Originally Posted by
Bergerie1
And, as hinted to by EASA and by some of you, was it really necessary to meet a regulatory requirement on stick force gradient when the aircraft may have been perfectly safe without any of these fixes?
Counter question: If the gradient requirement was not met only formally but the true effect is not relevant handling wise, why did Boeing go through with MCAS and not just simply declaring the behaviour and asking for relief?
I think it links to your conclusion on the (lack of) other fixes apart from MCAS. They seem to have honestly chosen a solution that was readily available, required less R&D and cost as little as necessary, all that without penalizing performance As much as
the internet likes to ridicule that decision, showboating and all [this thread is a great exception!!], what's being called
clearly obvious in the laymen media sphere was for sure well known and thoroughly considered by the dedicated professionals yet AFTERWARDS they chose MCAS. No matter the pathetic killer gremlin MCAS 1.0 which was born later, the initial choice of picking the MCAS tool was a fair one. If it would be done again, there's absolutely no presentable evidence to deny that particular path. And as matter of fact that's what happened: The proper and agreed solution to control forces is MCAS 2.0 which is all that 1.0 wasn't and at the same time the exact thing they originally planned for.
Without getting carried away too far: Imagine the trailing edge modification had been chosen resulting in all the super critical geeky cool effects
fdr explains. BUT THEN during the actual design and implementation aviation reality would be abused same as with MCAS 1.0. Such as failing to do ice contamination test and the additional load stress calculations. Resulting in flaps detaching a few years down the road - with crew performance same as on the second crash day, the death toll would have been identical.
Trying to say that selecting what is now disclosed and known as MCAS as a tool cannot be faulted. With extreme probability, it was well-reviewed against all the other options and chosen maybe even as a win-win.
Cons of the other suggestions, as picked up over the forums here1:
strakes
- Very badly predictable in the design stage. You do not know what it does unless you flight test it. Single engine, side slipped flight at high AoA with ice on them and only one gets a hot air blast the exhaust,? A/C departs controlled flight to the side. Unpredictable risk on the development scope and amount of effort. fdr's stories on fast jet nose section design speak volumes.
- Adding weight and drag penalties, no matter how small amounts, does count (for some). The largest customers do care, rightfully or not their Excels are sharp and furious.
- Extra maintenance requirement for inspections over the lifetime of the airframe. Cost, costs, costs... customer choice, customer choice, customer choice
- Increased risk of ramp collisions. IDK but any object with mass has its own gravity and on the ramp EVERYTHING gets hit eventually. New repair schedule, new DDG items... oh.
trailing edge mod on the wing or elevators
- Completely out of scope, design frozen, signed and dusted for. The simple little issue needs a simple little solution. Constant re-tweaking kills projects like nothing else. And why touch the wing unless you absolutely have to? You don't. Sure, for the MAX+ at 2028 it will be done.
stick pusher AS WELL AS artificial feel unit mod
- certification review of the F/CTL system
- training required, commonality tanked
- extra weight
- messing with what works never goes without problems. Probably best they did not - geez these guys failed to connect the AoA light and could not see MCAS acting on the sole most powerful aerodynamic control is class A critical item like no other.
MCAS
- a software routine, simple to model and dry test
- easy to update and change later across the global fleet
- does what needs to be done
- does not involve touching any of the existing systems that have been time-tested to perfection
- no extra hardware
- no additional training as it really is just an additional spinning mode for what the STS actually is - an autonomous THS compensator.
Yet, after all, the very same teams who understandably chose the proper way out is with MCAS
against the hard options, could not avail themselves to just doing anything but simply admit a less than perfect force characteristics on the control column. The EASA boss statement is inconclusive. Various otherwise dangerous aeroplanes (not the case of MAX)
can be flown safely if you know how to do it.