I remember someone here but a week ago told me that 777 has a very high wing loading. Sorry, I don't remember who that clever man was. And then I found this:
https://youtu.be/RGsz_toWM5A

The guy in the video talks way too much about redundancy and keeping the wing extended in flight, etc, etc. To be quite honest, I've never even thought about it before I saw this. But now I have a question. Will it fall if the windtip folds in flight? Or, to put it in scientific terms, will uncommanded windtip folding cause a catastrophic loss of control? I mean, we all know how well Boeing designs its airplanes. Rudder hardovers on 747-400 (was it a Northwest flight?), rudder hardovers on numerous 737 (which, by the way, Boeing still denies and hasn't fixed, last time I heard), etc, etc, etc. So I'm a bit curious about this folding wing thing. Can it fly with the wingtip folded?

Wouldn't that be mandatory by the regulators?

Makes me remember of this incident:

To answer that question correctly, you'll need to consult with the litterature Boeing submitted to the FAA/EASA in order to certify the folding wingtips. That litterature will tell which level of fail redundancy/fail safe mode has been incorporated into the design. My guess is it's a fail safe construction, i.e. the wingtips are no more susceptible to uncommanded folding than the wing is to break off. If it's certified with as fail redundancy, Boeing will have proved an uncommanded fail at the most inoppertune moment will not result in a loss of control situtation.

Having said that, I'm not a fan. First and foremost, having to incorporate such a solution tells me the basic wing is not fully up to the job, and the folding wingtips have been added to solve a set of particular issues with the basic wing.

Do you test for a gear down even at cruise speed? Or un-commanded spoiler deployment? The mechanism is fail safe, because it needs to power to fold, without the wingtip locks in the extended position.

I'll just emphasize the essense of this question. I'm NOT asking if it CAN happen. It can. There is no such thing as "fail-safe". I'm curious about what happens if it does. Can it fly with wingtips folded? Actually I'll add a bonus question. Can it fly with ONE wingtip folded?

B777LRF wrote:

Having said that, I'm not a fan. First and foremost, having to incorporate such a solution tells me the basic wing is not fully up to the job, and the folding wingtips have been added to solve a set of particular issues with the basic wing.

Sorry, but that's pure ignorance. The folding mechanism exists for *gate spacing.* It has nothing to do with flight profile.

First of all, this aircraft will have a LARGER wing, but the same MTOW, as the 773ER... so obviously the wing is more than up to par, even without wingtip devices.

Second, Boeing has already publicly addressed this issue... the aircraft will be fully capable of all phases of flight at maximum weight, should the wingtips fail, even if one fails when the other doesn't.

Third, have you even seen the design? The specs are already widely available.
Only the very tips of the wing fold. Even when folded, it's less of a percentage of the wingspan than the blended wingtip on a 763ER. Doesn't interfere with flight.

In laymans terms I assume an upfolded wing tip to effectively act like a winglet in many ways.

seahawk wrote:

Do you test for a gear down even at cruise speed? Or un-commanded spoiler deployment? The mechanism is fail safe, because it needs to power to fold, without the wingtip locks in the extended position.

747 needs power to actuate the cargo door locking mechanism. Yet, you had one instance of uncommanded actuation which resulted in fatality.

I would not say "fail safe because it needs no power".

I think a more significant concern would be what happens if a flap breaks off. You would have some serious asymmetric lift conditions there. Yet we seem to have managed 60 years of jet-airliner operation without a significant number of flap separations (I'm sure someone will dig one accident out to prove the point now). If they can manage to keep flaps attached, which when you look carefully at them appear to be rather precarious, then I have every confidence they'll be able to keep the folding wing tips attached too. Any potential issue is more likely to be one of the retract/extend mechanism not operating when commanded, but since this command will be on the ground, it isn't so much a safety of flight issue as a dispatch reliability one.

V/F

Dutchy wrote:

Wouldn't that be mandatory by the regulators?

