Text in force at CS25-28: from CS25-0, effective 17 Oct 2003.
(a) Drainage of the fuel system must be accomplished by the use of fuel strainer and fuel tank sump drains.
(b) Each drain required by sub-paragraph (a) of this paragraph must –
(1) Discharge clear of all parts of the aeroplane;
(2) Have manual or automatic means for positive locking in the closed position; and
(3) Have a drain valve –
(i) That is readily accessible and which can be easily opened and closed; and
(ii) That is either located or protected to prevent fuel spillage in the event of a landing with landing gear retracted.
ED Decision 2003/002/RM · Source