§29.979 Pressure refuelling and fuelling provisions below fuel level

(a) Each fuelling connection bel ow t he fuel level in each tank m ust have means to prevent the escape of hazardous quantities of fuel from that tank in case of malfunction of the fuel entry valve. (b) For sy stems intended for pressure refuelling, a m eans in ad dition to th e n ormal means fo r lim iting th e tan k co ntent m ust b e installed to prevent damage to th e tan k in case o f failure of the normal means. (c) The rotorcraft pressure fuelling sy stem (not fuel tanks and fuel tank vents) must withstand an u ltimate lo ad th at is 2 .0 tim es th e lo ad arisin g from the maximum pressure, i ncluding surge, that is l ikely t o occur duri ng fuelling. The maximum surge pressure m ust be est ablished wi th any combination of tank val ves bei ng ei ther intentionally or inadvertently closed. (d) The rotorcraft defuelling sy stem (not including fuel t anks and fuel tank vents) must withstand an ultimate lo ad th at is 2 .0 tim es th e load arising from t he m aximum perm issible defuelling pressure (positive o r n egative) at th e rotorcraft fuelling connection.