|Quoting A319XFW (Reply 1):|
You can always tell when an aircraft with a RAT extended is coming in to land - a funny and very loud (compared to the fans) turboprop noise coming from the aircraft!
|Quoting AvionicMech (Reply 3):|
If you think it is loud when it is outside and flying, you should hear the noise it makes when you back drive it in the hangar. It is very very loud!!!
|Quoting N766UA (Reply 7):
Keep in mind most airliners do not have RATs or ADGs
|Quoting N766UA (Reply 7):|
Aircraft like the 737, for example, use windmilling of the engines.
|Quoting Kaddyuk (Reply 12):|
Negative, the B747-400 at least does not have a Ram Air Turbine.
|Quoting HAWK21M (Reply 14):
The B757 has a RAT.
If the RAT is deployed on a Scheduled flight.Its something Serious.Considering its the Last option for Hydraulics and/or Electricals depending on the Aircraft.
On the B752.The RAT provides Hydraulics,while the HMG [Hydromechanical Generator] provides Electricals.
|Quoting AvionicMech (Reply 16):
The RAT on the 757 if I remember correctly powers the Centre system whereas the HMG is powered by the Right system. But the HMG uses so much power that when testing it on the ground you need to run both the Left and Right Electric Pumps with the PTU running as well.
Photo © Peter Holzer
Photo © José Ramón Valero - Iberian Spotters
|Quoting Zkpilot (Reply 13):|
sorry you are correct, it has a quadruple hydraulic systems so that in the event that 1,2 or even 3 don't work the aircraft is still controllable by hand. Having 4 engines of course reduces the need for a RAT also plus the APU can be used for electrical power.
|Quoting ReidYYZ (Reply 18):
I remember many moons ago, in the hangar we had this very senior, very experienced certified avionic tech trying to do the backdrive check on a '57. To do the check, you need both ctr system pumps running. I don't recall the elex logic, I think C2 has priority over C1. C1 would start to run, assuming C2 is already running, only after first engine start. To cheat the system, you had to jumper some ground in the Psomethingsomthing panel in the E and E bay. That way you get both pumps and enough volume to do the backdrive.
|Quoting A/c train (Reply 19):
isnt the 757 with HMG only for ETOPS aircraft ?