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When the Boeing 787 operates on autopilot, its sophisticated flight control system manages the flaperons to maintain stable flight, particularly during turbulence. The system continuously receives data from various sensors, including airspeed indicators, inertial navigation systems, and accelerometers. When turbulence is detected, the autopilot system automatically adjusts the position...

417,221 次观看 • 1 年前 •via X (Twitter)

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What is the RAT? The RAT is a small wind turbine stowed within the aircraft fuselage and deployed automatically when certain failure conditions are met. Once extended into the airstream, it uses the forward motion of the aircraft to spin and generate power—mechanical, hydraulic, or electrical. Primary Functions of the RAT on the 787-8 1. Hydraulic Backup Power On deployment, the RAT drives a variable displacement inline hydraulic pump. It pressurizes the center hydraulic system, enabling continued operation of critical flight control surfaces such as the ailerons, elevators, and rudder. This is vital in maintaining aircraft controllability if normal hydraulic sources are lost. 2. Supplementary Electrical Power While the RAT is primarily a hydraulic power source on the 787-8, it can also, in some configurations, drive an emergency generator. This generator provides sufficient AC and DC power to support essential avionics, flight displays, and communications systems. Deployment Scenarios: When Does the RAT Automatically Deploy? The RAT on the Boeing 787-8 deploys automatically—without crew input—under the following emergency conditions: 1. Dual Engine Failure If both engines fail, resulting in the loss of engine-driven electrical and hydraulic generation, the RAT deploys to maintain critical flight control power. 2. Complete Electrical Loss to Flight Instruments If there’s a total loss of electrical power to both the captain’s and first officer’s primary flight instruments, the RAT ensures these systems remain powered. 3. Low Pressure in All Three Hydraulic Systems If all three systems—Left, Center, and Right—lose hydraulic pressure, the RAT provides emergency hydraulic power through the center system. 4. EMP Failure + Engine Loss During Takeoff or Landing If all four Electric Motor Pumps (EMPs) fail and an engine fails during takeoff or landing, the RAT deploys to sustain flight control power during these critical phases. Automatic and Autonomous Operation One of the RAT’s key advantages is its fully autonomous activation. Pilots do not need to manually deploy it; the system is designed to react immediately to predefined failure logic, reducing workload and ensuring flight-critical systems remain powered. In Summary The Ram Air Turbine (RAT) on the Boeing 787-8 is not just a backup—it's a lifesaving last resort. It deploys automatically to supply hydraulic and limited electrical power when all other power sources fail. Designed with layered redundancy in mind, it is one of the unsung heroes of modern aircraft systems, ensuring that even in worst-case scenarios, pilots retain control to guide the aircraft—and its passengers—safely to the ground.

Turbine Traveller

293,307 次观看 • 1 年前

Following the Airbus A320 emergency airworthiness action, everyone will be talking about the ELAC (Elevator Aileron Computer) manufactured by Thales, which caused a sudden pitch-down without pilot input on JetBlue 1230 back in October. So here’s everything you need to know about ELAC. The ELAC System in the Airbus A320: The Brains Behind Pitch and Roll Control At the heart of the sophisticated fly-by-wire flight control system of the Airbus A320 lies the ELAC (Elevator Aileron Computer). This crucial component acts as one of the primary computational units that translate pilot commands into precise movements of the aircraft’s fundamental control surfaces: the elevators and the ailerons. ELAC plays a pivotal role in ensuring the aircraft’s stability and enabling smooth, safe, and efficient flight. What is ELAC? ELAC stands for Elevator Aileron Computer. On the A320, there are two main ELAC computers—ELAC 1 and ELAC 2—which operate together as essential elements of the aircraft’s fly-by-wire architecture. This system relies on electrical signals, rather than traditional mechanical cables, to transmit control inputs from the cockpit to the flight control surfaces. Key Functions of the ELAC System: Elevator Control: The elevators are control surfaces located on the horizontal tailplane of the aircraft. They govern movement around the lateral axis (pitch), determining whether the aircraft ascends or descends. ELAC receives signals from the pilot’s sidestick and translates them into precise commands to move the elevators, achieving the desired pitch attitude. Aileron Control: Ailerons are control surfaces situated on the trailing edge of the wings. They manage movement around the longitudinal axis (roll), controlling the aircraft’s banking to the left or right. The ELAC processes pilot inputs and moves the ailerons to achieve the intended bank angle. Implementing Flight Control Laws: One of ELAC’s most critical responsibilities is enforcing the pre-programmed flight control laws embedded within the Airbus computers. These laws ensure the aircraft responds to pilot commands in a calculated and safe manner, providing protection against maneuvers that could exceed operational limits (such as overspeed or critical angles of attack). Fault Monitoring and Redundancy: The ELAC system includes a high degree of redundancy to ensure safety. If one ELAC computer malfunctions, the other can seamlessly take over. ELAC also continuously monitors the performance of control surfaces and associated systems, issuing warnings to the crew if any anomalies are detected. ELAC 1 and ELAC 2: Distribution and Responsibility ELAC 1: Primarily controls the ailerons and certain elevator functions, especially those relying on the blue hydraulic system. ELAC 2: Primarily controls the elevators and the Trimmable Horizontal Stabilizer (THS), utilizing the green and yellow hydraulic systems. Info via Ashraf Yehia, Aircraft Structure Repair Engineer/LinkedIn.

Turbine Traveller

486,691 次观看 • 7 个月前