All Systems Failure...

khenleydia · Sat Feb 19, 2005 1:41 am

Years ago and on a.net I have read about a propeller (or something) that drops down into the slipstream to provide partial hydraulic pressure for a plane that has lost all of it.

Which planes have that feature? Any pictures?

KhenleyDIA

foxecho · Sat Feb 19, 2005 1:43 am

Sounds like a RAT- Ram Air Turbine....

I would think any aircraft with a 'glass' cockpit has it

Andrew

khenleydia · Sat Feb 19, 2005 1:53 am

I believe it was a 767 that ran out of fuel and landed on an old runway or race track. I believe that had it, but that old a 767 didn't have a glass cockpit.. Did it?

KhenleyDIA

stealthpilot · Sat Feb 19, 2005 1:58 am

If I am not mistaken an airbus 330 once ran out of fuel (fuel leak on right side) over the Atlantic and landed after gliding the farthest distance a commercial airliner has ever ….. glide before.
The RAT drops down from under the fuselage to supply power, in the event I mentioned both engines were obviously out.
-Nikhil

A10WARTHOG · Sat Feb 19, 2005 2:06 am

I do not know if this holds true on all aircraft with a RAT, but the RAT is used to drive a generator that provides electrical power which could include a hyd. pump.

The CRJ-200 has this, the Air Driven Generator is connected to the RAT, which provides electrical power and that power is used to power the hyd. system 3B.

foxecho · Sat Feb 19, 2005 2:09 am

The 767 has the same cockpit it always had......best 1983 tech has to offer

Andrew

BCAL · Sat Feb 19, 2005 2:10 am

The incident you are probably referring to is Air Transat A330-243 F/N TS236 that developed a fuel leak whilst en route from YYZ to LIS. The pilots misjudged the situation, thinking that perhaps the computers were displaying false readings. The plane eventually ran out of fuel just west of the Azores and a RAT was deployed to generate sufficient power to keep the vital equipment going. The plane glided into Lajes Airport in the Azores, possibly setting the record for a powerless flight of a passenger jetliner.

See http://aviation-safety.net/database/record.php?id=20010824-1 for details of the incident.

If you do a search in the forum for Air Transat, it might come up with the thread in which there was much discussion about RATs. I seem to recall that all modern Airbus aircraft have RATs, including the A380.

COEWR · Sat Feb 19, 2005 2:21 am

ah, the RAT...dont know if there are any pics laying around of it, but when I went through the Boeing factory in Everett (last week or 2 weeks ago) one was deployed from a 777. Looked to me like they had just installed it.

Basically, when you lose both engines this RAT deploys. It can power the planes essential systems (hydraulics, flight controls, backup gauges...) but not the extra stuff (you lose lavs, pax lighting, galleys...).

This RAT does not put out any thrust but can help the pilot maintain control of the aircraft after the loss of both engines. It has 2 blades (much like a propeller on a Cessna 172) that will automatically drop down and begin rotating in the event of losing both engines. It does deploy into the slip stream, underneath the fuselage just forward of the aft landing gear.

I believe they have RATs on all of the larger commercial jets. I know the 777, 747, and 767 have them because I know people that have worked on all those programs. Im not sure about the "Baby Boeings" like the 717 and 737.

Hope that helps. If you have any more specific questions drop me an email and I will try to get them answered Smile

SNATH · Sat Feb 19, 2005 2:27 am

Quoting Coewr (reply 7):
you lose lavs

Unfortunately, this is definitely the time when the passangers really need the lavs...

Tony

vc10 · Sat Feb 19, 2005 2:31 am

The VC-10 had a RAT and so did the Concorde, and neither of them were glass cockpits, heaven forbid!!!!!!!

AMSSFO · Sat Feb 19, 2005 2:31 am

some pics

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Click here for bigger photo!

Photo © Tommy Desmet

View Large View Medium
Click here for bigger photo!

Photo © Blair Clayton

you will find more when you do a search in the photo database

khenleydia · Sat Feb 19, 2005 2:50 am

Thanks for the information! After seeing the pictures, my reaction was... Shouldn't they be larger? You look at the picture of the 67 and below it you see this little propeller. It seems like it should be grander in some way.

