High-Efficiency Hydraulic Power Transfer Units for Multisystem Aircraft

Many contemporary aircraft requiring multiple hydraulic systems for power redundancy have utilized hydraulic power transfer units to provide that service. These units, which are commonly called reversible motor pumps (RMPs), have been heavy, noisy and inefficient with generally very poor differential pressure startup characteristics. A new-generation RMP that has solved many of these problems has been developed for the Douglas DC-9 Super 80 Series aircraft. The new unit emits significantly less noise than existing comparable units and is both weight- and cost-competitive, with excellent startup and running characteristics. It will provide an excellent means of attaining pumping redundancy in future hydraulic system configurations.