Rotor Blade Icing
 

For those who don't think icing in helicopters is a serious issue....

By 'Freezing Fog' he means sub-zero cloud and is surprised at minus 8 that it produced ice on the blades.................

Wow! Amazing! The scariest day of my life! Nearly crashed.....even though I was on the ground at FI! WoW! Fantastic! Wow!

How predictable was that sunshine?
What were you doing....fiddling around the edge of clouds @ -9 degrees?

Atleast he had the right gloves eh! Wow! Great! Goretex! Wow!

The point I was trying to make was that even with just a bit of leading edge icing he couldn't hover properly. I've bumped into several people who dismiss icing on rotor blades very lightly.

Textbook rime.

Icing on blades is incredibly serious, and de-ice is a major challenge in design, particularly in composite laminates that utilize 250 degree cure resin systems.

Ah come on "old and wise" guys, take it easy. I'm pretty sure you were not born as the knowledgeable pilots you are these days, but that you as well got your knowledge from experience.

Maybe he should have been a little bit less "news media" orientated and skip those words "nearly crashed..." and "scariest day of my life" but then again, he received all the attention he was aiming for: 6300 viewers and counting.

The good thing is, that there will be plenty of pilots who can learn from this.

Paco is absolutely right to highlight the seriousness of rotor icing.

But the guy in the video must have done some met study to get his licence and really shouldn't be let loose in the mountains without a thorough grasp of the conditions for and dangers of rotor icing.

Good training video. Including the part about landing and shutting down on a mountain peak in the winter with clouds blowing your way and then the belt actuator on the Cabri misbehavin’. Blade icing in freezing fog type visible moisture is pretty well known with older guys, especially in arctic conditions close to the ground. Paco, there is icing and there is icing, some slow and insidious, some that comes on really quick. You teach the difference and have yourself probably experienced it here in Canadian winters. Modern times too, send a text out on InReach instead of that whatever ELT. Jealous of the warm girlfriend part of his survival gear.

And with this forum and YouTube he gets the message out to all helicopter pilots without spending the rest of his evenings having to swill beer with his buddies.

Being in possession of that particular piece of met and mountain flying knowledge is a function of professionalism, not age.

Maybe next time if you have to land to de ice in a piston ship, keep the engine running and de clutch, perhaps the heat from the engine would help keep things warm!

And wear a hole in the stationary drive belts?

Icing is some serious ****, but it does not occur in a few seconds of some light clouds blowing past you when otherwise flying in clear weather.
That guy did for sure fly in sub-zero clouds several minutes.
Source: I'm (also) stupid.

Hi R88, just because you were in icing conditions for some time before it appeared significant, doesn’t mean it can’t happen in something less than a minute. I had an engine stop on a 365C because I allowed myself to be descended into an icing layer (that took about a minute) and I’m aware of two EC135s and an S61 that ended up descending at Vy and MCP in ‘uncontrolled fashion’ after a very short time in sub-zero temperature cloud. It can happen quickly!
Cheers
TeeS

R88 - for every degree below zero of a supercooled water droplet, 1/80th of it freezes on contact with the leading edge - that is instantaneous icing.

Maybe not seconds but just a few short minutes!
Was shooting a approach, on top of cloud and began our descent, at 2500' we entered the weather the 332 icing system had to be placed on Force mode at 1000'. Took all the pitch to level off at 400' for the landing!
Airframe was completed engulfed in rime!
Yes, can occur very very fast!😎

I worked in the past extensively in Canada's arctic with a 500.
The pilot I worked with had bags of 500 arctic time.
we encountered icing conditions quite often during our work.
because of his experience it was manageable for our operation moving drills or fuel drums.

Not withstanding his experience was only a factor in the big picture. The aircraft spoke to him in some unique way and he knew when it was time to shut down and take a break and clear the ice. Some magical torque number he used as a reference.
Either way, he was comfortable the way he operated and we never had any serious consequences. Not that he didn't have a few close calls as he built that experience, I'm sure his personal library had some stories to tell.

