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Helicopter crash off the coast of Newfoundland - 18 aboard, March 2009

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Helicopter crash off the coast of Newfoundland - 18 aboard, March 2009

Old 14th Nov 2010, 23:02
  #701 (permalink)  
 
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APU

Just to clarify, the APU will supply AC power to all the system except RIPS (de-icing), AVC (anti vibration), # 1 engine inlet anti-ice, windshield anti-ice and in case you are equipped the second compressor for the aircon. The AC power also the DC converter, which supply the DC power to all buses. Before Cougar accident the checklist was calling for the APU ON only as a recommendation, but since then it fully integrated in it.

Maybe we should ask if the crew of Cougar turn the APU ON during their emergency?

FH
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Old 14th Nov 2010, 23:23
  #702 (permalink)  
 
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zalt / 212. The version of the RFM I posted was current during the Norsk incident - according to the RFM they should have ditched, but (with hindsight) they made a good call and stretched it a few minutes to a platform. The version 212 posts is the revision as a result of that event, indicating that provided there is >5psi, you can continue. A little over 5psi is the sort of pressure you could get with a single pump failure at the time (not sure if it's still the case, I believe there has been some to-ing and fro-ing with check valves since then!)

Its interesting to note the continuing reference to increasing transmission drag in the RFM. I can't help thinking that there is a huge amount of energy going through the transmission - the transmission's job is to pass that whilst converting as little as possible to heat - and if more than a very small amount of that energy is converted into heat (such that you notice the loss of performance), and bearing in mind that heat will be quite localised, surely the metal will melt very quickly, as it does so increasing friction thus the amount of energy converted to heat in a runaway-up kind of way. In other words, surely once you notice you torque for fixed colective is increasing, it would be too late unless you are already in a hover?

HC
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Old 14th Nov 2010, 23:31
  #703 (permalink)  
 
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Flyinghead

A perfectly fair question that I hope the TSB will cover.

However the checklist doesn't suggest the APU is merely a recomendation! Again if that is how crews were trained, no doubt that would have also caused confusion on what other checklist items were optional.

HC

Thanks for the extra information. I agree that the other physical manifestations mentioned in the RFM are pretty terminal warnings!
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Old 15th Nov 2010, 02:42
  #704 (permalink)  
 
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I can see how some crews, reading an evolving RFM, without the benefit of frank insight to the S-92A service experience might have assumed this was a sign of greater confidence in the MGB, not as was the case, less.
Zalt, your posts just get more and more speculative. In fact a better word to describe this one would be ridiculous.
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Old 15th Nov 2010, 03:28
  #705 (permalink)  
 
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Zalt,
Smoke or fumes in the cabin
(plus, in my case, the 9 EICAS captions - easy decision )

I think it's incorrect to assume line crews monitor RFM changes in the way you suggest - what they actually do is follow their company SOPs and Emergency Checklists that are in the cockpit.
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Old 15th Nov 2010, 07:06
  #706 (permalink)  
 
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RFM with questionable contents

I must agree with 212man. The key is in company SOPs. The RFM is a document based on the basic aircraft and does not integrate these basic procedures with those variations required by the installation of customer options. It is also written in simplistic terms, devoid of context, at the start of an aircraft's life when everything is factory-fresh, shiny-new and unsullied by maintenance methods that are not fault-free at best and downright dangerous at worst.

There is one flight manual out there that invites you to 'continue flight' with both batteries indicating an overtemp condition. That is where good company SOPs step in and return our world to sanity and suggest that maybe any arguments about what to do next take place on terra-firma.

The RFM indicates the minimum you must do when reacting to a situation but only you (actually your CP) can put 'context' into your deliberations and therefore your SOPs.

G.
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Old 15th Nov 2010, 09:20
  #707 (permalink)  
 
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The RFM indicates the minimum you must do when reacting to a situation but only you (actually your CP) can put 'context' into your deliberations and therefore your SOPs
Unfortunately CP's don't always get it right either, witness the lack of understanding about Va in the fixed wing world when applied to the rudder. After all they are human too (CP's that is), although some might disagree.

