Flight Test And Limits Options

[UnderTow]

I found this interesting quote the other day. While wondering what the true limits of a 757 is I realized the only place we may find them is in the Boeing archive of flight tests. No normal flight will do. And the normal Flight Manual are also not going to say what the real Max is imho.

Still, in their more dramatic moments, flight tests aren't for the faint of heart.

Testing and certifying an airplane involves pushing it into what Phil Condit, general manager of the 757 program, calls "far corners" - performance situations one hopes an airplane will never have to encounter in actual service.

Far corners can be terrifying to the uninitiated.

A 757 cruises with maximum fuel efficiency at 80 percent of the speed of sound, or mach .8. Its maximum intended speed is mach .86. But Boeing pressed the airplane to mach .92 in flight testing. A far corner.

Such flights, said Rick Lentz, 757 flight-test aero-analysis lead engineer, "can be frightening, because the plane responds with buffeting. The tail assembly is groaning and wings are flapping - and until you've been through this a few times, you're not sure it will hold together."

Also, in relation to the DreamLiner wing snap video is this quote

The 757 test happened last July 16. Enormous pressures were applied to a 757 airframe inside a hangar. The wings were bent upwards ... first two feet ... then five ... eight ... 10 ... At 11 feet, 6 inches of deflection, both wings snapped.

"It's like loading a bridge," Condit said. "You just keep loading it until the thing finally goes 'kaboom!' That's exactly the sound it makes. I felt it in my knees. I don't know if that was the excitement or the boom"

The results were pleasing, because the airplane proved 12 percent stronger than engineering estimates, and because, in a tribute to Boeing engineering and quality control, both wings failed at the same place and at almost the same moment-just 14 thousandths of a second apart.

Source Article is here:
http://seattletimes.nwsource.com/news/business/757/part05/

[UnderTow]

Another

Consider, for instance, the plane's inertial-reference unit, a device made by Honeywell that uses a trio of lasers to perform navigational feats which in older planes were performed, less precisely, by a gyroscope.

The IRU, as it is called, keeps track of the 757's vertical and horizontal accelerations and decelerations, and by adding and subtracting is able to deduce the altitude and location of the plane. The IRU is so sensitive that it detects the effects of wind and displays wind speed and direction on a cockpit video screen.

[amazed!]

I wonder if they still even use Inertial Navigation? That's old stuff.

[UnderTow]

Well, unless someone wants to argue about a later upgrade work order because something better then 3 lasers was developed.

Every 757 that rolled out of Boeing has this IRU system.

[amazed!]

I don't know if "better" is the right word, but GPS is at least as accurate as Inertial Nav in the enroute portion, and there are GPS approaches that are common around the country. To my knowledge, they never did get any approaches approved for Inertial systems.

The Inertial systems were very demanding of the flight crew, and the maintenance was fairly high. GPS doesn't have those problems.

I would be surprised if they are still installed on production aircraft, but it could be.

This post has been edited by amazed!: Oct 5 2007, 09:48 AM

[UnderTow]

Well, here you go.

The purpose of this document is to provide an overview of the navigation capabilities of a 757/767 upgraded with the addition of a MMR with the GPS function, an updated FANS 1 FMC and EICAS.  The navigation capabilities described are expected to be FAA part 25 certified in the fourth quarter of 1997.  This document will be used as a working paper to provide the regulatory authorities with the data they require to provide the airlines with part 121 flight operations approval to fly enroute, terminal and approach flight operations using RNP, in a timely fashion following the certification of FANS 1.

http://www.boeing.com/commercial/caft/refe...s/RNP757767.pdf

Of course, everyone I talked to states factually that AA77 did Not have GPS installed.

But anyway..

To my knowledge, they never did get any approaches approved for Inertial systems.

What did they do before we even had GPS?

[amazed!]

Before GPS was "land based" radio aids. Low Frequency/Medium Frequency, then eventually VHF. They still exist and are operational, but have been rendered somewhat academic by the GPS revolution.

INS is relatively old technology, though I'm sure there are some still in service.

[dMz]

I found this interesting quote the other day. While wondering what the true limits of a 757 is I realized the only place we may find them is in the Boeing archive of flight tests. No normal flight will do. And the normal Flight Manual are also not going to say what the real Max is imho.

Still, in their more dramatic moments, flight tests aren't for the faint of heart.
...
A 757 cruises with maximum fuel efficiency at 80 percent of the speed of sound, or mach .8. Its maximum intended speed is mach .86. But Boeing pressed the airplane to mach .92 in flight testing. A far corner.

