Boeing - Design Issues...

Discussion in 'Rules and Regulations / Flight Safety / Better Pil' started by TXFlyGuy, Apr 11, 2019.

Help Support HomeBuiltAirplanes Forum by donating:

  1. Apr 26, 2019 #61

    gtae07

    gtae07

    gtae07

    Well-Known Member

    Joined:
    Dec 13, 2012
    Messages:
    1,731
    Likes Received:
    1,031
    Location:
    Georgia
    Essentially random distribution. The static and fatigue articles are typically built on the same production line to the same design as the first test airplane (albeit with unneeded stuff left off). They don't try to skew the parts to min or max tolerance; you get what you get.

    IIRC primary structure analysis is required to use "A Basis" allowables, which essentially are specs thst 99% of properly-formed material will meet or exceed. Then there are factors of safety, conservative assumptions, and so on. All of that is why static failures of aircraft structures are fairly rare (fatigue is a different matter) and stories of sirplanes surviving excursions past g limits seem so common. However, I'm not a stress guy; I've just had them bleed red ink all over my drawings.
     
  2. Apr 26, 2019 #62

    kgwilson

    kgwilson

    kgwilson

    New Member

    Joined:
    Nov 21, 2011
    Messages:
    3
    Likes Received:
    0
    Location:
    Corindi Beach, NSW, Australia
    That Al Jazerra story was covered by Australias SBS which aired it in 2002.

     
  3. Apr 27, 2019 #63

    bmcj

    bmcj

    bmcj

    Well-Known Member HBA Supporter

    Joined:
    Apr 10, 2007
    Messages:
    12,568
    Likes Received:
    4,592
    Location:
    Fresno, California
    Off topic, but any relationship to ScaleBirdsScott? ;)
     
  4. Apr 28, 2019 #64

    ScaleBirdsPaul

    ScaleBirdsPaul

    ScaleBirdsPaul

    Member

    Joined:
    Jul 6, 2015
    Messages:
    15
    Likes Received:
    11
    Location:
    Connecticut
    Haha, Yes, I’m one of the engineers that’s been working on the project for the past several years. I’ve been an HBA member for a while but decided I needed to start posting more after some discussions with HBA members at Sun n Fun.
     
  5. Apr 30, 2019 #65

    Richard6

    Richard6

    Richard6

    Well-Known Member

    Joined:
    Aug 14, 2010
    Messages:
    650
    Likes Received:
    71
    Location:
    Plymouth, MN USA
    If someone ask these question before, I may have missed it.

    I know that there are some commercial pilots on here that have experience with the 737 MAX.

    Q1 - Did the aircraft you flew have the optional faulty angle of attack sensor indicator?
    I understand that it was a $80,000.00 option the was seldom purchased.

    Q2 - Without the faulty sensor indicator, is there any way to know that the sensor is faulty before takeoff?

    Q3 - In a normal regularly scheduled fight in the USA, at what point after takeoff does the pilot engage the autopilot?

    Richard
     
  6. Apr 30, 2019 #66

    Scheny

    Scheny

    Scheny

    Well-Known Member

    Joined:
    Feb 26, 2019
    Messages:
    53
    Likes Received:
    14
    Location:
    Vienna, Austria
    I am not an active airliner pilot, but I was trained for A320 before I decided to take an office job in management instead (due to two wonderful little girls).

    It is not possible to detect any AoA problem prior to take-off, as the AoA aligns with airflow and has random value on ground.

    Basic AoA verification would mean to check that difference between two sensors is within a limit. Advanced verification would also take speed and vertical forces into account to model expected values. As to my knowledge, the later is only possible in new planes starting with B787 due to architecture of the systems.

    As for autopilot engagement, this is usually being done after initial climb, when you select climb thrust and retract the flaps.

    Andreas
     
  7. Apr 30, 2019 #67

    TXFlyGuy

    TXFlyGuy

    TXFlyGuy

    Well-Known Member

    Joined:
    Apr 26, 2012
    Messages:
    1,398
    Likes Received:
    394
    Location:
    Republic of Texas
    With an airline career dating back to 1987, here is my personal experience with the use of autopilots.

    If I were flying a B-727, the plane was completely hand flown all the way to top of climb. And then hand flown again starting at TOD (Top of Decent). The only portion of the flight where the autopilot was normally used was the cruise segment.

