Hey guys, I have a question, I was not even sure that it's on topic since it's not about the actual chromatography process, so I'd it's in the wrong section feel free to move it.

We traditionally call the external service technicians once a year for maintainance and operational qualification of our equipment, GC, detectors autosamplers etc'.
I personally see it as a good practice in general and good preventative maintenance for sensitive lab equipment in particular.
Now a higher-up manager wants to know if this is absolutely necessary, and I, seriously, don't know an answer to that question.
Is there any manual that specifically states when external maintainance/OQ should take place?
Take in account that our analysis is ISO/IEC 17025 Accredited, is there any requirement in this standard regarding maintainance intervals?

Thanks in advance,