Oh well, I will get over it. Smile

It is amazing how much help that little thing can be in an emergency. Seeing how small it is, I wouldn't be surprised if even the baby boeings have them. What was the first plane to incorporate this feature?

KhenleyDIA

dl757md · Sat Feb 19, 2005 5:29 am

Quoting KhenleyDIA (reply 11):
Shouldn't they be larger? You look at the picture of the 67 and below it you see this little propeller. It seems like it should be grander in some way.

On 57/67/77 the RAT drives a hydraulic pump that provides hydraulic power to the flight controls in the event of failure of all other hydraulic pumps (engine driven and electric standby or demand pumps). The size of the propeller, actually a turbine in this case because it is wind driven rather than driving the air, is adequate to fully power this pump at best glide airspeed. It doesn't provide full boost for the flight controls, they have a very heavy feel, but the amount of control is sufficient.

Quoting KhenleyDIA (reply 11):
I wouldn't be surprised if even the baby boeings have them

No Boeings smaller than a 757 have them that I know of . If they do it is an option that is rarely chosen.

Dl757Md

777DadandJr · Sat Feb 19, 2005 5:33 am

This is great information. I always wondered about the RAT.
I do have a follow up question though.
On the picture of the 767 above, For what reason would the RAT be deployed on what looks like a completely normal landing approach?

Coewr: I will be coming to Seattle with my son this June to tour Boeing, may I email you for more information?

Thanks!

Russ

PositiveClimb · Sat Feb 19, 2005 6:04 am

@777DadandJr

Just a speculation as I have absolutely no clue why the RAT was extended in the photo above... Maybe it was a test or check flight? Living in Hamburg, near XFW, it happens all the time. You can really make out if the RAT is extended even if you don't see the aircraft as the RAT makes a distinkt, serrating, rumbling noise.

Regards,
PositiveClimb/Fabian

khenleydia · Sat Feb 19, 2005 6:10 am

Quoting Dl757Md (reply 12):
No Boeings smaller than a 757 have them that I know of . If they do it is an option that is rarely chosen.

I wonder why the smaller planes wouldn't have that feature? I am sure that they have a good reason, be it weight, cost or space available problems to add such a feature, but it seems all of the should. At least all of them that have been developed since the RAT came to be. They fly 737s long distance now. Wouldn't it just stand to reason they should have them?

I don't claim to know everything about planes, but it would just stand to reason from a safety stand point, they should have them.

KhenleyDIA

ACYWG · Sat Feb 19, 2005 6:16 am

Quoting KhenleyDIA (reply 2):
I believe it was a 767 that ran out of fuel and landed on an old runway or race track. I believe that had it, but that old a 767 didn't have a glass cockpit.. Did it?

Your right on this one, it was an Air Canada 767 that ran out of fuel over central Canada and was forced to make an emergency landing in Gimli, Manitoba at a former Armed Forces base. the airport had 2 runways, one in usable condition, and the other had been converted to a road course and drag strip.

767-200 Fin 604 C-GAUN is actually still in service with Air Canada and is now approriately dubbed the "Gimli Glider"

phollingsworth · Sat Feb 19, 2005 6:17 am

Quoting KhenleyDIA (reply 15):
I wonder why the smaller planes wouldn't have that feature? I am sure that they have a good reason, be it weight, cost or space available problems to add such a feature, but it seems all of the should. At least all of them that have been developed since the RAT came to be. They fly 737s long distance now. Wouldn't it just stand to reason they should have them?

My guess is that you can fly MD-80s, MD-90s., and 737s without hydraulic pressure. The Mad Dogs are tab flown, with no hydraulic boost for normal aileron and elevator operation. I believe the 737 has directly cable connect controls, which the pilot is able to move even without any hydraulic pressure (this may have to be done through the use of tabs, which the 737 has on the ailerons, and the stabilizer trim). The 757, 767, 777 have no tabs on their ailerons or elevators, this combined with fully irreversible controls means that they are basically immovable without hydraulic pressure. The ability to control the airplane in loss of normal combustion driven pumps has nothing to do with the distance that the aircraft are flown.

