Due to the aerodynamic load, the force required for manual trim can be very high, and the higher the speed of the aircraft, the greater the force required.

Xu Qing couldn't help but think of a sentence in the Boeing training manual about manual trim: an excessive aerodynamic load on the stabilizer may require two pilots to work together to correct the wrong (stabilizer) trim. That is, at some point it even takes two pilots to spin the handwheel together to get a proper corrected trim.

The manual trim on the simulator is really not realistic enough, and the manual trim on the simulator is nothing compared to the manual trim under real conditions.

"Can't turn?" Instructor Chang saw Xu Qing's sweaty appearance and knew what the result was, and his right hand holding the throttle lever poked down, wanting to pick out the handwheel on his side and try his strength. It's just that as soon as the right hand left the throttle lever, it began to tremble uncontrollably.

Instructor Chang pursed his lips, as if he was enduring great pain, and immediately withdrew his outstretched right hand and put it back on the accelerator lever. When he is not in the air, the instructor can still slightly suppress the already disobedient right hand.

If you look closely, you can actually find that Teacher Chang's left hand trembles more obviously, not from the vibration brought by the shaker, but from himself.

It took less than a third of the time to reduce the EGT below the limit, but the EGT index has been fluctuating, and it is not sure when it will break through the limit again.

In Chang Instructor's plan, as long as he crossed the second mountain, even if the second shot was cut off, there was no problem, and he was quite sure that the single shot in the actual flight would land.

Xu Qing tried for a while, but he still couldn't do manual balancing flexibly, so he gave up in despair: "Master, this manual balancing speed is too slow to use." ”

"It's fine!" Teacher Chang said kindly: "Without matching, Master and I can still fly down, don't worry." ”

For pilots of the level of the instructor, there is not much difference between whether there is a trim or not under normal circumstances, but it is limited to normal conditions. Instructor Chang now only needs to move his hands, and he will face the pain of piercing the heart, especially in the left hand.

I used too much force just now, and my hands should have been injured!

Even if he endured the pain all the time, he was unwilling to hand over the manipulation to Xu Qing. In this case, whoever is the manipulator will have to bear almost all the pressure.

Now when I think about 2.19, the crew is disabled, the engine fire, the twin engine fails, the air starts, and the five-sided twin engines turn off again, what a thrilling thing it is, compared to the current one. How was Xu Qing able to bear such heavy pressure at that time.

"What a miserable child!" Teacher Chang sighed in his heart.

At that time, he, who was a master, was not by Xu Qing's side, so he couldn't share anything for Xu Qing, and today he had to take on the responsibility of being a master.

There is a tall man on top of the sky falling, let him shelter Xu Qing from the wind and rain this time!

He didn't want to fly and leave Xu Qing with only bad memories, he also wanted Xu Qing to continue flying!

Xu Qing hadn't noticed anything unusual about Teacher Chang, but was paying attention to the matter of matching. Manual trim is not going to work at all, and if you want to trim, you still need to rely on the main electric trim.

"Master, I feel like I've figured out what the problem is." Xu Qing said suddenly.

"Oh?" Teacher Chang and the one behind him all pricked up their ears curiously, wanting to hear Xu Qing's high theory.

Xu Qing: "This seems to be the kind of maneuver augmentation system you talked about before." Isn't it just to prevent stalling? There must be something wrong with today's AOA sensor, you have been fake jitter over there, and that system thinks the plane is stalling before ordering it to keep trimming downwards. ”

Instructor Chang suddenly realized, why didn't he think of this stubble! It's a pity that I didn't study the maneuvering feature enhancement system in detail during the previous training, otherwise I might have been able to find a way to deal with it.

Xu Qing didn't have much pity, because the training course really didn't mention the maneuvering feature enhancement system, he only knew that the maneuverability feature enhancement system belonged to speed trim, and speed trim was used in NG aircraft.

In addition to the original ST mode, the MCAS mode, i.e., Maneuvering Characteristic Enhancement mode, has been added to the MAX aircraft.

Speed trim is a speed stabilization enhancement system, which improves the performance of the aircraft under the condition of small total weight, backward center of gravity and high thrust when the automatic driving is not turned on, and makes the aircraft return to the trim speed by instructing the plane to move in the opposite direction of the speed change. However, the amount of automatic trim for speed trim is very small, and there is no unlimited trim in MCAS mode.

The training course talked about a new system, and then it was gone. However, after a series of automatic balancing performances, Xu Qing has summed up some working principles of the maneuvering feature enhancement system.

"This maneuvering feature enhancement system should only be activated when the AOA probe measures beyond the critical angle of attack. I just counted it silently, and it has a work loop. The first time we had an automatic trim, the trim wheel worked for a total of nine seconds and then stopped automatically, and then I used the main electric trim intervention, and after five seconds it started to automatically trim forward, and it was a high-speed trim mode. Xu Qing said while comparing the memory in his head, and after confirming that it was correct, he concluded: "The trimming method of this system should be under the premise of a large angle of attack, without the intervention of the pilot, and automatically move forward at 0.27 units per second to level for nine seconds or be intervened by other means." After a five-second intermittent stop in the absence of new commands, if the angle of attack does not decrease to the set range, restart the cycle until the angle of attack decreases to the set range. ”

"Now there is a problem with the AOA sensor, and the angle of attack has not been able to be reduced, so the maneuvering characteristic enhancement system will always work." Xu Qing's eyes flashed with wisdom: "I don't have a shaker on my side, only Master you have a shaker, which means that only one AOA sensor has a problem." However, the fact that the Maneuvering Characteristic Augmentation System has been working only indicates that the system is using a single AOA sensor data, rather than the traditional method of compromise, or deviation correction. ”

"At the same time, the intervention method that can be known now is that in addition to the stabilizer cutting off the electric door, it is the main electric trim." Xu Qing said again.

I have to say that Xu Qing's ability to observe and summarize is really quite amazing, just through just a few maneuvering characteristics to enhance the performance of the system, the operation mode of this system has been summed up, and it is exactly the same as the setting of the facts, just like a celestial!

Xu Qing has almost analyzed the working mode of the maneuvering characteristic enhancement system, but there are still some omissions in the entry conditions, but it is admirable enough!