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Sikorsky S-92: From Design to Operations

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Sikorsky S-92: From Design to Operations

Old 26th Mar 2009, 03:58
  #1401 (permalink)  
 
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Can anyone tell me what the S92 RFM states when there is indication of MGB low oil pressure
FWJ. I don't have the RFM in front of me so this will (hopefully) be a correct interpretation! I am sure it will be corrected by someone if I get it wrong

The drill covers both a MGB Oil Px CAUTION and an MGB Oil Px WARNING - one yellow, the other red.

1. If MGB Oil Px WARNING then select BYP (this is a MGB oil cooler bypass switch)

2. If MGB Oil Px CAUTION with px above 35 psi
Land as soon as PRACTICAL

3. If MGB Oil Px WARNING, or MGB Oil Px CAUTION with px below 35 psi
Descend MSA
Start APU
Land as soon as POSSIBLE

However if there are secondary indications, which are:
Oil px indicating below 5 psi
Smoke or fumes
Hydraulic failure
Increased power required
Unusual noise or vibration
LAND IMMEDIATELY


VL
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Old 26th Mar 2009, 16:23
  #1402 (permalink)  
 
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Droopystop

I agree that 30 mins is not really enough, but is better than nothing, and you have to bear in mind the probability of total loss oil on a Super Puma type system is extremely low - as we previously discussed, a few close calls but no actual ditchings in the SP's 28 years on the N Sea.

OW

Leak from the bottom of the sump on a 61 is land immediately, ditto on a 225, 139 etc is 30 mins. That is the difference and that is why the S61 does not comply with 29.975.

HC

Last edited by HeliComparator; 27th Mar 2009 at 06:01.
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Old 26th Mar 2009, 20:53
  #1403 (permalink)  
 
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Can anyone tell me what the S92 RFM states when there is indication of MGB low oil pr

Thanks VL:

I hope you don't mind a few more questions?

How is oil pressure controlled in the MGB?

What does the pressure need to drop to to initiate a MGB Oil Px CAUTION, vs a MGB Oil Px WARNING?

How many pressure sensors/transmitters exist in the MGP to provide this pressure data?

Are there specific actions provided in the RFM associated with Land as soon as PRACTICAL, and Land as soon as Possible?, or is this left to the discretion of the PF? I assume there is no discretion associated with Land Immediately.

Appreciate your info.

FWJ
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Old 26th Mar 2009, 22:06
  #1404 (permalink)  
 
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I'm sensing...and I may be wrong about this...but I get the impression that *some* people feel that the X-minute "run-dry" capability of a transmission is something that can be intentionally used.

Not me!

I don't care how much "run-dry" capability the manufacturer *says* I've got. Every second you run that trans without oil pressure is a gift from heaven. I'd take a controlled ditching even in the roughest and coldest of seas to a transmission seizure in flight, believe you me! "Send the SAR bird for me, laddies! And for the love of God make sure it's not another S-92!"

And like SASless asked, when does the 30-minutes (or whatever) begin? How do you know? Do you get a caption light alerting you to start the clock? Does the ECAS generate a sultry female voice that says, "You're emergency run-dry period has begun. You have twenty-nine minutes and fifty seconds remaining...You have twenty-nine minutes and forty seconds remaining...You have..."

And dear me, the sheer lunacy of the "slow down/go down" crowd! Are people seriously suggesting that in the event of a total loss of fluid (or some such) in which there is a genuine risk of transmission failure, that the best course of action would be to descend to a very low altitude AND SLOW DOWN? ...Thereby prolonging your inbound leg, of course?

Nope, if it comes to that we should just LAND. That is what helicopters do. And if we accept the responsibility of flying helicopters with just a single transmission far out over water, then we also have to accept the consequences. Remember, our FIRST responsibility is to keep ourselves alive. Everything...and everyone comes after that. I'll ditch the bitch - get it down on the water and then, "Everyone follow me!" as I go out the door. If it turns out that the ship could have flown around the world at 5 psi, oh well, I'll take the most conservative response, thankavrymuch.

