The European Aviation Safety Agency (EASA) has presented Boeing with five major requirements that need to be addressed, before the 737 MAX returns to service.
Reported by Bloomberg on the 6th of July 2019, the article notes the aircraft will not be allowed to fly again until the requirements are addressed and are tested accordingly.
The five requirements the European Aviation Safety Agency have listed so far are as follows:
- Reduce the difficulty manually turning the trim wheel
- Address the unreliability of Angle of Attack sensors
- Address the training situation
- Investigate software issues with a lagging microprocessor
However the biggest and newest to join the list of problems involves the autopilot system in the aircraft, which reportedly fails to disconnect in some emergency scenarios.
Investigations have concluded that pilots who encounter a stall scenario relating to the Manoeuvring Characteristics Augmentation System (MCAS) or similar flight control emergencies have difficulty disconnecting the autopilot.
Bloomberg notes the autopilot doesn’t completely disconnect. This could mean the system is designed in a way to work with MCAS so closely it still believes it has greater authority than the pilots.
Having to redesign, or modify, the existing autopilot system of new production and grounded aircraft would take enormous amounts of time and resources.
Adding to the woes is the latest software update which was expected to address the original MCAS problem, however it was rejected as errors were identified during simulator testing.
Past and present engineers within the aviation industry have flagged the aircraft as unsafe to fly because it is not a software problem, it is a structural problem that required the MCAS system in the first place.
A redesign of the engine position on the aircraft would cost a ridiculous amount of money and would likely render the grounded aircraft useless. Flight testing and new production methods would have to be conducted, leaving the idea in the scrap bin.
Despite this the idea to add or redesign hardware hasn’t been completely disregarded as EASA director Patrick Ky said, retrofitting additional hardware relating to the angle of attack sensors was still an option.
This alone would still be expensive and time consuming for Boeing. To this day, we still do not know when the aircraft will be flying again. We’ve seen it multiple times with airlines who are constantly shuffling their 737 MAX schedule around.
EASA is conducting one of the most thorough investigations of the aircraft design and has been focusing on the differences between previous 737 flight controls and the 737 MAX.
Due to the heat surrounding the Federal Aviation Administration, it is likely the world will take EASAs word first.
However, in an effort to regain passenger confidence, EASA along with the FAA, Canada and Brazil will jointly sign an agreement to permit the aircraft to fly again.
This will depend on whether the Boeing and the FAA accept and address EASAs requirements.
The current estimated return time to service is September, however many remain sceptical as this timeline includes the software update regarding the lagging processor, test flying, joint re-certification, repairs and flight resumption work conducted by airlines.
When do you think the aircraft will return to service?
Let’s look closely at Mark Forkner who worked for Boeing, the FAA and is now employed by the carrier most impacted by this debacle – Southwest Airlines. https://www.nytimes.com/2019/06/01/business/boeing-737-max-crash.html
Too many hands in the cookie jar. Boeing along with certain airline carriers (USA) pushed for the 737 to continue being manufactured. The FAA should have never allowed Boeing to certify their own planes. Why allow a plane with engines that are too big to take to the air? Why allow an aircraft with MCAS take to the air? Over 300 lives lost because the 737 had to continue. It’s disgusting on so many levels. Boeing executives should be fired and face legal action. The FAA should also bear the brunt of their decisions. Every carrier that that pushed to have the 737 continue should hang their heads in shame. LUV they’re coming for you next.
Well said. BA has been used software to cover up design flaws. Send all “flying coffins” to grave yard BA and FAA CEOs to jail for mass murder.
Let’s make the problem short.
Boeing should withdraw all the max8 destroy it and replace with the new model. This will cause a huge damage to the company finance, but it will start to gain a trust and gradually boeing will heal the wound after several years.
it’s true.
Boeing needs to stop hiding the root cause of this problem which is that the aircraft’s fuselage is not capable of handling the new engines and also that this old 1960 design no longer has a place in today’s technology and safety standards due to ergonomics.
This is Boeing’s chance to act intelligently and do the right thing; get rid of this very old thing which they think belongs in this age of aviation and become as innovative as Airbus.
I have no wishes to fly this junk of a machine and risk myself and passengers.
