PPRuNe Forums - Sikorsky S-92: From Design to Operations (2024)

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.

The Crane imposes a life limit on the plates.

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.

HC

Nick,

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!

The Sultan

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.

What, apart from PHI and Cougar you mean? :E

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.

HC

The Sultan wrote:

"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.

Thanks,
John Dixson

Ah, now look what you've gone and done - you've spoilt it all! Why let inconvenient facts get in the way of gossip and misinformation? :E

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?

:confused:

Guess.......engine management/fuelflow or it could just be that the altimeters don't go that high:}

Best Wishes

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:ugh:

sr

It's a fault that affects the earlier mod state AHRSs - they can't process the ADC input and effectively treat the value as 'off scale'. The AHRS feeds the VSI and so in this condition it shows 9999 ft/min RoC.

I'm surprised to hear the fleet was grounded because a) I thought they had the newer AHRS (or at least the latest a/c did) and b) the same thing happened in Norway last December and an operational solution was agreed between the regulator and operators, with SAC input, which I thought the UK operators had adopted too.

It's unrelated to the EC-225 problem which is at the opposite end of the scale - there is a density altitude limit (2000 ft) for take off, which cold and low pressure conditions can produce at low take off elevations.

Ain't technology great!

Considering the usual "Low" weather in that part of the world....it would seem the design engineers decided to allow flight crews a "Sunshine Holiday" when those especially nice days occur.

Quite yer moaning fellas....get out the Sun Screen, Beach Towel, and crank up the barbie!:E

212 - the 225 issue is unrelated as you say, but just to be correct the density altitude restriction was below minus 2000' DA. That was not too hard to reach, eg 1040mb and +5 deg C. Not exactly exceptional! Fortunately it has now been modded out and we can go to -3500', and should be -6000' by next winter.

Can I have my usual tirade about certification at this point? The certifying authorities force manufacturers and anyone else wanting to mod their aircraft, to jump through a seemingly endless sucession of hoops. But at the end of all that, there is no guarantee that the product is safe and robust: vis the S92 AHRS, the 225 flight envelope. You would think that basic testing would include checking the limiting values of a parameter such as pressure altitude.:ugh:

When an error gets through, as it inevitably seems to do, you try fixing it.

"Oh no Sir, you cannot possibly fly that bit of kit without my piece of paper. Without my piece of paper you are doomed to eternal flames. With my piece of paper you are floating on a cloud. Stop moaning that it doesn't actually work. Paper is God, functionality is irrelevant"

Or something like that:rolleyes:

SAS - bear in mind the peak temperature was +5 so more likely crank up the central heating and hit the pub:D

HC

So does this mean that all future S-92s will come complete with a garland of flowers and a picture of Krishna dangling from the power levers...? :E

Low-cost Indian car manufacturer to build S-92 cabin.

I/C