As it is not a common design feature it will be probably be addressed as a special condition.

BREECH wrote:

I mean, we all know how well Boeing designs its airplanes. Rudder hardovers on 747-400 (was it a Northwest flight?), rudder hardovers on numerous 737 (which, by the way, Boeing still denies and hasn't fixed, last time I heard), etc, etc, etc. So I'm a bit curious about this folding wing thing. Can it fly with the wingtip folded?

How "well Boeing designs its airplanes"? Every machine made by humans has flaws no matter if its you your lawn mover, laptop or a 100$ million airliner. There have been design flaws in other designs as well that caused accidents or serious incidents. The manufacturer has to prove to the certifying authority that the design is in compliance with the applicable rules (which also include maximum allowable probabilities for minor/major/hazardous/catastrophic failure modes) - this does not mean that the aircraft ist 100% fault free, but that it offers an acceptable level of safety (which is very high nowadays). Risk management is not about totally avoiding an accident, because this is definitely not possible but to reduce the chance of an accident to an acceptable level.
Boeing will have to prove to the authority that either the chance of an uncommanded wing folding is extremely improbable, i.e. less than 1x10^-9/flight hour or that this failure mode is not catastrophic, i.e. does not preclude continued safe flight and landing. LAX772LR mentioned that Boeing decided to go the second way here, i.e. to prove that this failure mode is not catastrophic.
(I fly Airbus aircraft for a living, but I don't think that current and future Boeing aircraft are any less safe than any other certified aircraft that is flying today - they are certified to the same standard as anything else...the difference between Boeing/Airbus/other manufacturers is not on the safety level but on the economy/comfort etc level)

fsabo wrote:

seahawk wrote:

Do you test for a gear down even at cruise speed? Or un-commanded spoiler deployment? The mechanism is fail safe, because it needs to power to fold, without the wingtip locks in the extended position.

747 needs power to actuate the cargo door locking mechanism. Yet, you had one instance of uncommanded actuation which resulted in fatality.

I would not say "fail safe because it needs no power".

And we had fatal accidents due to spoilers or thrust reversers deploying uncommanded, still nobody demands an airliner to show that it can be flying in that condition. In the it is not rocket science to design the locking mechanism so that it can not unlock under the loads experienced during flight.

The technology has already been explained long ago.

http://aviationweek.com/new-civil-aircr ... ng-wingtip

The original design of the 777 back in the early 90s had a folding wing option.

Bobloblaw wrote:

The original design of the 777 back in the early 90s had a folding wing option.

That was a much more substantial fold as moveable surfaces were beyond the folding point.

This is a much smaller change and I suspect it will even if it failed at a critical time have a much smaller potential impact on flight characteristics.

seahawk wrote:

fsabo wrote:

seahawk wrote:

Do you test for a gear down even at cruise speed? Or un-commanded spoiler deployment? The mechanism is fail safe, because it needs to power to fold, without the wingtip locks in the extended position.

747 needs power to actuate the cargo door locking mechanism. Yet, you had one instance of uncommanded actuation which resulted in fatality.

I would not say "fail safe because it needs no power".

And we had fatal accidents due to spoilers or thrust reversers deploying uncommanded, still nobody demands an airliner to show that it can be flying in that condition. In the it is not rocket science to design the locking mechanism so that it can not unlock under the loads experienced during flight.

The technology has already been explained long ago.

http://aviationweek.com/new-civil-aircr ... ng-wingtip

I didn't say that there is anything inherently unsafe about folding tips or boeing's design. I just said that "needs power to actuate" does not mean it is automatically failsafe.

AFAIK it can even fly with both wingtips taken off. (But not with just one).

Noshow wrote:

AFAIK it can even fly with both wingtips taken off. (But not with just one).

I think that is despatched with both removed. It will fly with one missing.

seahawk wrote:

Do you test for a gear down even at cruise speed? Or un-commanded spoiler deployment? The mechanism is fail safe, because it needs to power to fold, without the wingtip locks in the extended position.