737 MAX: A Software Fix Might Not Be the Complete Answer
A very talented mechanic in the food processing industry once explained to me that there would always be those who knew how to do a thing (think highly skilled engineers in the case of the 737 MAX) and those who knew what to do; think generalists with less specialized knowledge, but across a wider range of disciplines, those whose talents and interests allow them to “think outside the box”. I think this element may be missing in the search for solutions in case of the 737 MAX.
A few days ago I watched (on YouTube) Mentour Pilot’s co-pilot struggle to adjust the 737 Max’s pitch trim manually in the simulator.
https://www.youtube.com/watch?v=aoNOVlxJmow
The copilot needed his (Mentor pilot’s) assistance because of the forces required to accomplish this, even in the calm and low pressure environment of the simulator. In the real world the effort required by this mechanically flawed system would have caused both pilots to be limited in their ability to find other solutions to the immediate problem.
In an earlier video, I had noted (with discomfort) the apparent difficulty of being able to grip the runaway trim wheel and stop it by force. He also stated that the manual system is a mechanical system based on cables, which I think is generally a good thing. Hindsight is easy but…
From a human engineering and safety standpoint, the design of the horizontal tail surfaces and the pilot’s mechanical trim system on the 737 MAX seems poorly thought out and poorly implemented. The speed at which the trim wheel runs in the simulator video seems to indicate a poor choice of mechanical advantage and mechanical ratios in the manual trim system, producing large forces that the pilots must overcome manually in an emergency and also require too many revolutions of the trim wheel to accomplish the needed trim control adjustments. If this is in fact true, large forces would be required to control a runaway trim by force; or to simply use the manual trim in normal flight. In order to get a good grip on the runaway trim wheel one would need to be able to grasp the outer perimeter of the wheel using the full capabilities of one’s grip. This appears impossible in the video because of the design and placement of the trim wheel.
If such a stabilizer, as opposed to an elevator trim system was disabled after the stabilizer had been run to an excessive nose down trim position before the MCAS system was disabled and; under a busy and pressured emergency environment; with an excessive number of turns of the (difficult to operate) trim wheel required to correct the stabilizer position; and with relatively limited elevator vs stabilizer control authority (read: area relationships), it is understandable that the pilots of the Ethiopia flight might have elected to re-engage the (faster) electric trim system, while unfortunately possibly simultaneously re-engaging the MCAS system.
The Boeing engineers seem to have made an (unsuccessful) attempt to address some of these issues by providing a fold-out handle attached to the trim wheels, but it appears to be marginally effective. I also doubt that it (the handle) could be accessed while the trim wheel is running. There are numerous other ways that these difficulties could be addressed:
• Increasing the mechanical advantage available to the pilots by changing the mechanical ratios involved;
• The trim wheels could be a larger diameter, clearing the console and thus providing the ability to better grasp the wheel;
• Changing the relative areas of the elevator and stabilizer in ordered to create a more balanced control authority between them;
• Adding a completely independent (from the autopilot, MCAS, and other computer controlled systems) and redundant second trim motor and control system for the pilot’s emergency use;
• Utilizing a (recirculating) ball screw mechanism in place of the conventional jackscrew in order to reduce forces and the number of turns of the trim wheel required to be effective. Since ball screw mechanisms require significantly less force to operate and can be “self-driven” their use opens up additional possibilities for redundancy in the system.
• Another advantage of ball screw actuators is that they do not require lubrication; think of the Alaska Airlines Flight 261 accident. The probable cause was stated to be “a loss of airplane pitch control resulting from the in-flight failure of the horizontal stabilizer trim system jackscrew assembly’s acme nut threads. The thread failure was caused by excessive wear resulting from Alaska Airlines’ insufficient lubrication of the jackscrew assembly”, similar to the system we are discussing on the 737 MAX.
• Self-actuating aerodynamic servo and/or anti-servo tabs on the elevator and/or the horizontal stabilizer (while un-conventional) might be a part of the solution.
• Other aerodynamic, possibly self-actuating, solutions having nothing to do with the trim system may be possible in addressing the thrust vector caused issues that MCAS was designed to address.
Is this same (737 MAX) trim system installed on all versions of the 737? Have these issues been addressed in earlier versions? If so, were they lost in later design iterations, perhaps not requiring a change to the type certificate?
The industry, the FAA, and many others worldwide have created perhaps the safest transportation system the world has ever seen, but we need to maintain that system under constant review, surveillance, and improvement by competent parties to ensure decisions and rules are made, and compromises decided upon, by those best qualified to do so.
