Mystery 7/16 inch hex nut appeared on copilot side floor

[IslandPilot]

Found a 7/16-20 hex nut on the floor about 6 inches aft of the rudder pedals on the copilot side of my 1988 M20J 205SE.  The nut is 1/4 inch thick. Just a basic hex nut; not a locking nut. Brakes are only on the pilot side.  I spent a good while looking up under the panel on the copilot side and at the center console area and around the copilot rudder pedals.  All flight control linkages, control linkage mounting points and other hardware use substantially smaller nuts.  This 7/16 inch hex nut is much larger than any others I saw being used in the cockpit area.  Maybe it came off some part of the seat; I haven't checked that.  Any idea where this nut fell from?

[KSMooniac]

Look around and behind the console or other areas where a push-pull cable might route. There are quite a few of those.

It shouldn't be anything related to flight controls... Those should be lock nuts or have cotter keys.

Sent from my LM-V405 using Tapatalk

[N201MKTurbo]

You may find that nut on the starter solenoid or the ammeter shunt.

[GeeBee]

There has got to be a lock washer somewhere.

 

[glenn reynolds]

Speaking from personal experience; I have lost a nut during a hard to access assembly and after spending ten minutes looking for said dropped nut, I'll give up and go get a replacement and finish the assembly.  This then means that some time later the darn nut shows up.  So your found nut could simply be an orphan nut that ran away during a maintenance project and has now returned.  I was just working on my engine mount bolts which are hard to see behind the panel and found my engine borescope (the vividia which connects to my ipad) to be invaluable for seeing behind the panel.  

[KB4]

Clarence would know, my guess is fell out of some mechanics pocket when he crawled under
7/16 is massive relative to the 3/8’s everywhere. Linkages behind throttle quadrant are 3/8 I believe.  It didn’t come from firewall aft. Don’t recall nuts that big on seat assembly either. 

[EricJ]

10 hours ago, N201MKTurbo said:

You may find that nut on the starter solenoid or the ammeter shunt.

Oh, that'd suck.

It might be worth snaking an endoscope up to inspect these and make sure nothing important is missing.  

[N201MKTurbo]

I checked the starter solenoid hardware and they would be either 5/16-24 or 3/8-24.

[Guest]

7/16-20 nuts are used on all the power plant control cables where they pass through the firewall.  They are plain machine nuts and normally use a plain washer and a lock washer on each side of the firewall.  Have you had any new cables installed recently?

Clarence

[carusoam]

@IslandPilot…

Check your thread…. You may have answer…

-a-