16,you will see some photos of icing on the rotor/etc on the Wessex/Wasp/Gazelle/Sea-king trials I was involved in between 1969-75.Admittedly old technology aircraft/aerofoil sections,and different engines to todays helos; however ,we did it as test flying with specific limits and modifications to the aircraft,wore parachutes,had lots of instrumentation,and generally operated in an area where the weather was benign,and with a safe cloudbase ie generally stratiform cloud, hopefully with uniform cloud density,and water content/droplet size(or,hopefully so,not always true.)As a general limit,we used 15-20 % TQ rise as a guide if the blades were `shedding ice(no blade heating) as a limit to descend /get out.now if it didn`t shed/or Tq rose(fixed collective).We had also decreased the Minimum blade pitch at Min.pitch on ground,as the engines were susceptible to ingestion and could surge(Gnome/T58)readily,to cover,hopefully,the rapid drag/blade stall if both engines failed.And you can see on one of the photos the shape of the ice build-up that occurs.`Idle-stop ` and others will hopefully endorse it if I say that you cannot/should not consider flight into known icing unless you have a fully prepared /cleared aircraft; and if you inadvertently get into it in a non-certified a/c,get out as soon as you can.
A last point for those with certified a/c...Do you have a `stabiliser` de-icing system..?as the autopilot may have difficulty holding attitude.IAS if the `stab starts to pick-up ice.....
Safe flying all....Syc..

ps.I would also endorse SAS`s freezing rain..any rain around +-2 can give you a slow TQ rise,and little or no shedding,even with heated blades,maybe because of heated blades,as it will form behind the heating elements and re-freeze.....Sometimes you have to give the head a real shake/stir to get it to break.If you lose an engine,or two,crank it into a steep bank to get the RRPM back...RRPM is life...don`t lose it. See also the discussion on entering autos...

[ShyTorque]

From some time I started to read a lot about helicopter iceing. I also have a little experience with ice on R-44 , just two cases , one during hovering in "backyard" in foggy freezy day just to see how it react - nothing special but ice build up was smaller than I expected in such conditions.

Ice build up is proportional to how many supercooled water droplets hit the aircraft. If you're hovering, you are less likely to see ice build up than in the cruise in the same conditions.

Best advice is: don't try it, because once you disobey the RFM, you're a test pilot.

[sycamore]

Shy, not always true; if you look at those pics on RHATW,the head-on blade one is of a Wasp,same as Scout,hovering in the ice rig ,about 4 mins,overtorqued..! Can`t give specifics,ie w/d/temp etc,but in flight bending/flapping would probably have given another 3-4 minutes..!
Message...don`t go there....

[ShyTorque]

Sycamore, perhaps I wasn't quite clear enough In my last. What I hoped to put across was that hovering may give an over-optimistic indication of icing rate when compared to cruise flight in the same conditions.

Never mind, whatever, as you say, avoid the conditions, especially icing rigs!

[Bladestrike]

Having flown S61s out of Eastern Canada for years, rigs some 150 to 200 miles offshore, day/night with relatively poor and inconsistent forecasts, icing was always a huge concern. There were guys who did not mind "climbing on top" but in my experience, even if you know how thick it is and expect little if any icing climbing/descending through, I've had more than enough scares to avoid any risk of flight in cloud below zero. It does not always react as you expect it to. You'll get away with it often enough, but if you keep playing in it, you will get caught. I've got plenty of ice when expecting none and vice-versa. The scattered will become broken then overcast, and you'll start to climb, and climb to stay above it, and you'll find the 2000 feet forecast ceiling offshore to now be 700 feet and you've got 6000 feet of cloud to descent through. Just avoid it. Been at this thirty years and I do not like ice, at least in aircraft not certified for flight in icing.

My stress levels dropped by 85% when they replaced our S61s with fully deiced Super Pumas. That is a piece of kit!