Boeing 777 Ram Air Turbine (RAT) function test

[@mrifixplanes1813]

Hi Corey, I can't reply to your message directly for some reason. This isn't a propeller no, it's a turbine, meaning that air moving past it makes it spin. In certain emergencies, pretty bad ones at that, this can be deployed into the airstream and it spins as the air passes over it. As it spins it drives an electrical generator, just the same as a wind turbine in a wind farm on the ground. The electricity it makes can be used for the essentials, flight instruments and flight controls. Although they are massive and heavy, an airliner can still glide for a while if the engines stop working. Not as good as a glider, but from 35,000ft something like 60-100 miles as a rough guess. It also has a small hydraulic pump attached to it too, which is also used to move the flight controls. Like I said, it's a really bad day if you're relying on the RAT for electricity and hydraulic power. This video shows a test of the RAT, instead of air moving past it, we make it spin using hydraulics to test the generator essentially. Thanks for watching.

[@黃爾均]

MrIfixplanes 愛

[@mrifixplanes1813]

If you mean blow air over the blades then no. The RAT has an hydraulic pump for emergencies, but if we pump fluid through that pump, it acts like a motor turning the blades so we can test the electrical generator. There's more detail in the description, hope that answers your question, thanks for watching.

[@AviationNZ]

Thanks for sharing and the explanation! Learned something new today!

[@birrymcg]

It's actually the 777's back up engine. XD

[@birrymcg]

@British Airways Boeing 747-436, I appreciate your expertise on the subject. Please learn to recognize when someone is joking, even if you don’t find the joke funny. Cheers.

[@boeingb-17g18]

Haha, Engine go brrrrrrrrr

[@KandiKlover]

i learned about this on discovery channel so long ago, or nat geo i forget, one of those aircraft disaster shows, back when they used to show good stuff listen to the sound btw, good demostration of the technology behind old mechanical air raid sirens

[@Tigerkos]

I just didn't know how it was you turned it. Thanks for the explanation and the great video!

[@ivormectin515]

What is the power output of the generator, and what is the operational airspeed range for this RAT?

[@joelwirz4746]

after beeing deployed, can the rat be retracted in the air after the apu kicked in or does it have to be done manually on the ground? I'd see the main problem in adjusting the propeller so that it fits back in.

[@mrifixplanes1813]

The RAT has to be manually retracted on the ground using the RAT stow handle that is located in the wheel well. Before stowing the RAT you manually turn the turbine blades to align two marks. As the RAT is retracting into the fuselage a pin extends from the RAT strut and goes into a hole in the back of the turbine hub, locking it into position. If the turbine isn't aligned and the pin stops short because it doesn't go into the hole then the retraction stops. This same locking pin stops the turbine blades being spun by the airflow before the RAT has fully extended, so they don't make contact with the fuselage or RAT compartment door.

[@PowerFR2]

but on the a320, i see a video where the RAT retracted by self..?

[@kratos6363]

Music to my ears

[@boeingb-17g18]

So, if the RAT can rotate with enough airflow, then how the hell is it spinning with no wind? Some sort of motor or like a unpowered DC motor that generates electricity when you hand crank it.

[@mrifixplanes1813]

The RAT has a hydraulic pump, to test the RAT that pump is back driven using the aircraft's other hydraulic pumps, essentially turning it into a motor. By motoring the RAT it is fair to say the hydraulic components are working satisfactorily and without leaks. The output from the electrical generator is also checked during motoring.

[@boeingb-17g18]

@@mrifixplanes1813 Ooohh ok that makes sense.

[@mohamedsalih3487]

the hydraulic pressure and return line Connect directly to the rat or the center hydraulic ground connection????

[@mrifixplanes1813]

If you are going to use an external hydraulic ground cart, you would connect it to the centre hydraulic system ground connection. We use the aircraft's air driven pump to pressurize the centre system, we connect an air start cart to provide the air for the air driven pump.

[@Tigerkos]

Are you using the Huffer to blow enough air to test it?

