Hi AeroTech,
There is not big differencies btwn. 737 and 320 design and principles in mentioned qestions. Engine driven pump is cooled by case drain hydraulic flow on both, but 320 do not use fuel tanks collers (heat exchangers).Hydraulic tubing is long enough to serve as cooler during normal operation. This make 320 more sensitive to posible system trip due to fluid overtemperature, which can develop quickly due to internal leak or blockage in suction line. Remeber one case , when hose ruptured on normal system pressure in less than two minutes due to overheated fluid.
APU shroud in pressure cabin is dained to drain mast located in centre of belly fairing behind main landing gear compartement, leak monitor valve(which is normal fuel tank drain valve) is located near for leak check.
Last edited by LEVEL600; 2nd Feb 2015 at 21:14.