WIederling wrote:

waly777 wrote:

I would assume the lighter weight of the 737NG vs the 320 is due to the narrower fuselage, not grandfathering. What standards exactly were changed?

MTOW difference is 79t vs 78t.

IMU some "achieved height above runway" at the end of the runway
and initial climb (all one engine out, requires more installed thrust).
Cabin g forces : 9g --> ?14?g,
But new seating has to be 14g certified. mixing a 9g fuselage with ?14?g seats.
( again IMU the broken up fuselage of the AMS TK 737 crash could be indicative here.)

I believe STIM would have been referring to empty weights.

Do you have evidence to prove the 737NG cabin isn't certified to 14g standards? I'm genuinely curious as i haven't seen anything outside "anet facts" to suggest this was the case.

Surely this applies to the a330/340 developed from the a300 fuselage as well?

WIederling wrote:

The "inch" is defined as exactly 25.4 mm ( i.e. metric system derived unit.)
So if you convert 1 inch to metric you get 25.4 mm, no rounding or excess resolution necessary .

I hadn't really thought about it but it's true that the current inch is actually a metric unit. Ha ha ha! Based on Napoleon's thumb wasn't it? (Historically it used to be rather loosely defined but was supposed to be based on Julius Caesar's thumb if I recall correctly.) Fun fact: an inch is called a "duim" (thumb) in Dutch.

.... except for the US "survey inch" being defined as
3937 survey inch = 100 m
1 survey inch = 100⁄3937 m ≈ 25,4000508 mm

Yeah, because that makes it much easier to use, right?

seabosdca wrote:

Quoting tortugamon (Thread starter):-EK also says "the 8x is as popular as the 9x in our planning"
   Like Lightsaber, I would really like to know what the mouth of EK actually means by this...

It probably means that their Route planners se just a much advantage in the 8X as the 9X, The only Question is?
Will the Aircraft's Cost be offset by potential generated profits? All things being equal?
The 9x might be the better airplane if the paperwork comes back even..

waly777 wrote:

BoeingVista wrote:

travelhound wrote:

Don't ever think grandfathering is some form of cheating. It is a legitimate practice , as the best form of testing is done in the real world!

No, its cheating as grandfathering allows derivitives to be certified to a lower safety standard than a new design.

In what way exactly does grandfathering exit limits compromise safety by certification to a lower standard? Or do you have other examples of grandfathering that show this?

AFAIK, derivatives are tested just rigorously as new designs for safety... though new designs like the 787 (electrics) and 380 (size) do bring in additional testing challenges.

The 747 bubble is probably the most obvious. The 747-8i does not require an emergency exit forward of seating up in the bubble section as it was grandfathered in, as well as in the 747 nose section.

There was also an issue with the British CAA concerning the wiring on the 747-400 when BA was introducing the aircraft. The CAA wanted the wiring from the cockpit relocating, and after some arguing they eventually certified the aircraft using grandfathering from the 747-200 which was demonstrated to be safely installed.

Channex757 wrote:

waly777 wrote:

BoeingVista wrote:

No, its cheating as grandfathering allows derivitives to be certified to a lower safety standard than a new design.

In what way exactly does grandfathering exit limits compromise safety by certification to a lower standard? Or do you have other examples of grandfathering that show this?

AFAIK, derivatives are tested just rigorously as new designs for safety... though new designs like the 787 (electrics) and 380 (size) do bring in additional testing challenges.

The 747 bubble is probably the most obvious. The 747-8i does not require an emergency exit forward of seating up in the bubble section as it was grandfathered in, as well as in the 747 nose section.

Ah thanks, I knew a good chunk of the 747 design was grandfathered through the generations. I imagine exit limit capacity or distance wasn't reached for a new exit to be required.

There was also an issue with the British CAA concerning the wiring on the 747-400 when BA was introducing the aircraft. The CAA wanted the wiring from the cockpit relocating, and after some arguing they eventually certified the aircraft using grandfathering from the 747-200 which was demonstrated to be safely installed.

Thanks again, excellent examples. Doesn't seem either of those were certified to lower standards than the safety standard in place today. I seriously doubt the FAA or CAA etc would accept to certify designs not meeting current safety standards.

