Fuel Tank Drains

From Bondline

Over the years there have been several reports of incorrect fuel tank drain valves found fitted to AA5’s, which in some cases have resulted to engine failures due to water contaminated fuel, although fuel samples from the tank did not detect any. The correct p/n should be a MDI F-391-53S or the equivalent SAF-AIR SA53S. Unfortunately it is possible to install other fuel drains with the same thread but which are much longer and sample fuel from higher up in the tank thus not picking up any water from the tanks lowest point. A typical incorrect drain valve that will fit is shown below (left) together with the correct SAF-AIR drain (right) where you can see the difference in sampling hole heights. One easy visual way of detecting a commonly used incorrect valve is that the head is 11/16” with usually a safety wire hole as against the correct 3/4" head for the correct valve, see picture.