    Fast forward to a 777, and I would hand fly the jet up to 12000 feet, or FL180. But that is only if the weather was very nice, and the SID was not highly complicated. On approach the A/P was left on until 1000' AGL. The 777 A/P is certified for single engine auto land, CAT III approaches (300 feet RVR was our minimum).

    But that was just me. I have flown with guys who would engage the A/P at 200'. That was the certified minimum altitude for departure.

    I would say it varies from airline to airline, and from pilot to pilot. There is no "standard".
     
  8. Apr 30, 2019 #68

    TFF

    TFF

    TFF

    Well-Known Member

    Joined:
    Apr 28, 2010
    Messages:
    11,139
    Likes Received:
    3,017
    Location:
    Memphis, TN
    A comment on airlines buying optional equipment. They are too cheap to do that. I was with a regional that bought 150 new CRJ200s. The first 50 or so had the 8 deg flap detent deleted. Saved $5000 an airplane. When the regional started flying to Denver, taking off with zero flaps has insane takeoff speeds. We had to convert all those and new planes came equipped. $80,000 option is not an option. It’s a dream. They are only interested in minimum standard to appease their certification oversight.
     
  9. Apr 30, 2019 #69

    davidb

    davidb

    davidb

    Well-Known Member

    Joined:
    Jun 3, 2008
    Messages:
    1,599
    Likes Received:
    413
    Location:
    Vacaville, CA
    The Max can be equipped with an optional AoA indicator (an instrument displaying AoA). Most carriers that have been operating 737s don’t get that option because they don’t train and fly by reference to an AoA indicator. Don’t confuse that with the AoA disagree caution indicator which is standard on all newer 737s but was mistakenly not activated on the Max unless the AoA indicator instrument option was installed. Honestly, the press is making this seem like a big deal but it is not a causal factor. It would not have alerted the crew to a problem before takeoff.

    We typically don’t engage the autopilot until above 10,000 feet. One could engage it as low as 800 feet agl but not lower than that per the stated limitations. I suspect USA pilots are much more comfortable hand flying than some other foreign carrier pilots. The last crew was attempting to engage the autopilot below 800 feet with indicator and control anomalies. That action is contrary to what we would expect of a USA trained 737 pilot.
     
  10. Apr 30, 2019 #70

    Richard6

    Richard6

    Richard6

    Well-Known Member

    Joined:
    Aug 14, 2010
    Messages:
    650
    Likes Received:
    71
    Location:
    Plymouth, MN USA
    Thanks for the response to the questions. Clears up somethings for me.

    I understood that the MCAS is disabled when the auto pilot is enabled. So I was wondering what the normal procedure is. And as described above, it very's.
     
  11. Apr 30, 2019 #71

    davidb

    davidb

    davidb

    Well-Known Member

    Joined:
    Jun 3, 2008
    Messages:
    1,599
    Likes Received:
    413
    Location:
    Vacaville, CA
    The MCAS trimming is also disabled when the flaps are down. All takeoffs are made with flaps down. The MCAS trimming started after the crew selected flaps up. The stick shaker was activated shortly after liftoff and remained active.

    IMHO, the Ethiopian crew was startled and overwhelmed by the stick shaker and airspeed anomalies both of which were caused by the bogus AoA. The chain of events started there. Without specific training and a clear understanding of what was happening, the crew was ill equipped to handle the situation. Hindsight.
     
    Vigilant1 likes this.
  12. May 1, 2019 #72

    litespeed

    litespeed

    litespeed

    Well-Known Member

    Joined:
    May 21, 2008
    Messages:
    1,221
    Likes Received:
    184
    Location:
    Sydney
    I will throw my two cents worth of opinion in.

    No I am not a airline pilot, nor aircraft designer, nor a armchair critic having a bash.

    Just a guy concerned about the safety of aircraft and the humans involved in the whole scheme from boardroom to flying the aircraft.

    The history of Boeing and the closeness of the FAA is a major concern, it appears to be way too cosy and too trusting. Complaints appear to be either ignored or given little attention. Having the FAA in a situation where it allows the maker to self certify a commercial airliner is ridiculous, claiming they don't have the expertise to assess the aircraft is a admission of failure.
    If the FAA had lacked the skills it should have demanded more funding and got the needed expertise. The process of certification is expensive and if the design is new, even more costly. Those are expenses that should fall on the manufacturer through fees or whatever the government chooses. To allow a maker to do whatever is considers profitable and certify itself is a complete failure of the very systems that give safety to aviation.