But the exits clearly do not conform to current standards. You must always have two ways to go in an emergency. Sit in the nose of a 747 or near the cockpit in the bubble and you only have one way to get out. So if it wasn't grandfathered it would not have been certifiable.

The point of grandfathering is that you can demonstrate to the certifying authorities that an existing design is safe by pointing to considerable operational experience. New aircraft will need to be built to the latest standards, but ones built under grandfathering are demonstrably safe thanks to millions of hours of usage (and are just updated versions of existing aircraft anyway).

To go back to the CAA issue, they were actually stating that they thought the 744 was different enough to require serious modification to the wiring designs. It related to where the cockpit wiring was located. Boeing and BA argued that the 744 was an updated version of the 747-200 and therefore didn't need this hugely expensive rework. Their argument was accepted and the design grandfathered in based on that and all the data of 747-200 operations.

waly777 wrote:

Do you have evidence to prove the 737NG cabin isn't certified to 14g standards? I'm genuinely curious as i haven't seen anything outside "anet facts" to suggest this was the case.

Surely this applies to the a330/340 developed from the a300 fuselage as well?

IMU the change was in the 70ties. More or less preceeding the A320 introduction.

A330/A340 do not grandfather on the A300 certification.

In context this might be of interest:
http://lessonslearned.faa.gov/ll_main.c ... LLTypeID=2

WIederling wrote:

waly777 wrote:

Do you have evidence to prove the 737NG cabin isn't certified to 14g standards? I'm genuinely curious as i haven't seen anything outside "anet facts" to suggest this was the case.

Surely this applies to the a330/340 developed from the a300 fuselage as well?

IMU the change was in the 70ties. More or less preceeding the A320 introduction.

A330/A340 do not grandfather on the A300 certification.

In context this might be of interest:
http://lessonslearned.faa.gov/ll_main.c ... LLTypeID=2

You might want to read the posted article, the 16G rule had everything to do with the seats and not the airframe. In addition this was a 737 classic and not an NG. An NG would have beem required to meet the new standards as it was certified after the new rule.

How is the A330/a340 not granfathered on the A300? It's history dates back to being derivatives of the A300 with modifications and addition of FBW introduced on the 320.

waly777 wrote:

How is the A330/a340 not granfathered on the A300? It's history dates back to being derivatives of the A300 with modifications and addition of FBW introduced on the 320.

Just because an aircraft uses developments of technologies on existing aircraft that does NOT mean it is grandfathered!

To be grandfathered means that it is classed as a variant of THE SAME AIRCRAFT. So it's certification is an extension of the existing certification where you just do some additional proof for the CHANGES you make.

You can't say to the authorities that the A330 is actually an A300 in disguise - and you absolutely can not call an A340 an A320 XL in order to grandfather the FBW certification.

What you can do is roll-out an "all new" Fokker F100 which is actually registered as a Fokker F28 Mk 0100...

And for the record, Exit Limit certification leveraging is not unique to Boeing. The A350 was required to only perform a new Evacuation Test from Doors 1 and 3 because Airbus switched from a double escape slide to a single. They did not need to test evacuation via Door 2 and Door 4 because they use the same door type and escape slide type as the A330 and therefore could leverage the A330's Evacuation test. If Airbus had not made the slide changes, they would not have had to perform an Evacuation Test at all as they would have been allowed to use the A330's test to prove they could evacuate the plane (as they both max out at 440 seats).

SomebodyInTLS wrote:

waly777 wrote:

How is the A330/a340 not granfathered on the A300? It's history dates back to being derivatives of the A300 with modifications and addition of FBW introduced on the 320.

Just because an aircraft uses developments of technologies on existing aircraft that does NOT mean it is grandfathered!

To be grandfathered means that it is classed as a variant of THE SAME AIRCRAFT. So it's certification is an extension of the existing certification where you just do some additional proof for the CHANGES you make.

You can't say to the authorities that the A330 is actually an A300 in disguise - and you absolutely can not call an A340 an A320 XL in order to grandfather the FBW certification.

What you can do is roll-out an "all new" Fokker F100 which is actually registered as a Fokker F28 Mk 0100...

If I remember correctly, the vertical stabiliser, rudder were carried over from the A300-600 to the 330/340 and they all use the same fuselages with varying lengths of course. That is a bit more than development of technologies.

