How much water (rain/spray) can a helicopter fly through?

[RenegadeMan]

Hi there

Tonight (Wed 19/Dec) I saw something on television I've never seen before. Australia's newest surfing champion Joel Parkinson (he's just won the 2012 World Championship in Hawaii) arrived at the Gold Coast airport by helicopter after flying back into Brisbane on an international flight and then being transferred down to Coolangatta by (what looked like) a chartered helicopter. As part of the celebration for his homecoming two firefighting trucks sprayed the traditional 'wall of water' that a new airline or aircraft type taxis through on an inaugural flight. I was amazed to see the helicopter taxi hovering right through the middle of it! I'm not sure what helicopter type it was, modern 4 or 5 seater about the size of a Jetranger or Squirrel.

I would imagine the volume of water from two firefighting trucks would be way more than even the most torrential tropical downpour. Can anyone enlighten me as to what effect this would have on the rotor blades? Is it the done thing (as I said I've never seen it before) and a good idea. Surely that amount of water can't have been too great a thing for the blades of that machine. I have no knowledge on the effect of water droplets but would be interested in people's views.

Also I expect things would have gone seriously IFR for the pilot for a couple of seconds going through the spray. Would have been exciting.

Thanks

Renegade Man

[rgnewboy]

Don't know the answer, but this video of the venerable S61N definitely impresses.

Sikorsky S61-N hit by huge wave - YouTube

Don't fancy the guy on the wire's job much.

[ShyTorque]

Undoubtedly type dependent.

A certain UK AAC pilot thought he would get his Gazelle a free wash by hovering under a spray boom irrigator in a farmer's field.

Not a clever idea.

The turbine engine flamed out and he damaged the aircraft in the subsequent heavy engine off landing.

We used to sometimes carry out compressor washes (on the ground) on our Pumas' Turmo 3C4 engines. It wasn't unknown for the engineers to over do it with the water and flame them out, albeit it at low Ng speed. I also had one where the brass nozzle came off the hose and got ingested by the engine, but that's another story.

[Aesir]

Pictures or it didn´t happen :E

.
or link to the tv news. Would like to see that!

[Fareastdriver]

WE were having problem with the Gnome gas turbine fitted to Whirwind 10 helicopters in the Far East. The were running down in flight for no apparant reason. I trial I did with a Westlands test pilot was strapping one down on the tie-down base and going through certain perfomance sections with a fire engine directing a jet of water into the engine's intake.

It could cope with most high power settings but there was always a point, sometimes quite high, where the water flow would gag and then run down the engine.

In my considerable experience in the tropics I have never known rainfall cause an engine to stop. Shred the rotor blade tape, yes, but not the engine.

[mickjoebill]

News story with video...not quite the deluge it could have been!

Cooly kid returns home to the roars of an adoring crowd | CQ News (http://www.cqnews.com.au/news/cooly-kid-returns-home-to-the-roars-of-an-adoring-/1692395/)

603wP3Bo7Rk

Mickjoebill

[John Eacott]

BK117 inside view:

http://www.eacott.com.au/gallery/d/2408-1/Bird+bath+Nowra.jpg


outside view:

http://www.waterflowcontrol.com.au/default/images/rainwatersystem/gallery/2d_big.jpg

[Brilliant Stuff]

It depends on the aircraft but looking at the video that was pretty harmless "rain".

On some aircraft you can block the air intake for the engine off with snow and heavy very heavy water ingress but I would have thought you need to work very hard for that to happen.

Snow or leaves or the like would be a danger to the engine intake compared to water.

I have heard though that the German ADAC who operate the EC135 with Inlet Barrier Filters when they fly through a heavy downpour this then sets off the monitoring system of said filter which then require a clean up / dry out...before the next flight.

On the EC135 without the Filters the air intake is tucked away right at the back inside the dog house.

The Bell 206 has baffles you fit to the intakes to stop snow getting into them.

[Old Age Pilot]

There was a 206 that suffered a flame out when departing a Las Vegas airport during a heavy rain shower some years back. The cause was put down to water ingestion and I recall there being a specific measurement of water / water to air ratio that would cause this - but I can't find any reference to it right now?

I did find this (http://www.bellcustomer.com/files/Storage/TB_206-95-156_Rev_A.pdf) though

Not directly related to this thread but interesting none the less, mainly because of the following statement...

The installation recommendation is based on data gained from an investigation concerning an in-flight flame out caused by water ingestion. The water ingestion and subsequent flame out stemmed from water being inadvertently sprayed up the fuel cell vent line and into the fuel cell, while attempting to clear a clogged engine pan drain line.

[212man]

I know of an AS332 sitting on deck on a semi-sub, where the rig pitched down at the just the right moment for a freak wave (I say 'freak' - it was around 55 kts at the time, so it's relative) to hit the edge and engulf the helideck. The co-pilot was almost washed off, and the bemused pilot found himself sitting in the aircraft with both engines spooling down, outside of the wind limits for shutdown!

In the Toulouse Etihad A340 accident and the QF32 A380 engine failure in Singapore, the fire services used water to try and put out the (uncontrollable) engines - took a long time and a lot of water!

[rotheli]

Many years ago an RNZN Wasp was engaged in a winch recovery from a foreign fishing vessel in southern waters, with the usual southern wind & seas. Observers on the frigate watched as the Wasp was engulfed by a large wave, perhaps broken by the FFV. All watching thought the Wasp would be gone, however, after the spray cleared, there it was, still winching! On return, the cabin was awash with seawater. The Nimbus obviously took it all, the cabin perhaps taking the bulk of the solid water. Somewhere there is a good b&w photo sequence, I dont have it. A good freshwater washdown & back to work.