And speaking of which, I don't know about the rest of you guys, but are we really supposed to believe that a transmission pressure of 5 psi is acceptable? I mean, to me that would be within the realm of gauge error. If I ever see 5 psi on a transmission pressure gauge, I'm not waiting for the secondary indications (chip lights, loud squealing, etc.) I'm putting that bastard down! (See above.)

Parenthetically, it's almost laughable. In a previous post someone supposedly quoted the S-92 RFM. It mentions in the LAND IMMEDIATELY category that two of the factors would be "increased power demand" and "unusual noise or vibration."

Kids, I gotta tell ya, if your trans is already at the point where it's starting to seize up, requiring an increase in torque, you've probably waited too long to land. Sorry, you're probably done. I'd start praying like an out-of-fuel Tunisian ATR-72 pilot if I wuz you.

There are a few anomalies with which I might continue flying a recalcitrant helicopter. A main transmission problem is not one of them.

Last edited by Senior Pilot; 26th Mar 2009 at 22:24. Reason: Personal attack deleted
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Old 26th Mar 2009, 22:29
  #1405 (permalink)  
 
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OW

Leak from the bottom of the sump on a 61 is land immediately, ditto on a 225, 139 etc is 30 mins. That is the difference and that is why the S61 does not comply with 29.975.

HC

I sure wish people would stop misquoting me and putting words in my mouth.....never once did I say that the S61 meets 29.975

I was only taking you to task over your "old Technology" statement. Done.
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Old 26th Mar 2009, 22:54
  #1406 (permalink)  
 
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FH-1100,

The crisis occurs when the water above which you are flying invites certain death if you do make that decision to ditch!

There lies the other question I have always had about drawing the line at operating in "all sea states and wind conditions".

I would suggest if one is out over the Oggin in sea states that exceed the tested capability of the aircraft emergency flotation system then one is taking way too much risk. It does not have to be a mill pond and enduring a long rough ride in the rafts is one thing but to know you will immediately roll over and almost assuredly sink upon alighting on the water is asking a bit much.

Lord knows I have seen the North Sea below me when I preferred to pop up into the clouds and not have to look at the sea knowing it was telling me it was waiting for me with a pair of pinking shears in one hand and a big steak knife in the other just as one of my Ex's was prone to do when seeking to avenge some poor thinking on my part.
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Old 27th Mar 2009, 00:16
  #1407 (permalink)  
 
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SAS, this "crisis" you refer to applies to all helicopters without the benefit of a backup main transmission. It is not enough, IMHO to say, "Well, transmission failures are a fairly rare event..." I think we've all heard enough anecdotal stories that attest to the fact that they *do* happen, and in all types!

So that is the eventuality for which we must prepare, and for which there is really no hardware solution. I'm sorry, but I just cannot...will not trust the engineers who say to me, "Bob, don't worry, it'll last a goooooood thirty minutes without oil at MGW. Yepper, good thirty minutes."

Uh-huh. Right.

I guess that's part of the reason (perhaps subconscious) I never got into the deepwater stuff. There is always that lingering helicopter pilot distrust (paranoia?) of the machinery.

No matter what solution the manufacturers come up with, we'll still be in the same boat, so to speak, should we ever again be faced with transmission oil pressure gauges at zero or nearly so, and an hour to go to "feet dry."

Stop. Subject change.

As you all can plainly see, my last post was edited by one of the mods, who took issue with a comment I made and felt that it constituted a vicious personal attack on a someone, and then had to berate me in the remarks section. Just to set the record straight, I DID NO SUCH THING. I intended no such thing. Anyone who read the post before it got edited can back me up here.

I cannot even mention the subject again under fear of excommunication - you all know how pissy the mods can be when they get on their high horse. I'VE BEEN WARNED!