One, I don't think no power means fail-safe. More on that in a reply above. Two, there is quite a lot of pressure being applied on the folding mechanism in flight, and the mechanism acts as a weak link. And three, it's one thing if it has no power at all, and very different if the power is turned off. Because it can be turned on at the computer's command. Side thought, if a computer gives a wrong command, does it still count as uncommanded?

I am pretty sure that if you rip of one or both folding wing ends during the flight, the 777-8/9 will safely fly on and land safely somewhere.

I do not understand this discussion creeping up again.

VirginFlyer wrote:

I think a more significant concern would be what happens if a flap breaks off. You would have some serious asymmetric lift conditions there.

I may be wrong, but can't you just actuate the opposite flap to counteract the asymmetric lift? I'm also no sure flaps participate in the lift, but I may be wrong there, too. Gosh, I may be SO wrong in the end!

Flow2706 wrote:

Risk management is not about totally avoiding an accident, because this is definitely not possible but to reduce the chance of an accident to an acceptable level.

In theory yes. In reality, risk management is the probability of an accident times out-of-court settlements. If that figure is below the profit, the chance of accident is always acceptable.

BREECH wrote:

There is no such thing as "fail-safe".

Clearly not an engineer... Fail-safe is a very well-defined technical term which applies to parts of almost all aerospace products.

SomebodyInTLS wrote:

Clearly not an engineer...

Hmmm... engineers designed Space Shuttle Challenger and Columbia, the Titanic, the train that crashed in Eschede, and that Boeing 747 cargo door that opened in flight and took the life of a 20-year-old kid. You were saying?

BREECH wrote:

SomebodyInTLS wrote:

Clearly not an engineer...

Hmmm... engineers designed Space Shuttle Challenger and Columbia, the Titanic, the train that crashed in Eschede, and that Boeing 747 cargo door that opened in flight and took the life of a 20-year-old kid. You were saying?

They also designed your car, your microwave oven, the computer or phone you are using to write that post. Your obtuse point being...?

BREECH wrote:

seahawk wrote:

Do you test for a gear down even at cruise speed? Or un-commanded spoiler deployment? The mechanism is fail safe, because it needs to power to fold, without the wingtip locks in the extended position.

One, I don't think no power means fail-safe. More on that in a reply above. Two, there is quite a lot of pressure being applied on the folding mechanism in flight, and the mechanism acts as a weak link. And three, it's one thing if it has no power at all, and very different if the power is turned off. Because it can be turned on at the computer's command. Side thought, if a computer gives a wrong command, does it still count as uncommanded?

No, it is fail safe as it requires 2 conditions to be met. The wing needs to be unloaded and you need power to unlock the mechanism and move the wing.

Bobloblaw wrote:

The original design of the 777 back in the early 90s had a folding wing option.

didn't even progress beyond that glossy offer. No trail in 777 certifications.

BREECH wrote:

VirginFlyer wrote:

I think a more significant concern would be what happens if a flap breaks off. You would have some serious asymmetric lift conditions there.

I may be wrong, but can't you just actuate the opposite flap to counteract the asymmetric lift? I'm also no sure flaps participate in the lift, but I may be wrong there, too. Gosh, I may be SO wrong in the end!

You can't actuate individual flaps, at least not from cockpit controls.

Flaps very much participate in lift. Altering the lift profile of the wing is the whole point of flaps.

Navy Fighter/Attack aircraft and USAF F-4s all had/have folding wings for decades. The few that have folded in flight (and some fatal to the crew) were not locked down before takeoff due to ground crew screwups or aircrew failure to check 'down and locked' or erronous cockpit indications (I think only one).

