EC120 Fogged over windows

[Pilot DAR]

During a recent evaluation flight for a modification, the winshield and windows of the EC120 I was flying completley fogged over, to the point where I flew circles over the airport for ten minutes completely eyes in, while my fellow pilot managed all the heat, air and fans he could, to clear the winshield. Even after this effort, only a modest amount of the winshield was useable to see to land.

Conditions of flight: Midday, temp 16C, RH or dew point not reported, but I'm guessing near 100%, higher overcast, 1000 feet ragged broken, and 500 feet ragged scattered, with light rain. Vis 4-5 miles.

Thoughts on this alarming experience, and what to different next time, would be welcomed...

http://i381.photobucket.com/albums/oo252/PilotDAR/Jims%20DAR%20Testing/IMG_0176.jpg


Pilot DAR

[Bertie Thruster]

This is a perennial problem for us in 'sunny' UK winters;

Pouring rain, soaked paramedics and casualty; cab steams up immediately and completely on loading.

Answer; Air Con! It's the only way! (clears the screens in less than 1 minute)


....or was your fogging on the outside surface? different matter then......

....your side sliding window looks big enough for vis reference.

[VeeAny]

Besides what you did , how about

Slide open the pilots door window and get your external reference out of the hole.

If you can't cope with that small a view of the outside world then if the cabin is secure, open the door and look out of it. should give you enough references to land and sort out the visibility problem.

Obviously opening the door is not ideal in some circumstances but perhaps better that option than crash into the ground because you have lost external reference.

Were your clothes wet ?

[ShyTorque]

As Bertie says, it's a common problem in UK and is potentially a killer!

I always keep an absorbent microfibre cloth to hand to help clear windows in conditions like this.

The worst case is a night departure on a cold, night, where the aircraft is cold soaked and the occupants bring extra moisture into the aircraft. It's best to turn the heat on full (pull some pitch to get N1s up to give enough airflow if necessary) and wait on the ground until the windows are cleared and will stay clear on take off.

The checklists for twin turbines often call for airbleeds 'OFF' for final landing checks, in the case of single engine failure. My take is that losing visual reference on short finals in a fully serviceable helicopter is far more dangerous than the tiny possibibility of an engine failure, so I sometimes keep the heat on if the conditions require it to keep the screens clear.

[VeeAny]

ShyTorque

That reminds me of the night (just before the end of official night) I came out of Castle Air in Cornwall. CAVOK, stars twinkling in the dark sky.

Aircraft taken out of chilly but not freezing hangar into cold air outside.

Lights on around the site give very good visual cues for departure.

Helipad departure to the North and just at the point of rotation (going upwards and backwards at 0 IAS) all the windows froze over on the outside. It wasn't gradual it was instant, can see one moment, can't the next.

Followed the helipad procedure (although only 5 deg nose change down as engine failure was the last of my interests at that moment) on instruments rather than reverse into the hill or down onto the hangar I now can't see.

I suppose with the attitude hold / force trim etc in the 109 I could have taken the door open approach but it came as such a shock I really didn't want to risk letting of the controls, once I had the attitude set I let go of force trim and flew through the springs, it worked out, but I don't fancy it again.

The windows eventually cleared at 2000ft.

I was glad it was the E and not the AII that day.

I believe its related to the proximity of the stream to the helipad and me taking a condensation nucleus (the helicopter) through very cold, very damp, but very clean air.

GS

[s1lverback]

Hi, hasn't happened to me yet, but then I am relatively new.

The Ec120 I fly has duct guides that when flipped up are against the screen. I assume a combination of that, the fan and the heater control would help clear the screens quickly if mist on the inside.

We had the heating on yesterday as it was cold - only for a minute (at most) at a time, because it was noisy and the cabin warms up quite quickly.

For the excursions I have had recently we have also cleaned & polished the canopy glass before the first flight of the day - not sure that helps except with immediate visibility, but guess it gives her a chance to adjust to the air temp outside the hangar..

