Engineers working hours is an age old can of worms and unfortunately will only start to be addressed properly when an accident has occurred and engineer fatigue is proven to be a causal factor. Working hours are logged for reference by the recording of individuals on their rostered shift and then any extra hours by overtime returns. However there is no upper limit to the number of hours that can be worked within a set time and the lure of double time or extra days off can sometimes sway the most disciplined of people. We've all been there at the end of a shift, "Any chance you can stay on to get this finished?" or "We've an AOG in XYZ can you go on the next flight and deal with it?" Human factors training has raised awareness of how to identify and deal with fatigue and what might happen if you don't but it is still up to the individual to admit he or she is too tired and put the tools down. The limits on pilot working hours are a cornerstone of the way they operate, they are enforced, tightly regulated and exist through years of experience, negotiation and developing working practices. To have a similar set of rules for engineers would come at a huge cost for most organisations (shouldn't be an issue but usually is) and would entail meaningful dialogue with regulatory authorities that are actually prepared to enforce those rules.