I am not sure, whether the following links have been discussed:
Here we have some credible statements, which are not hearsay because the name of the source is known (Rick Ludtke, a former Boeing designer, who worked on the MAXs cockpit interfaces):Statement 1: Penalty charges based on training requirements
As contracted, Boeing owed WN "$1 million per plane if its design ended up requiring pilots to spend additional simulator time". So the "business case", to make MCAS invisible and non existent in the sim and in the training was $280 millions worth for Boeing.
The full text from the article is:
Mr. Ludtke recalled midlevel managers telling subordinates that Boeing had committed to pay the airline $1 million per plane if its design ended up requiring pilots to spend additional simulator time. "We had never, ever seen commitments like that before," he said.
Source is the following full copy of the original WSJ article, which is behind a paywall:https://www.marketwatch.com/press-relea ... quote_news
More from Ludtke here:https://www.seattletimes.com/business/b ... _inset_1.1
More statements from the following two links:https://www.satcom.guru/2019/03/regulat ... stems.htmlhttps://www.satcom.guru/2019/03/aoa-van ... g-fix.htmlStatement 2: Pressure to implement no-additional-training solution
Statement 3: MCAS runaway hard to detect
"Rick Ludtke, a former Boeing engineer who worked on designing the interfaces on the MAX’s flight deck, said managers mandated that any differences from the previous 737 had to be small enough that they wouldn’t trigger the need for pilots to undergo new simulator training."
"He said that if the group had built the MCAS in a way that would depend on two sensors, and would shut the system off if one fails, he thinks the company would have needed to install an alert in the cockpit to make the pilots aware that the safety system was off. And if that happens, Ludtke said, the pilots would potentially need training on the new alert and the underlying system. That could mean simulator time, which was off the table."
For the first time, Boeing admits MCAS is an extension of Speed Trim, which I have long suspected, and why it was designed with a single input. Speed Trim is constantly applying stabilizer trim commands in manual flight. This masks MCAS trim commands. Further, MCAS trim commands are effectively a slowover and in the case of the Lion Air flights, intermittent. These factors, combined with the flight deck effects from the high AoA value causing high workload, interfere with the expected human response. There has yet to be any acknowledgement of this, rather the opposite by ignoring it. The FAA repeatedly made the same assertion, the MCAS malfunction is easy to detect.
Statement 4: After trim cutout, using the trim wheel may be inadequate to deal with the situation
As discussed in earlier posts, in fact MCAS failure is hard to detect as it is a slowover, and Speed Trim System (STS) applies automatic trim routinely, masking MCAS motion. JT043 only related the situation to a stab trim runaway after an observing pilot suggested it. JT610 crew never figured it out. It is possible ET302 flight crew did not detect the failure in spite of specifically be briefed to look for it. The situation was compounded by the AoA trigger of Stall Warning. Boeing should not assume so readily how pilots will perform when MCAS fails, while the evidence is in stark contrast.
Statement 5: Trim cut out checklist is flawed
The response to a stabilizer runaway is to cutout the electric trim. Nowhere does anyone caution the consequences of using manual (turn the wheel manually) trim. The manual trim wheel can be very hard to turn if subject to high aero loads, and particularly if the elevator is commanded significantly (loading the stabilizer).
The standard response to just hit the stabilizer cutout switches and manually trim is actually flawed. If the nose has been pushed down by significant mistrim (nose down stabilizer, nose up elevator), and as airspeed increases, it may not be possible to trim the stabilizer manually nose up without letting the elevator go to a neutral position. The reality, under the MCAS runaway scenario, trimming nose up immediately stops MCAS as well as trims the stabilizer back towards an in-trim position. At that point, you would be best off to cutout the stabilizer.
To illustrate, let me explain this hypothetical scenario:
- JT610, after the captain handed over to F/O
- In this hypothetical scenario, the nose down out-of-trim situation would have become obvious to the crew and they would have cut out the trim.
- Now the trim wheel has stopped, they are in a dive, at a low altitude, at high speed, and their task is now to turn the trim wheel to bring the nose up again.
- But - the force to turn the wheel is now too heavy unless they stop pulling the yokes!
- Situation is not recoverable