This guy however....he will be a statistic one day. mark my words. I've seen other videos of him and right from the get go I marked him as someone to watch because he's going to make it to the TSB file at some point if he continues.

His exact words were "for about 5 seconds, just the slightest bit of fog" I think we can agree that was not the case. Also if I was in a "super critical situation" my priorities would be to get myself and my passengers safely out of the situation, and not do any youtube-selfie thing. However, I'm glad he did so we got the opportunity to have this discussion.
I've had my fair share of poor weather flying, also in winter conditions, and to completely eliminate the possibility of icing conditions while doing aerial work would eliminate a big part of winter days. But your cloud descending experiences sounds really scary, and I think it is really important for any of us flying in possibly icing coditions to remember the real danger included.

The company was approved to operate in icing (with limits) and we did so 7 months of the year. Picking up ice enroute or on approach was common.
But that experience (I was actually doing a upgrade on a new PIC and very talented) left both of us going WTF during the taxi in. He got his upgrade.
Before others say.,,, should not have been there, stupid, bad CRM, aircraft knowledge etc etc.
There is a lot more to the story why we were there!

you need to define the limits that you were 'approved' to operate in - airframe icing is generally defined as below zero degrees C in visibility less than 1000m - were you 'approved' to operate at or below those conditions without adequate airframe protection?

There are plenty of stories about surviving icing, often due to dumb luck and it can sometimes be difficult to find icing in the normally accepted conditions for it (again dumb luck) but to accept it as 'normal' is asking for trouble so I hope your 'more to the story' is based on more scientific evidence than just 'we went - we survived' and turning that into an SOP.

And I would not slag the driver in this vid... I belive he posted this in the interest of flight safety... remember the old saying here in Canada, learn from the mistakes of others... you don't have enough time to make them all yourselves.... I believe he is a very competent trainer and driver.... quit trying to make yourself look better...

he certainly seems to spend an inordinate amount of time videoing himself and trying to make himself look better................

Your just jealous Crab because he is young and flying around with a fit bird on board ......🤢!!!

You might have a point there Nige:)

Helicopter Ice Fog?
 

Hello! On the off chance someone reads this. I am looking for a video I had once viewed about helicopter blade icing. I think, clear air ice fog that forms rapidly. It was a Bell Jet Ranger, a 206B, that was running at 100% on the ground in clear air. They then proceeded to a hover and within a very short time frame the 206 settled back back to the ground. Ice horns had formed very quickly on the rotor blades destroying the lift. If you've seen this video or have a copy you can send me it would be greatly appreciated!

Edit: Hopefully the video you are seeking.
This post merged from its own Thread with the old one: the Search function is a wonderful tool to use. This thread is interesting, too https://www.pprune.org/rotorheads/21...g-ice-fog.html

Senior Pilot

What scared me is he's out of Abbotsford BC and this ice has surprised him?

I spent several winter months in Ottawa as a helo TP when the RAF/RN/Army decided to do something about helo icing and snow flying,as it curtailed many ``exercises` during Winter time.So we went to Canada with 4 a/c,a Wasp,2 Wessex ,3/5,and a S-King,all heavily instrumented,and cameras all over.`(Parachutes`` as well).The S-K had modified heated intakes,like Russian Mils ,all had heated w/screens,but no blade anti/de-icing gear.