Such flights, said Rick Lentz, 757 flight-test aero-analysis lead engineer, "can be frightening, because the plane responds with buffeting. The tail assembly is groaning and wings are flapping - and until you've been through this a few times, you're not sure it will hold together."

Also, in relation to the DreamLiner wing snap video is this quote

The results were pleasing, because the airplane proved 12 percent stronger than engineering estimates, and because, in a tribute to Boeing engineering and quality control, both wings failed at the same place and at almost the same moment-just 14 thousandths of a second apart.

My recall of "hearsay" commercial airliner "safety factor" is 1.25- I'd like correction or verification if possible. This should be 125% wing/fuselage design strength at mach 0.86 (100% operational load).

I'd estimate this test level at 0.92/0.86 ~= 1.0697674419, so the Boeing could have been capable of still more- the turbofans- probably not.

1.25 design strength * 1.12 verified test level ~= 1.4 failure "margin" by my estimation for this test. I'd say 14 milliseconds, but that's a small nit, probably from the newspaper writer's translation.

Great find- thanks for the post.

[dMz]

Update on drag estimate:

I've looked for information on high-altitude "thin air" drag vs. velocity variations, and didn't find much.

Using this NASA page:
http://www.grc.nasa.gov/WWW/K-12/airplane/drageq.html

Assuming the same altitude (& air density) and same plane (area profile), the [subsonic?] drag force equation above should depend on velocity^2, and the relative velocities squared would be the "dominant terms."

This correction for ratio of velocities^2 would give:

(0.92)^2 / (0.86)^2 = 0.8464 / 0.7396 ~= 1.1444023797 "overtest" drag level (still below an assumed 125% design "safety factor" for airframe strength). Having run both "non"-destructive and destructive aerospace structure tests personally, I doubt anyone here at P4T would be interested in the 0.92 Mach experience.

The jet engines are another matter entirely- that would likely need wind tunnels and test data (from Rolls Royce, Pratt-Whitney, General Electric, Boeing, etc. to answer anything there).

[dMz]

Further searching has revealed the following:

http://ecfr.gpoaccess.gov/cgi/t/text/text-....16&idno=14

Title 14: Aeronautics and Space [of CFR]
PART 33—AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES

Turbines are covered in Subparts E & F

Specifically, see FAR Section 33.83, Vibration Test.

"b. The surveys shall cover the ranges of power or thrust, and both the physical and corrected rotational speeds for each rotor system, corresponding to operations throughout the range of ambient conditions in the declared flight envelope, from the minimum rotational speed up to 103 percent of the maximum physical and corrected rotational speed permitted for rating periods of two minutes or longer, and up to 100 percent of all other permitted physical and corrected rotational speeds, including those that are overspeeds. If there is any indication of a stress peak arising at the highest of those required physical or corrected rotational speeds, the surveys shall be extended sufficiently to reveal the maximum stress values present, except that the extension need not cover more than a further 2 percentage points increase beyond those speeds."

According to General Electric's "Engines 101, Safety" page, their engines are tested "up to 105% of the manufacturer's specified redline speed."

http://www.geae.com/engines/index.html

My personal opinion here is that ANY statements made (by FEMA, ASCE, the Kean/Hamilton 9/11 Commission, MIT, NIST, Purdue, and/or others) about the survivability of turbofan jet engines running over 105% of maximum rated angular speed beyond two minutes' duration is PURE speculation, in absence of further supporting documentation or empirical, instrumented test data.
--------------------------------
EDIT: Transport Category Airplanes are covered in Part 25:
http://ecfr.gpoaccess.gov/cgi/t/text/text-....1.3.11.3.162.2

Section 25.303 deals with Factor of Safety:
" Unless otherwise specified, a factor of safety of 1.5 must be applied to the prescribed limit load which are considered external loads on the structure. When a loading condition is prescribed in terms of ultimate loads, a factor of safety need not be applied unless otherwise specified.

[Amdt. 25–23, 35 FR 5672, Apr. 8, 1970]"
----------------------------------
Section 25.251 covers Vibration and buffeting.
" (a) The airplane must be demonstrated in flight to be free from any vibration and buffeting that would prevent continued safe flight in any likely operating condition.

b. Each part of the airplane must be demonstrated in flight to be free from excessive vibration under any appropriate speed and power conditions up to VDF/MDF. The maximum speeds shown must be used in establishing the operating limitations of the airplane in accordance with §25.1505.

c. Except as provided in paragraph (d) of this section, there may be no buffeting condition, in normal flight, including configuration changes during cruise, severe enough to interfere with the control of the airplane, to cause excessive fatigue to the crew, or to cause structural damage. Stall warning buffeting within these limits is allowable.

