Improving Direct Operating Cost (DOC) help please

[Bearcat F8F]

Hi guys,

I need to improve the DOC of the Fokker F27 specifically in terms of the avionics and control system (if applicable). Searching google for an exact definition of aircraft DOC is proving a bit difficult as most sites just give some formula to calculate it but don't really mention anything specifically in terms of time-scales involved.

We are told that modifications have to be cheap because of DOC. So how do I justify a new avionics suite for the F27 to improve DOC? Does it need to pay for itself in a week, a month, a year?

And the second thing is, would it be feasible to change the control system to something else (e.g. FBW) for lower maintenance costs? Again, I am not 100% by which point a modification has to pay for itself.

(P.S. I know its stupid "improving" the F27 as its obviously a century behind modern technology but nonetheless that's the little assignment I need to do).

Any info and advice welcome.

Thanks