Aircraft petcock lock

A lock apparatus for precluding operation of petcocks operable by longitudinal movement of a valve stem, said lock apparatus comprising in combination:

• (a) a housing for receiving a segment of the valve stem to preclude movement of the valve stem with respect to the petcock, said housing including a base apertured to penetrably receive the segment which is either a valve stem having a cross arm or a valve stem having a button disposed proximate the end thereof;
• (b) means for restraining withdrawal of the received segment;
• (c) a ring rotatable within said housing for actuating said restraining means in response to rotation of said ring relative to said housing, said ring including a pair of diametrically opposed depressions for receiving opposed ends of the cross arm to locate the cross arm out of alignment with the aperture of said base upon relative rotation between said ring and said housing after penetration of the cross arm through said base, said retaining means including laterally displaceable spring elements for interferingly retaining the button and lugs for repositioning laterally said spring elements upon rotation of said ring relative to said housing after penetration of the button through said base.