Here is a tool that every crew chief should take to the starting line with them. It is a alum. adjustable crescent wrench with a Dzus fastener driver on the end.
With this tool in hand if the engine is started and there is a leak this will allow you to tighten from a -6 fuel line to a -16 oil line without damaging the fitting or having to carry a big heavy steel crescent wrench.
The wrench is made from billet alum. so it weights almost nothing and is plated for corrosion protection.