Originally Posted by
The Lev
It's not "harder to trim" - try physically impossble. Bu no mention of that by Boeing. Also no mention that even though ailerons are supposed to be able to overcome effects of trim that they don't at higher speeds due to blowback. Kindly point to where in the AD it said to keep speed below maximum let alone to reduce speed to ensure that you are physically able to manually trim. Sorry but it didn't.
They get gradually more difficult to manually trim as the airspeed increases. This is common knowledge for any 737 pilot, as is the advisability to keep air speed below max. The purpose of the AD is not to restate common knowledge.