[BlenderPilot]

I remember a Puma that flew thru one a one of those huge fountains and had a double flameout, anybody remember where it took place?

[Impress to inflate]

Many years ago while flying along in a Mk1 Super Puma, looking at the cloud we were flying in, we fly straight though the centre of a water spout. It was like flying underwater! I have never seen so much water. I still to this day can't work out how the engines stayed alight

ITI

[John Eacott]

Salt spray on the Sea King windscreen was a PITA, especially running a Ripple 3 for a week or two with no opportunity to wash the muck off. A chat with the ground crew achieved a bucket of fresh water available to chuck over the screens during rotor running crew changes on Ark Royal which worked very well.

Until the enthusiastic young lad managed to throw the water over the cockpit and straight into the (then exposed) intakes of the Gnome which responded by saying 'cough, I'm not playing any more'.

Boss not amused, solution scrapped and days of flying around squinting through salted up screens. The barn doors came much later, and would have saved me yet another b0llocking ;)

[RenegadeMan]

Thanks for your replies and interesting links everyone.

Rgnewboy that Sikorsky S61 in the video you posted sure copped it. Amazing!

From the video you posted mickjoebill I can see the machine was an Eurocopter EC120 VH-VHJ from ABC Heli on the Gold Coast. And yes, the amount of spray it taxied through was nowhere near as bad as it could have been.

And Fareastdriver you touched on what I'm really interested in when you mentioned the shredding of the rotor blade tape. And that is: at what point is a deluge so bad (in terms of volume and period of time) that the rotor blades are starting to be badly affected by the water hitting them (i.e. they're either 1. getting damaged or 2. being severely decelerated by the mass of water hitting them?) Just watching the Sikorsky video one would expect another 2 or 3 of those waves sending spray down from above in quick succession would have been disastrous.

Ren

[Thone1]

@RenegadeMan:

I´m no scientist, just a pilot, but I doubt that any realistic amount of water (waves, wash down, etc) on the rotor blades of a helicopter the size of the mighty Sea King can do much to slow them down.
Looking at the power that moves them and the mass that is in motion, I doubt that even a series of waves can have much impact.
It will shake as hell, the airflow might get disturbed, I´d get worried in the RHS but it should keep flying anyway.

Talking about salt accretion becomes a whole new story, not so much for the engines equipped with EAPS though.

Tom

[500guy]

I know the more you fly in rain the faster your blades loose their paint. But as for actual blade damage im sure it would take a lot!

[Chopper Doc]

The story I was told was that the gazelle tried it after a scout had already done the same. The scout obviously was better able to deal with it.

[bast0n]

I may have posted this elsewhere in the past, in which case I apologise for boring you.

Long ago in the seas off the Falklands before we were sunk, the Wessex 5 played a major role in support to the motley fleet scraped together to make up the task force. Basically doing the HDS role or whatever was required.

One very stormy day the task force commander decided to hold a conference for all Captains and Masters of the gathered fleet. Off we went to pick them up and deliver them, winching them up one by one from their vessels.

I had about six of them in the back and was in the middle of winching up the Master of the MV Elk, an ammunition ship, when a huge rogue wave came over her bows and hit us full frontal.

The next few moments were really quite full of interest as the starboard engine “ran away up” and the port engine stopped. This was very fortuitous as it gave me full power on this engine and allowed me to fly away from the ship whilst recovering the Master! It now seemed a good moment to restart the port engine, hoping that all the seawater had drained out of it.

It started as though nothing had happened and so up with the speed select to let it join in the fun. The starboard engine all the while was giving it’s all, so speed select back to ground idle and switch off the computer. Nothing happened!! Only answer was to fly back to Atlantic Conveyor and shut the starboard engine down on finals when it became difficult to control the rotor RPM. Lots of wind over the deck and a willing port engine saved the day. After landing it was interesting to view the damage. All the panels in the bottom of the nose door had blown downwards from the weight of water, taking all the DZUS fasteners with them.

So it seems that the same amount of water had different effects on each engine and thank goodness for that!

[Sanus]

Bast0n that's one hell of a story. From all the stories I've heard (mostly on pprune) the Wessex 5 appears to have been a remarkable flying machine. I've read that a lot of Wessex flights during the Falklands conflict were flown single pilot. Just for the record and your chance to appear totally awesome were you single crew during this event?

[JimBall]

This thread points to one of the advantages of pistons! An R44 can fly in wetter weather than a machine costing 10 times more.

[bast0n]

were you single crew during this event?

Sanus - yes. We rarely flew with two pilots at that point in the conflict.

[skadi]

This thread points to one of the advantages of pistons! An R44 can fly in wetter weather than a machine costing 10 times more.

I just imagine what might have happened to a R44 in the situation of the S61N from the previous video :E:E:E

skadi

[chopperaguilera]

look this:

http://www.subirimagenes.net/pictures/fd0b0c074b7db2e71b17b622be0c88ee.jpg

http://www.subirimagenes.net/pictures/878791c824143b542b7daecb71d6985f.jpg

[mtoroshanga]

While in the Rhodesian Air Force in the 60's washed the engine by flying in the spray off Victoria Falls. aircraft was an Alouett 3 and pilot was Ozzie Penton, a great guy.

[FSXPilot]

Oh please! The Robinson collection of helicopters are cheap and cheerful. The one thing they are not is resilient! Look at the blades wrong and they break.