(d) There may be no perceptible buffeting condition in the cruise configuration in straight flight at any speed up to V MO/ M MO,except that stall warning buffeting is allowable.

(e) For an airplane with MDgreater than .6 or with a maximum operating altitude greater than 25,000 feet, the positive maneuvering load factors at which the onset of perceptible buffeting occurs must be determined with the airplane in the cruise configuration for the ranges of airspeed or Mach number, weight, and altitude for which the airplane is to be certificated. The envelopes of load factor, speed, altitude, and weight must provide a sufficient range of speeds and load factors for normal operations. Probable inadvertent excursions beyond the boundaries of the buffet onset envelopes may not result in unsafe conditions.

[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as amended by Amdt. 25–23, 35 FR 5671, Apr. 8, 1970; Amdt. 25–72, 55 FR 29775, July 20, 1990; Amdt. 25–77, 57 FR 28949, June 29, 1992]"
-------------------------
Section 25.253 deals with High-speed characteristics:

" (a) Speed increase and recovery characteristics. The following speed increase and recovery characteristics must be met:

(1) Operating conditions and characteristics likely to cause inadvertent speed increases (including upsets in pitch and roll) must be simulated with the airplane trimmed at any likely cruise speed up to V MO/ M MO.These conditions and characteristics include gust upsets, inadvertent control movements, low stick force gradient in relation to control friction, passenger movement, leveling off from climb, and descent from Mach to airspeed limit altitudes.

(2) Allowing for pilot reaction time after effective inherent or artificial speed warning occurs, it must be shown that the airplane can be recovered to a normal attitude and its speed reduced to V MO/ M MO,without–

(i) Exceptional piloting strength or skill;

(ii) Exceeding V D/ M D, V DF/ M DF,or the structural limitations; and

(iii) Buffeting that would impair the pilot's ability to read the instruments or control the airplane for recovery.

(3) With the airplane trimmed at any speed up to VMO/MMO, there must be no reversal of the response to control input about any axis at any speed up to VDF/MDF. Any tendency to pitch, roll, or yaw must be mild and readily controllable, using normal piloting techniques. When the airplane is trimmed at VMO/MMO, the slope of the elevator control force versus speed curve need not be stable at speeds greater than VFC/MFC, but there must be a push force at all speeds up to VDF/MDFand there must be no sudden or excessive reduction of elevator control force as VDF/MDFis reached.

b. Maximum speed for stability characteristics. VFC/MFC. VFC/MFCis the maximum speed at which the requirements of §§25.143(g), 25.147(e), 25.175.b.(1), 25.177, and 25.181 must be met with flaps and landing gear retracted. Except as noted in §25.253.c, VFC/MFCmay not be less than a speed midway between VMO/MMOand VDF/MDF, except that for altitudes where Mach number is the limiting factor, MFCneed not exceed the Mach number at which effective speed warning occurs.

c. Maximum speed for stability characteristics in icing conditions. The maximum speed for stability characteristics with the ice accretions defined in appendix C, at which the requirements of §§25.143(g), 25.147(e), 25.175(B)(1), 25.177, and 25.181 must be met, is the lower of:

(1) 300 knots CAS;

(2) VFC; or

(3) A speed at which it is demonstrated that the airframe will be free of ice accretion due to the effects of increased dynamic pressure.

[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as amended by Amdt. 25–23, 35 FR 5671, Apr. 8, 1970; Amdt. 25–54, 45 FR 60172, Sept. 11, 1980; Amdt. 25–72, 55 FR 29775, July 20, 1990; Amdt. 25–84, 60 FR 30750, June 9, 1995; Amdt. 25–121, 72 FR 44668, Aug. 8, 2007]"
------------------------
And Section 25.255 covers Out-of-trim characteristics:
" (a) From an initial condition with the airplane trimmed at cruise speeds up to VMO/MMO,the airplane must have satisfactory maneuvering stability and controllability with the degree of out-of-trim in both the airplane nose-up and nose-down directions, which results from the greater of—