[Shawn Coyle]

The certification regulations require that the windows be capable of being demisted / defrosted.
Can't quote chapter and verse, but it is a requirement.
Which makes me wonder how you can deliver a helicopter without a heater as a baseline piece of equipment....
I'd make sure that a service difficulty report is submitted just to highlight the problem.

[victor papa]

The EC120 comes standard with heater and demisting functions. Aircon is optional. I've never had a problem with the demister even on cold winter mornings. Did you have the flaps open on the centre overhead panel with the demister on? Is the system fully operational? I have had ducts come loose after maintenance causing insufficient airflow.

[RVDT]

Be careful opening the RH door on a 120. If the strut lets go the door can swing around and contact the rotor blades!!!! Ugly.

[Brilliant Stuff]

We used to suffer this offshore on the N Dauphin. CAA were alarmed at this but nothing got changed we simply had to cope with it. It used to clear not long after but it wasn't brilliant.

[TeeS]

We used to have occasional problems on the 135 after engine washes. If the wash is carried out with engines not running then during the drying run the heater is switched on. This would then waft a gentle flow of nice hot, very moist air over the cool screens; instant fog on the insides!

If we got a job immediately after the wash then it was not unusual to go IMC for half a minute just after takeoff!

TeeS

[Pilot DAR]

Thanks for the great responses...

The address a few of the very valid points raised in the responses:

Fortunately neither of us were wet. We had departed 45 minutes earlier for pilot (mine) familiarization, and aside from flying in rain part of the time, had otherwise not opened a door or window, or otherwise got wet. There were a few drops of water dripping in from somewhere around the fuel cutoff lever, but no volume of consequence.

The fog was on the inside of the windows, were it to have been on the outside, the delightful rain would have certainly washed it off.

This helicopter is very well maintained, and the director of maintenance had been flying with us the previous evening, as he is a valuable part of the effort. We did get a little for the night before, but the heat cleared it immediately. He has been notified of our difficulty, and I will presume that he will file an SDR, but I will ask him today...

Opening sliding windows and doors was an option that we did not get to, but knew it was there. Being the recipient of the training, I just kep flying on the instruments while my very experienced mentor pilot dealt with the the problem. He had al the heat, and fan going, and I was certinly pulling enough power to keep the bleed air flowing well.

This helicopter is not AC equipped, though I bet the owned will be thinking about that now! My new diesrl VW Jetta uses AC to clear the windows, even on a cold morning (I kept looking ad the light on the AC switch, thinking "I selected heat, did I bump the AC button by accident?"). AC systems are not popular because of the weight, but if it clears the windows right away, I'd be thinking it's minumum safety equipment for an EC120.

For those who fly 120's, who have not experienced this alarming event, I can tell you that it did not appear to be caused by any particular change in conditions. We were over the airport setting up for a second practice auto, and as I was climing up between 400 and 600 AGL, the fog started, and obscured about 50% of the lower outboard portions of both windsields. I asked my mentor to get me some defog going, and he was right on it. Within a second or so, complete IMC inside the cabin, which remained for close to ten minutes with only minor improvement. If this had happend to a pilot on low approach, it could have been very bad. As it was, I would not have attempted to land next to the hanger, I would have just landed on the runway, where there was lots of peripheral contrast with which to judge.

The saving element of this would have been the fact that we also had a FLIR camera working on board, and landing with reference to that image would have made things much safer. My opinion is that FLIR is a major safety tool for helicopter operations.

Thanks for your thoughts fellow pilots....

Pilot DAR

[handysnaks]

Both the AS 355 that we had and the EC 135 suffered from similar problems. The AS 355 heater did demist....eventually. The EC 135 has an unfortunate design flaw of a 'box' in the heater ducting which does seem to collect standing water. The best way to avoid the problem is (if you have moist clammy conditions), to put the heater on full blast prior to take-off, if the 120 is anything like the 135 then that should cause the screens to mist up almost instantly, after a minute or so the screens shopuld clear and then...problem gone (for that flight anyway)!