Personally I take the view that what is written in the RFM/SOP's is a best suggestion written by an engineer, or some other, in the comfort of a nice warm office with a cup of hot coffee to hand. Mind you there are some emergencies where the course of action required is not up for debate. Some times the course of action required is dictated by the circumstances in which you find yourself, and that decision may be founded on someone else experience, or your own prior experience, and some times taking the bit in your mouth and hoping to hell it gets you out of the jam in which you find yourself.

An example, would you ever recommend a pilot of a single engine turbine taking off after the engine oil pressure had suddenly dropped to zero? The crew of a Huey found themselves with just that predicament. To stay where they were was fraught with risk so they took off and transited until the engine chip came on and then performed a auto into a clear area. People safe and aircraft undamaged save for a burnt up T-53 and a new oil cooler required (hole in which dumped all the oil). The outcome had they not done so does not bare thinking about. To be recommended? Definitely not, but sometimes ............ Fate is the Hunter.
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Old 15th Nov 2010, 13:41
  #708 (permalink)  
 
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Brian

Agree entirely save for warm room and cosy chair I would say that the perspective frequently suggests they are downwind in the circuit on a lovely summer's day. They also appear never to have read an accident report in their lives and therefore cannot subscribe to the theory that there are any lessons to be learnt from what has gone before.

What 'has gone before' include 'Sioux City', the Everglades and countless other lessons about improbable outcomes to unlikely events. Wise virgins would be well-read on such topics and put their own veneer of experience on to the advice given in the RFM.

As to the quality of CPs - what can you expect when you have an industry almost totally devoid of managerial training and consequently constantly populated by more ex-CPs that current CPs.

G
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Old 16th Nov 2010, 21:22
  #709 (permalink)  
 
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I accept the points made above that the RFM is mostly actually used by the team producing OMs and checklists. I do think may basic point is still valid as Sikorsky's changes influence those management/trainers and their changes then affect crews.

Having said that, it is not uncommon for operators in North America flying large aircraft to actually have their crews use uncontrolled checklists produced by the simulator training companies! I bet that would shock the North Sea jocks.

When I read:
you have an industry almost totally devoid of managerial training and consequently constantly populated by more ex-CPs that current CPs
I did think for a second I was reading the work of Shell Management! But on reflection it does highlight one weakness of many operators when it comes to the continuity of effective flight operations management.

I have recently been pointed (via a series of PMs) at some past comments by Nick Lappos after one of the Shell Brunei incidents (here on 27 Jan 2008 http://www.pprune.org/rotorheads/163...ml#post3867445) - I have made some text bold:
I wrote the S76 checklist, and in the intro paragraph to Chapter 3 gave the pilot the latitude to be more than a sweaty flight-manual reader. The difference between airmanship/wisdom and memorizing flight manuals is the difference between pilots and stick wigglers, IMHO. If the flight manual words say "XXX" and you think you must do it, then do so. However, if the PIC decides to actually try some airmanship, in many cases it would be welcomed.

The ease of saying and preaching (in the ease of a Sunday at the keyboard criticizing your fellow pilot) blind obedience to the flight manual, "land immediately" is often confounded by the actual conditions, and by the fact that the aircraft is still flying nicely, even if a few lights are on. I am reminded of the American Airlines DC10 Chicago engine drop-off accident: In simulator trials afterward, the crews that obeyed the checklist and slowed to Vy (while they were climbing at over 2000 fpm before the slow-down) all died like dogs, those that flew wisely like airmen landed successfully.

I do not know what happened with this specific aircraft, at all, but I am lead to believe from 212man's posts that it did not lose all or most of its oil, rather, it might be that it had an oil leak. Any pilot who ditches a load of passengers with an oil leak (even if he memorized the flight manual in that case) might deserve to be ppruned to death, afterwards.
I note in the last para that "lose all or most oil" is treated differently to an "oil leak". I assume in the latter case a 'ppruning' is not considered to be deserved...

I also see that other people failed to appreciate the subtly of the S-92A RFM, like Variable Load (same page http://www.pprune.org/3868816-post974.html) as they defended the S-92A and compared it to its competitors:

I can tell you that the S92 FM does not say to Land Immediately with low MGB oil pressure, the Land Immediately comes into play when secondary indications of impending gearbox failure are present, such as unusual noises, smoke in cabin, etc.
Nothing about continuing pressure drop there.

