If you mean can an IPT make groundcrew sign off a short term problem such as a fuel leak in theatre.....then absolutely not, and I dont think that they would. Its upto the engineering team in theatre to sort those types of problems out. They are guided and governed by their maintenance manuals and APs and cannot just come up with a quick fix.
Sure they can call on as much advice and technical expertise as they want but no one can make them sign off the jet as serviceable. If there is any doubt on a safety critical system to make the ground crew in any way shape or form doubt its integrity, the ac is going nowhere. Knowing the vast majority of guys at ISK and being proud to have worked alongside them, I can say that with confidence.
An IPTs job is to provide recovery action and logistical support for longer term issues generally, they cannot get involved with short term snags. Thats the job of NLS. If those short term problems display patterns and regularity, then it is the job of the IPT to investigate and correct/monitor/recover. Not to be a 1000 yard screwdriver to situations they are not all that familiar with (ie on ops).
Does that answer your question TD?