Crashworthy pilot seats
Crashworthy Pilot Seats
I am sure the 225 could do a zero/zero auto at max all up weight provided it never had to fly again!
And provided one could talk some not too bright but very heavily insured pilot into doing it!
The appropriate FAR 29.75 and accompanying Advisory Circular AC 29-2C do not specify a landing speed requirement, and in fact the AC only states that less than 40 KIAS is recommended.
I don't know, HC, whether you have access to an S-92 RFM, but the discussion about flying the aircraft following an inadvertant float deployment, wherein it cites holding the speed to 80 kts and provides information regarding indicated airspeed to follow for climb, level flight and descent/autorotation to achieve a calibrated airspeed of 80 kts, represents actual flight test results. There are no surprises in store here.
And provided one could talk some not too bright but very heavily insured pilot into doing it!
The appropriate FAR 29.75 and accompanying Advisory Circular AC 29-2C do not specify a landing speed requirement, and in fact the AC only states that less than 40 KIAS is recommended.
I don't know, HC, whether you have access to an S-92 RFM, but the discussion about flying the aircraft following an inadvertant float deployment, wherein it cites holding the speed to 80 kts and provides information regarding indicated airspeed to follow for climb, level flight and descent/autorotation to achieve a calibrated airspeed of 80 kts, represents actual flight test results. There are no surprises in store here.
Thread Starter
John
No, I don't have easy access to a 92 rfm but I am curious about the comment on not firing the floats until in the water. Does this apply to power on ditchings as well or just to autorotation landings (or neither)?
Regarding flight speed following deployment, many years ago my captain deployed the floats on a 332L on a platform 280nm from base whilst I was downstairs having a pee (maybe he was bored?) and there was no alternative but to fly it back into a 40 kt headwind (via 3 refuelling stops if memory serves correctly!) and I seem to remember that 80kts was about all we could build up the courage to do, especially as after a while one of the bags started to sag and was flapping alarmingly! The 332 was certified to 135kts for arming and deployment (or was it 130?) but I would not like to be the one testing it!
HC
No, I don't have easy access to a 92 rfm but I am curious about the comment on not firing the floats until in the water. Does this apply to power on ditchings as well or just to autorotation landings (or neither)?
Regarding flight speed following deployment, many years ago my captain deployed the floats on a 332L on a platform 280nm from base whilst I was downstairs having a pee (maybe he was bored?) and there was no alternative but to fly it back into a 40 kt headwind (via 3 refuelling stops if memory serves correctly!) and I seem to remember that 80kts was about all we could build up the courage to do, especially as after a while one of the bags started to sag and was flapping alarmingly! The 332 was certified to 135kts for arming and deployment (or was it 130?) but I would not like to be the one testing it!
HC
The limitation (stated in Part 1 Section 1: Limitations, and repeated in Section 3: Emergency Procedures,) is as follows:
"Deploying the floats in flight is prohibited."
It's pretty clear cut, and even the ditching drills require alighting first before deploying the floats (presumably in case they haven't deployed automatically!)
Personally, if I was carrying out a controlled ditching with power I'd probably pop them first, in the hover. At least if one doesn't inflate you know you are going to roll over!
It would be interesting to know waht pitot static error is present on the 332 (I may have known once but have forgotten). In the event of flight with the floats deployed on the 92, you should fly at no more than 50/55/60 KIAS for climb/cruise/descent, which equates to 80 kts actual IAS. Your 80 kts may have been much higher!
"Deploying the floats in flight is prohibited."
It's pretty clear cut, and even the ditching drills require alighting first before deploying the floats (presumably in case they haven't deployed automatically!)
Personally, if I was carrying out a controlled ditching with power I'd probably pop them first, in the hover. At least if one doesn't inflate you know you are going to roll over!
It would be interesting to know waht pitot static error is present on the 332 (I may have known once but have forgotten). In the event of flight with the floats deployed on the 92, you should fly at no more than 50/55/60 KIAS for climb/cruise/descent, which equates to 80 kts actual IAS. Your 80 kts may have been much higher!
Would posters to this thead comment on the detailed pictures of the recent S350 crash in Germany where two on board suffered spinal injuries.
http://kurier.at/galerie/index/3930/.../chronik/74208
It appears that the seats did not deform, I understood that the rear seat would collapse/deform in a heavy landing.
