2) There is a school of thought that HUMS sees the future, and this is almost foolish in its very concept. HUMS is a very important tool, but only by connecting it to the rad alt and the fuel gage can it become more prescient, since most accidents are caused by us, unfortunately.
Well doesn't this just typify all that is wrong in SAC. HUMS was not invented here so its crap. In fact HUMS and its couterpart HOMP (aka Flight Data Montoring) are probably the two most significant innovations in flight safety in the recent past, yet NL and SAC derides them. SAC grudginly has HUMS (though I don't think its very good, certainly not learning from and building on the experience in Europe) but it does not support HOMP. So long as that attitude continues, the product is doomed to an unhappy future, relying on its certified crashworthiness to avoid too many law suits.
Apparently the airstair project has taken some pretty high priority, from the sound of things.
Great: we've only been through 5 (or was it 6) so far!!
HC: harsh and not true! The SAC HUMS is the first truly integrated HUMS system on any modern type (even more so than ARMS or M'ARMS), and is so integrated that perhaps SAC have failed to realise the importance of appropriate information/guidance to aircrew on the information it yields.
Certainly, I can say that there is no indication that HUMS would have predicted this particular event (it could easily have been caused by 'floating' debris blocking a pipe) and equally I can confidently say it could readily predict many other failures before they became significant.
HUMS does support HFDM: not sure where that statement comes from. Workarounds are always necessary, as well you know from your HOMP experience and EAG/RACAL discussions.
Just because a HUMS is integrated doesn't automatically mean that it is good. I think a HUMS should have the capability to make quality measurements which can be used to indicate impending faults like the one this thread is discussing.
vibguy
Last edited by vibguy : 12th February 2008 at 06:13.
Reason: make it nice
Both the S64 and the S61 had problems with planetary plates in their evolution. The S61 eliminates it in RHL operation by using steel plates instead of the original titanium, to avoid an overhaul (inspection) period limitation.
212: I said "I don't think its very good" because that is what I had heard from people that know a lot more about this complicated subject than I do, but I am not in a position to argue with you.
In what way does the S92 support FDM? If it does why is it that no-one is doing FDM except Norsk - who had to carry out hardware modifications in order to do so? I believe that it might support FDM in the future but the aircraft has already been in service for 3 years...
NL's stance has always been that HUMS is no use at predicting failures, and if the (ex) programme manager has an attitude like that, its seems unlikely that much care went into the system design.
vibeguy - I agree. It would be interesting to know how many real problems S92 HUMS has detected. 212 is right that it can't be expected to detect an oilway blocked by debris, however it might have detected the fault that resulted in debris being released into the oil system, though I suppose it could have been debris left over from manufacture.
Take personal attacks to Jet Blast. As to having a brain they did find I had one and therefore would never be an "AIRMAN" because I would follow the flight manual emergency procedures.
Now to the technical side comparing a transmission design to be similar to a CH-53 does not build confidence as this type has probably the worst drive system related safety history of the 70's through 90's. E's were being lost left and right due to transmission/swashplate failures and even made "60 Minutes" with a crew chief sending a tape to his mom saying he was afraid of it. Guess what, he died in a crash shortly after due to a transmission failure.
Wasn't the 53 the reason for the whole U.S. Navy HUMS program?? I doubt this was done because it was so reliable!
Helicomparitor does not have the capacity understand what I said and did for HUMS in modern helicopters. Furthermore, he is not my designated transcriber. I would appreciate it if he did not even try, on either count, because his failures are so painful.
As 212man has said, the HUMS on the S92, "The SAC HUMS is the first truly integrated HUMS system on any modern type (even more so than ARMS or M'ARMS)...."
I claim some small credit for giving the S92 HUMS advocates the resources to make that statement from a valued customer come true. What I specifically did as Program Manager was to mandate the S92 HUMS as primary, required kit, assure that the HOMP capabilities and maintenance manual tie-ins were part of the basic premise of the S92, and to set the requirements for the read-back and diagnostic software that is integral to the usefulness of the device.
I also believe that 212man is quite correct, when he further said, "and is so integrated that perhaps SAC have failed to realise the importance of appropriate information/guidance to aircrew on the information it yields."It will take time for the true potential for that excellent operational, maintenance and failure data to be properly mined to gain what it can teach us. HUMS is an essential part of the 21st century helicopter.
