Ethiopian 737-8 MAX down. No survivors. | Page 29 | FerrariChat

Ethiopian 737-8 MAX down. No survivors.

Discussion in 'Aviation Chat' started by RWatters, Mar 10, 2019.

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  1. F1tommy

    F1tommy F1 World Champ
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    Here is a photo of the second Electra to crash. Midway Airport Chicago 1959 photo (N121US) This is the plane that crashed at Tell City, on 17th March 1960. It was the second Electra crash from wing separation. What investigators called 'whirl mode.'
     

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  2. Bob Parks

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    Yeh! I remember now! It was all about gyroscopic prescriptions and whirl modes. Those big turbo props had too much unilateral and difronctional forces that reacted to the turbulence that had the nacelles gravitizing and elevatoring in the the reaction direction to the two whirly modes of the incantabrated disc plane. That always makes things break. Seriously,I worked with the engineer that figured out the cause of this failure, Elizabeth "Pete' Plunket. Proved it with a balsa wood and magnesium sparred wind tunnel flutter model.
     
  3. Gatorrari

    Gatorrari F1 World Champ
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    Apparently there had to be some pre-existing weakness in the structure of one of the outboard nacelles in order to allow whirl mode to proceed.

    In the case of the second crash (the aircraft in the above photo), the previous landing at Midway may have been hard enough to weaken the structure; then when the aircraft hit clear-air turbulence over Indiana, the whirl mode started and the aircraft was doomed. In the case of the first crash (Braniff in Texas), the aircraft had been used for flight training for a while before revenue service began, and some think that sometime during that, an event like a botched stall recovery might have weakened a nacelle, but what caused the whirl mode to start on the fatal flight was never ascertained for certain; some witnesses reported a sound like a runaway propeller. (The Braniff plane had been in service less than three weeks.)

    The bottom line is that those outboard nacelles were strong enough, but not stiff enough, and were prone to structural damage. The long life of the P-3 Orion fleet shows how thorough that Lockheed's redesign was.
     
  4. Gatorrari

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  5. Bob Parks

    Bob Parks F1 Veteran
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    This must be "Pete" Pluncket's" model. She mentioned balsa sections and spar chords made of small magnesium sections.
     
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  6. Tcar

    Tcar F1 Rookie

    There's a vid online of that wind tunnel test.... showing the 'whirl' that developed. Saw it a couple years ago.
     
  7. Tcar

    Tcar F1 Rookie

    "Ice Pilots" really like the Electras... they have several.

    One of the episodes is of them going to England and buying the last one flying there, and flying it back over the Atlantic. Also tons of spare parts....
     
  8. Gatorrari

    Gatorrari F1 World Champ
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    Reeve Air Aleutian flew them in combi service into the 2000s before finally giving them up. Their tremendous horsepower made them great for short fields, and Buffalo is continuing to use them thoroughly.
     
  9. tomkatf

    tomkatf F1 Rookie
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    #709 tomkatf, Mar 15, 2020
    Last edited: Mar 15, 2020
    Tests here, although test to destruction portion seems to be edited out. Flutter evident though...



     
  10. Bob Parks

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    Pluncket said that the original skins on the nacelles were not stiff enough and they were thickened and some of the structure was beefed up. The wing skins also got thickened. I went to Google and found a dissertation on the Electra that clearly showed the discontinuity in the crown loft curve of the nacelle after the angle of thrust incidence was increased. Maybe I should promise not to goof around with physics terms anymore. Not much fun, though.
     
  11. Gatorrari

    Gatorrari F1 World Champ
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    I've seen the first two of these, but I've never seen the footage of the actual failure of the wing; that footage is still being kept secret. The best visual view of the flutter is starting at about 8:35 of the second video; you can clearly see the prop wobbling out of plane and transmitting the flutter to the wing. This would have been at the early stage of what happened to the two doomed aircraft.

    The third video is interesting in that it shows the effect of stiffness. With enough stiffness the flutter is damped out, but with insufficient stiffness, the flutter gets worse, which is what happened in reality. The effect is like disturbing a perfectly-rotating top spinning on a smooth table.

