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Robinson R44

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Robinson R44

Old 27th Jun 2008, 09:50
  #1041 (permalink)  
 
Join Date: Mar 2008
Location: A land not far from here.
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Yea i got that email! Shouldn't suffer out here though! We're lucky if it reaches 10'C! Welcome to Ireland! :L
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Old 17th Jul 2008, 13:59
  #1042 (permalink)  
 
Join Date: May 2006
Location: Philippines
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never never fly the r22/44 solo from the left because of lateral cg. the main tank (r44 @ 38gals) + your weight is just way too much for the aux tank to balance. besides the aux fuel gets transfered to the LH main tank.
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Old 25th Jul 2008, 12:54
  #1043 (permalink)  
 
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bogey:

Sort of, sort of not.

The fuel tanks, when full, are at the same level. Fuel's taken out, IIRC, below both tanks and there's a crossfeed. So, if 6 gallons is used, 3 come from each tank (assuming full). When the aux is empty, then only main fuel is left so that's used. There's no ACTIVE transfer between tanks.

The "transfer" may be what you see if the main is topped off and then the aux fills up as a result of the normal pressure difference.
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Old 25th Jul 2008, 19:44
  #1044 (permalink)  
 
Join Date: Aug 2005
Location: Sweden
Age: 41
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Thumbs up Hyd off and then on again

Hi there folks!

Let me get your opinion on this matter:

Some pilots say it's forbidden, or atleast unwise, to switch the hyd off and then back on again in flight. The reason would be that when you turn hyd on there can be a sudden uncontrolled cyclic movement.

However I can not find anything in the POH about this.

So, has anyone felt this "uncontrolled cyclic movement" when you put the hyd on in flight?

Have a nice summer

RS
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Old 25th Jul 2008, 20:27
  #1045 (permalink)  
 
Join Date: Sep 2007
Location: Hong Kong
Posts: 103
I'd be surprised at an uncommanded movement. I think the issue here is putting serious stick force to counteract the lack of hydraulics and then with that force still applied flicking the hyds back on... then for the unwary you get a sudden "geared" and substantial deflection..

never happened to me of course but "a friend of mine" might have accidentily switched off the hyds with his map whilst leaning it on the cyclic and then leant down to pull the breaker with head down on the floor and significant forward pressure on the stick...

If you know what to expect o wouldn't expect it to be a significant issue and I certainly haven't seen a p.o.h or safety notice restriction...
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Old 26th Jul 2008, 05:48
  #1046 (permalink)  
 
Join Date: Oct 2007
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Posts: 343
I believe the POH limitations say it is not allowed to fly with hydraulics off, unless for training of hydraulics failure.

Last edited by Runway101; 26th Jul 2008 at 06:02.
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Old 26th Jul 2008, 08:21
  #1047 (permalink)  
 
Join Date: Nov 2000
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Can't recall the PoH limitation, but it makes sense to use the hyds if they're there, cos it makes life sooooo much easier.

generalspecific:

Someone wrote off a Scout (yes, not an R44, bear with me) when they felt a cyclic restriction in pitch, and switched off the hydraulics then switched them back on again without controlling the aircraft first. Accident report here - turns out the Pilot's Assistant's map was restricting rearward movement of the cyclic. Moral - think before acting.
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Old 26th Jul 2008, 16:22
  #1048 (permalink)  
 
Join Date: Jul 2002
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Hi all,

hydraulics:

The Robinson hydraulics are absolutely the nicest out there!
Reason: If you should ever have a hydraulic failure your emergency procedure is: Just keep flying the helo! No switches, no breakers!
Eventually you're getting really tired if you don't settle into the kind of neutral around 55-65 kts and about 22" max, but the idea is to be able to fly to a decent spot and land, not keep operating for hours on end.

The hydraulic switch has only one reason: To be able to switch off hydraulics for training.
It is a "little different" to fly without hydraulics, so you need a way to practise.

The way to switch on/off hydraulics in any helo is to "unload" your controls - try not to excert ANY force on ANY of the controls - OFF. After that you will certainly feel some need to handle the machine!!

Now to get the hydr. back on: same story - try to have no force on any of the controls at all, even if you have to slow down a bit, lower the collective, etc., when you feel that you only have 2 fingers on each control, not excerting any force - ON! ....and you should not feel anything but the cylic stop kicking. After that back to business as usual!

The danger in playing with hydr. ON/OFF is when you are actually "working" hard without them: Normally you need next to nothing to move the controls. Without hydr. it is some serious pounds you need - to stir the stick.
If you switch ON while excerting these pounds you might kick the stick to the stops in short order. It takes a lot of concentration to avoid any big excursion while switching ON under a load.
It is about impossible to avoid a small/medium excursion!
So again, try to fly (NEARLY....) hands off, while switching ON and you will be fine!

