Originally Posted by
SLF3
Despite the quirky website address the moonofalabama article is both interesting and well written. Hard to argue the 737 NG is not 'safe' given it's track record, but Boeing (and the FAA) will struggle to explain how they got to this place: 'We made the stabiliser bigger, which increased the loads it could generate, and made the trim wheel smaller, so it was harder to turn. And then deleted the procedure that told you how to use the trim wheel at high loads.'
They also put a damper in there as well because there was also a new trim motor.
Regarding the trim wheels: When the NG was being introduced, I happened to be the Lead Engineer in charge of them and a whole lot of other stuff. There were some issues. The new display system created a pinch point between the dash and the wheel. We had to make the wheel smaller. And the new trim motor resulted in the wheel, which is directly connected to the stabilizer by a long cable, springing back when electric trim was used. It was an undamped mass on the end of a spring. We had to add a damper.
Result: Depending on the flight conditions, the force to manually trim can be extremely high. We set up a test rig and a very fit female pilot could barely move it.
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