A series of tests on some of these fuel systems was undertaken. Aircraft were tested in the field under real world conditions to determine how much water would be retained in the tanks after compliance with the manufacturers recommended methods of draining the system before flight. To date no aircraft has met the requirements of the regulations for fuel system design. All aircraft tested fail to meet the drain requirements of CAR 3.553, CAR 3.444 (c), FAR 23.971 (b), or FAR 23.999. Some fail to meet the venting, draining of compartments, and isolation requirements as well.

Aircraft tested to date are:

Cessna 177
Cessna 206
Cessna U206
Cessna T207
Cessna 182
PA-24-250
PA-23-150

In all cases excess water was retained in the tanks after intentional introduction of water into the tanks through the regular filler neck. The water was dyed for easier sighting and positive collection before introduction. In one case, as much as a gallon of water remained in the aircraft tanks after compliance with the Owner's Manual procedures for pre-flight. In all cases extraordinary methods for removal did not find and purge all the water from the systems.

Several 210 aircraft of varying vintages have been examined, post crash, and were found to have had water in excess amounts in the fuel system prior to the crash. This applies to those aircraft with integral tanks as well as those equipped with bladder tanks.