Need advice navigating a new job

[engineheat]

I work at a global company as a manufacturing engineer. My job entails improving the production efficiency of a high impact new production line they are bringing in and minimizing scraps. It's the most complex line at my current plant. I was hired for that line due to my technical background and also my foreign language skill which would be an asset in dealing with suppliers.

Another colleague (alias David) working in a different but related role is taking a long time off (1 year) and wants others to take over his tasks.

My manager spoke with another colleague (alias Tom) who is in my role (but responsible for another production line) but started 6 month earlier than me, to see if he's interested. Tom declined, saying it doesn't fit into his career goals. Then my manager asked me if I'm willing. Being new, I didn't want to flat say no, I merely said I will talk to the guy who is leaving to understand his job more.

Honestly, this first month has been all training (mostly corporate related stuff) and I haven't even started my "real" work yet. But I know what I need to do because my company gives each person a "list of task" that they'll be judged on each year. I got mine, and I'll be needing to put in more than 40 hours a week.

I talked to David today and he showed me a list of tasks that he's finding successors for. I mentioned I can help with one or two of them, only because the knowledge gained will help my own work. There was a couple of other tasks that he wants me to do, but I told them it's not in my interest area and I don't feel I can fit in my schedule, that it may adversely affect my performance, etc. He seemed a bit frustrated and implied that I'm "cherry picking" tasks, and that "sometimes one has to do certain tasks even if they are not interesting."

Um, no. That's not what I was hired for and I already got a full plate. My own work is just as important to the company if not more. The fact that he's seems more aggressive than my manager on pushing his work on me made me even less willing to take on his tasks. We are on the same level as far as reporting structure goes.

What should I do? Doing his work is not a promotion and I won't get paid more.

[capt bullshot]

Keep your current position.