Thread size - bulkhead bracket front wing

[Phil Maddox]

Hi all,
Does anybody know what the thread size/ type is for the bolts that hold the wing onto the bulkhead bracket ( see pic)?. I thought it was 1/4 BSF but I have tried a new bolt and it binds up a couple of turns in.
Thanks in advance.

 

[mystery]

1/4 UNF

 

[Phil Maddox]

1/4 UNF

Thanks for the prompt response. Cheers