Originally Posted by
Grebe
Suggest take time to read this link - which includes pics and diagrams
https://www.satcom.guru/2019/03/aoa-...-fix.html#more
IMHO- the use of set screw(s) for such an instrument is or should be verboten
D shaped shaft with snapon keeper, splined shaft with d ring keeper or similar should be used for all such assemblies especially counterweight to gear shaft and gear shaft to resolver and arranged that any broken part vane gives a nose down ? result with mechanical limits as to movement or resolver output. Wilbur and orville may have used a few setscrews on their flyer- but that was then ...
Of course if you want to adjust your lionel railroad and engine parts, or your kids toys, even then set screws are now doubtful, since they may be swallowed. Maybe to adjust your clock or doorbell chimes is OK ?
D-shaped shaft or splined shaft have clearance that has to be taken out somehow. Usually on a D-shaft there is a setscrew set against the flat. Splines are a poor choice for reversing loads. If not pre-loaded, they fret (particularly in high-vibration environments such as aircraft,) producing fod and increasing the clearance and eventually leading to a large amount of backlash. That article mentions that one AoA sensor on a plane 13 or more years ago had one loose screw. That does not make it typical. For all I know the current gears are press fit with a bit of shaft locking compound and a set screw with thread locking compound, but we have no picture of the 737 Max AoA sensor to be sure.
How would the AoA sensor assembly detect it had a broken part in order to generate a "nose down result"?