[Edited 2005-02-18 22:18:33]

pilotaydin · Sat Feb 19, 2005 6:23 am

i think the smaller a/c don't have a rat because they wouldnt be flying over remote areas as much, where a suitable place to land would be an issue....i mean take the 737 for example, yes it has a long range and all, but still the majority of them dont cross large oceans and airportless landmass, so there would be options for landing in a total failure situation. not to mention the statistical side of a total black out in the systems would be ultra low nowadays....

it's there in case of the double trouble.... smack in the middle of the atlantic for example at night and everything goes out....

again this is my view...dont know the official take of companies on this issue...but that's what a forum is for Smile

opinions!

COEWR · Sat Feb 19, 2005 6:31 am

777DadandJr:

yea feel free to email me...hopefully I can be of some help...I Have actually been wanting to go on the tour of the factory since I haven't done that yet...compare the difference to actually being on the floor!

Back to the topic:

I believe the 737s are cable driven, so that would reduce the need for a RAT...

Also, I know they make test flights with the RAT out to gain FAA certification. There is a FAA pilot and Boeing pilot on board. The Boeing pilot straps in and gets ready for the shutdown then the FAA pilot turns off the engines. The flight controls get real hard to maneuver, but without the RAT it would be even worse.

--C

777DadandJr · Sat Feb 19, 2005 6:36 am

Coewr,
Thanks, I will email you tonight when I get home.

Bobster2 · Sat Feb 19, 2005 8:27 am

Air Transat incident was on the National Geograhic Channel last night. Doesn't anybody watch TV? Smile/happy/getting dizzy

khenleydia · Sat Feb 19, 2005 8:37 am

Quoting COEWR (reply 19):
Also, I know they make test flights with the RAT out to gain FAA certification. There is a FAA pilot and Boeing pilot on board. The Boeing pilot straps in and gets ready for the shutdown then the FAA pilot turns off the engines. The flight controls get real hard to maneuver, but without the RAT it would be even worse.

They actually shut the engines down completely during the flight to test it? Wow. I mean, I understand the need to do it and that the planes will actually glide, but that still is pretty amazing. To me at least.

Quoting Phollingsworth (reply 17):
I believe the 737 has directly cable connect controls, which the pilot is able to move even without any hydraulic pressure (this may have to be done through the use of tabs, which the 737 has on the ailerons, and the stabilizer trim).

I understand fly-by-wire and having controls directly linked, but you lost me on the "tabs". As to being able to move them without hydraulic pressure, is that also due in part to the relatively small size of the plane, as compared with... say a 747? That has direct cable connect controls also, right? I would assume that they couldn't control the plane though without at least some hydraulic assist.?

KhenleyDIA

POR2GAL · Sat Feb 19, 2005 8:49 am

I guess the A380 is gonna house some BIG RATS!!

Can you imagine that beast being that next "Azores Glider"?!?

Wow!

daedaeg · Sat Feb 19, 2005 8:52 am

yea feel free to email me...hopefully I can be of some help...I Have actually been wanting to go on the tour of the factory since I haven't done that yet...compare the difference to actually being on the floor!

COEWR, you aint missing anything. Being on the floor is much more interesting then the tour. During the tour they only give you a glimpse of the 747 line from the mezzanine. I think it'll get better once the 787 production starts.

khenleydia · Sat Feb 19, 2005 8:55 am

Quoting POR2GAL (reply 23):
Can you imagine that beast being that next "Azores Glider"?!?

If I was on board for a gliding test, I would be asking for a parachute. I am sure it will glide and with the help of a RAT probably maneuver a bit, but in the end gravity will win! Even with a safe landing, gravity wins.

KhenleyDIA

CRJ200Mechanic · Sat Feb 19, 2005 11:29 am

Quoting KhenleyDIA (reply 15):
I wonder why the smaller planes wouldn't have that feature?