Can HUMS protect us from the majority of accidents? No, because pilot error is the primary cause of accidents. Since helicomparitor rejects safety kit like EGPWS, we cannot blame HUMS when the aircraft he helped equip fly into terrain and the sea.
Wait, perhaps we can improve passenger safety and prevent pilot error. We could program HUMS to check the operator's name on the crew manifest and tell passengers to stay off helicomparitor's poorly equipped helicopters.
The issue as I see it with HUMS on a new aircraft is the lack of a statistical data base. Sikorsky has to collect data to establish a base line for Go / No Go criteria. The difficulty comes with where to establish initial HUMS criteria. If you set the limits too low then you may affect operability while addressing each warnings activation. If you set the limit too high then safety may be compromised as actual component limits may be exceeded. Following the Blackhawk methodology, Sikorsky built the S-92 to a US Army safe-life criteria. Building to these criteria negated any requirement for a HUMS as the robustness designed and built into each component established relatively high component lives i.e. 5000 MGB.
HFDM/HOMP: OK but PHI, Cougar and CHC have had to carry out hardware modifications to the aircraft to enable HFDM, so as I said the aircraft does not support HFDM (out of the box). Any aircraft can be modifed to enable HFDM but that is not the point.
The 225 & 155 come with functional HFDM out of the box.
"E's were being lost left and right due to transmission/swashplate failures and even made "60 Minutes" with a crew chief sending a tape to his mom saying he was afraid of it."
Here is what I believe, after asking a few people who should know, is the actual history:
There was a single 53E in-flight main box failure, while towing, resulting in a water landing and a successful short swim by all of the crew. My source recollects a heat treat issue with a gear in the No. 2 ( center ) engine being the cause.
There were three swashplate overheat failures, the first being the one at Sikorsky during a production test flight and in a high hover, a second in the USMC fleet and a probable third in Japan.
May I observe that sometimes the verbage used in this forum could be on a higher plane. Certainly would tend to keep the quality of discussion at a professional and therefore more useful level.
Just to add a little clarification to some of the issues experienced by the H-53E series. The CH-53E experienced multiple MGB failures early in its development and fielding. Most were due to problems with the number 2 engine bull gear input. One occurred at Stratford resulting in a safe landing on a small light house island in Long Island sound. A second one occurred in a west coast Marine squadron once again resulting in a safe landing. Other numerous in flight chip lights and other impending failure indications occurred with no additional problems.
In addition, the E experienced multiple tail rotor drive train failures resulting from the basic design of the system. Like the S-92 the tail rotor drive train of the 53E runs through a box inside the overhead of the cabin and tail transition. Initially this box did not have sufficient drainage to keep the tail drive shaft bearings clean and dry in heavy rains. On one occasion at Stratford a number two engine fuel leak resulted in the tail rotor drive shaft bearings being submerged in fuel. A second Navy MH experienced a failure after flying through a very heavy rain storm in Norfolk, VA. Neither resulted in the loss of a machine. Additional drain holes and lines were incorporated into the design of the tail rotor drive train structure and a bearing monitor system was added.
The swash plate bearing problems did result in the tragic loss of machines and their crews. One was the result of improper maintenance (lack of proper greasing) and one from a faulty assembly delivered from the vender. I believe that a third remains unknown. The diameter of the 53E swash plate is more than 6 feet at the bearing. At this diameter the bearing race velocities are more than 60 fps. Any impending failure results in a very rapid increase in temperature and further damage. As a result, a bearing monitor system was added to help monitor this.
I hope this clears up a few of the misconceptions concerning this magnificent beast.
I'm just an inquisitive passenger flying from Scatsta out to the North Sea rigs. Yesterday the new S-92 helicopters were grounded because "the atmospheric pressure was very high (>1040mB)".
Could someone please explain why high atmospheric pressure should stop these new choppers flying?
I don't know about the S92s but with 1042hpa in Glasgow yesterday, Dash8-400s have only 8hpa of subscale left before we reach the maximum altimeter setting of 1050hpa. Maybe the manufacturer will have an extremely expensive mod to add another 10hpa
Can't say it's the same reason for the 92, but the EC225's had similar restrictions for high pressure / low temperature due to the forces on the pitch rods(?) to move the blades or something along those lines...
as someone that takes a keen interest in the weather and how it works and its trend - 1050+ will be common within the next 5 years....!!!!! i call it the world cycling itself not global warming - however we have not helped matters thats for sure...!
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Scatsta S-92s grounded due to High Pressure?
Linear Mode