(1) A three-second movement of the longitudinal trim system at its normal rate for the particular flight condition with no aerodynamic load (or an equivalent degree of trim for airplanes that do not have a power-operated trim system), except as limited by stops in the trim system, including those required by §25.655.b for adjustable stabilizers; or

(2) The maximum mistrim that can be sustained by the autopilot while maintaining level flight in the high speed cruising condition.

b. In the out-of-trim condition specified in paragraph (a) of this section, when the normal acceleration is varied from +1 g to the positive and negative values specified in paragraph .c. of this section—

(1) The stick force vs. g curve must have a positive slope at any speed up to and including VFC/MFC; and

(2) At speeds between VFC/MFCand VDF/MDFthe direction of the primary longitudinal control force may not reverse.

c. Except as provided in paragraphs (d) and (e) of this section, compliance with the provisions of paragraph (a) of this section must be demonstrated in flight over the acceleration range—

(1) −1 g to +2.5 g; or

(2) 0 g to 2.0 g, and extrapolating by an acceptable method to −1 g and +2.5 g.

(d) If the procedure set forth in paragraph ©(2) of this section is used to demonstrate compliance and marginal conditions exist during flight test with regard to reversal of primary longitudinal control force, flight tests must be accomplished from the normal acceleration at which a marginal condition is found to exist to the applicable limit specified in paragraph (B)(1) of this section.

(e) During flight tests required by paragraph (a) of this section, the limit maneuvering load factors prescribed in §§25.333(B) and 25.337, and the maneuvering load factors associated with probable inadvertent excursions beyond the boundaries of the buffet onset envelopes determined under §25.251(e), need not be exceeded. In addition, the entry speeds for flight test demonstrations at normal acceleration values less than 1 g must be limited to the extent necessary to accomplish a recovery without exceeding VDF/MDF.

(f) In the out-of-trim condition specified in paragraph (a) of this section, it must be possible from an overspeed condition at VDF/MDFto produce at least 1.5 g for recovery by applying not more than 125 pounds of longitudinal control force using either the primary longitudinal control alone or the primary longitudinal control and the longitudinal trim system. If the longitudinal trim is used to assist in producing the required load factor, it must be shown at VDF/MDFthat the longitudinal trim can be actuated in the airplane nose-up direction with the primary surface loaded to correspond to the least of the following airplane nose-up control forces:

(1) The maximum control forces expected in service as specified in §§25.301 and 25.397.

(2) The control force required to produce 1.5 g.

(3) The control force corresponding to buffeting or other phenomena of such intensity that it is a strong deterrent to further application of primary longitudinal control force.

[Amdt. No. 25–42, 43 FR 2322, Jan. 16, 1978]"

NOTE: The (B) and © Smileys were giving me trouble, but the reader should be able to grasp the idea.

Conclusion: In my personal opinion, the engine RPM appears to be the limiting case in a gross overspeed condition for subsonic transport category airliners.

This post has been edited by dMole: Aug 17 2008, 04:52 AM

Reason for edit: Turned off smileys

[amazed!]

And do we know at what RPM the engines were operating? If so, how do we know this?

[dMz]

As UnderTow was kind enough to point out long ago in my very first thread here, a single FDR was recovered for AA77 (I know- that's YET ANOTHER industrial-size can of worms). I still haven't had time to dig into the N1 and N2 RPM data yet, but I have since learned that Rolls Royce engines apparently add an N3 to the mix...

Often in science, it is necessary to make a "reasonable" assumption in order to proceed. If we ASSUME that the FAA datasheet engine maximum shaft RPM specifications (that I recently posted links to at the 757 and 767 Limitations threads very nearby here) correspond to V_mo for the applicable aircraft, then the 105% number could be informative.

If that assumption is found to be invalid (either now or down the road), then I/we would need to come back here and re-evaluate our work. If any of the "guests" lurking out there are GE or Pratt Whitney turbofan engineers, PLEASE by all means feel free to chime in and correct the path I'm on here (esp. regarding aircraft V_mo vs. MAX shaft RPM, [non]linearity of engine output, etc.)...

Arguments could be made for commonality in performance of similar engines, but I'm not that far along yet. I suppose I'll assume an "OCT-friendly" perspective again and and see how well (or poorly (IMG:http://pilotsfor911truth.org/forum/style_emoticons/default/wink.gif) ) I do in my next investigation. I just wanted to find some "hard" numbers, as there has been entirely too much hand waving, etc. for the last 6 years.