Suffice to day, in a discussion of this sort, to wit: a potential serious problem with a production aircraft that is touted as having a superior level of safety compared to the VH-71, it's good to hear all viewpoints and opinions. I wonder how the President of the United Skates would feel if he were riding around in an aircraft based on the S-92 right now? That's all I'm saying. So although the mods like to wield their power like a cudgel, I believe they/he over-reacted in this case.

~Bob

Now, back to your regularly scheduled discussion of transmission failures!
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Old 27th Mar 2009, 00:37
  #1408 (permalink)  
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Originally Posted by FH1100
I cannot even mention the subject again under fear of excommunication - you all know how pissy the mods can be when they get on their high horse. I'VE BEEN WARNED!
You were, and have chosen to ignore that. "Vicious" is your description, not mine.





Bye bye
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Old 27th Mar 2009, 02:15
  #1409 (permalink)  
 
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Actually there are some of us who would wish for our new President to be riding around in a Baku Rocket Plane rather than a time tested Sea King!
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Old 27th Mar 2009, 02:32
  #1410 (permalink)  
 
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Has anyone SEEN a published (as in RFM) run dry xmsn capability in any helicopter. I seem to recall we had something in the AS350 but am not sure.

(Who is it that is calling me a Mad Tasmanian ???!!!)
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Old 27th Mar 2009, 02:48
  #1411 (permalink)  
 
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Peter there was no run dry time on the as350 but it did have a shear point on the mast incase the geabox seizes.
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Old 27th Mar 2009, 03:25
  #1412 (permalink)  
 
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EC-155 has a RFM statement of 25 minutes following total oil loss. It has a main pump that uses the cooler, and a standby pump that bybasses it and only comes on line when the main pump has failed or ceased to draw oil. Should the standby pump fail to deliver pressure, that is considered an indication of total oil loss.

Below is a section of a 155 checklist I wrote some time ago, which mentions the 25 minutes, and my advice that it should ideally be used to allow for a safe ditching, rather than for continued flight.


SUBSEQUENT ACTIONS:

If single indication, land as soon as practicable.

If double indication, land IMMEDIATELY.

If immediate landing an untenable option, reduce speed to Vy, descend to low level and land as soon as possible within 25 minutes of first indication.

If noise, vibration or erratic engine indications occur, land IMMEDIATELY

CONSIDERATIONS:

The 25 minutes ‘run dry’ capability should not be intentionally used unless landing immediately really is impossible (e.g dense jungle) or, for instance, an offshore installation is close by. Ideally it should be used to enable a planned and controlled landing or ditching.
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Old 27th Mar 2009, 04:44
  #1413 (permalink)  
 
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Has anyone SEEN a published (as in RFM) run dry xmsn capability in any helicopter. I seem to recall we had something in the AS350 but am not sure.
I think the part in brackets (as in RFM) is key here, as I just googled "run dry helicopter" and came up with a very nice page about the H-92 Super hawk. An excerpt from:
H-92 Superhawk Multi-Mission Helicopter - Air Force Technology

Vital systems are installed with widely separated redundancy. The gearboxes have a run-dry capability of 30 minutes allowing the pilot to return the helicopter to safety in the event of a catastrophic oil loss.

And here about the Bell 214ST: Bell Model 214ST helicopter - development history, photos, technical data


Initial orders included several for offshore oil support and utility transport roles, in which configura-tion the aircraft seats 18 passengers plus two crew. The twin engines drive a one-hour run-dry transmis-sion with fiberglass rotor blades and elastomeric bearings in the rotorhead. The 214ST is cleared for two-pilot IFR operation, and is the first large Bell helicopter to offer an optional wheeled undercarriage in-stead of skids.

And last but not least the 225:

Rotor & Wing Magazine :: Helicopter Intellect

While the main gearbox has been redesigned and reinforced for greater power and safety, the key benefit for the pilot is a guaranteed 30-min. "dry run" capability. And while it is certified to run dry for 30 min., actual tests have taken it up to 52 min.

