PurposeUSED FOR MANUALLY MOVING THE PCU INTERNAL MODE SELECT VALVE FROM BLOCKING POSITION TO BYPASS POSITION TO ALLOW PCU PISTON MANUAL EXTENSION OR RETRACTION WITH NO HYDRAULIC OR ELECTRIC POWER AT THE PCU.Airplane777-200, 777-200ER, 777-200LR, 777-300, 777-300ER, 777FUsage CodeMAINTENANCE 