achimha - Thankyou.
The 100 SID's are not SB's or AD's or SIL's or AC's. They are PART OF THE MAINTENANCE MANUAL. They are mandatory in the any country that uses the manufacturer as the source for maintenance data for the issue of an airworthiness certificate. Unless you maintain your aircraft under a completely different schedule of maintenance ignoring the maintenance manual then they are mandatory.
Most people think that in the US under the FAA and here in Aus under CASA that there's no obligation to do SB's. However, if you read the Manuals for most aircraft, you will find that the manuals state that the aircraft must be maintained in accordance with 'this manual' and any supporting documentation relating to this aircraft. Or something to that effect.
The point is, if you ignore an applicable SB, as an engineer, your asking for trouble.
There are many cases where litigation has found the A&P liable for not carrying out SB's on an aircraft where the owner proved the A&P should have known better and the owner was ignorant or unaware of implications.
Caution any engineer/A&P who says 'Don't worry about SB's. They're not mandatory in this country.
If any of my clients specifically ask me not to carry out an SB after they or I have found it, I get them to sign a letter stating that they are fully aware of the information and have elected not to have the work done. I also sign it, give a copy to the owner, put a copy in the logbook and keep a copy on file.