[toptobottom]

I've experienced this problem occasionally, but nothing that hasn't been fixed by a couple of minutes full power blast on the de-mister (on the ground). If it's a known problem however, why not try an anti-fog solution such as this (http://www.highergear.ie/Catalog/10200/FogTech-Demister-bottle---up-to-40-applications)? As any biker will know, fogging on the inside of a helmet's visor is common in the winter, but this (and many other similar products) do a great job at preventing condensation.

[Elvis70]

Transportation Safety Board of Canada - AVIATION REPORTS - 2008 - A08Q0110 (http://bst-tsb.gc.ca/eng/rapports-reports/aviation/2008/a08q0110/a08q0110.asp)

In depth discussion of an accident with the EC-120 and how the heat/demist/air/windows should best be utilized to prevent this from happening.

I flew EC-120's in the GOM. Didn't fog up any worse than any other bird.

If you have fog on the inside, cold air (AC is best) will clear it up. If you have in on the outside heat will do it. Of course the outside will clear up quickly after lift off. If you can see to lift off. The inside stuff is more dangerous.

[HELOFAN]

Well.......
my .02c.

Firstly well done on dealing with the issue and flying the aircraft.

You say it started when...." as I was climing up between 400 and 600 AGL, the fog started, and obscured about 50% of the lower outboard portions of both windsields. I asked my mentor to get me some defog going, and he was right on it. Within a second or so, complete IMC inside the cabin, which remained for close to ten minutes with only minor improvement.


Essentially you made a sauna.
by adding heat at that point it evaporated the moisture, increased the inside air temp at a great rate and the moist air was spread all over the A/C.

maybe adding heat to the moist air was not the best solution when you were at this alt.
Sometimes when the heat is applied without the AC, it fogs up worse because your accelerating the condensation. It gets worse until the temp is equalised between the air & objects inside and the windscreen and the moisture gets reduced cause its so much warmer.

essentially what you did is turn the slowly forming dew into rapidly forming.

The dew point/fog on the outside shouldnt be so bad as long as you kept your airspeed up? I not know about a fancy ship like the EC120 but most moisture on the outside would start to collect into bigger bits would blow off I would imagine.

It wouldnt have been an issue so much if you had AC and used heat or cold becuse the AC is removing the moisture in the air especially well when its on recirculation & not fresh.


Think about rear window defoggers in a car for a sec. All it is, is some wire usually inbetween layers of laminate glass that heats up the glass on BOTH sides so that fog or dew can't form.
Large dew point spread !

Or even anti ice windows in jets (cause I have not seen one up close in a heli) it is a small section of glass that is surrounded by heat strips that keeps it very warm so the fog/dew/ice can't form.

I would say the best thing to have done with out AC would have been to land when you saw the dew forming on the inside and wipe it off.

Rainex & similar products are great on cars and bike screens but not sure how it would react with the screen in a heli.

That was a lot for .02c wasn't it.
:ok:
HF

[Tarman]

Thinking back, many years ago, if I was parked up in a lay-by with a member of the opposite sex and the car windows "steamed up" I would simply open both windows and it cleared up in a few seconds. No AC back in those days. Never joined the Mile High club though, can't verify that it works at altitude !! :E

!:ok:

[VfrpilotPB/2]

A few years ago, I employed an old coach driver who wanted to do some HGV driving before he retired, we had problems with some trucks steaming up due to getting in with wet or dampish clothes after loading or unloading in the bad Wx, however his truck always seemed to be "mist free", so I asked him how he managed to keep his windows clear, apparantly it was an old coach drivers trick of using an absorbent cloth, dipped in liquid soap(Fairy Liquid I use) the secret is though this has to be done when the windows are bone dry, you simply wipe over the glass surface depositing a fine coating of liquid soap, eventually it drys off, but then when things get damp and moisture laden air is about the coating of soap resiststhe water and Hey Presto, not only can you see out from the Truck , but also the coach/bus and I would think Heli, try it , but remember to apply only to dry windows.

Peter R-B
Vfr:ok:

[John R81]

Old motorcyclist trick, that. Specks & visor.