The initial trials were hovers at the NRC site at Uplands,which has a `spray-rig` which can simulate various`water droplet densities,and so depending on the wind-speed,temperature,you hover(IMC) at about 10-30 ft downwind ,whilst the FTEs gather their data,and you notice the increase in power reqd/collective ,vibration,`Ring-twitch/clench.Having gathered ice,we then moved out of the spray-rig, assuming we had power-to spare for the basic handling,ie up-down,sideways/back/spot-turns to see if there was any `shedding`- off ,of the ice,TQ reduction,change in vibration,;we`d then land and the FTE`/Photogs would phot where ice had/had not accumulated,and it`s depth/thickness,especially the rotors and engine intakes.If all was OK,we would then proceed to `open the envelope` a bit more into forward flight to see whether `trouble lay ahead` or the ice would `shed`

As you can see ,with 4 a/c,4pilots,FTE`S and groundcrew,there was a lot of cockpit-jumping,and changing routine to vary with the ambient temperature ,visibility,or snowing to get as much info as possible to make a Performance `MATRIX` of conditions for each aircraft...So,I`ll continue tomorrow,maybe,if anyone is interested.I`ll include some photos of interest...
https://cimg5.ibsrv.net/gimg/pprune....67b622fccf.jpg
https://cimg9.ibsrv.net/gimg/pprune....e898a10e46.jpg
https://cimg5.ibsrv.net/gimg/pprune....d8536f8c6d.jpg
https://cimg9.ibsrv.net/gimg/pprune....0948b1ba76.jpg
https://cimg0.ibsrv.net/gimg/pprune....2bd95adf8e.jpg
The Gazelle is in `73-4; The engine ,damaged,in WX5,THE `Head-on` is of a Wasp blade with typical `ram`s-horn` icing on the LE( That is a real `killer`,about 3 minutes in hover,Tq rise`FFFFing` fast.....

.

Years ago I was tasked with a presentation on helicopter icing, for my upgrade to an RAF "A Cat". The obvious reference to use was the relevant Air Publication. However, to my great surprise, the section on helicopter icing was not actually in the manual! It had never really occurred to me to seek it out, having spent most of my time on the "Belize Squadron".

I was lucky enough to go and visit the late Geoff Connelly, who was the incumbent RAF helicopter test pilot at Boscombe Down at that time and who had been involved in helicopter icing trials. He generously gave me a lot of information and having subsequently spent a great deal of time "camping out" at weekends in my office I was able to come up with a decent set of hand drawn OHPs and narrative, which I presented at the due time. I later discovered that the Norway Puma Squadron had nicked it and never gave it back!

Does anyone have the photo that appeared on the cover of an RAF incident report summary, of a Wessex that was forced to land short of dispersal after getting caught in a shower of severe rain ice? It had been on an underslung load training sortie on the south side of Gutersloh airfield and the clear ice built up so rapidly it was too heavy to hover taxy back.

Late? Really? Oh - Connelly not Connolly?

ICING,PT2.
To further explain the pics; The `Cheyenne` also happened to be doing similar trials to us,but we were not permitted to get close to it or meet the crew.You can see the rig and steamspray droplets ,but even on a sunny day,it still ices the blades.Other times and temperature will give a continuous cloud stream ,so one is in IMC,but we had a `volunteer` on an extra `long-lead`,outside the rotor disc to warn if we were drifting,also spray painted lines,like on ski-slopes,otherwise hover/radalt hold,and use the Doppler...!! luntil the aerials iced up..