Surely some design standards were grandfathered as I imagine Airbus would also like to save costs and time like any other manufacturer.

Ah looks like stitch already mentioned this.

Channex757 wrote:

The point of grandfathering is that you can demonstrate to the certifying authorities that an existing design is safe by pointing to considerable operational experience. New aircraft will need to be built to the latest standards, but ones built under grandfathering are demonstrably safe thanks to millions of hours of usage (and are just updated versions of existing aircraft anyway).

The two major OEM's have exercised excessive influence in respect to grandfathering, something other OEM's view as a barrier to entry.

Taking the 737 and A320 cabins as examples, whether the numbers are correct or not, if 16g is THE standard, and new models of this family are certified post-dating the 16g standard, then generous grandfathering exists.

Grandfathering came about to protect owners of earlier-build aircraft, ships and buildings having to retrospectively comply with new standards. It's Airbus and Boeing that persuaded/lobbied authorities to grandfather new models, something incidentally that is not permitted in most countries in respect to constructing ships and buildings.

waly777 wrote:

Spinning the question around i not an answer, I assume my question was clear. Give examples of grandfathering that show lower standard is accepted. Exit limit is a common example and clearly this does not compromise safety or a lower standard.

I believe 737 exit slides are grandfathered both in its intitial arming and not being floatation devices, clearly this is a safety issue

Also 737 benefits from V1 decision "thinking time" of 1 sec verses A320 2 sec [ammendment 25-42] this is clearly safety related as it could lead to overrun accidents and artificially massages 737 take off performance.

747-8 first class seating has already been mentioned; there are lots of examples of grandfathering leading to less stringent safety standards.

Planesmart wrote:

Grandfathering came about to protect owners of earlier-build aircraft, ships and buildings having to retrospectively comply with new standards. It's Airbus and Boeing that persuaded/lobbied authorities to grandfather new models, something incidentally that is not permitted in most countries in respect to constructing ships and buildings.

We are talking about grandfathering a new model from an old certification. ( not about having to drag your old design forward to new requirements.)

In the "going overboard" domain this seems to be limited to Boeing. 737 jurassic, classic, ng, max all live on the same certification baseline from the 60ties. Next big attention catcher will be the revamped 777 that again keeps the center wingbox to make it "just another little 777 model change.

waly777 wrote:

Surely some design standards were grandfathered as I imagine Airbus would also like to save costs and time like any other manufacturer.

Ah looks like stitch already mentioned this.

But there is a difference between using prior art as part of your certification justification (in this case similarity between exit doors of A350 and A330) and grandfathering. Actual grandfathering, as I understand the term should be used, is ONLY applied when 1) you are heavily redeveloping an existing airframe and 2) you are complying to older standards which would not be valid for a new airframe.

All the justification examples you use are not grandfathering.

Is there any evidence that grandfathered planes are not a safe is newer models? So far as I know, there is not. Safety is the same, and grandfathering is not an issue.

frmrCapCadet wrote:

Is there any evidence that grandfathered planes are not a safe is newer models? So far as I know, there is not. Safety is the same, and grandfathering is not an issue.

I would say that a grandfathered aircraft *is* less safe, but nevertheless has been operationally proven to be *safe enough* for now.

There's little question that you're in more danger in a fire in the very front of a 747 than you would be in any modern aircraft with doors in both directions, but it turns out that the 747 doesn't burst into flames every hundred flights, so you're probably okay.

If safety is the same why were the changes implemented.

I suggest the easiest one to look at is the exit door layout on the 747-8. There must at some point have been an accident investigation that identified that one of the major items was the inability to get out due to only one route to an exit. The regulations then changed to ensure that for all new frames that must be the case.

Thus is must be that there is a slightly higher risk to you if you sit in the nose of the 747-8.

Would I worry - hell no flying up there is great and quiet. My favourite location.

SomebodyInTLS wrote:

frmrCapCadet wrote:

Is there any evidence that grandfathered planes are not a safe is newer models? So far as I know, there is not. Safety is the same, and grandfathering is not an issue.

I would say that a grandfathered aircraft *is* less safe, but nevertheless has been operationally proven to be *safe enough* for now.

There's little question that you're in more danger in a fire in the very front of a 747 than you would be in any modern aircraft with doors in both directions, but it turns out that the 747 doesn't burst into flames every hundred flights, so you're probably okay.

