I'm sure the pitch up tendency is worse on the MAX, but I don't believe MCAS was added to enable the re-use of the same type certificate. The handling problems were worse than anticipated as is evidenced by the low-speed activation of MCAS.
My guess is that the 737 MAX on its own wouldn't meet the handling requirements. It's been a while since the Ducommun scandal, but more recently Boeing was caught knowingly installing unsafe parts (NG/MAX slat tracks that didn't meet spec) and forging repair documentation for Air Canada. Pardon me if I take any claims that Boeing is spewing with a lump of salt.
inadequate pilot training.
It's hard to train for something that the manufacturer won't disclose or implement in the sims. It's even harder when the remedy (moving the trim wheels) is physically impossible.
That was the demand from the airlines; that there be no training delta. For that you need to remain within the same type, or at least close enough that they're equivalent.
>My guess is that the 737 MAX on its own wouldn't meet the handling requirements.
Correct.
>It's hard to train for something that the manufacturer won't disclose or implement in the sims. It's even harder when the remedy (moving the trim wheels) is physically impossible.
Yes. The training the pilots received on the differences between the MAX and the NG (i.e. no training) was inadequate to prepare them to fly the aircraft safely.
Those are two separate issues. There are currently four generations of 737 on the TC[1] and sim time is required between the different generations. Look at the 777 vs 777X, there are radical changes and yet the 777X is (for now) grandfathered on the 777 TC. A change requiring a new TC (or STC) is an order of magnitude more dramatic.
The training mandate drove the poor design of MCAS but wasn't the reason MCAS was implemented. Even with training the MAX would never have met FAA regs without something like MCAS.
The list price of the MAX is around $100 million, and Southwest wanted $1 million per aircraft if training were reqiured. If it were simply a matter of more appropriate training Boeing would've already taken the 1% haircut and moved on. American talked a good game about not wanting the MAX at all if training were required, but let's face it they'd probably rather take the training hit than wait in line for an A320 production slot. Instead Boeing shuttered the production line because the problem is simply not that easy to solve.
If it were simply a matter of stick force gradient Boeing could've likely just modified the elevator feel computer. Instead Boeing went the route of moving the whole damn stabilizer, a particularly odd choice because the stabilizer moves very slowly -- slower than a reasonable person would want to prevent an impending stall.
1: http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgMakeMod...
It's no longer an engineering problem.
Now it's a trust problem.
Boeing, the FAA, and the airlines have demonstrated that they can't be trusted to make the right decision when passenger safety conflicts with quarterly earnings per share.
They'll roll the dice and hope they can fix the problem, as cheaply as possible, before the next catastrophe.
So it doesn't matter if they find an engineering fix.
The public will never trust that it's really fixed, and re-branding this dud won't fool anybody.
The sooner Boeing figures this out, the less money they'll lose.
Where the heck did you get that from? The MCAS failures were caused by a failure of the AOA sensors, not any kind of handling characteristics.
MCAS was originally intended to handle high speed, high altitude situations. Flight testing found that there were handling problems at lower speeds and altitudes that MCAS could "fix". So MCAS was given roughly twice the authority it was originally designed with and it was then programmed to activate in lower speed situations as well. The FAA, of course, was kept in the dark.
If you're curious go through the Seattle Times articles.
I'd say the handling is bad enough to require something like MCAS in order to be safe. If not, they would have just disabled it and ate the cost of training pilots for the new variant. Instead they think it's better (cheaper) to try to fix MCAS while letting planes pile up that will likely require extra training on the new fix anyway.
In other words I agree. It probably doesnt fly well without help, as opposed to just flying differently.
Boeing used a 737 airframe for economic reasons (it wwas way cheaper, didnt require pilot retraining), but needed more ground clearance for bigger engines. The 737 design cant be practically modified to have taller main landing gear. The solution was to mount to engines higher on the plane. This made the plane more unstable, so they slapped the software solution on. This "fixed" the problem, but then the plane was more complex to fly, which led to the crashes. But Boeing didn't want a plane that required retraining, so they hid the complexity of the software solutions, which led to crashes because the pilots didn't know what was going on.
Sure you can say the plane was structurally fine, but this is semantics, they created a plane that was unstable because it was cheaper.
In the aerospace industry, semantics matter. "Structurally deficient" implies that the aircraft structure itself (i.e. the spars, ribs, load-bearing skin, etc.) is unsafe. This is not accurate, and neither is it accurate to say the MAX is "unstable". These are terms of art with precise engineering meanings.
Precision in language matters, and to dismiss it as "semantics" pre-empts any meaningful discussion of the issue at hand. It's like saying float vs char is "semantics". Those differences matter.
edit: Also, when you say the engines were put "on top of the plane" it makes me question if you've ever actually seen a MAX 8.
Apart from that, I don't have to like people saying "it's just semantics" if they mean the exact opposite.
Interpreting your comments in the most charitable way, you must have reasons for your opinions that convince you, so it would contribute more to the discussion if you explained why.
Nobody rejects "semantics".
Aerospace engineer here. This is incorrect. The MAX exhibits different pitch behavior at high angles of attack than the 737NG, which would normally require a different type certificate. MCAS was their attempt to change the handling characteristics of the MAX aircraft so that it was sufficiently similar to previous iterations of the 737.
This is not the same as being "structurally deficient". The fatalities arose from a combination of ethic failures at Boeing, financial pressures from large customers, bad safety design of the MCAS system, and inadequate pilot training.
Plenty of aircraft flying today exhibit nose-up pitch tendencies at high angles of attack. This is not an intractable problem; it's just not a problem that Boeing could solve while keeping to the 737NG type.