Helicopter Auxiliary Gearbox

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The following was excerpted from United States Army Materiel Command; 19800721; AMCP 706-201 CHANGE 1 ENGINEERING DESIGN HANDBOOK, HELICOPTER ENGINEERING, PART ONE PRELIMINARY DESIGN; §7-4.5

This arrangement provides independent drives to each hydraulic and electrical system when the primary engine(s) is operating or both systems are driven simultaneously by shaft power from the Auxiliary Power Unit (APU). Variants of this arrangement maybe applied to combining gearboxes, accessory boxes, or other boxes, depending upon the drive system configuration.

thank u sir.i also need some failure measures against lubricant leakage inside the gearbox.