As far as I know, none failed during normal high G loading or during normal flight after they were down and locked. There are isolated instances (3 or 4) where unlocked wings folded on T/O symmetrically, and the crew were able to land the aircraft albeit high speed with cable engagements. No reason to doubt that Boeing will make this feature absolutely safe.

seahawk wrote:

No, it is fail safe as it requires 2 conditions to be met. The wing needs to be unloaded and you need power to unlock the mechanism and move the wing.

The wingtip folds upward, which is exactly how the forces push on it. So it can fold in that direction without power and under load. And any locking mechanism can unlock by itself. Again, the Boeing 747 cargo door. It was locked but it turned out that the locking mechanism was badly designed.

RetiredWeasel wrote:

Navy Fighter/Attack aircraft and USAF F-4s all had/have folding wings for decades. The few that have folded in flight (and some fatal to the crew) were not locked down before takeoff due to ground crew screwups or aircrew failure to check 'down and locked' or erronous cockpit indications (I think only one).

As far as I know, none failed during normal high G loading or during normal flight after they were down and locked. There are isolated instances (3 or 4) where unlocked wings folded on T/O symmetrically, and the crew were able to land the aircraft albeit high speed with cable engagements. No reason to doubt that Boeing will make this feature absolutely safe.

Navy mechanics and ground crews only have what?... 80-90 planes to service. At a busy airport they have thousands. So where is the guarantee the same screwups or erroneous cockpit indications won't happen with civilian aircraft which, by the way, fly A LOT more than any military one can ever dream of.

BREECH wrote:

seahawk wrote:

No, it is fail safe as it requires 2 conditions to be met. The wing needs to be unloaded and you need power to unlock the mechanism and move the wing.

The wingtip folds upward, which is exactly how the forces push on it. So it can fold in that direction without power and under load. And any locking mechanism can unlock by itself. Again, the Boeing 747 cargo door. It was locked but it turned out that the locking mechanism was badly designed.

You need to differentiate between the locking mechanism and the folding mechanism. The important part is the locking mechanism. The latch pins for the locking mechanism can only be moved when applying power and when the wing experiences no load. That is why it is called a double locking mechanism, which is considered fail safe.

BREECH wrote:

RetiredWeasel wrote:

Navy Fighter/Attack aircraft and USAF F-4s all had/have folding wings for decades. The few that have folded in flight (and some fatal to the crew) were not locked down before takeoff due to ground crew screwups or aircrew failure to check 'down and locked' or erronous cockpit indications (I think only one).

As far as I know, none failed during normal high G loading or during normal flight after they were down and locked. There are isolated instances (3 or 4) where unlocked wings folded on T/O symmetrically, and the crew were able to land the aircraft albeit high speed with cable engagements. No reason to doubt that Boeing will make this feature absolutely safe.

Navy mechanics and ground crews only have what?... 80-90 planes to service. At a busy airport they have thousands. So where is the guarantee the same screwups or erroneous cockpit indications won't happen with civilian aircraft which, by the way, fly A LOT more than any military one can ever dream of.

You're concern in your opening post is valid. You're continuing posts indicate some sort of 'fear' that this feature is unsafe. If this mechanism comes to fruition, it will be just as safe as reverse thrust, flaps, flight controls, gear, pressurization, auto-flight etc that are susceptible to malfunctions and vital to safe flight. No reason to 'invent' scenarios that dozens of Boeing engineers have thought through extensively. I would have no worries.

BREECH wrote:

I'll just emphasize the essense of this question. I'm NOT asking if it CAN happen. It can. There is no such thing as "fail-safe". I'm curious about what happens if it does. Can it fly with wingtips folded? Actually I'll add a bonus question. Can it fly with ONE wingtip folded?

Hi Breech, “Fail Safe” is an aeronautic terminology. And yes, it exist.
It does not means that some item wil not fail ever.
What it means is that is an Item fail, it will no cause an accident.

For instance, engine’s Fan Blade fail and depart de Rotor. Fail Safe system (in this case, containment ring around Fan/LP Compressor) should be designed in a way that the blade will lost most of the energy when hitting it and do not penetrate the fuselage nor the wing straucture.