All the aircraft rotor blades actually had the same blade section,NACA0012,root to tip,and varying twist,but constant chord.However, the Wasp(and Scout) are more `rigid` spanwise,compared to the `paddlewheels` on the WX,S-King and later Gazelle,and so flex more over their length during rotation.There are videos taken by cameras mounted on rotorheads showing blades bending and flexing,and this is why,when we started going into `natural icing(IMC) in the cruise,fixed collective,there would be a rise in `tq`,ng ptit,some increase in vibration ,and then a fall in tq,etc as ice was shed, then it would start again the process.
We only flew in IMC IN `stratiform clouds` as there is usually a fairly constant droplet size,and fairly constant temperature as well,all measured in the a/c instrumentation.Also ,for safety ,Ontario around Ottawa is fairly flat,and we only flew with a minimum cloud base of 2000ft agl.Of course not all days are the same ,but if it wasn`t clear,then we`d do more `rig` work,or fly in snow.Also,excursions into IMC were for short periods,ie 5 mins,pop out check for shedding, try for 10 mins,and so on,until one had a good feel for what was happening,then maybe climb 1-2000ft,different temp/droplet size,more power,stir/rinse repeat as required.Then you get the unexpected,TQ starts going up,vibrations increase,not shedding,start turning and descending to get out of it ,go back and have a coffee...or three..Well,how do you know when to quit....? Whadddya do if the `donk(s)` quit? Autorotate..? Yes,but you`ve got ice on the blades as welll?
Before we went to Canada we had to set-up the autorotation RPM by doing full autos back at minimum RRPM,range and transient setting on the collective ,and hence blade angles,then join up the power and set those collective setting noting how much` torque` you were using...now compare that `change in blade angle` TQ differential,in increments up to max TQ ,to check it is a consistent `Delta `TQ.You now have a figure for what is`hopefully` a realistic TQ rise,and shedding.You now go and adjust the collective,to give about another 20 RRPM increase ,`,to be sure,to be sure`,and that is one reason for wearing parachutes as well...I think for the WX,we used about 5-600 ftlbs,as a maximum`D TQ`.....However,prudence usually dictated that we chickened-out if the TQ was rising fast,or the w/droplet size/temp changed rapidly..
I`ll continue 2morrow ,if you want more tales from Cold Winters..

TGIFin Ottawa as interesting 50 yrs ago,Capital city,lots of Company HQs=lots of secretaries= 7-1 ratio f-m...!!

Note for `Crab`,please do not use my name if you go punting around in icing in that WX...!!!!

Bell 47G4-A blade. Ice fog encounter after dropping off mineral exploration crew.
Pilot was solo, less than 1/2 fuel. Landed less than 5 minutes later with full throttle and decreasing rpm..
I think I have posted this photo before.
Feel free to use it in a lesson plan
https://cimg3.ibsrv.net/gimg/pprune....f2ad1e22d.jpeg
,.

In 1983 we did Bell 214ST icing trials out of Aberdeen with a Bell test pilot and our company pilots. The trials resulted in a moderate icing clearance down to -10C - the first such clearance for any North Sea helicopter - as long as there was a 500ft band of positive temperature air over the sea or above safety altitude. In icing conditions a torque rise of 5% did not require any action. If the OAT was below -10C or if the hot rod ice accumulation exceeded 1 cm in 22 nautical air miles action had to be taken to find less severe icing conditions. Down to -5C the trials showed that the torque rise would not exceed 5%. From -6C to -10C there were periodic increases and decreases in one per rev rotor vibrations as ice shedding took place.

The helicopter had a standard equipment fit of engine inlet anti-ice, pitot static heat and windshield heat. The only additional equipment apart from cameras was an unheated wire basket in front of the inlet on one engine so comparisons could be made with the unprotected engine. The windshield wiper arms were a much better indication of ice accumulation than the hot rod ice detector. There was no rotor blade deicing fitted. I remember on one occasion during the trials when below -10C (can't remember the exact temperature) I saw a 15% torque rise followed by a sudden shedding of ice on one blade. That was not pleasant! One problem was getting down quickly so photographs could be taken before the ice melted. A couple of photos.......

https://cimg7.ibsrv.net/gimg/pprune....6c8bc80d82.jpg
214ST nose ice. The hot rod detector is in the upper central but clear of ice as it had probably been burnt off.
https://cimg8.ibsrv.net/gimg/pprune....59eaee8e3c.jpg
Inlet basket on the starboard engine.
https://cimg8.ibsrv.net/gimg/pprune....99e1808c19.jpg

In the winter of 78/79 we were operating a Dollar Bell 47 in the north.
We went to fly around 10am and for some reason I climbed onto the centre frame for a good look around.
Our blades were painted one black and one white to give that moving finger effect.
I was shocked to see that one blade had water on it while the other was covered in a thick layer of ice.
Took me over an hour to clear the blade. Fortunately the 47's tailboom makes a good stand and I weighed considerably less in those days.
Would have been interesting on start up.