Design always involves compromise and trade-offs. This requires good judgment, good management, and oversight by qualified people, but the teams can become too specialized and lose sight of the forest. When you bring in one or more “outside” team members into a discussion, their seemingly un-informed insights can be profound. For example, in another YouTube video
https://www.youtube.com/watch?v=kERSSRJant0
“Sully” explained the root cause of the Air France Flight 447 accident (poor human engineering, very similar to the 737 MAX issues we are discussing). I would guess that his wide range of separate areas of knowledge and experience (while seemingly unrelated to engineering) allowed him to reach this insight, and I expect that he probably has many others related to possible improvements of the characteristics of the control system of the A330 and other Airbus aircraft. Unfortunately I have seen no evidence of response to his accident prevention insight and lesson by Airbus or the industry in general.
Sincerely,
Phil Hertel
The Practical CFI
CFI ASMEL-I
In private discussions, with engineers, the return to flight is now measured in years, not months.
The Max is done. It will be scrapped – there is no way any airline or passengers will fly a plane that has a fundamental hardware (aka engine placement) flaw. Boeing is just going through the motions until they realize the cost of fixing is more than the cost of starting afresh. To my mind, they should offer airlines one of their other, non-problematic planes in an even exchange and move on, either traditional 737 or the 757.
I think that Eugene and Bob have said it all. This is exactly how I feel, and as a member of the flying public I would personally never want to fly in a 737 Max no matter what is done to fix its problems. Boeing has always had a wonderful reputation for its beautiful aircraft. This reputation should be maintained at all costs no matter what needs to be done to accomplish this if they wish to stay in business. Bad engineering cannot be swept under the rug to protect the bottom line.
FAA/NTSB should do its job.
I still contend some of the blame lays with the airline for first crash as same plane had same problem the day before but a jump seat pilot saved it. Why no communication for next day pilot and was the AoA sensor replaced and documented it was calibrated? The saving pilot likely just let up the throttle shut off the MCAS without reengaging it. The second crash pilots went full throttle and reengaged instead of flying it. Could have been physically weak but Boeing should have known that. Also wonder if both planes met requirements for passenger & cargo weight distribution not making it even worse as occurred for a cargo plane crash.
Read the financial analyses of Boeing’s current predicament. Numbers are down but still within recent dips, leaving capitalists hopeful that Boeing will scrape by and recover. While not wanting to see an iconic American company fail, I believe Boeing will never fully recover its historic quality leadership within the industry unless its current leadership team is entirely purged. That will only happen if the financial impact of the current leadership’s team inept mismanagement results in forcing them out. A replacement leadership team needs to focus on the strategic value of the Boeing brand name, not any short-term financial goals. Quality and safety need to be restored as a primary goal within Boeing.
All planes should be returned to Boeing with the owners hands out for their purchase price back and start buying planes from Boeing competitors. Boeing is just too greedy and arrogant!
Nailed it.
It is crucial to aviation safety that Boeing not be permitted to “fix” the 737 MAX with software. The plane was made unstable due to new, larger and heavier engines which were stupidly located upward and further forward for ground clearance. This causes the 737 MAX to often pitch up at max thrust on take-off. Basic aerodynamic stability was compromised. MCAS is compounding the error: for an airplane that lacks essential stability, software only “papers over” the underlying problem, and Boeing management knows this.
But they decided to allow a flawed fifty year old design decision to continue rather than implement a costly re-design. The “reasoning” in the 1960’s was that smaller airports would not have lifts to permit ground crew to access the baggage hold, so they purposely made the landing gear short, giving the engines only 17 inches ground clearance. Thus, 346 people have so far been killed by what amounts to negligent homicide in two incidents. New software will not cure this problem. Every in-the-loop manager at Boeing is criminally liable, from the CEO on down. Of course this will not happen, as Boeing has become too big to fail.
Lemon laws should apply to aircraft. Boeing should have to buy back all the grounded aircraft since they are not “fit for use” and cannot be corrected in a reasonable amount of time.
New flaws are being found faster than Boeing can attempt to fix many, many known flaws.
VW execs went to jail and had to pay large personal fines for dieselgate. Why are Boeing execs not in jail for causing 346 deaths?