If the SB details an amendment to the AMM, and is supported by an authority AD, then I think you're fine in assuming that the SB overrules the AMM. But, you say it doesn't reference the AMM.
If the SB is not supported by an AD - or does not list any AMM amendment, then I'd take the most restrictive of the two to be on the safe side. Which in this case probably means write it up as a 50hr Boro until below whichever is the most severe of the SB/AMM cracking limits.
That said, I'd personally pick up the phone to the TC holder's support department - it sounds suspiciously like a left and right hand not talking properly, and maybe they don't realise there's a discrepancy and need to be aware of it. It does happen - a properly constructed SB or similar document should reference all affected parts of the AFM/AMM, but it's frightening how often this gets missed, I had the great pleasure of bouncing a load of paperwork recently back to a certain national airworthiness authority because THEY had failed to do so.
G
Hoping desperately this is no type that I'm signatory for.
On a lighthearted note, your phrasing reminds me of a scene from Reggie Perrin, where Reggie goes to Doc Morrisey complaining that his "friend" had an embarrassing medical problem.
Doc: "So you're quite sure this is your friend and not you"
Reggie: "Absolutely Doc"
Doc: "Shame, if it was you I could sign you off work for a month".
Last edited by Genghis the Engineer; 30th July 2004 at 13:34.