Sikorsky S-92: From Design to Operations
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Not dissappointed at all Nick! I admire how much hard work you have put in to the S92. Lighten up! Just asking questions to clarify rumours that are going around, in the true spirit of PPRUNE. I thought your initial "tired old" snide remark should not go unresponded to though.
As a matter of fact I believe the entire EC225/725 production is sold out for several years anyway. The S92 order book is a credit to Mr Lappos! The dollar/euro situation is certainly going to be to the S92's advantage.
I will take your failure to mention the blade shedding safety advantage of the 225 as a point to EC.
Thank you for the assurance that you are not aware of any engine problem delaying the Norsk aircraft.
As a matter of fact I believe the entire EC225/725 production is sold out for several years anyway. The S92 order book is a credit to Mr Lappos! The dollar/euro situation is certainly going to be to the S92's advantage.
I will take your failure to mention the blade shedding safety advantage of the 225 as a point to EC.
Thank you for the assurance that you are not aware of any engine problem delaying the Norsk aircraft.
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We have not had any problems with our -8 engines and very few with our -2A's in our 214ST's. We did replace the EECU's in aircraft #6 for a software upgrade. Support from GE, Hamilton Sundstrand and Sikorsky has been outstanding. Reflex, do you know Robbie Robinson near London?
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vertalop,
Touche on the "tired old" I started the snit, I agree. Sorry!
For ppruners, regarding blade shed on an engine, what vertalop refers to is the fact that newer aircraft must be protected from a bursting engine (turbine burst) which can cut shafts and controls causing vast safety problems. The latest makila engine is designed to theoretically not burst, and tested to high overspeeds, where it tosses its blades before the disk bursts, a demonstration of the most likely disk burst scenario. This allows the EC 225 to pack vital components next to the engines, anyway, so the basic airframe on the 225 is vulnerable to a turbine burst, but the engine is certified to not burst. IMHO, the ability to withstand a turbine burst by basic airframe design is a much stronger solution, thus I would believe the point might go to the S-92, but buyers will decide.
Touche on the "tired old" I started the snit, I agree. Sorry!
For ppruners, regarding blade shed on an engine, what vertalop refers to is the fact that newer aircraft must be protected from a bursting engine (turbine burst) which can cut shafts and controls causing vast safety problems. The latest makila engine is designed to theoretically not burst, and tested to high overspeeds, where it tosses its blades before the disk bursts, a demonstration of the most likely disk burst scenario. This allows the EC 225 to pack vital components next to the engines, anyway, so the basic airframe on the 225 is vulnerable to a turbine burst, but the engine is certified to not burst. IMHO, the ability to withstand a turbine burst by basic airframe design is a much stronger solution, thus I would believe the point might go to the S-92, but buyers will decide.
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Nick, your gentlemanly qualities are showing through that hard salesman exterior!
I believe I am right in saying that when we climb aboard a Boeing or an Airbus we are protected from turbine burst by compressor blade shedding technology in most cases. The idea certainly seems to have been accepted as the way to go by our fixed wing cousins.
Have a nice day y'all!
I believe I am right in saying that when we climb aboard a Boeing or an Airbus we are protected from turbine burst by compressor blade shedding technology in most cases. The idea certainly seems to have been accepted as the way to go by our fixed wing cousins.
Have a nice day y'all!
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vertalop,
Actually not. The turbine burst protection is gained mostly by working the physical geometry of the engine installation, such as the placement of the pods, which are carefully packaged to place the burst zones away from hydraulics, spars and the like. The old wing-root packaging (Comet) and tail mounts (B 727) are now gone. In fact, it was an L-1011 burst that caused the change in FAR. Recall how that third engine was packaged. No blade shed excuse would work on that machine.
The packaging of critical control rods next to engines, along with primary servos and the close proximity of a sister engine would be frowned upon in that airliner world, but are accepted when grandfathering an older helicopter.
Actually not. The turbine burst protection is gained mostly by working the physical geometry of the engine installation, such as the placement of the pods, which are carefully packaged to place the burst zones away from hydraulics, spars and the like. The old wing-root packaging (Comet) and tail mounts (B 727) are now gone. In fact, it was an L-1011 burst that caused the change in FAR. Recall how that third engine was packaged. No blade shed excuse would work on that machine.