One could also argue the other direction. An aircraft model that has been been in use since the 1960's has flown many more miles, had many more of its flaws exposed (and thus fixed), and is therefore safer than a newer model. It's possible that there's a catastrophic design flaw in the 787, A350, 777X, etc. that is rare enough it hasn't been exposed yet.

Put another way, an older aircraft has much fewer unknown issues, but more known ones.

I don't see it as grandfathered aircraft being less safe. I see it as clean-sheet models being more safe. A 777X certified to the same standards as a 772 in 1995 is not less safe - it's just as safe (if not safer).

How often do we hear about a 747 (of any type) having flight control issues? Not often! It is the newer aircraft that have these issues.

As such, there are many factors that determine "how safe" an aircraft is. Grandfathering would just be one piece in the statistical puzzle!

If it is a huge issue the FAA/EASA are free to reject the grandfathering by creative methods. Being grandfathered from the 737 Jurassic/Classic wasn't enough to prevent Boeing from having to change the overwing exit doors for the NG (to a design that is probably safer/better than the A320's! ) at I believe the insistence of the JAA who would only certify the plane at the current passenger counts with the new doors.

Both Boeing and Airbus benefit tremendously from grandfathering though, so of course neither is going to rock the boat and try and stop it.

StTim wrote:

If safety is the same why were the changes implemented.

I suggest the easiest one to look at is the exit door layout on the 747-8. There must at some point have been an accident investigation that identified that one of the major items was the inability to get out due to only one route to an exit. The regulations then changed to ensure that for all new frames that must be the case.

I've watched hundreds of air crash video investigations and none of those have shown the above to be an issue. If the door was required as per today's standard, it would have been installed as a requirement. The post of the overwing exit doors on the 737NG is an indicator of this.

SomebodyInTLS wrote:

waly777 wrote:

Surely some design standards were grandfathered as I imagine Airbus would also like to save costs and time like any other manufacturer.

Ah looks like stitch already mentioned this.

Actual grandfathering, as I understand the term should be used, is ONLY applied when 1) you are heavily redeveloping an existing airframe and 2) you are complying to older standards which would not be valid for a new airframe.

All the justification examples you use are not grandfathering.

No offence but this sounds made up by you, but fair enough if that's how you understand it. Grandfathering is simply the exemption of someone or something from a new law or regulation. In the case of aviation, this would be because the previous design has proven to be safe. The a350 leveraging the a330 exit limit experience is most certainly grandfathering and that term is not limited to an aircraft family.

Grandfathering is not unique to aviation and you are welcome to research this.

BoeingVista wrote:

waly777 wrote:

Spinning the question around i not an answer, I assume my question was clear. Give examples of grandfathering that show lower standard is accepted. Exit limit is a common example and clearly this does not compromise safety or a lower standard.

I believe 737 exit slides are grandfathered both in its intitial arming and not being floatation devices, clearly this is a safety issue

This is untrue, the NG slides are floatation devices and ditching in water requires the slides to be disarmed on the NG at least.

Also 737 benefits from V1 decision "thinking time" of 1 sec verses A320 2 sec [ammendment 25-42] this is clearly safety related as it could lead to overrun accidents and artificially massages 737 take off performance.

747-8 first class seating has already been mentioned; there are lots of examples of grandfathering leading to less stringent safety standards.

I don't know about the 737 vs 320 V1 decision, pilots would know better.

If the 747-8 exit limit on the upper deck was an issue, it wouldn't need to be grandfathered..... 747 operations over decades have proven it's not needed or any less safe by current standards without an extra exit.

waly777 wrote:

Grandfathering is not unique to aviation and you are welcome to research this.

Grandfathering is not unique to commercial aviation. For example, it's common for a ship or building constructed in 1990, to be grandfathered to the applicable maritime or construction regulations current in 1990 (or when approval was granted), exempt from new rules being retrospectively applied.

In such examples, grandfathering can be lost. For example if modifications proposed are deemed to be significant.

What is unique to aviation, is the ability to design a new aircraft model, incorporating grandfathered conditions applicable to earlier models, equivalent to an architect wanting to build an identical building next to the 1990 constructed building today, to 1990 standards, using grandfathering arguments.