    The culture of Boeing appears to have gone for profit at any cost since it merged and changed direction. As far as the video of the 737neo and relative safety in service, the current safety record appears as it should be. Any new design should inherently have better numbers, if they are not after a better and safer aircraft? what are they doing? We live in a time of mass airtravel but also generations of flight safety improvements in design, manufacture, training, operations and regulation. To not have a improvement would mean one of the above is failing or in the case of the manufacture of the neo at least manufacture and regulation, internally and external.

    I make my comments based on the video and other sources and can only go on what is available and what I have read/seen. I am happy for other information to refute my opinion.

    The aircraft was certified as having CNCed parts to very close tolerances as a part of its design. You have to prove the parts are made this way for every part and to the specified tolerances. It is meant to be part of builders quality control and legal requirements for every single aircraft.We are not making a homebuilt aircraft but a certified passenger jet liner that is certified in the USA and sold on worldwide. Other countries certify on the basis of the FAA approval.

    Any comparison to a part designed to be made in a fixture is not relevant, they are two completely different things as far as the design and manufacture are concerned. To do fixture and hand manufacture with considerable change in tolerances, stresses and alignment over the certified part is making a illegal part if it goes anywhere near the 737.Even if you could make the parts absolutely to the exact specs, including stresses and safety margins- it is not the legal part. Only the part as designed, manufactured and tested for quality control and signed off is the legal one.

    I can not imagine the illegal part is anything but inferior to the designed cnc part. The part has been purposely used in aircraft after paperwork was forged, with the apparent knowledge of Boeing. This was done on mass- not a isolated incident.The part is integral to the safety of the airframe and is critical to ensuring the fuselage holds together particularly in a heavy landing, off runway landings or potentially fatal accidents. Its use doesn't mean a CFIT can be safe, but just like safety features of a car - some mistakes are survivable.

    These illegal parts have been shown to be the places Neo aircraft have broken apart in survivable incidents, they have failed and caused death and injury.
    This type of incident is rare, just like aircraft are rarely crashing. But when it does happen, it would appear the failure to manufacturer the legal parts means the airframes are suspect in service.

    That leaves a huge quandry- the parts appear to have been installed in all Neo's built and no way to legitimately discern which are using correct parts- due to the forgery of paperwork. That would mean all affected aircraft are Not certified to fly, it is incapable of certification and has been since that part was installed. Nothing short of rebuilding the aircraft could make it legally certified to type. So no airworthiness either. See this leads us to the point where a manufacturer may have launched a entire fleet and everyone is a experimental aircraft incapable of been used for passengers.

    This naturally assumes the letter of the regulations are followed and enforced by the FAA or other legal authority. Any country or airline with a Neo could make a massive case out of this and ground the entire fleet on certification grounds.

    Even if no accidents ever happened to the Neo it still has this inherent problem, a problem that clearly Boeing is responsible for. This is scandalous but seems a non issue to the FAA.

    This is a flashing red light before we even consider the issues of the 787 and now 737 max.

    I will get to those latter.

    Before I get a flame job, I am not anti Boeing or American aircraft nor alarmist. I am just following the logical path. If Boeing has done everything right- glad to be wrong.

    What are your thoughts?
     
    Last edited: May 1, 2019
    kgwilson and jedi like this.
  13. May 1, 2019 #73

    BJC

    BJC

    BJC

    Well-Known Member

    Joined:
    Oct 7, 2013
    Messages:
    8,901
    Likes Received:
    5,750
    Location:
    97FL, Florida, USA
    My thought is that it would be prudent to wait until the crash investigations have been completed, the Boeing and FAA actions are fully understood, and all human factors have been evaluated before arriving at an uninformed opinion.


    BJC
     
  14. May 1, 2019 #74

    TXFlyGuy

    TXFlyGuy

    TXFlyGuy

    Well-Known Member

    Joined:
    Apr 26, 2012
    Messages:
    1,398
    Likes Received:
    394
    Location:
    Republic of Texas
    Another quick take on auto pilot usage...

    Using the A/P on departure depends on how many legs you have flown that say, how tired you are, how bad the weather is, etc., etc.

    Another thing is that on an engine failure at or just after V1, I would engage the A/P at 200 feet AGL. That is our published minimum altitude. And using the A/P takes a huge amount of workload off the crew, allowing an extra margin of safety.
     
    davidb likes this.
  15. May 1, 2019 #75

    Hot Wings

    Hot Wings

    Hot Wings

    Well-Known Member HBA Supporter

    Joined:
    Nov 14, 2009
    Messages:
    5,998
    Likes Received:
    2,001
    Location:
    Rocky Mountains
    There is nothing inherently wrong with self certification. Commercial aviation is the most regulated business in the US. It has trashed general aviation's ability to advance. Even the FDA allows more self certification. The ASTM/LSA method of self certification seems to be working. There have been a few violations but the public safety has been adequately protected without the massive oversight currently in place for GA and transport aircraft.