Amazing what the spin doctors can suck us into
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Old 27th Mar 2009, 05:48
  #1414 (permalink)  
 
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Leak from the bottom of the sump on a 61 is land immediately, ditto on a 225, 139 etc is 30 mins.
HC
Pls can you clarify? Are you saying the 225 is the same as the 61; leak at the bottom then land immediately? Or are you saying that the published RFM on the 225 and 139 say "land within 30mins" if there is no oil?

Did we get an answer on how the 139 achieves the 30mins dry running? Any special cooling system or something?
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Old 27th Mar 2009, 05:53
  #1415 (permalink)  
 
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Quite unfortunate that the CV/FDR on the Cougar 92 quit minutes before the crash. I would assume that the electrical bus the recorder was on was shed due to loss of generators. Questions:

1. What electrical bus(es) provide power to the combined recorder?
2. What failures would shed that bus? Are they automatic or manual?
3. Where are the generators on the S-92? Assumption would be one on each engine and one on the transmission.
4. Is it an incorrect assumption that other recording devices (HUMS, QAR, etc) are on less reliable power sources than the CV/FDR?

Maybe the design should be altered to put the recorder on a battery backed up bus to insure the critical data is not lost in the future.

The Sultan
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Old 27th Mar 2009, 05:54
  #1416 (permalink)  
 
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Outwest,
you have to appreciate that the H-92 and the Cyclone are NOT S-92s they are derivatives. Who knows what changes have been made to the Transmission etc. If there are any Canadian Armed Forces guys on this site, who are involved in the Cyclone project, may be they can enlighten us - or maybe they can't
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Old 27th Mar 2009, 06:17
  #1417 (permalink)  
 
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Or maybe Sikorsky used the same 'smoke and mirrors' sales pitch as they have with the S-92
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Old 27th Mar 2009, 06:18
  #1418 (permalink)  
 
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He1iaviator

... Leak from the bottom of the gearbox on a 225 is "Land as soon as possible, maximum flight time 30 mins". That assumes the emergency cooling/lube glycol system is working. If not (and the red light comes on), it's land asap.

The Sultan

Couldn't the recorder have stopped due to the g switch activating when the transmission seized in flight?

HC
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Old 27th Mar 2009, 06:22
  #1419 (permalink)  
 
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1. What electrical bus(es) provide power to the combined recorder? The DC Essential Bus

2. What failures would shed that bus? Are they automatic or manual? Loss of DC Power from both Primary DC Converters (TRUs) without the APU running and the Backup DC Converter on. The Primary DC Converters are powered by the AC Generators, the Backup converter is powered by the APU Generator.
The Bus is not 'shed' in the conventional sense - it ceases to be powered, which is a slightly different thing.


3. Where are the generators on the S-92? Assumption would be one on each engine and one on the transmission. Two Primary Generators powered directly by the transmission and cooled with oil, one APU Generator powered when the APU is on.

4. Is it an incorrect assumption that other recording devices (HUMS, QAR, etc) are on less reliable power sources than the CV/FDR? NO

The CV/FDR also has a 'g switch' set to stop recording at 10g - this is to prevent over writing data in the event it remains powered following an accident (also has an immersion switch, for same reason.)

So, the loss of electrical power to the recorder 'scenario' seems quite plausible as the AC Generators have proved already that they will fail when hot - which they would be if no longer cooled.

Crab,
allowing the pilot to return the helicopter to safety in the event of a catastrophic oil loss
They are clearly referring to a complete oil loss following combat damage, so I doubt spin is involved! The Cyclone is NOT an S-92. It is FBW for starters.
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Old 27th Mar 2009, 06:55
  #1420 (permalink)  
 
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you have to appreciate that the H-92 and the Cyclone are NOT S-92s they are derivatives.
I agree, however I would be very surprised if Sikorsky developed an entirely different transmission for the H-92, the costs would be enormous.

Having said that, if indeed they did develop and manufacture a "run dry" transmission, why for god's sake would that not be used in a civil version.
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