Is a simple improvement of energy absorbing foam in seats worth considering made law?
While on the topic, looking at these pictures, for the sake of say 40 kilos of a carbon fiber rollbar couldn't the integrity of the cabin of the AS350 be significantly improved?
Mickjoebill
http://kurier.at/galerie/index/3930/.../chronik/74208
It appears that the seats did not deform, I understood that the rear seat would collapse/deform in a heavy landing.
Is a simple improvement of energy absorbing foam in seats worth considering made law?
While on the topic, looking at these pictures, for the sake of say 40 kilos of a carbon fiber rollbar couldn't the integrity of the cabin of the AS350 be significantly improved?
Mickjoebill
Last edited by mickjoebill; 7th May 2007 at 11:34. Reason: tiepoes
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That photo tells a whole story about crashworthiness, which has 4 major constituents:
1) Primary structural integrity - where the fuselage has the basic strength to maintain its shape under an impact from any of the principle directions.
We speak of the passenger/crew compartment keeping its primary shape (like a roll bar helps a car) during crashes of 20 g's vertically or forward, 10 g's laterally and 10 g's upside down. If the compartment does not hold its shape, it will crush the occupants, and stroking seats would be worthless.
2) Passenger and crew seats that allow the bodies to be decelerated smoothly and not injured, even though the strong cage they are in decelerates more quickly. The seat holds the occupant, and descends as the fuselage stops abruptly, thus allowing the person to "feel" less deceleration, and experience less spinal stress.
3) Anti-plowing and anti-rollover protection, so that the fuselage does not dig in and flip/roll but rather slides to a stop. The anti-plowing beams on many helos look like sled skids as the fairings around them crumple. These skids allow the fuselage to skid rather than digging in and causing dangerous flips and rolls.
4) Fuel system bags that both stay whole during the crash, and are not subject to the twisted and deformed metal structure causing punctures. Without crash bags for the fuel, a post crash fire could kill those who otherwise survived.
In these discussions I have tried to tell the story that latest regulations give measurable increases in safety. Note that the 350 is allowed to come apart at 4 g's of crash, while a newer part 27 aircraft has to stay together until 16 g's - newer aircraft are four times stronger, and arguably very much safer.
It is a shame that manufacturers are allowed to continue to sell the older machines as "new" and not tell anyone about this very important reason to look only at more modern machines.
FAR 27.561 (latest):
(3) Each occupant and each item of mass inside the cabin that could injure an occupant is restrained when subjected to the following ultimate inertial load factors relative to the surrounding structure:
(i) Upward—4g.
(ii) Forward—16g.
(iii) Sideward—8g.
(iv) Downward—20g, after intended displacement of the seat device.
(v) Rearward—1.5g.
FAR 27.561 (old version):
(3) The occupant experiences the following ultimate inertia forces relative to the surrounding structure:
(i) Upward--1.5g.
(ii) Forward--4.0g.
(iii) Sideward--2.0g.
(iv) Downward--4.0g, or any lower force that will not be exceeded when the rotorcraft absorbs the landing loads resulting from impact with an ultimate descent velocity of five f.p.s. at design maximum weight.
Roll Bars?
Thanks Nick.
As a back seat AS350 driver I'm aware of the large mass behind rear passengers head that is likely to crush passengers who in some accidents would (by my best guess) otherwise could have survived.
What kind of internal "roll bar" structure would have prevented the rear seat being deformed in the above photo?
I have been musing about some kind of carbon fiber internal framework that would include floor members for seats to be fixed.
This would have a place for those that regularly fly low and only carry 3 or four souls, ie police, inspection, sling and filming work.
It would form a seperate inner shell that could? deflect the engine and gearbox up to a point where G would cause fatal injuries to passengers.
The open nature of the AS350 would enable such a framework to be easily installed.
A cross member would be required from the top rear to the floor.
Having seen incredibly lightweight carbon fiber sections used on F1 I wonder if similar technology could have its part to play to improve crash worthyness of the most popular light utility helicopter.
Reports of last weeks fatal accident of the AS355 in the UK suggest that the aircraft is largly intact with no post crash fire.
Is their a market for this?
Or if one was designing a new heli from the ground up, a self contained F1 style monocock that seperates itself from the heavy metal of engine and gearbox in an accident rather than absorbing their energy?
