[Lemmingman]

I know that there is a rule of thumb about the alignment of bolts that goes something like, Top to Bottom, Front to back. Is there a preference when a bolt is set laterally across the plane?

 

[jdeas]

Out

If not defined in the drawings, threads pointing outboard

 

[David Paule]

Put the head on the higher side, if dihedral is present.

In general, the idea is that if the nut should fall of, the bolt shouldn't fall out.

Dave

 

[az_gila]

If not defined in the drawings, threads pointing outboard

..or backwards...

 

[Tom Martin]

Generally,

Threads in, towards the centre line
Threads back, towards the tail
Threads down, towards the ground

 

[Ironflight]

And remember - these aren't "laws"....they are more like "guidelines" - there are numerous exceptions (if the reasons are good).

 

[Lemmingman]

Thanks for all the answers. Is accessibility for inspection considered a good reason?

 

[Jesse]

Yes, accessibility for inspection is a great reason on some bolts. For example: on a zenith 801 there is a pushrod for the flaperons inside a channel in the fuselage with a bolt that connects it to the flaperons. I put the nut on the outboard side so I can verify it's still there and hasn't loosened during preflight. Seeing the head of a bolt has much less value on inspection than seeing the nut.

I have always heard that the threads should point inboard, but one reply is saying the same and another is saying the opposite.

 

[flion]

One consideration I use - can I put a wrench, preferably a socket, on the nut? I don't want to be holding a nut and spinning the bolt if I can avoid it.