    Whirl mode flutter was nearly unheard of with piston engines, mainly because the masses in the engine were moving in different planes from the propeller. In a turboprop, though, everything is rotating in unison, even if at different RPMs. The wide paddle-blade props the Electra needed in order to maintain enough propwash on the relatively short wing didn't help the matter, and I don't believe the lower-powered Vickers Viscount ever encountered the phenomenon.
     
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  12. F1tommy

    F1tommy F1 World Champ
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    #712 F1tommy, Mar 16, 2020
    Last edited: Mar 16, 2020
    Just wanted to point out how many crashes the L188 Electra's had, although some were not the aircrafts fault it would still raise rad flags to the public. The MAX is being compared to this but in reality the MAX problems are closer to the original A320's problems. My father was on his way to work when he was a Motorola Engineer at their offices near O'Hare when the last NWA aircraft crashed. He took a few photos wich I cannot find.

    Even without these crashes the advent of smaller jet aircraft would have killed the Electra. They only buily 170 Electra's with 7 lost in the first 2 1/2 years of service is a bit much even back then.

    L188 crashes:

     
  13. F1tommy

    F1tommy F1 World Champ
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    By the way that is a list of only the write offs. There were more crashes that the aircraft were repaired and made flyable in the same time frame.
     
  14. Gatorrari

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    The first crash on your list was attributed to pilot error: the pilot was an experienced DC-6 pilot but had only 50 hours on Electras. On approach, due to the Electra's high wing loading, it was necessary to keep the propeller speed high (to maintain propwash over the wings) while reducing engine speed, and there was a technique to do that which this pilot forgot. That resulted in a high sink rate and the aircraft pancaked into the East River short of the LaGuardia runway. (The aircraft was brand new.)

    The second and third, of course, are the two "whirl mode" disasters. The Eastern crash in Boston was due to massive bird ingestion on takeoff and the last one on the list was due to a maintenance screw-up. I don't know much about the fourth and sixth accidents on the list but they sound similar to the first one: poor technique resulting in high sink rates and landing short.

    Then there was the 1968 Braniff crash that I described in post #700 above. Of course, that was well after the end of production and had no impact on the aircraft's future prospects.
     
  15. jcurry

    jcurry Two Time F1 World Champ
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    Do you have a reference for this?

    The accident review Board may other determinations in the cite posted by F1tommy.
     
  16. tazandjan

    tazandjan Three Time F1 World Champ
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    Funny how history repeats itself. WW-1 fighters generated much of their lift from prop wash from the large and slow turning propellers. Assisted rudder authority, too.
     
  17. Rifledriver

    Rifledriver Three Time F1 World Champ

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    I think it was the JU52 that had the outboard engines slightly canted outward to improve rudder authority. I have heard lack of it at lower speeds was a complaint in DC3's.
     
  18. Bob Parks

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    That may have been true for the DC-1 and DC-2 but the DC-3 had a huge rudder and very effective and it was a "rudder airplane". I flew one several times in the right seat and there was no problem with rudder control at any speed. My son said that any wing drop at lower speeds could be brought up with rudder.
     
  19. Gatorrari

    Gatorrari F1 World Champ
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    I believe that was Robert Serling's opinion in his book "The Electra Story", but it makes sense. The probable cause was pilot error, but the board pointed to other failings. It took place on a rainy night in poor visibility, which didn't help.
     
  20. Gatorrari

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    The DC-3's vertical tail was much larger than the DC-2s. The Air Corps acquired some "DC-2 1/2" which were, I believe, DC-2s with DC-3 tails and were designated C-39.

    Boeing had a bad habit of designing vertical tails that were too small; they did this on the B-17 (and 307), the C-97 and the KC-135/707; all eventually had to be enlarged.
     
  21. Bob Parks

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    Thanks to George Schirer, he figured out the formula to get enough tail volume designed for any airplane. The B-17E was the first. The 314 was perhaps the worst example of low tail volume, something like 1/16th of what it should have been. So, two additional vertical tails had to be added and it was still marginal. The B-29 had it correct and the B-50 was correct. The KC-135 had two revisions to the vertical; increase of 24" to the tip chord (really 360-80) to stretch out the closure rate of the section to stop flutter, and additional height to the fin. Good ol' dutch roll issue. The 767 had no problem with it's "Mighty Tail".
     
