My question for Chinook drivers is, can you have a problem where you would be unsure as to the origin,either from the fuel or the hydralics?
As I said yesterday, I can think of no instances where I would be confused between hydraulics and fuel. In addition, I can think of no reason why the fuel system would cause vibrations of any kind.
Fuel tank, cross feeds, engine. Done. If there was a block in the tank the other tanks would feed the blocked engine. If there was a block in the cross feed the tanks would feed the engine on their respective side. If there was a block at the engine, I would imagine it would simply stop running. None of these scenarios should be coupled with vibrations.
Generally, vibrations on takeoff are caused by blades, shafts, or hydraulics.
Ignoring vibrations completely and I still can think of nothing which would create confusion between the two. Fuel obviously is used only for the engines and the APU. The only time hydraulics even gets close to these parts is during initial start-up. Stored hydraulics pressure gets the APU spinning and then it creates pressure to start the main engines. It is very easy to differentiate between a hydraulics problem versus fuel problem on start-up: doesn't spin, it's hydraulics; doesn't fire, it's fuel.
Clear as mud?