sportingrifle wrote: ↑Fri Mar 15, 2019 12:57 am
One of the things that drives me nuts is how the airframer sales people sell these airplanes to their airline customers - usually bean counters and MBA's.
"Really easy to fly, no problem bringing low time cadets on board."
" Reduced training costs. All your XXX pilots need is an internet based differences course."
" There is nothing to it, you can covert your XXX pilots with a short course."
But let one of their nearly self driving airplanes create a new underground aluminum deposit and the same airframers say "Not our fault, your guys didn't fly it like our test pilots would have."
Boeing (and many posters) say "Hey, it's just a trim runaway. Do the drill and all is good." But this is not the simple trim runaway that the QRH contemplates. It starts with a stall warning stick shaker shortly after lift off. Close to the ground this will, and should consume both pilots undivided attention. After a number of seconds they realise that the airplane hasn't stalled and they start figuring out that they may have an airspeed and/or AOA problem. This is a second problem to deal with on top of the first. And they can't shut the &%$#@ stick shaker off once they realise that it may be spurious. The PM will be frantically scanning the panel to try and find some clue what is going on. And this whole time, among the din of the stick shaker, crews concern for the airplanes flight path, and the confusing instrument indications, MCAS has been intermittently dialing in nose down trim. Not steadily, in a calm cockpit at altitude like the QRH contemplates. But intermittently in the background of chaos, noise, and confusion. At some point, well past when it would have been timely, the task saturated PF realizes that the trim is working against him/her and the stab cutout switches get turned off. (hopefully)
But the shitshow isn't over. Because of everything else going on, this took too long and the airplane is way out of trim. The Lion Air crew reportedly had 60 KG of back pressure on the yoke. Close to the ground, and relying on the lifting component of the underslung engines to help keep the nose up, the crew do not dare reduce power. Now the crew needs to manually trim the airplane, but the airplane is way, way off its trim speed. The B737 QRH makes reference to the large forces that may be required to break free a servo clutch:
"3 If needed:Use force to cause the disconnect clutch to disengage. Approximately 1/2 turn of the stabilizer trim wheel may be needed.
Note:A maximum two-pilot effort on the trim wheels will not cause a cable or system failure."
Worse, the "Manual Stabilizer Trim" section of the Boeing FCTM talks about the air loads on a grossly out of trim stab requiring a speed change to reduce the force required to manually trim:
"Excessive air loads on the stabilizer may require effort by both pilots to correct mis-trim. In extreme cases it may be necessary to aerodynamically relieve the air loads to allow manual trimming. Accelerate or decelerate towards the in-trim speed while attempting to trim manually."
Sweet Jesus how did this thing get certified? A guy (or petite gal) has a 60 KG+ force on the yoke trying to stop the airplane from impaling itself into the hard ground just a few thousand feet below, and now he/she has to brute force trim the airplane as well, requiring involved coordination with the PM. Still with all the stick shakers, aural warnings, goofy instrument readings, and whatever else is happening to distract the crew and making communication almost impossible. It is not hard to see how quickly it becomes overwhelming.
In addition to a fix for the airplane, if they keep the MCAS system (instead of designing a whole new wing or tail for the airplane), they will have to train the pilots who fly it to deal with its failure. Right now, there is not a single Max pilot in the world who has been trained for this failure because - there isn't a single simulator in the world that can replicate it. But when they do, all those pilots that claimed "it's just a trim runaway" are going to have a very eye opening simulator session.