I tend to agree with Prismatic's POV.
What is more important is the risk to personal health.
I think it is a very undesirable attitude to say that if it is not within my "job scope", it is not my duty. I would go the further mile, and help my company in anyway I could. But if climbing a crane can endanger my health, then I would point out the problem to my boss.
Years ago, I took up a job in Jurong in a textile factory. My job scope was to flatten frabic to a certain specification. But I took on carpentry work, electrician work, washing, cleaning, and helping others in their various duties such as color assessment etc. I did all these extras for free. Within 4 months I was offered a job as foreman. I did not take up the offer, and went to NUS (US those days). In retrospect, I should have taken up the job. I might have been a very successful businessman today!
As far as doing things out of your scope, I say, do it! If it does not damage your health.