    While I believe there may be a cultural problem within the Boeing company, not unlike a lot of other large corporations, the overall safety record of the companies products is still quite good. Imagine what your car would cost if the manufacturer had to document and certify it's entire supply chain - with prior approval?
     
    Himat and bmcj like this.
  16. May 1, 2019 #76

    12notes

    12notes

    12notes

    Well-Known Member Lifetime Supporter

    Joined:
    Aug 27, 2014
    Messages:
    693
    Likes Received:
    446
    Location:
    Louisville, KY
    The FAA is not in a position to demand funding. You may recall, way back - four months ago - they couldn't keep their doors open for lack of funding.
     
    jedi likes this.
  17. May 1, 2019 #77

    davidb

    davidb

    davidb

    Well-Known Member

    Joined:
    Jun 3, 2008
    Messages:
    1,599
    Likes Received:
    413
    Location:
    Vacaville, CA
    Agreed. Engaging the autopilot during an emergency or abnormal situation is usually the prudent thing to do as it allows one to then focus and think through the situation. The exception is when the situation involves flight control systems or flight instrument anomalies. Specific to the 737, the first steps to any control or instrument anomalies is to disengage the autopilot and auto throttle.
     
    Vigilant1 likes this.
  18. May 1, 2019 #78

    BBerson

    BBerson

    BBerson

    Well-Known Member HBA Supporter

    Joined:
    Dec 16, 2007
    Messages:
    11,424
    Likes Received:
    2,099
    Location:
    Port Townsend WA
    But when MCAS fails maybe the prudent thing to do is engage the autopilot to disable MCAS?

    All very confusing to keep up with this. Disregard if nonsense. :D
     
  19. May 1, 2019 #79

    TFF

    TFF

    TFF

    Well-Known Member

    Joined:
    Apr 28, 2010
    Messages:
    11,139
    Likes Received:
    3,017
    Location:
    Memphis, TN
    Oversight is a society problem balance thing. Taxes and the size of the government are the bullets. US government since the 60s has been cutting back services from the boom of WW2 ramp up and in general holding taxes at the value of inflation. That means as things get more expensive the government lets jobs go instead of making you really pay for the same service. As long as you can pile the let go workers work on another, you are holding your own. When it gets deferred, different solutions to get the work done are put into play. I don’t like government running my business, but they have to run the business or they are not doing their jobs. Those jobs cost money. Where do you get that money? It’s supposed to be taxes not deferred to who you are supposed to be overseeing. On one of the interviews I heard on this if the FAA was to man up like they use to for this work, they need 100,000 experts in the field. Not warm bodies, experts. They are not there. Private industry has no excess, you can’t just decree it. It in the end is about no one wanting to pay but get everything they want. That is why we drive on roads your grandfathers built in WW2 and don’t make new ones or keep those up. Falling apart is falling apart and stuff like Max is really fringe problems of a strong society. Not the deaths, but how we handle the problem. Until politicians stop being yes men and women and do what they are supposed to do for the 80% of agreement, it will always fall apart.
     
  20. May 1, 2019 #80

    davidb

    davidb

    davidb

    Well-Known Member

    Joined:
    Jun 3, 2008
    Messages:
    1,599
    Likes Received:
    413
    Location:
    Vacaville, CA
    Disregarded. Even the “experts” are getting the explanations half wrong. So, you are appropriately confused.

    The autopilot is not a magical “save me” button. The 737 autopilot is not advanced enough to determine which inputs are bogus. In general, it won’t engage or disengages when conflicting inputs are detected. True: MCAS trimming is not active with the autopilot engaged. False: the autopilot can be engaged to stop MCAS trimming.

    The first indication of a problem with both of these accidents was the stick shaker shortly after liftoff. With hindsight, we know this was caused by a faulty AoA input. We also know now that there’s a fifty percent probability that faulty AoA input will lead to unwanted MCAS trimming as soon as the flaps are selected to up. Had the crews knew that, they could have simply left the flaps down and come around for a normal landing after determining which instruments were accurate.
     

Share This Page

arrow_white