On Mar 17, 5:42*am, ContestID67 wrote:
Now, I have mounted many instruments with their accompanying brass
screws and never used lock washers. *Then a friend asked why not? *I
opened my mouth to spout the obvious answer, but no sound came out. *I
realized that I have never used lock washers, never seen them used,
and have never seen a loose instrument. *Hmmmmm.

- Lock washers are used everywhere when vibration is an issue.
- An airplane is certainly a vibration prone environment.

So I hazarded these ideas;

- The screws, and nut, are (non-magnetic) brass and somehow brass
stays "stuck" better because brass is softer than steel.
- A brass lock washer wouldn't keep its "bite" as it would flatten
over time.
- I don't have any more good ideas.

So, why is it that we never use lock washers when mounting
instruments? * And why don't the instruments vibrate loose? *Please
keep the answer this side of a physics lecture.

Thanks, John

They don't vibrate loose because there is no vibration! Without the
engine there are no serious vibrations except when rolling on a rough
surface.

In most of the power plane installations I've seen they use a brass
nut-clip that fits into the back of each instrument hole and IS a lock
nut.

In my Grob the nuts used on the instruments are plastic insert lock
nuts. That's the way it came to me.

Mike