Grandfathering has become incredibly fragmented, to the point a 2017 build aircraft, is a composite of components and sub-structures from differing standards and dates. Could there me incompatibilities between such interconnections that haven't been fully explored, and are weak links?

Grandfathering is incredibly valuable, both in time and dollars, to Airbus and Boeing. So valuable, they each employ a team of engineers and lobbyists, many recruited from airworthiness authorities, to counter / pre-empt arguments put forward by airworthiness authorities.

There was (may still be) a loose alliance of other commercial aircraft manufacturers, including representatives from Russia, China, and Japan, that had dialogue with airworthiness authorities and WTO, to limit / abolish grandfathering, which creates artificial trade barriers and costs to clean sheet designs versus those with grandfathering.

This group also lobbied the insurance and finance industries to view grandfathered commercial aircraft as higher risk. There will only need to be one major accident where grandfathering is in part or totally attributable (or grandfathering mix and match), for premiums and funding costs adjusted to adjusted to bring the practice into line with other industries.

DoctorVenkman wrote:

SomebodyInTLS wrote:

frmrCapCadet wrote:

Is there any evidence that grandfathered planes are not a safe is newer models? So far as I know, there is not. Safety is the same, and grandfathering is not an issue.

I would say that a grandfathered aircraft *is* less safe, but nevertheless has been operationally proven to be *safe enough* for now.

There's little question that you're in more danger in a fire in the very front of a 747 than you would be in any modern aircraft with doors in both directions, but it turns out that the 747 doesn't burst into flames every hundred flights, so you're probably okay.

One could also argue the other direction. An aircraft model that has been been in use since the 1960's has flown many more miles, had many more of its flaws exposed (and thus fixed), and is therefore safer than a newer model. It's possible that there's a catastrophic design flaw in the 787, A350, 777X, etc. that is rare enough it hasn't been exposed yet.

Put another way, an older aircraft has much fewer unknown issues, but more known ones.

But that doesn't change the fact that in most cases if the old design complied to newer standards, it would be even more safe... That is what I was trying to say.

The 747 nose exit question is the best illustration of this. You can't deny that - despite proven to be safe - it would still be safer if you could bail out somewhere else when there's a fire near door 1...

waly777 wrote:

SomebodyInTLS wrote:

Actual grandfathering, as I understand the term should be used, is ONLY applied when 1) you are heavily redeveloping an existing airframe and 2) you are complying to older standards which would not be valid for a new airframe.

No offence but this sounds made up by you, but fair enough if that's how you understand it. Grandfathering is simply the exemption of someone or something from a new law or regulation.

I was willing to agree to disagree - but a quick search online supports my definition:

"The arrangement under which later derivatives of an initial aircraft type design can be manufactured under variations to the original Type Certificate thereby avoiding the more complex procedures involved in gaining approval under a completely new Type Certificate."

http://www.skybrary.aero/index.php/Grandfather_Rights

I still firmly believe that grandfathering for any manufacturer should be allowed, subject to a reasonable operational safety review. In the case of the 737, there is an existing body of evidence of countless cycles and flight hours that demonstrates that the design is fundamentally safe. While there have been a few issues over the years, all have been correctable items in line production and for units in use. That being the case, I see no reason to force an aircraft manufacturer to make a major change to a platform to address a situation that just doesn't come up in the real world.

An example where I would heavily restrict grandfather in is the MD-11 and it's noted issues with landing. Given how few were made, how few of cycles that they have flown relative to production numbers, and it's comparatively high landing mishap rate including total hull loss numbers, the statistics point to a fundamental design issue that has resulted in below industry average safety numbers. It's still a statistically safe plane, but it definitely lags other frames in that area. That is a situation where I, if I was a regulating authority, would require some significant changes before allowing a new derivative to go forward.

LightningZ71 wrote:

An example where I would heavily restrict grandfather in is the MD-11 and it's noted issues with landing. Given how few were made, how few of cycles that they have flown relative to production numbers, and it's comparatively high landing mishap rate including total hull loss numbers, the statistics point to a fundamental design issue that has resulted in below industry average safety numbers. It's still a statistically safe plane, but it definitely lags other frames in that area.

IIRC one of the MD-11's biggest issues is its rather small horizontal stabilizers. That is not a problem with grandfathering, as MD actually did reduce the size of the horizontal stabilizers compared to the DC-10.