An idea for the future perhaps?
You dont ask, you dont get...
Mickjoebill
As a back seat AS350 driver I'm aware of the large mass behind rear passengers head that is likely to crush passengers who in some accidents would (by my best guess) otherwise could have survived.
What kind of internal "roll bar" structure would have prevented the rear seat being deformed in the above photo?
I have been musing about some kind of carbon fiber internal framework that would include floor members for seats to be fixed.
This would have a place for those that regularly fly low and only carry 3 or four souls, ie police, inspection, sling and filming work.
It would form a seperate inner shell that could? deflect the engine and gearbox up to a point where G would cause fatal injuries to passengers.
The open nature of the AS350 would enable such a framework to be easily installed.
A cross member would be required from the top rear to the floor.
Having seen incredibly lightweight carbon fiber sections used on F1 I wonder if similar technology could have its part to play to improve crash worthyness of the most popular light utility helicopter.
Reports of last weeks fatal accident of the AS355 in the UK suggest that the aircraft is largly intact with no post crash fire.
Is their a market for this?
Or if one was designing a new heli from the ground up, a self contained F1 style monocock that seperates itself from the heavy metal of engine and gearbox in an accident rather than absorbing their energy?
An idea for the future perhaps?
You dont ask, you dont get...
Mickjoebill
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Tractor_Driver,
Specifically, no, the S-76 family meets older FAR, current when it was designed. I make these observations without ANY bias toward any brand or manufacturer.
How can you tell which of the "new" helos is new? It isn't easy, but it is available as public record in every country but France.
Each helo type design has a "Type Certificate Data Sheet" which gives the basic limits and the "certification basis" which is the EXACT rule that the helo was certified to, listed as the regulation (like FAR 29) and the exact amendment for each paragraph (like 29.561 amendment 16).
Let's be practicle, when you design a helo, you cannot easily "chase" the regs as they get tougher and tougher. So you nail them down when you apply to the FAA/JAA, and both parties agree to the cert basis. The cert basis is usually just the exact FAR 27 or 29 amendment, with perhaps a few newer paragraphs or 'special conditions" that embrace the nature of the helo to be certified. The application cert basis is usually good for 5 years, which means you start a clock on application, and have 5 years to certify or lose the cert basis. (It is said that the EH101 was in real trouble, and had to rush thru a certification because the FAA/CAA were about to close the door and pull the old cert basis!)
The S-76 is designed to FAR 29 amendment 10. The S-92 meets FAR 29, amendment 47. On a web site called "Historical FAR" you can find the exact old paragraphs that the older helos were designed to, that is how I pulled the two crash strength paragraphs that I posted below.
As I have repeatedly said, the S92 and the AB-139 are the only two Part 29 helos that meet the latest FAR/JAR. Period.
Specifically, no, the S-76 family meets older FAR, current when it was designed. I make these observations without ANY bias toward any brand or manufacturer.
How can you tell which of the "new" helos is new? It isn't easy, but it is available as public record in every country but France.
Each helo type design has a "Type Certificate Data Sheet" which gives the basic limits and the "certification basis" which is the EXACT rule that the helo was certified to, listed as the regulation (like FAR 29) and the exact amendment for each paragraph (like 29.561 amendment 16).
Let's be practicle, when you design a helo, you cannot easily "chase" the regs as they get tougher and tougher. So you nail them down when you apply to the FAA/JAA, and both parties agree to the cert basis. The cert basis is usually just the exact FAR 27 or 29 amendment, with perhaps a few newer paragraphs or 'special conditions" that embrace the nature of the helo to be certified. The application cert basis is usually good for 5 years, which means you start a clock on application, and have 5 years to certify or lose the cert basis. (It is said that the EH101 was in real trouble, and had to rush thru a certification because the FAA/CAA were about to close the door and pull the old cert basis!)
The S-76 is designed to FAR 29 amendment 10. The S-92 meets FAR 29, amendment 47. On a web site called "Historical FAR" you can find the exact old paragraphs that the older helos were designed to, that is how I pulled the two crash strength paragraphs that I posted below.
As I have repeatedly said, the S92 and the AB-139 are the only two Part 29 helos that meet the latest FAR/JAR. Period.