[@patrickharris3194]

This drops from the bottom of the airplane automatically if you lose both engines (meaning you have no hydraulic or electrical power generated any longer by the engines). the airplane glides through the air and that turns the propeller on the RAT which turns a small electrical generator and a small hydraulic pump. The hydraulics are most important because that is what is used to move the flight controls, no hydraulics means no control of the airplane by the flight controls. All the RAT does is buy you some time to try to get the engines running again, of find someplace to put the airplane down.

[@mrifixplanes1813]

The electrical output is just as important on the 777, it's a fly by wire airplane, no electrics, no control.

[@d.markdetrixhe3367]

+MrIfixplanes And key word being control. A biggie. No fly by wire can be controlled without electrical power. On a cable controlled MD80, you can turn off everything included the battery switch and it Flys fine. Thanks for a great video!

[@ROTAXD]

Why test it with a start cart instead of just having the pilot deploy it during the next flight ?

[@wwommy]

It could break too and imagine if it broke on the flight it was being tested on and then was later needed

[@driftliketokyo34ftw35]

This sounds better than the new F1 engines. That should not be the case.

[@Nyck461]

In this test, is this turbine driving a hydraulic pump or the hydraulic pump is driving the turbine? I don't see any kind of air blowing the turbine to make it spins. At what speed (RPM) this RAT is moving? Is it optional to the pilot makes the RAT to move a hydraulic or electric generator or it is already set to a specific equipment?

[@mrifixplanes1813]

Nyck461 Nyck461 We're using the hydraulic pump as a motor by passing hydraulic fluid through it. The RAT spins at 3900-4500RPM, in the air this is accomplished by the RAT having variable pitch blades. In the air the RAT provides centre system hydraulic pressure and limited electrical power which is used for primary flight displays and the electro-hydraulic servo valves on the flying control actuators.

[@christaylorchristaylor]

Was that BA

[@Geo001yt]

Actually when i was on a flight to Los Angeles on the 777-300ER the whole plane lost its power then they had the Ram Air Turbine go off

[@mrifixplanes1813]

Interesting, after a quick bit of research there has been some issues in the power distribution panels,, thankfully most of these have happened on the ground because only one ground power connector was plugged it. Couldn't find anything on the particular flight you mentioned, I would have been interested to find out more about it.

[@tickyul]

Badass, can I install one on my Yugo?

[@mohamedsalih3487]

It is Spin by Hydraulic pressure instead of air...??? how???

[@mrifixplanes1813]

The RAT has a hydraulic pump to give hydraulic pressure to most of the flight control surfaces if there's no other source available. To test the RAT that pump is back driven using the aircraft's other hydraulic pumps, essentially turning it into a motor. This is done by operating a handle on the RAT checkout module that is located in the right wheel well/bay. By motoring the RAT it is fair to say the hydraulic components are working satisfactorily and without leaks. The output from the electrical generator is also checked during motoring.

[@mohamedsalih3487]

this mean the hydraulic pump work like motor actuated by Hydraulic to drive the Rat??

[@mrifixplanes1813]

Mohamer Salih Yes

[@martman7796]

It may be confusing as in a workshop situation in a hangar, and cost you can not deploy wind past the RAT at 130 mph plus to test it. The engineers test it by using the aircraft hydraulics and systems in reverse to test it. So the YT video shown is not how it actually works. When deployed in an emergency airflow past the turbine blade generates power to the 777 central hydraulic system and limited electrical power for essential systems.

[@mohamedsalih3487]

U say there is Rat check lever what is this

[@TheMan1510]

Reminds me of a trolling motor, lol.

[@mrifixplanes1813]

You're very welcome.

[@Bandicoot803]

The RAT couldn't help UA232, don't blame it.

[@Trashie01]

Apu? I am good with a-7 corsair because what is a teen to do when bored? Learn. I don't know what it is it being apu

[@mrifixplanes1813]

Auxiliary Power Unit, a small gas turbine engine that is in the tail of most airliners that can supply electricity and pneumatic air to the aircraft.

[@seymaaydn6712]

Perfect thanks 👍👍

[@Cblome3]

INCOMING STUKAAAAA