The Wells Report is due out this week: N.L. inquiry to release report on fatal offshore helicopter crash

Cougar and Sikorsky are in court next week.
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Old 17th Nov 2010, 05:43
  #710 (permalink)  
 
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like Variable Load (same page http://www.pprune.org/3868816-post974.html) as they defended the S-92A
Zalt, unlike you I like to base my posting on facts. If that means I am taking a defensive position, so be it. Surely that is a good quality?

Postings based on dangerous speculation, half truths and damn lies I will leave to some on this forum like yourself
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Old 17th Nov 2010, 06:56
  #711 (permalink)  
 
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In fact VL your post from 2008 is the one that contains the dangerous half truth because you have missed out a key part of the Flight Manual.

Your post above does not put you in any better light.
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Old 17th Nov 2010, 17:49
  #712 (permalink)  
 
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Flight Manual Emergency Procedures

Just an observation that many pilots seem to believe that the flight manual emergency procedures are written, reviewed and approved by a group of people sitting in offices far from the flight line. I cannot testify for Bell, Boeing, Eurocopter and the rest but I have some experience with what Sikorsky did and can attest that those procedures received a lot of review, to include the crowd who wear flight suits*. No one writes Land Immediately without considering the circumstances that might exist, be it over the swirling ocean or finding the lowest point of foliage over the jungle. The instruction is aimed at making a landing under control, because the alternative is a lot worse.
* As I am sure is the practice at the other manufacturers.

My copy of the S-92 manual is the basic 2002 manual as revised Sept 11, 2004, and it is clear that Land Immediately was called for if, after the bypass was selected ( MGB Oil Press warning on ), the pressure continued to decrease, OR ( my caps ) there are loud/unusual noises, unusual vibrations or progressively increasing power required to maintain flight.

That may have been modified after 2004, but the 2004 writing was pretty clear in that it was OR, not AND.

Thanks,
John Dixson
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Old 17th Nov 2010, 22:26
  #713 (permalink)  
 
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John

Thanks for further confirming that Sikorsky did water down the RFM from 'continuing pressure drop' after the 35psi warning to '5psi or below' after the incident in Norway in 2005.

I guess they never expected the vespel spline problems.

A 2002 manual would have been pre certification (FAA, TC or JAA). Your approved Sept 2004 amendment came after the foreign certifications. Funny that!
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Old 17th Nov 2010, 23:32
  #714 (permalink)  
 
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The Wells Report Phase 1 is out: C-NLOPB || Offshore Helicopter Safety Inquiry
The Phase 2 Inquiry starts after the TSB report comes out.
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Old 17th Nov 2010, 23:50
  #715 (permalink)  
 
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Thanks for further confirming that Sikorsky did water down the RFM from 'continuing pressure drop' after the 35psi warning to '5psi or below' after the incident in Norway in 2005.

I guess they never expected the vespel spline problems.

A 2002 manual would have been pre certification (FAA, TC or JAA). Your approved Sept 2004 amendment came after the foreign certifications. Funny that
What is the exact point you are trying to make, Zalt?

Prior to the Norsk incident, the advice was that if the pressure continued to drop following the activation of the MGB Bypass, then land immediately, as it was assumed that this indicated an uncontained leak. Following the Norsk incident it was realised that the vespel spline failure would result in a very low, but steady, pressure remaining and that tests had proved the integrity of the MGB would not be compromised at that pressure. Therefore, the additional advice about 5 psi was inserted.

This extra information was intended to stop pilots ditching unecessarily, following a pump failure. It quite clearly, though, maintained the original stance that if the pressure continued to drop - below 5 psi - then land immediately. Bear in mind, too, that a pump failure results in an instant drop, whereas a leak is a steady continuous reduction.
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Old 18th Nov 2010, 00:01
  #716 (permalink)  
 
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Bear in mind, too, that a pump failure results in an instant drop, whereas a leak is a steady continuous reduction.
Why is that then? Surely a leak gives no pressure drop until the pump inlet is uncovered and the pump starts pumping air? With a slow leak there would perhaps be a period of fluctuating oil pressure as the oil sloshes around and covers/uncovers the pump inlet. With a rapid leak such as loss of oil filter lid, I suspect pressure drop would be near-instant. And with a pump drive failure, surely it might not stop dead but start slipping etc, or if internal damage to pump gradually get worse. I just can't see how your statement is robust!