[toptobottom]

Fairy liquid does work but smears badly and needs to be re-applied regularly, hence the suggestion for a properly formulated solution :}

[500e]

Have used all 3 on visors

1. Comma ProVision Fog Clear Gel
2. Rain-X Anti-Fog
3. Farécla Smart Anti Mist
Read more: Anti-mists Reviews | Anti Fog | Windscreen Cleaner | Glass Cleaner Anti Fog | Car Mirror Cleaner | AutoExpress (http://www.autoexpress.co.uk/products/products/204747/antimists.html#ixzz0UVjkikjG)

[Runway101]

Divers usually spit on the inside of their mask to keep it from fogging up.

[toptobottom]

I'll try that next time I jump in. Not sure what my VIP pax will say when i start gobbing all over the inside of my helicopter though :p

[Runway101]

Just ask them for a little help :ok:

[Pilot DAR]

I appreciate the informative responses.

I suppose that Hughes still has an edge over Eurocopter when it comes to clear windshields. I just completed an ALaska to Vancouver flight in a 500D in even worse conditions at times than I was in in the EC120, and never a hint of fog. Thank goodness for that, ans that route has a lot more to bump into if you cannot see where you are going!

Pilot DAR

[John R81]

Am I being slow, or is it just a case of running the heating / de-mist vented onto the window before leaving the ground to ensure that the laminate is warm and hence does not fog?

I ask as a novice to the 120 and with winter coming up......

[TiPwEiGhT]

I used to find in the damp winter months in the UK, you had not choice to put the heater on to de-mist the windows before lift. Usually as soon as you jumped in the windows fogged up. I found the P2 bleed in the 120 quite effective at de-misting the windows, with flight power the airflow is pretty good.

TiP

[victor papa]

Tipweight, that is my experience with the 120. I suggested a possible loose duct or closed duct not because I think the maintenance is not of the best in the world, but because normally the airflow is sufficient and I have operated in icing conditions plenty time in winter in the mountains. The minute that first blade comes passed on startup by the fourth count of a blade you are iced up until you open the demister and it has always cleared the windows in my experience.

[John R81]

This topic came up at the Redhill safety evening yesterday. I don't have air-con, and I am VERY low time, I don't want to be in the same situation as the original post. So, my thinking (and question) goes like this:

Fogging is a function of relative humidity of the air inside the cabin and the temperature of surfaces in contact with that air. Avoiding condensation means I want the plexiglass temperature to be above the dew point.

So, on jumping in for start, is there a problem with applying full heat and fan, directed at the glass, as soon as the burner is properly lit? If that is added to the start procedure (and we learned last night that we can add to the start checklist) then by the time all checks are completed we should have one of two results. Either:
a) The fogging experienced by the original poster would have occurred, sit still and wait a couple of minutes for it to clear; or
b) If not, the plexiglas would be warmer than the dew point of the cabin air, now reduce (but not turn-off the heat unless you need the power) and keep a slight warm flow over the window.

1. Any problems with running the heater full whilst the remaining checks are carried out?
2. Would that be long enough to ensure adequate heat in the glass to avoid this problem?

Thanks

John

[Elvis70]

When I light it off I am not on the ground long after that. The easy thing to do is sit a small (good quality to avoid fires) heater in the aircraft and leave it until ready to fly. We do that at night in the winter to keep drugs warm and it also prevents the fogged up windows. When warm enough for the drugs but cool out at night I walk out to a helicopter with condensation all over the windscreen. Kind of a pain.

[Freewheel]

Elvis,

You're in EMS, right?

[Pilot DAR]

I was surprised to find (while reading the latest Aviation Safety Letter at my Transport Canada office this morning) this article..

Aviation Safety Letter - TP 185 - Publications - Aviation Safety - Air Transportation - Transport Canada (http://www.tc.gc.ca/civilaviation/publications/tp185/4-09/flight.htm#helicopter)

It seems I'm not the only one to have experienced this problem, and I faired better. There is also a reference to a Eurocopter Information Notice on the subject.