There are many examples of fail safe design, like, for example, wing structure that should be built in a way that a crack will be contained by a member of the wing structure, stringer, or other, till next check in which this area should be checked and crack should be detected and repaired., Or You have o/b 3 VHF System, powered by different electrical buses, totally independently in a way that even if You have only Battery power, at leat one VHF and one HF system will be operative.

Rgds

Hi: I had no time to look ar Folding System Schematics, but I,m sure it has:
1. A good / duplicate indication system
2. A safe blocking mechanism that allows it to be energized only on ground.
3. A manual Lock system

Which this properties, if a/c on parking spot will have a warning of malfunction, or a message of lack of power or similar, 200% sure, that Boeing had incorporated a subsystem to extend it manually and lock, secure for next flight and for some small period of time, till MEL need to be closed while solving the problem.
Sames applies for any other Manufacturer.-Authority.

Rgds

Breech,

I suggest you not leave your bedroom with so little faith in modern design. The 737 rudder was fixed years ago and retrofitted to all planes. If you don’t fly Boeing’s, why do you think Airbus is so much safer? After all, they’ve had their failures.

GF

BREECH wrote:

Flow2706 wrote:

Risk management is not about totally avoiding an accident, because this is definitely not possible but to reduce the chance of an accident to an acceptable level.

In theory yes. In reality, risk management is the probability of an accident times out-of-court settlements. If that figure is below the profit, the chance of accident is always acceptable.

The defined figure is 1x10^-9. The manufacturers needed to do a lot of analyses (fault tree etc etc) before the authority certifies the aircraft. Of course in the end its all about costs. But are you seriously suggesting the Boeing risks a huge financial loss just to save a few bucks on that design? If there was an unsafe design feature that was known by the manufacturer that causes an accident the costs for the manufacturer would be extrem (lawsuits, loss of image etc etc - its not only the "direct" costs of the accident, but also lost orders due to image loss etc). Therefore they are playing by the rules.
And I do not see why you are trying to convince everybody that this specific design feature is unsafe - as I said I fly Airbus and I personally think that it is the better design, but from the safety point of view there is no difference (all certified aircraft are very safe nowadays). If you don't believe me check the accident statistics. Airbus also has flaws - one example is the undue Alpha protection activation incident that happened a few years ago (there was an red OEB issued about it as well later on). This could well have caused a serious accident if it happened in different circumstances (f.e. at a lower altitude). As others have mentioned failures in other design features of aircraft can also have catastrophic consequences - but the design is robust enough (f.e. through redundancy) to reduce these probabilities below the mentioned threshold (1x10^-9).

GalaxyFlyer wrote:

Breech,

I suggest you not leave your bedroom with so little faith in modern design. The 737 rudder was fixed years ago and retrofitted to all planes. If you don’t fly Boeing’s, why do you think Airbus is so much safer? After all, they’ve had their failures.

GF

Exactly. BREECH is being a drama queen. Boeing and Airbus are equally as safe. Not sure why he's being so paranoid about this wing-tip folding.

Dutchy wrote:

Wouldn't that be mandatory by the regulators?

Makes me remember of this incident:

That’s a stunning picture


How that F8 became airborne with next to no wing remaining with most of it folded is hard to believe

Every post made in this thread by BREECH just gets more and more annoying. What in the world is your issue against Boeing? and even more so why are you so worked up over a folding wingtip?!?
No offense, but some of the things you said in your posts indicate you have fairly minimal knowledge of aircraft, yet you are being so critical over Boeing.

Dear Breech, at least I think you learned from this thread what "fail safe" means.

It is engineering terminology. It means that a certain failure shall not be possible to happen as a consequence of a single other failure. It shall only be able to happen following multiple unrelated other failures.

I am sure Boeing made the tip folding fail safe, but I don't know how they did it.

