IIRC do the hydraulic pipes not go through the ceiling rather than the floor in the 747? I thought that was why the crew were so concerned about hydraulic loss during UAL811...
Also, I think that JAL123 and UAL232 caused the development and retrofitting of fuses to the hydraulic systems in passenger transport. The DHL A300 was built in '79 so may not have been modified in this manner. Having said that it lost a lot more than a wingtip.