There are a number of issues of the flight manual but for the two aircraft that I have owned there was a warning that fuel flow from the main tank was not assured in the climb attitude when the low quantity warning was illuminated, the first aircraft I had was a DR400-140 with only the main tank fitted, my current aircraft (DR400-180) has the same warning in the flight manual but no limitation in which tank to use for take off and landing, I would send you a copy but the FM is in the aircraft, not at my desk.
You are correct about the nose wheel centering mechanism being mechanical but it operates as a function of nose leg extension and is engaged at the last 20mm or so of leg extension.
So if the nose gear is extended to far, ether by being over extended by over pressure in the nose leg or under pressure in the main gear legs then this will effect the disengagement of the centering lock.
Unfortunatly this is not a simple matter of air pressure in the legs as the oil level in the legs is critical to getting the correct rising spring rate from the leg and therefore the correct ground attitude for the aircraft to ensure that the centering lock disengages when it should.
To get the legs set up correctly you will have to jack the aircraft free of the ground and check and adjust the oil level in the legs before pressurizing the leg to the correct pressure for the variant.
It is essential to understand that just pumping up the air in the leg to get the correct extension is useless without the oil level being correct as this will not provide the correct rising spring rate.
Last edited by A and C; 26th Dec 2012 at 08:34.