It does seem a strange (ie bad!) design that with 2 pumps you get 60 psi or so, with 1 pump you only get 1/10th of that. I'm still glad I fly EC!

HC
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Old 18th Nov 2010, 00:25
  #717 (permalink)  
 
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I suspect pressure drop would be near-instant
In my experience of two MGB loss of oil that was the case. Normal one second, nothing the next. One caused by a blown oil filter seal, the other a hole in MGB case where the rotor brake quill once resided.
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Old 18th Nov 2010, 00:41
  #718 (permalink)  
 
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Obviously there will be variables in both a 'leakage' and a 'pump failure' scenario. The fact that the Bypass needs to be operated within 5 seconds of the MGP OIL PRESS warning indicates the kind of worst case leakage rate that SAC envision - which is rapid, but not instant - but there could be lower rates of loss and it is my belief that these would register as pressure drops too, based on my experience of the type. Similarly, it is true to say that some pump failure modes may show instability initially, but once the drive fails the pressure drop will be pretty much instant.
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Old 18th Nov 2010, 01:36
  #719 (permalink)  
 
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If the S92 MRGB lube oil system is 2-stage then failure of one of the vespel splines will IMHO cause a large knock-on effect to the next stage e.g. 35 down to 5 psi. If the system is a dual-redundant parallel system then perhaps there are no reverse flow prevention bypass check valves thus causing "windmilling". Perhaps one of the S92 engineers can clarify?

I would guess that a small leak would show up as a loss in net suction pressure to the pumps causing a respective drop in discharge pressure based on the pump curves.

I do not see an Achilles heel present in the current RFM as it does account for total loss of MRGB press i.e. < 5 psi land immediately, regardless of the possible false temperature indication and/or lack of secondary indications of MRGB lube oil loss.

Safe flying

Max
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Old 18th Nov 2010, 14:34
  #720 (permalink)  
 
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Max, that's a fair summation of the current situation. The vespel spline failure, as opposed to a pump seizure, would cause the MGB indicated pressure to fall from 60ish to something "above" 5psi. The pumps are sitting in a "parallel" type circuit, but without check valves.

The check valves were fitted and then removed due to the knock on complications for input module scavenging. Improper scavenging then leads to a build up of oil and then overheating, etc.

So my understanding is that there are plans to improve the scavenging situation in an oil pump fail scenario, which will then enable refitting of the check valves. Net effect will be a much less dramatic fall in oil pressure due to a non-seized but failed MGB oil pump.

In addition to this 'long term enhancement', there are more immediate modifications that will indicate to the pilot if a MGB oil pump has failed, this utilising a "vacuum" sensor in each of the scavenge lines.

I have never perceived any of the RFM changes or modifications as a "watering down" of procedures or safety. They have been robust responses by Sikorsky in the light of experience - something I much prefer compared to the ECF standard response of "it is not a problem" (you have to say that with a strong French accent!). Sure, with hindsight anybody can say "surely you saw that coming", but that's the easiest game in town to play.

MY personal stance in this offshore game is to be open minded and be critical. Always ask why? Don't believe the marketing crap. Always drive for better.

But when challenged by b*llsh*t I will try and play "devil's advocate", because that's how the truth is obtained. The trouble is it's easier to be a doubter than to find the truth. I can start a rumor tomorrow that is complete boll"cks, but it falls within peoples perceptions, it will then become the truth. Just look at snopes.com to see how much crap is out there that people are willing to believe in. Your inbox is probably full of it?

I believe this is what differentiates a professional from the crowd. He makes is own mind up, without bias, always keeps an open mind and is willing to accept his original stance may be wrong.

Long may we continue to have professionals in this industry, rather than those that think that whatever they are currently strapped to is perfect! The perfect helicopter does not (yet!) exist.
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