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Nick
Glad to see there was no rush by Sikorsky. See http://www.easa.eu.int/doc/Certifica...0Issue%203.pdf
While this does not show the original application date to FAA, that must predate the JAA application date, giving 7.5 years at least (mid 1995 to late 2020).
6. National Certification Date: 17 December 2002
7. JAA (Validation) Application Date: 12 June 1995
8. JAA (Validation) Recommendation Date: 14 May 2004
9. EASA Type Certification Date: 08 June 2004
I heard a rumour though that the FAA certification washed rushed so that when the JAA team visted Sikorsky that the first thing they (in fact Mr KO) could show was the FAA TCDS, even though the S-92 was meant to be the first truely joint simultaneous certification project.
Glad to see there was no rush by Sikorsky. See http://www.easa.eu.int/doc/Certifica...0Issue%203.pdf
While this does not show the original application date to FAA, that must predate the JAA application date, giving 7.5 years at least (mid 1995 to late 2020).
6. National Certification Date: 17 December 2002
7. JAA (Validation) Application Date: 12 June 1995
8. JAA (Validation) Recommendation Date: 14 May 2004
9. EASA Type Certification Date: 08 June 2004
I heard a rumour though that the FAA certification washed rushed so that when the JAA team visted Sikorsky that the first thing they (in fact Mr KO) could show was the FAA TCDS, even though the S-92 was meant to be the first truely joint simultaneous certification project.
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Zalt,
Do I detect some attitude there?
The reason why the cert time was longer than 5 years is because Sikorsky did what the other manufacturers never do - update the certification basis to INCLUDE the FAR/JAR changes that were being made while the aircraft was being designed. In other words, the S-92 met the absolutely latest FAR/JAR the day it was certified. The EASA TCDS doesn't make this obvious, because it lists JAR 29 rev 1, which was the same as FAR 29 rev 45 (the latest as of Dec 2002.)
Rolling the cert basis upward to the newest regs meant designing to draft FAR's, redoing tests as the FAR's matured, and also breaking new ground as to how to meet the FAR, since no cert guidelines were written. The FAA guys were first class, and (while they were tough) they worked many weekends and late nights to approve or mark up cert documents. They also traveled on weekends and holidays to be there when the tests were performed. Since then, the 92 has been certified to rev 47, which is the most current, yet again.
The reason why the 92 did not have a simultaneous FAR/JAR cert is that when it fell behind, I could not have the cert team do double work (I was the Program Manager then). I personally spoke to the JAR team lead and apologized, but we could only spread the team so far. As soon as the FAR cert was finished, we brought the JAR team in and began that work. The JAR guys were similarly gentlemanly and worked hard to be sure they did not hold the schedule up.
BTW, I also believe the 139 was certified to the latest FAR/JAR, but I am too lazy to look it up tonight.
Do I detect some attitude there?
The reason why the cert time was longer than 5 years is because Sikorsky did what the other manufacturers never do - update the certification basis to INCLUDE the FAR/JAR changes that were being made while the aircraft was being designed. In other words, the S-92 met the absolutely latest FAR/JAR the day it was certified. The EASA TCDS doesn't make this obvious, because it lists JAR 29 rev 1, which was the same as FAR 29 rev 45 (the latest as of Dec 2002.)
Rolling the cert basis upward to the newest regs meant designing to draft FAR's, redoing tests as the FAR's matured, and also breaking new ground as to how to meet the FAR, since no cert guidelines were written. The FAA guys were first class, and (while they were tough) they worked many weekends and late nights to approve or mark up cert documents. They also traveled on weekends and holidays to be there when the tests were performed. Since then, the 92 has been certified to rev 47, which is the most current, yet again.
The reason why the 92 did not have a simultaneous FAR/JAR cert is that when it fell behind, I could not have the cert team do double work (I was the Program Manager then). I personally spoke to the JAR team lead and apologized, but we could only spread the team so far. As soon as the FAR cert was finished, we brought the JAR team in and began that work. The JAR guys were similarly gentlemanly and worked hard to be sure they did not hold the schedule up.
BTW, I also believe the 139 was certified to the latest FAR/JAR, but I am too lazy to look it up tonight.
Last edited by NickLappos; 8th May 2007 at 04:28.
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Nick,
Thank you for that clarification. But if there are only 2 helicopters that meet current regulations, isn’t it just a little premature to proclaim:
“It is a shame that manufacturers are allowed to continue to sell the older machines as "new" and not tell anyone about this very important reason to look only at more modern machines.”
especially in red ink!
