Text in force at CS27-10: from CS27-0, effective 14 Nov 2003.
Each oil tank must be designed and installed so that it can withstand, without leakage, an internal pressure of 34 kPa (5 psi), except that each pressurised oil tank used with a turbine engine must be designed and installed so that it can withstand, without leakage, an internal pressure of 34 kPa (5 psi), plus the maximum operating pressure of the tank.
ED Decision 2003/015/RM · Source