Agreed, however, if MD/Boeing were to decide to make a derivative Md-12 for example, I would refuse to allow that same horizontal stabilizer setup to be grandfathered and require significant changes.

LightningZ71 wrote:

Agreed, however, if MD/Boeing were to decide to make a derivative Md-12 for example, I would refuse to allow that same horizontal stabilizer setup to be grandfathered and require significant changes.

I believe it stands to reason that if the MD-11-X was going into design and production today, even without input from certification authorities the horizontal stabilizer would be redesigned to give it a larger surface area to correct the flaws and increase the plane's appeal to customers.

Stitch wrote:

LightningZ71 wrote:

Agreed, however, if MD/Boeing were to decide to make a derivative Md-12 for example, I would refuse to allow that same horizontal stabilizer setup to be grandfathered and require significant changes.

I believe it stands to reason that if the MD-11-X was going into design and production today, even without input from certification authorities the horizontal stabilizer would be redesigned to give it a larger surface area to correct the flaws and increase the plane's appeal to customers.

The horizontal stabilizer on the 787-9 is larger than the one on the 787-8. As such, I'd suggest Boeings internal engineering standards would be robust enough to not allow a situation like the MD-11 happening again!

I highly doubt there will be an MD-12. An aircraft of that size need not be a tri-jet these days - it will be a twin. And there are many twins available already!

LOL, I didn't mean to imply that such a beast would ever see the light of day. I was just using that one frame as an example of my point. I would believe that Boeing is reviving the 727 using biz jet engines before I'd ever even consider the possibility of an MD-11 derivative...

So long as we can have proper window blinds please? Not only can the cabin crew lock me out of control and make me sit in darkness all afternoon, I can't even pull the shade half down to block direct sunlight whilst retaining ambient daylight to read.

Technically, grandfathering in changes isn't cheating, since it is definitely playing by the rules. If anybody has a problem with the concept, it should be with the rules themselves, and the agencies which enforce the rules, not the companies that follow the rules.

GE commenced GE9X certification tests.

GE Testing For Boeing 777X Engine Moves Into High Gear

KarelXWB wrote:

GE commenced GE9X certification tests.

GE Testing For Boeing 777X Engine Moves Into High Gear

Indeed. The part I found interesting was:

SETT, also known as GE9X test engine 002/1, is the first to incorporate all the design changes from lessons learned during validation runs of the first engine. One of the primary results was a change to the nozzle, or throat, area between the outlet from the HP turbine into the inlet of the low-pressure (LP) turbine. Alterations to the geometry of the HP turbine nozzle exit, the turbine’s pinch point, are key to setting the operating line of the compressor, turbine and fan.

Although Jackson describes the differences between FETT and SETT as “minor tweaks,” any modifications here are therefore pivotal to hitting, or missing, GE’s efficiency goals for the GE9X, which are guaranteed to be 10% better than that of the GE90-115B on the current 777. “The good news is everything we can tell from the measurements so far is that the SETT is right where we want it to be for flow function and operability,” he says.

Glad to read that things are on track. It was also interesting to read about the monster pylon they're making so this can fit on a 747 testbed.

I was wondering how things were going, good to hear some positive news about engines these days...

KarelXWB wrote:

GE commenced GE9X certification tests.

GE Testing For Boeing 777X Engine Moves Into High Gear

Great news for the 777X program!

How far away are we from a rollout? 12-15 months?

waly777 wrote:

No offence but this sounds made up by you, but fair enough if that's how you understand it. Grandfathering is simply the exemption of someone or something from a new law or regulation. In the case of aviation, this would be because the previous design has proven to be safe. The a350 leveraging the a330 exit limit experience is most certainly grandfathering and that term is not limited to an aircraft family.

Grandfathering is not unique to aviation and you are welcome to research this.

Grandfathering is when the same type certificate data sheet is amended with the new model. For example if you look at the 747 TCDS for the 747-400 it says "Certification Basis: Part 25 of the FAR, effective February 1, 1965, as amended by Amendments 25-1 through 25-59 with the following exceptions", that is not when it was certified.

The A330 (1996 certification basis) was not grandfathered from the A300 (1974 certification basis), it was a totally new TCDS. The A340 (1998 certification basis) also has a totally different TCDS to the A300 and A330.