The packaging of critical control rods next to engines, along with primary servos and the close proximity of a sister engine would be frowned upon in that airliner world, but are accepted when grandfathering an older helicopter.
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Take a look at Advisory Circular 20-128A it shows methods of compliance for rotor burst (admittedly for Part 23 / 25 airframes). Basically the burst zones are defined by fragment size and cone angle from the disk centroid +/- 3, 5 and 15 degrees with fragment size going from a third of a hub down to blade fragments. Each Part 33 engine is certified to contain blades but the necessary shielding to contain a tri-hub failure would normally preclude the airframe from flight. I believe Allied Signal / Honeywell looked at ballistic shielding for the ill fated Ayres Loadmaster beastie, where two T800's were in close proximity to each other.
The AC shows a method of compliance based around system redundancy, sytem placement and total enery of the fragments, not sure how it would work in a Part 27 / 29 installation with so many critical systems in such a small space.
"Tangling turbines" (to shed blades during a shaft shear event and stop overspeed) are not a new idea and designed in to at least two engines I can think of but not sure if they have ever been proven "in battle". It is definately an energy "thing" since smaller APU's per TSO C77 are commonly certified to contain a tri-hub failure and actually do a burst test to prove it - dynamic computational modelling is getting very close in it's predictions though.
To Nick's comment regarding an L1011 burst, I thought it was a DC10 at Sioux City (?) that pushed changes into new design but the tri-jet is alive and well at Dassault!!
Vive la differance ??
The AC shows a method of compliance based around system redundancy, sytem placement and total enery of the fragments, not sure how it would work in a Part 27 / 29 installation with so many critical systems in such a small space.
"Tangling turbines" (to shed blades during a shaft shear event and stop overspeed) are not a new idea and designed in to at least two engines I can think of but not sure if they have ever been proven "in battle". It is definately an energy "thing" since smaller APU's per TSO C77 are commonly certified to contain a tri-hub failure and actually do a burst test to prove it - dynamic computational modelling is getting very close in it's predictions though.
To Nick's comment regarding an L1011 burst, I thought it was a DC10 at Sioux City (?) that pushed changes into new design but the tri-jet is alive and well at Dassault!!
Vive la differance ??
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PT6er,
You are right, it was a DC-10, still a tri-jet with the engine buried in critical systems.
Thanks for your clarification about the PT 25 airframe rules (slightly different for 29, but same derivation).
You are right, it was a DC-10, still a tri-jet with the engine buried in critical systems.
Thanks for your clarification about the PT 25 airframe rules (slightly different for 29, but same derivation).
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I understand that the EC225 Makila 2A was certified following an actual burst test during which the engine was oversped following a simulated drive-shaft failure. No debris escaped the engine casing.
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It was not a burst test, it was an overspeed. The underlying premise is that the engine only bursts when oversped (an assumption not borne out by history but accepted by the French). The EC 225 airframe is not capable of protecting its vital systems from a true burst.
As far as I can find out, ALL engines must be certified to stay together and not burst, at least those currently flying (FAR 33.75 and .77). In FAR, the ability of the Aircraft to withstand the burst is not tied to the ability of the engine to not burst. To explain that the engine demonstraton satisfies the airframe requirement is another example of grandfathering the latest regs, I think.
As far as I can find out, ALL engines must be certified to stay together and not burst, at least those currently flying (FAR 33.75 and .77). In FAR, the ability of the Aircraft to withstand the burst is not tied to the ability of the engine to not burst. To explain that the engine demonstraton satisfies the airframe requirement is another example of grandfathering the latest regs, I think.
Last edited by NickLappos; 22nd Dec 2004 at 08:13.
