Details of Report
The C 172 S taxi checklist calls for the fuel selector to be positioned in both the left and right and then both positions as part of the start/taxi/runup/pretakeoff checks This check is supposed to be to ensure that fuel is feeding from both tanks. However since all fuel that goes to the engine comes from the reservoir tank you would have to run for over 1/2 hour on the ground and on each tank to actually determine the tank is feeding. This check accomplishes nothing and opens a human factor risk of taking off with the selector not on the both selection
Since this check 1) Is not required by the POH 2) Accomplishes no meaningful action 3) Provides an opportunity to take off in an unsafe condition I recommend that the checklist be amended so that the fuel selector remains in the both position for all checks
14-0016 New checklist have been developed and installed into the aircraft. Safety report 14-0016 is closed 2015-04-23.