But it could be that:
1. Folding is not possible when tip is loaded.
2. Folding is not possible when airspeed is greater than, say, 50 mph.

That would be fail safe. But still the tips could be folded in flight, if the pilot was doing a parabolic zero-G maneuver (like astronaut training), and at the same time all airspeed indication failed. Still it would qualify for the term fail safe. If that's not good enough, then the manufacturer can add more conditions, for instance:
3. Folding is only possible when landing gear is extended.
4. Folding is only possible when wheels are loaded.
5. Etc.

I really dont see much difference between this wingtip and like the one found on the 764ER and 77W. The actual mechanism to connect this to the aircraft has been proven to work in much high loads like carrier aircraft.

The locking mechanism I have seen on carrier aircraft tended to be a pin through lugs, I understand what has been said able about the locking mechanism only being able to work when the wing is unloaded and has power to it. Will this be a symmetrical feature, for example if there is a problem on one side will the other side mirror it ?

I would think if the extension were to float up in flight it would go to a position between horizontal and vertical thus never being totally unsymmetrical, anyone have some thoughts on this ?

Does anyone know if the CDL/DDG will permit the dispatch of the aircraft with the extension removed from one side like we see wingtips these days ?

Max Q wrote:

Dutchy wrote:

Wouldn't that be mandatory by the regulators?

Makes me remember of this incident:

That’s a stunning picture


How that F8 became airborne with next to no wing remaining with most of it folded is hard to believe

Wings are overrated: https://theaviationist.com/2014/09/15/f ... -one-wing/

RetiredWeasel wrote:

You're concern in your opening post is valid. You're continuing posts indicate some sort of 'fear' that this feature is unsafe.

I disagree. His posts don't indicate concern or fear, his posts indicate that he's a troll. Please stop feeding him.

cerealspiller wrote:

Wings are overrated: https://theaviationist.com/2014/09/15/f ... -one-wing/

There is a history channel documentary on YouTube about Ziv Nadivi landing his F15 jet after losing the right wing after a mid air collision.

[quote=

Does anyone know if the CDL/DDG will permit the dispatch of the aircraft with the extension removed from one side like we see wingtips these days ?[/quote]

Hi: I don’t think so, apples versus tomatoes!


Should You remove a tip of B777 alone, there will be uncomanded (uncontrolled?) roll to side were tip were removed. In my opinion, what should be allowed to deactivate it’s just the mechanism, It is a good question, time to look for MEL/CDL

Rgds

You fly around without the wingtip on the 744.

Zeke, with all due respect, again comparing Apples with....

“Thera is a history channel documentary on YouTube about Ziv Nadivi landing his F15 jet after losing the right wing after a mid air collision.”

Here We are talking about another kind of plane, with different Thrust/Weight relationship and with a PILOT onboard.

Rgds

Apprentice wrote:

Here We are talking about another kind of plane, with different Thrust/Weight relationship and with a PILOT onboard.

That is like saying civil mechanics are not real mechanics.

zeke wrote:

I really dont see much difference between this wingtip and like the one found on the 764ER and 77W. The actual mechanism to connect this to the aircraft has been proven to work in much high loads like carrier aircraft.

The locking mechanism I have seen on carrier aircraft tended to be a pin through lugs, I understand what has been said able about the locking mechanism only being able to work when the wing is unloaded and has power to it. Will this be a symmetrical feature, for example if there is a problem on one side will the other side mirror it ?

I would think if the extension were to float up in flight it would go to a position between horizontal and vertical thus never being totally unsymmetrical, anyone have some thoughts on this ?

Does anyone know if the CDL/DDG will permit the dispatch of the aircraft with the extension removed from one side like we see wingtips these days ?

Way to soon for that kind of data. If the wing tips are not down and locked, you will get a EICAS message and at this hour at least, there is no Non Normal checklist for the wing fold failures.

I think it would be well advanced and already presented to the FAA