What is the principal aerodynamic function of the turbine exhaust nozzle and exhaust plug working together?, The nozzle controls the inner boundary of turbine exhaust flow while the plug controls the outer boundary and fan-air flow., The nozzle and plug define the outer and inner boundaries of turbine exhaust flow so exhaust-gas velocity is increased to contribute to engine thrust., The nozzle redirects turbine exhaust forward during reverse thrust while the plug maintains the normal aft-flow path., With the thrust reverser translating sleeves fully deployed, what combination of blocker-door and cascade operation produces reverse thrust?, The blocker doors close the normal fan-duct path and the exposed cascade segments redirect fan exhaust radially and forward., The blocker doors remain open while the translating sleeves redirect turbine exhaust through the cascade segments., The blocker doors close the cascade openings while fan exhaust is redirected through the turbine exhaust nozzle., Why do the three hydraulic actuators on each thrust reverser half require synchronization even though each actuator receives hydraulic pressure from the same control system?, The actuators are mechanically independent, so the flexible synchronization shafts force their drive mechanisms to rotate together and maintain equal linear sleeve movement., The actuators operate at different hydraulic pressures, so the synchronization shafts regulate pressure between the upper, middle and lower units., The upper actuator normally moves first, so the synchronization shafts delay the other actuators until its lock has released., Different cascade segments may be fully open, fully blocked or partially blocked. Why must the specified segment effectivity and position be maintained?, The cascade configuration determines hydraulic actuator loading and therefore controls translating-sleeve deployment speed., The different vane configurations tailor reverse fan airflow to avoid adverse effects such as fuselage impingement, flight-control interference, excessive cabin noise and foreign-object damage., The blocked segments provide the mechanical stops that prevent the translating sleeve from exceeding its full-deploy position., During thrust reverser deployment, why is hydraulic pressure supplied to both sides of the actuator piston rather than only to the head side?, Equal pressure acts on unequal piston areas, creating a net extension force while rod-side pressure also helps control actuator deployment speed., Equal pressure removes all actuator force so the synchronization shafts alone can move the translating sleeves aft., Head- and rod-side pressure alternates rapidly so the internal actuator locks can disengage without sleeve movement., Why does the thrust reverser deployment sequence include an approximately 100-millisecond delay before hydraulic deployment pressure is enabled?, It allows the locking hydraulic actuators to reach full extension before the translating sleeves start moving., It allows the Electronic Engine Control to verify that both sleeves are already more than 60 percent deployed before opening the hydraulic isolation valve., It gives the synchronization locks time to electrically unlock before hydraulic pressure attempts to move the actuators and synchronization shafts., During stowage, the reverse thrust lever has returned to the forward idle region and the translating sleeves are moving forward. Why are the synchronization locks and hydraulic isolation valve kept enabled for approximately ten seconds?, The delay maintains the required hydraulic and mechanical freedom for the sleeves to complete stowage and allows the actuator locks sufficient time to re-engage., The delay maintains reverse thrust until the aircraft has decelerated below the rejected-takeoff speed threshold., The delay keeps the deploy solenoid energized so deployment pressure remains available if either sleeve stops before reaching full stow., Hydraulic system A becomes unavailable while thrust reverser 1 requires hydraulic operation. How is backup hydraulic power provided, and what system-specific characteristic exists during subsequent stowage?, Hydraulic system B automatically cross-connects directly to thrust reverser 1 through the directional control valve with no fluid transfer between reservoirs., The standby hydraulic system can supply thrust reverser 1 through shuttle valves, and fluid can subsequently transfer from the standby system into hydraulic system A during stowage., The standby hydraulic system operates only the synchronization locks while the thrust reverser actuators remain supplied by trapped hydraulic system A pressure., The engine indication display shows an amber REV message for one engine. What thrust reverser condition does this most accurately represent?, The translating sleeves are fully deployed but one internal actuator lock has not released., The translating sleeves are fully stowed but hydraulic pressure remains in the thrust reverser control valve module., The translating sleeves are between the fully stowed and fully deployed positions., A REVERSER LIMITED light illuminates on the ground after the thrust reverser has completed a normal stow cycle. Which condition could independently generate this indication?, Loss of a synchronization lock function, actuator-lock proximity sensor input or locking-actuator position indication., A normal hydraulic isolation valve pressure indication above approximately 750 pounds per square inch during commanded deployment., Both translating sleeves reaching full deployment before the reverse thrust lever moves beyond reverse idle.

ATA 78

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