CS 29.975 Fuel tank vents and carburetor vapour vents

• ED Decision 2003/16/RM found in: CS-29 Amdt 10 - Large Rotercraft (Jan 2023)

CS 29.975 Fuel tank vents and carburetor vapour vents ED Decision 2003/16/RM (a) Fuel tank vents. Each fuel tank must be vented from the top part of the expansion space so that venting is effective under normal flight conditions. In addition: (1) The vents must be arranged to avoid stoppage by dirt or ice formation; (2) The vent arrangement must prevent siphoning of fuel during normal operation; (3) The venting capacity and vent pressure levels must maintain acceptable differences of pressure between the interior and exterior of the tank, during: (i) Normal flight operation; (ii) Maximum rate of ascent and descent; and (iii) Refuelling and defuelling (where applicable); (4) Airspaces of tanks with interconnected outlets must be interconnected; (5) There may be no point in any vent line where moisture can accumulate with the rotorcraft in the ground attitude or the level flight attitude, unless drainage is provided; (6) No vent or drainage provision may end at any point: (i) Where the discharge of fuel from the vent outlet would constitute a fire hazard; or (ii) From which fumes could enter personnel compartments; and (7) The venting system must be designed to minimise spillage of fuel through the vents to an ignition source in the event of a rollover during landing, ground operations, or a survivable impact. (b) Carburettor vapour vents. Each carburettor with vapour elimination connections must have a vent line to lead vapours back to one of the fuel tanks. In addition – (1) Each vent system must have means to avoid stoppage by ice; and (2) If there is more than one fuel tank, and it is necessary to use the tanks in a definite sequence, each vapour vent return line must lead back to the fuel tank used for take-off and landing. CS 29.975 Fuel tank vents and carburetor vapour vents ED Decision 2003/16/RM (a) Fuel tank vents. Each fuel tank must be vented from the top part of the expansion space so that venting is effective under normal flight conditions. In addition: (1) The vents must be arranged to avoid stoppage by dirt or ice formation; (2) The vent arrangement must prevent siphoning of fuel during normal operation; (3) The venting capacity and vent pressure levels must maintain acceptable differences of pressure between the interior and exterior of the tank, during: (i) Normal flight operation; (ii) Maximum rate of ascent and descent; and (iii) Refuelling and defuelling (where applicable); (4) Airspaces of tanks with interconnected outlets must be interconnected; (5) There may be no point in any vent line where moisture can accumulate with the rotorcraft in the ground attitude or the level flight attitude, unless drainage is provided; (6) No vent or drainage provision may end at any point: (i) Where the discharge of fuel from the vent outlet would constitute a fire hazard; or (ii) From which fumes could enter personnel compartments; and (7) The venting system must be designed to minimise spillage of fuel through the vents to an ignition source in the event of a rollover during landing, ground operations, or a survivable impact. (b) Carburettor vapour vents. Each carburettor with vapour elimination connections must have a vent line to lead vapours back to one of the fuel tanks. In addition – (1) Each vent system must have means to avoid stoppage by ice; and (2) If there is more than one fuel tank, and it is necessary to use the tanks in a definite sequence, each vapour vent return line must lead back to the fuel tank used for take-off and landing. #### CS 29.975 Fuel tank vents and carburetor vapour vents *ED Decision 2003/16/RM* (a) *Fuel tank vents.* Each fuel tank must be vented from the top part of the expansion space so that venting is effective under normal flight conditions. In addition: (1) The vents must be arranged to avoid stoppage by dirt or ice formation; (2) The vent arrangement must prevent siphoning of fuel during normal operation; (3) The venting capacity and vent pressure levels must maintain acceptable differences of pressure between the interior and exterior of the tank, during: (i) Normal flight operation; (ii) Maximum rate of ascent and descent; and (iii) Refuelling and defuelling (where applicable); (4) Airspaces of tanks with interconnected outlets must be interconnected; (5) There may be no point in any vent line where moisture can accumulate with the rotorcraft in the ground attitude or the level flight attitude, unless drainage is provided; (6) No vent or drainage provision may end at any point: (i) Where the discharge of fuel from the vent outlet would constitute a fire hazard; or (ii) From which fumes could enter personnel compartments; and (7) The venting system must be designed to minimise spillage of fuel through the vents to an ignition source in the event of a rollover during landing, ground operations, or a survivable impact. (b) *Carburettor vapour vents*. Each carburettor with vapour elimination connections must have a vent line to lead vapours back to one of the fuel tanks. In addition – (1) Each vent system must have means to avoid stoppage by ice; and (2) If there is more than one fuel tank, and it is necessary to use the tanks in a definite sequence, each vapour vent return line must lead back to the fuel tank used for take-off and landing.