Rivet information

[clun]

I'm trying to determine the characteristic of the rivet in a nose cowl of a RR-524 engine. The Part no. of rivet is SP157U-40. From the Engine-IPC, I know that the "SP" is stand for British Standard Institute, so what does the letter "U" means in here?
Does anyone could share your experience with me?

Thanks a lot.

 

[rikman]

Hi Clun,

I've worked on several of the RB211 engine nacelles and I think that the callout you have may be a typo - there is no 'U' callout on the (admittedly abbreviated) spec sheet that I have for SP157 and I'm not aware of a separate SP157U specification. Normal callout would be SP157-40[-R if required]. Since the SP157 is a universal headed rivet, this may be where the 'U' came from.

SP157 has been superceded in any case, so you could look for the equivalent MS20470AD spec that was the direct replacement.

Hope this helps,
Rikman