PurposeUSED WITH GROUND CREW HEADSET TO TEST B3131003 AMP. IF AIRPLANE POWER HAS BEEN REMOVED FORM AMP, TEST SET CAN BE USED TO SUPPLY REQUIRED 28VDC, EITHER BY CONVERTING AVAILABLE 105-125VAC 47-420HZ POWER OR BY CONNECTING AN INDPENDENT 28VDC POWER SOURCE.Airplane787-10, 787-8, 787-9Usage CodeMAINTENANCE 