On 8/18/2010 2:00 PM, William R. Bayne wrote: > The Ercoupe fuel system with unvented caps accepted by the CAA for use > on a production aircraft under CAR 3 in the normal category, which > vents wing tanks from the inboard end (well below the fuel level of > full wing tanks), would have been excepted from your CAR 4a.606 rule > by virtue of the engine being fed by gravity from the nose tank
CAR 4a.606 only applys to tanks from which the engine can (directly) draw fuel. The Ercoupe wing tanks are transfer tanks and do not fall under the same rules. They are not critical to flight safety. A temporary interruption in fuel flow from the wing tanks to the header tank would likely go completely unnoticed (which begs the question of whether and how often it happens...) When the header tank is removed then the regulations come into play and the wing tanks move up to the critical list. Due to the wing dihedral, there is no easy way to configure an effective vent line to connect the air spaces of the two wing tanks, hence no easy way to meet the regulations other than introducing a valve that prevents drawing fuel from both tanks simultaneously. -- John Cooper Skyport East www.skyportservices.net
