Here’s just a bot more about the RAT.
My expectation is that there is an electrical sensor attached to an electrical bus that is deemed to be an “essential” bus. This might be termed the battery bus. If that sensor determines that the voltage falls below a certain level, this triggers the deployment of the RAT. It would release an electro- mechanical device/solenoid. Am I correct? If so and if the sensor looks at the battery voltage, and if the battery voltage is OK, then the RAT does not deploy. Is that correct? But that gets to the question of the hydraulic pump’s power and the flight control actuators. Bob Ditchey From: Robert Ditchey via Mifnet <[email protected]> Sent: Tuesday, June 17, 2025 12:27 PM To: [email protected] Cc: [email protected] Subject: [Mifnet 🛰 72762] RAT, Flight Control, and Hydraulics Importance: High This question is directed to Mike Borfitz and the Mifnet pilots for possible response, which I seek. There have been a few discussions about the RAT and the Air India crash. But this e-mail pertains also to the Muan/Jegu Air crash in Korea and to the “Miracle on the Hudson” crash of “Capt. Sullie.” It is my understanding that all of the aircraft involved in these accidents have flight controls (ailerons, etc.) that rely upon hydraulic actuators to move and position the flight controls, whether or not they are “fly by wire.” In turn, the actuators depend upon electricity to function, and the hydraulic system is powered (I think) by electric hydraulic pumps, not engine driven pumps. That is also important when we consider that in the Sullie case and in the Jeju case, bird ingestion caused the engines to fail (both.) So, in these cases, I am of the belief that the RAT deployed immediately when the engines failed. And I also believe that the RAT permitted the electric and hydraulic systems to continue to function, allowing the flight controls to continue to function. (Obviously, with Sullie and Jeju, the flight controls functioned up until impact, with both engines out.) But with the Jeju case, both the CVR and FDR failed before the crash. I would guess that both the CVR and FDR are connected to the battery bus. Or else the RAT could have or should have powered the recorders. Why did the flight controls continue to function but not the recorders? I ask for some explanations from our esteemed group. If not, please send me a good link. Bob Ditchey
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