  22. Jeff Kennedy

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    Maybe the FAA will finally move forward and let the 737 MAX fly again.


    Boeing Flies 737 MAX On Simulated Airline Runs Despite Shutdown
    Guy Norris March 25, 2020
    [​IMG]
    Credit: Stephen Brashear / Getty Images
    Amid signs that Boeing is hoping to resume production of the 737 MAX in May the company says flight tests of the three current versions of the model, the -7, -8 and -9, are continuing despite the general shutdown of its Puget Sound facilities because of the coronavirus.

    Although production of all aircraft has been temporarily halted across its northwest facilities, Boeing is still working to finalize changes to the maneuvering characteristics augmentation system (MCAS) flight-control law in the MAX—which was grounded in March 2019 following two fatal accidents in less than six months. The changes to the MCAS logic, which provides automatic horizontal stabilizer input in certain flaps-up, manual-flight profiles, will be accompanied by more extensive training.

    The MAX fleet meanwhile remains grounded until regulators approve the changes and training requirements, although Boeing owned or leased pre-delivered development aircraft continue to fly as part of testing and evaluation of the changes. With approval taking longer to achieve than originally expected, Boeing also opted to temporarily suspend production of the aircraft at its Renton site in January. In an unrelated move, manufacture of the company’s widebody aircraft at Everett was additionally halted for two weeks starting Mar. 25 in a bid to slow the spread of the COVID-19 disease.

    To evaluate the changes to the MAX, Boeing is conducting a flight test program called “operate like an airline,” which closely resembles the function and reliability flights the company runs as a standard part of pre entry-into-service checks for all new models. “We have been working with regulators to appropriately address all certification requirements and safely return the 737 MAX to service. This includes operating flights of 737 MAX 7, -8 and -9 aircraft to extend testing capacity and ensure a more complete representation of our customer’s diverse fleets and operations,” Boeing said.

    On Mar. 25, as part of the program, a 737-8 intended for eventual delivery to Southwest Airlines was operated from Boeing Field to Spokane, Washington, while a 737-9 built for Alaska Airlines was flown from Seattle to Moses Lake. “In each of the cases, a small test team on board exercised short- and long-haul engineering flights that will help satisfy specific test conditions for the updated software. These are not certification flights,” the company added.

    Flight tests of the 777-9, the first of the company’s long haul 777X family, have meanwhile been temporarily suspended for two weeks as a result of the coronavirus precautions. Although Boeing declines to comment on the move, first reported in the Air Current, the initial 777-9 WH001 remains on the ground at Boeing Field where most flight testing is based. The halt in 777X flight testing comes just days before the second aircraft, WH002, was set to join the program with a first flight from Everett’s Paine Field.

    Indications of the 737-production restart, together with agreement on Mar. 24 over the U.S. Senate’s coronavirus relief bill, meanwhile dramatically boosted Boeing share value to more than $168 in early afternoon trading Mar. 25 from a low of around $94 just two days earlier. The turnaround followed comments by Boeing CEO David Calhoun reported by Reuters that indicated the MAX could return to service by early summer.
     
  23. F1tommy

    F1tommy F1 World Champ
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    #723 F1tommy, Mar 27, 2020
    Last edited: Mar 27, 2020
    Thought you all might like a few Kodachrome photos of an L188 taking off from Midway back in summer of 1959, the worlds busiest at the time. Pretty airplane that after it was sorted became a workhorse for cargo airlines around the world, as well as a great Navy aircraft as the P3. Nice to see a parking lot full of American cars instead of Toyota's and Honda's. Infact almost everything in this picture was made in the USA by US companies(or USA north aka Canada:). Grampa had a clue!!




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  24. Jeff Kennedy

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    Joke with the P3 was that Lockheed had to keep making them since "work on the P3" was the cover story for people who actually worked in the Skunk Works and out at "The Ranch".
     
  25. Rifledriver

    Rifledriver Three Time F1 World Champ

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    Reminds me of a close up view I had of a heavy 747 leaving SFO at about the same height. Going over the long term parking lot he set off every car alarm in the place.
     

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