Ram Air Turbines

[Ericgkl]

Anybody know what is required to test one of these? Is there a test stand out there we can be used to test these components or do we need a wind tunnel together with a specialize test stand?

[Dizzee Rascal]

I had a CL604 depart the other day just to test the RAT. When it landed, the RAT was still deployed.

[TURIN]

I think most big jets have a test function backdrive mechanism that reverses the hydraulic/electric motor to drive the RAT. :ok:

[NSEU]

Correct. The designers seem to think that if aircraft hydraulics can backdrive the fan, then the fan (in the slipstream) can drive the aircraft hydraulics :)

[subsonic69]

which aircraft is it ???

cause i have seen some MD11 guys use an air start motor and a huge gun like funnel for the air to turn the RAT

[Ericgkl]

Hmm. But before it leaves a workshop, does it undergo any form of testing?

[TURIN]

Like this you mean?

Sunstrand RAT Wind Tunnel (http://www.aerosysengr.com/Wind_Tunnels/WTProducts/Design_Build/design_build.html)

[mafibacon]

In a previous operation I was involved in that operated 2 CL604 aircraft, we would deploy the RAT prior to landing before a maintenance check.
Special work sheet to confirm everything OK signed by commander.
RAT (CL604) is subject to NDT on blades after deployment. With is done the Rat was stowed ready for use.
No great shakes really.
MB

[mitzy69]

To test the RAT on a VC10, just an electric generator, so no hydraulic backdrive, a diesel engine driving a fan on a trolley was supplied which was put in front of the lowered RAT blades, and with lots of noise it just about got the RAT up to frequency and supplied power.
On later aircraft and with H.and S. the back driven RATs had to have a shield/cover over the spinning blades, which was not very well made locally, Boeing one being to expensive to buy, the blades hit the the shield
and wrecked them. Another case of penny wise pound foolish.

[tristar 500]

As far as I remember on the 757 & 767 you could back drive the RAT from the hydrualics.

The M.M. gave you the figures to watch for.

On another point I have to say I went on several test, pre delivery flights where one of the tests was the RAT. I was very inpressed to observe the main Hydrualics turned off with zero pressure on the EICAS screen, the RAT deployed & flying the Lambourn hold on the autopilot with no problems of any sort.

tristar500

[cessna24]

On the A320's, there is a cage to go around the RAT and there is an external hydraulic power supply which drives the RAT. Then you can set up a control panel and control the speed.
Not much info im afraid. It was awile ago since I last did it.

c24

[subsonic69]

cessna.. no speed control.. but the others are correct.

[grababadger]

Iv'e done this test in a hanger on an a320, what happens is the Rat is covered with a cage and then an external hydraulic rig is connected to the aircraft to drive the RAT, then the blue pump is selected on and the test is to see whether the RAT supplies the hydraulic pressure required (2500-3000psi).

[HESMADSIR]

There is a touch more than just putting the blue system on, there is also the check to see the correlation between flow/speed and pressure and remember at the end of the test make sure you do not empty the blue system reservoir, its very easy to do and a tad embarrassing when the a/c goes back to the line with blue system empty DOH!! :O

[prattgamco]

RAT spin test on A320,A330,A340/300/500/600,we use external hydraulic motor that spins RAT hydarulic pump.but it requires external hydraulic power generator.believe me it's risky.once the rat blade sheared and damaged the wing structure.
In B777 we dont need external motor and power generator.it has rat check out module where we can reverse fluid direction so the rat hyd pump acts as motor.in this case we have to pressurize centre system with ADP to meet high flow demand.