Makila Turbine Burst v CT7 Turbine Burst
If Turbomeca have come up with a casing that will hold a turbine burst ,I would be supprised ! Iwas in Norway when the engine on a AS332 L1 exploded ,the first engine blew into the second engine which blew as well and cut through the 3 main flightcontrol rods under the number 2 eng and thru the fwd suspention bar the A/C never had a chance, the problem was caused by a Xmsn vibration , leading to shaft failure takingout the overspeed protection an BAM! The Makila is an old design engine which keeps getting stretched , I put it in the same class as the CT58, it is read drive with a short PT shaft which is hard to balance, and hard to put O/S control on, The AS 332 i think is only one generation ahead of the S61 and although a very good A/C can not be put in the same group technicaly as a Blackhawk let alone a S92. The 2 latter Sikorsky A/C with the CT7 series fitted have widely spaced engines with with little chance of a catostrauphic of one engine taking out the other, or any main flightcontrols, only T/R rrive and T/R control cable are at risk.
The CT7 is a front drive engine with a long P/T shaft which is much easier to balance and install O/speed protection on, basicly the CT 7 series is about 20 years ahead of the Makila series and are not in the same class.
P.S. sorry about the spelling i left my dictionary at work!!
The CT7 is a front drive engine with a long P/T shaft which is much easier to balance and install O/speed protection on, basicly the CT 7 series is about 20 years ahead of the Makila series and are not in the same class.
P.S. sorry about the spelling i left my dictionary at work!!
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OK I'm not a technically minded pilot like Nick!
The Makila 2A is protected from overspeed by dual FADEC and an additional back-up system. If all these fail and the engine still overspeeds the compressor blades shed. In the test the engine was oversped until the compressor blades shed. (No compressor blades: no more acceleration.) Nothing escaped the casing. This fully satisfied the EASA. This is thought by some clever people to be a worthwhile safety feature, but, it would appear, not by others. Fine! I guess they won't be using it in the future.
Happy Christmas all!
The Makila 2A is protected from overspeed by dual FADEC and an additional back-up system. If all these fail and the engine still overspeeds the compressor blades shed. In the test the engine was oversped until the compressor blades shed. (No compressor blades: no more acceleration.) Nothing escaped the casing. This fully satisfied the EASA. This is thought by some clever people to be a worthwhile safety feature, but, it would appear, not by others. Fine! I guess they won't be using it in the future.
Happy Christmas all!
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vertalop,
You are talking about overspeed. That is fine. We are talking about bursting, a subject that is quite different. A turbine can burst when struck with debris, or from an oil system failure, or from a manufacturing flaw, or when a missile is shoved up the engine's ...exhaust.
The lack of airframe protection against burst is the subject, and a magic engine that doesn't overspeed is a partial answer.
PS You brought it up.
You are talking about overspeed. That is fine. We are talking about bursting, a subject that is quite different. A turbine can burst when struck with debris, or from an oil system failure, or from a manufacturing flaw, or when a missile is shoved up the engine's ...exhaust.
The lack of airframe protection against burst is the subject, and a magic engine that doesn't overspeed is a partial answer.
PS You brought it up.
Last edited by NickLappos; 22nd Dec 2004 at 15:34.
Thanks Nick...you beat me to the keyboard....I have been hearing overspeed only....and there are lots of other ways for the things to come apart....that is commonsense thinking.
It seems the French fix to problems is through grand-fathering or obtaining cover by certification waivers or something. The Puma series always was an interesting setup with everything important stuck right overhead the pilots and all right together.
It seems the French fix to problems is through grand-fathering or obtaining cover by certification waivers or something. The Puma series always was an interesting setup with everything important stuck right overhead the pilots and all right together.
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First S92 at ENZV
Not a rotorhead, but......
A little bird (ok, I found it on the web!) tells me that the first S-92A for Norsk Helikopter arrived at Stavanger Sola via An-124 on friday.
Link in Norwegian
A little bird (ok, I found it on the web!) tells me that the first S-92A for Norsk Helikopter arrived at Stavanger Sola via An-124 on friday.
Link in Norwegian
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I'm glad to see they got theirs! Nice looking paint job. The Sikorsky factory pilot I've been working with is headed over to their location to help with training flight crews.
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rjsquirrel, We've had a few small problems, but nothing really unexpected for a first production aircraft. Support from Sikorsky has been outstanding, the pilots can't wipe the grins off of their faces and the pax love it.