3top,

5K+ in 44(hydr. and electric)
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Old 27th Jul 2008, 09:17
  #1049 (permalink)  
 
Join Date: Mar 2006
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Does make you wonder why it is in such a prominent position on the cyclic that it could be easily bumped??? Surely somewhere on the dash or on the breakers panel would be better and more unlikely to be hit by a map etc and it doesn't take much pressure to move it!
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Old 27th Jul 2008, 15:44
  #1050 (permalink)  
 
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bvgs,

if you put the switch anywhere else but the controls, you need to take at least one hand off the controls to switch ON/OFF.

Although you need to loosen up on your grip, you cannot let go of the controls while switching.

Sure R might have put this on the collective, but you really just have to get better organized in the cockpit! Don't cram your lap space with charts and other parafernalia - Use the left seat or lap of the passenger there. Don't mount your GPS on the T-bar etc.
Besides it is a rather harmless thing to accidentally switch the hydr. off. If you don't realize they're off - you don't need them!

3top
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Old 27th Jul 2008, 20:05
  #1051 (permalink)  
 
Join Date: Jul 2007
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In my limited experience if the hydraulics are off on the 44 it's hard to miss.
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Old 27th Jul 2008, 21:52
  #1052 (permalink)  
 
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"In my limited experience if the hydraulics are off on the 44 it's hard to miss. "

...my point.

If you don't realize you got the hydraulics off - don't worry anymore...
.....you're already dead

3top
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Old 27th Jul 2008, 22:06
  #1053 (permalink)  
 
Join Date: Mar 2006
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HMMMMMMM It is prohibited to fly the 44 with the hydraulics off apart from the training to do so in an emergency. Sure if you bump it off at 2000 ft you realise and switch it back on but say you bump it off just before you land or just before you lift into the hover(despite being one of the things you should check) it could be a different story. I have only flown with it off when doing my refresher training and therefore would see no reason for it to be mounted somewhere else and for the instructor to "pull the breaker" or whatever other switching device was introduced. I have personally never bumped mine off, so I've no axe to grind, just think it would be better elsewhere.
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Old 27th Jul 2008, 22:31
  #1054 (permalink)  
 
Join Date: Jan 2004
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A hydraulic failure in a R44 is not as simple as keep flying etc, I can tell you from an unfortunate experience that they do not "simply" fail, they can kick in and out due to pump cavitation leaving an uncontrollable machine.

My problem was that I did not instantly know that it was a hydraullic failure, I experienced large vibrations in the cyclic and my immidiate thought was it was a problem with the main rotor head

So what no one tells you is what to expect from a partial failure of the hydraulics!
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Old 28th Jul 2008, 05:30
  #1055 (permalink)  
 
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Nr Fairy: You won't get equal flow from each tank. As it's gravity fed the levels in the tanks will drop together (like a manometer), but the main having a larger surface area than the aux will provide more fuel. I haven't done the math, because calculus was a long time ago for me. 2/3 main 1/3 aux works as a guesstimate. Or two hours / one hour and use the guages like a clock.
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Old 28th Jul 2008, 17:02
  #1056 (permalink)  
 
Join Date: Jul 2002
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it's not 2 tanks - it is one split up....

You have 2 tanks if you can select them individually.
On any R you switch the tank ON or OFF.

As a matter of fact: the aux-part of the tank drains into the main-part of the tank and then there is a line going from the main-part of the tank down to the gascolator.....

On the II models the return line from the fuel-pumps T's into the connecting line from the aux to main....

3top
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Old 29th Jul 2008, 08:11
  #1057 (permalink)  
 
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On the hydraulics off point, page 4-11 of the POH says:

"Hydraulic system failure may be simulated using the cyclic-mounted hydraulic switch. CAUTION: To avoid overcontrolling, relax force on cyclic and collective before switching hydaulics from off to on."

During my hydraulics off training, it did not bump me when the switch was flicked back on. All you have to do is to hold the cyclic and collective with a stable grip, maintain airspeed but do not chase attitude.

raven2, in a partial failure due to pump cavitation, could I suggest turning hydraulics off and continue to fly with an airspeed at the bottom of the power curve ? That's what one would do if it happened in (say) a Squirrel where control problems after hydraulics failure can easily kill you.

When landing, never try to hover - always use a bit of forward speed and do a run-on at (say) not above 35 knots in an R44.
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Old 30th Jul 2008, 09:28
  #1058 (permalink)  
 
Join Date: Jan 2004
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Hi Reverse Flight,

You are spot on, I should have switched off the Hyd and kept going, but in my innocence and the heat of the moment I wasnt aware that it was a "cavitation" problem

Man & beast came out to fight another day

R2
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Old 30th Jul 2008, 10:22
  #1059 (permalink)  
 
Join Date: Aug 2005
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Cool

Thank you all for the input
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Old 31st Jul 2008, 16:46
  #1060 (permalink)  
 
Join Date: Nov 2007
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No worries, raven2.

I didn't know about it either when I was flying the R44 until I did my endorsement for the AS350.

Glad to be of help - pass it on to your mates.

Fly safe.
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