I sometimes wonder whether our regulators are really doing us favours by insisting on a “zero risk” approach on certain parameters which leads to very long lead times and huge expense for any progress, which in turn means that we have to fly with ancient technology. We all know that the $300 sat nav that we buy at radio shack is far more reliable and accurate that the $30,000 kit on our instrument panel but it hasn’t been through the approval process and we are not allowed to use it.
The automotive industry moves so much faster. Now we all have highly efficient small, agile, turbo diesel powered vehicles, we have difficulty imagining using 5.7 litre V8 trucks with flatbeds the size of tennis courts and cart springs to bring the groceries home from Wallmart. Well. we do on this side of the pond anyway.
Thank you for that clarification. But if there are only 2 helicopters that meet current regulations, isn’t it just a little premature to proclaim:
“It is a shame that manufacturers are allowed to continue to sell the older machines as "new" and not tell anyone about this very important reason to look only at more modern machines.”
especially in red ink!
I sometimes wonder whether our regulators are really doing us favours by insisting on a “zero risk” approach on certain parameters which leads to very long lead times and huge expense for any progress, which in turn means that we have to fly with ancient technology. We all know that the $300 sat nav that we buy at radio shack is far more reliable and accurate that the $30,000 kit on our instrument panel but it hasn’t been through the approval process and we are not allowed to use it.
The automotive industry moves so much faster. Now we all have highly efficient small, agile, turbo diesel powered vehicles, we have difficulty imagining using 5.7 litre V8 trucks with flatbeds the size of tennis courts and cart springs to bring the groceries home from Wallmart. Well. we do on this side of the pond anyway.
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Tractor,
You raise a very valid point! The problem is a chicken and egg thing....if the comparatively knowledgeable pilot community doesn't know this stuff, how can they lead their bosses/backers to buy the good stuff? If they don't buy the good stuff, then why would anyone stop making the old stuff? If all we have is old stuff, then there will be many more broken backs and post crash fires, and our market will stay small because the public knows that helicopters are dangerous!
Seriously, I misspoke when I said only two helos meet the new criteria, I think several Part 27 smaller helos meet the newest standards, also.
You raise a very valid point! The problem is a chicken and egg thing....if the comparatively knowledgeable pilot community doesn't know this stuff, how can they lead their bosses/backers to buy the good stuff? If they don't buy the good stuff, then why would anyone stop making the old stuff? If all we have is old stuff, then there will be many more broken backs and post crash fires, and our market will stay small because the public knows that helicopters are dangerous!
Seriously, I misspoke when I said only two helos meet the new criteria, I think several Part 27 smaller helos meet the newest standards, also.
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An FAA inspector found an unapproved shoulder harness on a airplane I was working on with the owner. The inspector said " get the installation approved or remove the shoulder harness, your choice."
The owner removed the shoulder harness in order to make the aircraft "airworthy". True story.
If I was the FAA inspector in this case, I would have helped the owner get the existing belts approved.
The FAA should "help" all owners retrofit crashworthy seats and other improvements, but the FAA rules sometimes impede safety.
I share your frustration Tractor Driver.
The owner removed the shoulder harness in order to make the aircraft "airworthy". True story.
If I was the FAA inspector in this case, I would have helped the owner get the existing belts approved.
The FAA should "help" all owners retrofit crashworthy seats and other improvements, but the FAA rules sometimes impede safety.
I share your frustration Tractor Driver.
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Originally Posted by MickJoeBill
I have been musing about some kind of carbon fiber internal framework that would include floor members for seats to be fixed.
This would have a place for those that regularly fly low and only carry 3 or four souls, ie police, inspection, sling and filming work.
It would form a seperate inner shell that could? deflect the engine and gearbox up to a point where G would cause fatal injuries to passengers.
The open nature of the AS350 would enable such a framework to be easily installed.
A cross member would be required from the top rear to the floor.
This would have a place for those that regularly fly low and only carry 3 or four souls, ie police, inspection, sling and filming work.
It would form a seperate inner shell that could? deflect the engine and gearbox up to a point where G would cause fatal injuries to passengers.
The open nature of the AS350 would enable such a framework to be easily installed.
A cross member would be required from the top rear to the floor.
Mart