Daddy, are we there yet? (IMG:http://pilotsfor911truth.org/forum/style_emoticons/default/doh1.gif)

[UnderTow]

Thank you dMole (IMG:http://pilotsfor911truth.org/forum/style_emoticons/default/biggrin.gif)

Back to the OP bold text

Google Math: mach 0.92 = 700.310487 mph

The Citation X has a top speed of Mach 0.92, which at its normal flight altitude of 43000 feet (13 km) is about 525 knots (605 mph or 970 km/h)

Also, since our subject was below 2000' we need to keep in mind the Mach value variable.

Mach 0.92 (607 mph, 977 kph) at 50000 ft
Mach 0.92 (690 m.p.h) at 36000 ft.

And, I am very sure that a 757 can not break the sound barrier. (IMG:http://pilotsfor911truth.org/forum/style_emoticons/default/biggrin.gif)

Intersting quote I just read

To find the local speed of sound: 38.94 times the square root of the temperature in kelvin. The answer is in knots. That's mach one

?
Oh this is cool.

CODE

Speed of sound = sqrt(gamma*R*T), where gamma = 1.4
                                               R     = 287.05 K m2/s2
                                               T     = temp in Kelvin

at sea level, T = 288,15 K, so Speed of Sound = 340.29 m/s = 761 mph

According to standard Atmosphere (ISA):
With increasing altitude, T decreases by 6.5 deg per 1000 m, up to 11000 m
(troposphere).
then it remains constant up to 20000 m (stratosphere), then it increases
again through the mesosphere.

This post has been edited by UnderTow: Dec 2 2007, 12:30 AM

[dMz]

?
Oh this is cool.

Update: I posted a good, related technical paper over on amazed!'s UA175 Mach thread.

The paper should be at:
http://www.tscm.com/mach-as.pdf

I'd bet that a chart is worth at least a half-dozen equations (IMG:http://pilotsfor911truth.org/forum/style_emoticons/default/wink.gif) , so see "Alt_mach.PDF" (my "translation" of UnderTow's above code and also the paper above):

http://www.orbitfiles.com/download/id3103239538.html

A word of caution: I have put speed of sound for BOTH knots and mph on the same "Y" axis, but the applicable "mach" curves should be labeled and color-coded. Also, the variable "A" is altitude in thousand-feet (which largely determines temperature, air density, and thusly speed of sound and mach number).

NOTE: From my research, opinions seem to vary from 18,000 to 25,000 feet on V_mo vs. M_mo being applicable, so I've just put a green box around this "transition" region. I'll defer to Boeing pilots on exactly what goes on between/in the red V_mo and green M_mo boxes and where that boundary lies for various aircraft.

This post has been edited by dMole: Jul 15 2008, 04:50 PM

[amazed!]

Thanks guys! (IMG:http://pilotsfor911truth.org/forum/style_emoticons/default/yes1.gif)

[dMz]

NASA on Turbofan Thrust:

http://www.lerc.nasa.gov/WWW/K-12/airplane/turbfan.html

http://www.lerc.nasa.gov/WWW/K-12/airplane/shortp.html

The turbofan page above is getting into several simultaneous differential equations (why wind tunnel test data is generally used to profile engine and airframe performance). Most of these test values are unknown to me at this point for the various aircraft in question and at various operating conditions.

This post has been edited by dMole: Dec 16 2007, 07:56 PM

[dMz]

My very-minorly updated Mach chart "for Boeings" (mainly with Troposphere/Tropopause added and minor formatting changes) is located at:

http://www.orbitfiles.com/download/id3103239538.html

I've also found that transonic "wave drag" is a MAJOR factor on upper speed limits for most transonic aircraft, but I still don't have any Boeing wind-tunnel numbers on C_d (complex drag coefficients) for various aircraft at various air densities.

[dMz]

Some recent flight test info on the B777-200LR:

http://www.boeing.com/commercial/777family...ng_the_flu.html

19 October 2005
Testing the flutter
Frank Roney, Loads and Dynamics manager, Structures
Keith Wing, lead flight test engineer, Structures

Safety, obviously, is the top consideration in flight testing the 777- 200LR or any other Boeing airplane. The Structures group plays a key role in making sure all flight tests that could affect the airplane platform are conducted within guidelines that guarantee its structural integrity and airworthiness. We don't want to inadvertently damage an airplane in flight test.