The A350 emergency evacuation certification was not grandfathering, FAR § 25.803 states "Compliance with this requirement must be shown by actual demonstration using the test criteria outlined in appendix J of this part unless the Administrator finds that a combination of analysis and testing will provide data equivalent to that which would be obtained by actual demonstration." The A350 did partial evacuation test (doors 1&3), and they were able to use analysis to obtain data that satisfied the regulator for the whole aircraft. It is only logical to show that if the A330/A340 could evacuate 440 passengers with 4 type A doors, the A350 also could also. The A350 is certified for 440 passengers, the same as other aircraft with 4 type a doors.

waly777 wrote:

The a350 leveraging the a330 exit limit experience is most certainly grandfathering and that term is not limited to an aircraft family.

The A350 performed evacuation tests in XFW.

travelhound wrote:

The horizontal stabilizer on the 787-9 is larger than the one on the 787-8. As such, I'd suggest Boeings internal engineering standards would be robust enough to not allow a situation like the MD-11 happening again!

That would imply the stabilizer on the 787-8 to be to small. As the 787-9 is the longer frame, the horizontal stabilizer should be rather bigger on the 787-8, as it works on the shorter arm. So if the internal engineering standards would than be robust enough, it should have led to upsizing the horizontal stabilizer on the 787-8 the moment the stabilizer on the 787-9 was upsized.

I think the that actually the 787-8 and the 787-9 have the same size, the change was in regards on how they are manufactured.

mjoelnir wrote:

That would imply the stabilizer on the 787-8 to be to small. As the 787-9 is the longer frame, the horizontal stabilizer should be rather bigger on the 787-8, as it works on the shorter arm.

Moment is the operational concept, not just moment arm.
Horizontal stabilizer balances the wing's rotational moment, which might be greater at critical sizing conditions for the -9 than for the -8 due to higher weights (thus more lift, thus more rotational moment from wing).

...not sure which Hstab is bigger, too lazy to look up ACAP. Boeing might have designed a commonly-dimensioned Hstab sufficient for both planes even if optimal for neither.

KarelXWB wrote:

waly777 wrote:

The a350 leveraging the a330 exit limit experience is most certainly grandfathering and that term is not limited to an aircraft family.

The A350 performed evacuation tests in XFW.

It's okay, I'm not sure why one would try to argue against people who work on this topic but it's over now. No need to keep on pressing the point...

Matt6461 wrote:

mjoelnir wrote:

That would imply the stabilizer on the 787-8 to be to small. As the 787-9 is the longer frame, the horizontal stabilizer should be rather bigger on the 787-8, as it works on the shorter arm.

Moment is the operational concept, not just moment arm.
Horizontal stabilizer balances the wing's rotational moment, which might be greater at critical sizing conditions for the -9 than for the -8 due to higher weights (thus more lift, thus more rotational moment from wing).

...not sure which Hstab is bigger, too lazy to look up ACAP. Boeing might have designed a commonly-dimensioned Hstab sufficient for both planes even if optimal for neither.

As we are talking also about the same wing I am ready to believe the lazy from you. Anyway I checked and they are all the same size -8 -9 and -10.

Anyway if you can show me one example of an increased size of the horizontal stabilizer needed for a stretch of a frame!?

KarelXWB wrote:

waly777 wrote:

The a350 leveraging the a330 exit limit experience is most certainly grandfathering and that term is not limited to an aircraft family.

The A350 performed evacuation tests in XFW.

As zeke noted, it was for Doors 1 and 3 only and was required by Airbus changing the type of escape slide as used on the A330 (single lane as opposed to dual lane) used on those two door sets. If they had stayed with the original dual-lane slides on all four doors, they would not have needed the test as they could have leveraged (which I understand is different from grandfathering so I am not arguing that ) the A330's evacuation test (as Boeing did with the 767 for the 787 - also a case of not grandfathering in practice ).

Look I don't know what role the A330 played in the A350 evacuation certification, the exit limit is 110 passengers per type A door just like any other widebody, it is not special to the A330. The A330 uses single lane slides and dual lane life rafts at door 3 (we have both types in out fleet) so I don't know if that post is factual. From what I understand most of the slide certification was done at Zodiac facility in NJ, USA.