I flew into rain ice once in Germany in that classic active warm front scenario - the windscreens and airframe started to ice up so quickly it was horrendous - a very prompt 180 and away from the precipitation was the only course of action.

Curious, Democritus: prior to your Aberdeen testing, had the ST been exposed to any icing behind the US Army CH-47 icing tanker?

Crab, you did exactly the right thing. I was based in Germany when severe rain ice fell. On one occasion, the ice built up very, very rapidly, to the extent that the weight of it was bringing down large branches of well established trees. The Wessex I mentioned had something like a two to three inch depth of ice build up in very short order.

It’s not often I’ve cancelled flights on a weather forecast, but if rain ice is in there, no thanks.

As far as I'm aware that didn't take place.

https://cimg9.ibsrv.net/gimg/pprune....6127d9bf69.jpg
https://cimg6.ibsrv.net/gimg/pprune....aca0c5c09a.jpg
Icing Pt3.
A few more bits about icing..You may get `droop-stops` becoming frozen out on shutdown,if more modern helos have such things these days.Windscreen wipers give a good early indication you are picking up ice,and the `rate` as well.The OAT gauge may well show 0(*),as it is now iced up...as shown on the Wasp.. Surprisingly,we did not encounter much of a problem with the tail rotors/fenestron,but as most a/c have a fixed `stabiliser`,they can get iced,and usually showed as a`slight pitching` in a coupled cruise,but it may well depend on it`s height vs engine exhaust stream/airspeed.The engine damage we encountered was always the WX 5,,as it`axial flow with Inlet guide vanes,,where ice would build in the intake system/chamber and break-off ,enter the compressor `face` ,and a `blade`(s) would flex forward and rip the `back of the IGVs which would usually be `fully open` .>20000rpm appx.One then had to be very careful when reducing power,as any damage could cause a `surge` /flames,bang,so hands were always ready to shut an engine down..The problem was solved by our erstwhile R-R Rep,on site,by getting and changing the IGVs from the S-K Engine,and putting them in the WX5..different shape and clearance from the compressor..(iT should be noted that R-R and WHL Reps are also very good hosts,socially....don`t know about now though..!!) and it was not an overnight job either...
The skis on the Gazelle were French designed ,but we modified the front end,as it appeared one could `face-plant` in a heavy run-on landing in soft snow...Don`t know if our Army ever used them ,but great fun,nevertheless...
The `MUSHROOM ` intakes on the S-K worked well,but the front cowling,and top of the cabin area needed more electrical power than available/possible without another `gene`,which is why S-Ks got a `barn-door` fit.
I mentioned ` Parachutes` that we all wore,and one day our S-K crew were operating about 20-25 nm S of Ottawa at about 5-6000ft in IMC,IN CONTROLLED AIRSPACE,when the MRG/BOX oil filter blew its top.After the `mayday` calls,and alarms on the airfield,we prepped a WX for a search;.meanwhile,the S-K made it`s way back towards base,and 4 of the 5 crew got ready to jump if it appeared that the g/box might seize.They became VMC and maintained a safe height(for parachuting),until a couple of miles from the airfield,then a quick auto to land
by our hero RN pilot ,the late `Chalky` White.(later was a pilot for JCB..?)The groundcrew pushed the S-K into the hangar,and the R-R and WHL REPS`pushed the boat out that night !!!
I know this was all 50+yrs ago,and modern helos are different,better systems etc,but icing is still the same,and if you decide to "Dance with the Devil`,just think.."`tis better to be down here,wishing you were,`oop there,than `oop there.wishing you were down here``..
Here endeth the lesson..
Syc

I don't have them, but I have seen images of the ST on icing tests behind the Chinook. They had Yellow dye in the ice... Only reason I remember it...

Was the ramp down? Never trust a crewman and don't eat yellow snow!