The Loads and Dynamics organization determines the airplane's structural requirements based on the configuration definition and basic performance characteristics. The airplane design incorporates these requirements and is tested in two ways: to validate that the requirements have been met, and to ensure that FAA certification criteria have been addressed. One of the first tests we perform is "flight flutter," to make sure the airplane is stable in flight at speeds greater than 270 knots, or Mach 0.70. Flutter is a phenomenon that is related to vibration modes. When an airframe is exposed to high aerodynamic forces, these vibrations could become unstable and grow to a point where the structure may fail. Our goal is to make sure the aerodynamics, weight and stiffness come together to make an aero-elastically stable airplane.

As a result, flight flutter testing is considered "high risk." Consequently, it is the flight test engineer's responsibility to produce a safe test plan. One tool we use to mitigate the risk during flight flutter testing is telemetry. Using telemetry allows us to have a minimum crew (pilot and co-pilot) onboard the aircraft while the balance of the test crew supports the flight from the Telemetry Room where they analyze data and keep the airplane safe.

One of our main safety-related jobs in the flight test program is to prepare a series of structural Temporary Operating Limitations (TOLs). To get an airplane certified, we test all of its performance requirements, including stalls, engine-outs, 2.5 G maneuvers, and so forth. The TOLs set test-limit values so that if the tests are conducted within the prescribed constraints, we can be confident that the maneuvers will be completed safely. If the tests exceed the guidelines, we have to conduct data analysis and/or inspections to make certain that the airplane structure will not be, or has not been compromised.

The initial TOL values are less than or equal to limit load. Limit load is established by a mixture of FAA certification criteria and Boeing design requirements. Coupled with a safety factor, this establishes the strength at which we design and build the airplane. And as much as we aim to get our structure-related testing done inside the TOL values, we know that many tests just can't be done that way. For example, speed and over-weight landing tests need to push the envelope. Or we may be required to go to the edge of 2.5 Gs and stall the airplane. We design the airplanes to take the stress and loads, but only under closely controlled conditions. This is where the Flight Test Structures group gets involved. We monitor the day-to-day testing performed by other flight test disciplines, such as Stability and Control, and make sure what they're doing is safe.

Overall, we believe a lot of the Structures group's talents come to the forefront when we're able to develop a test that works for everybody. We feel the pilots are very comfortable with stability and control and how the airplane feels and how it's controllable. But they depend on us to make sure it's structurally capable. We all use our processes to make sure the airplane is safe. That's one thing I think we can hang our hat on. We have the best processes in place to make sure safety happens, from start to finish.

[dMz]

It's not "flight test" per se, but here's a video of a progressive "static load" B777 wing test. Keep in mind there is no wind, drag, flutter, turbulence, engine thrust (or engine pylons for that matter), dynamic loading, vibration, etc.

Both wings failed very near 154% near the end of the video (which wasn't specific as I could determine regarding the FAR mandated safety factor).

http://www.youtube.com/watch?v=pe9PVaFGl3o

<object width="425" height="344"><param name="movie" value="http://www.youtube.com/v/pe9PVaFGl3o&hl=en&fs=1"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="http://www.youtube.com/v/pe9PVaFGl3o&hl=en&fs=1" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="425" height="344"></embed></object>

[dMz]

It's not "flight test" per se, but here's a video of a progressive "static load" B777 wing test. Keep in mind there is no wind, drag, flutter, turbulence, engine thrust (or engine pylons for that matter), dynamic loading, vibration, etc.

Both wings failed very near 154% near the end of the video (which wasn't specific as I could determine regarding the FAR mandated safety factor).

http://www.youtube.com/watch?v=pe9PVaFGl3o

Here's a recent GL "spun" version of above:

"The 777 was tested and I think the wing cracked near 7 Gs. Tested on a test rig in a hanger. 77 was 757, I expect it could handle 6 Gs for a one time event; may be broke for the next flight.

Any rolling moment and pulling lots of Gs, more than 4 would be more Gs on the rolling up wing. Complications set in when you are really flying. So pilots try not to roll and pull too much depending on their plane, but airliners would not even think of it unless you knew someone was trying to shoot you down, then what the heck throw in a roll, a loop and try to get away, you would be surprised at what a big jet can do with the right crazy pilot behind the wheel."

Ummm, the video above shows B777 wing failure at "154%" and doesn't specify a scale or any stated correlation to 7g... I'd expect to see some verifiable documentation or flight test results in order to make the quantum? leap from a rather vague 154% in Boeing highbay to 7g in flight.