The CRJ200 has one. Its located on the f/o's side just behind the radome. Unforntunatley I couldn't find any pictures

jetstar · Sat Feb 19, 2005 12:07 pm

Aloha uses their 737-700's to fly between Hawaii and the West Coast, I would assume for ETOPS certification a RAT would be required.

777wt · Sat Feb 19, 2005 12:21 pm

View Large View Medium
Click here for bigger photo!

Photo © Blair Clayton

What are the four poles touching the ground from each corner of the white pickup truck in the background for?

CRJ200Mechanic · Sat Feb 19, 2005 2:54 pm

I would assume they are being used instead of wheel chocks, or the bed of the pickup is equipped with a man lift and the poles are for stability. Only a guess though.

bsergonomics · Sat Feb 19, 2005 3:11 pm

To give you an idea how useful this system is, take a look at the military. We don't (generally) include these systems on smaller aircraft, (mainly) due to weight issues.

If you get a full 'engine(s) out' situation, you are trained to stick the aircraft into a shallow dive (to keep the engines windmilling) and attempt an engine restart. You (generally) have between 30 seconds and a minute to get those babies restarted before the hydraulics go. If not, you're either going out through the ceiling, or you're going to be a large lump of strawberry jam in the middle of a smoking hole in some farmer's field.

I'm sure that the hydraulics (and electrics) on a heavy would last longer, but this should give you an idea of the timescales that we're talking about.

HAWK21M · Sat Feb 19, 2005 5:16 pm

Quoting KhenleyDIA (reply 2):
I believe it was a 767 that ran out of fuel and landed on an old runway or race track.

The Famous Gimli Glider B767.

Quoting BCAL (reply 6):
The incident you are probably referring to is Air Transat A330-243 F/N TS236 that developed a fuel leak whilst en route from YYZ to LIS. The pilots misjudged the situation, thinking that perhaps the computers were displaying false readings. The plane eventually ran out of fuel just west of the Azores and a RAT was deployed to generate sufficient power to keep the vital equipment going. The plane glided into Lajes Airport in the Azores, possibly setting the record for a powerless flight of a passenger jetliner

The Crew did the Fantastic job in the Landing part.

Quoting Coewr (reply 7):
Im not sure about the "Baby Boeings" like the 717 and 737.

The B737 Does not have a RAT.

Quoting Jetstar (reply 27):
Aloha uses their 737-700's to fly between Hawaii and the West Coast, I would assume for ETOPS certification a RAT would be required.

Where would that be located.

regds
MEL

Klaus · Sat Feb 19, 2005 9:56 pm

Interestingly, the A380 RAT appears to have a deploy/restow actuator if I read that correctly. As far as I know, most RATs are deploy-only, aren´t they?

AvionicMech · Sat Feb 19, 2005 10:23 pm

Quoting 777DadandJr (reply 13):
I do have a follow up question though.
On the picture of the 767 above, For what reason would the RAT be deployed on what looks like a completely normal landing approach?

I think you might find that this aircraft was on a test flight as it has just joined the 'world of tui' with Tui Airlines Belgium but has Jetair logos on the side as I think they are the tour operator that is joined with them.

Quoting Jetstar (reply 27):
Aloha uses their 737-700's to fly between Hawaii and the West Coast, I would assume for ETOPS certification a RAT would be required.

I think you will find that if you have lost both engines and all hydraulic pumps you would want to be closer than 60 mins from a suitable airport.

But I know for certain that a RAT is not required for 737NG ETOPS as the ones in our fleet are ETOPS certified and do not have one fitted. It is more to do with things such as fire suppression systems like 60 min time delays in the cargo fire system. Also the other differences are things like having HF radios fitted.

Avionic Mech

air2gxs · Sat Feb 19, 2005 10:24 pm

Klaus,
The Restow feature is probably there so that maintenance can stow it on the ground, same as B757/B767.

AvionicMech · Sat Feb 19, 2005 10:57 pm

Quoting Klaus (reply 32):
Interestingly, the A380 RAT appears to have a deploy/restow actuator if I read that correctly. As far as I know, most RATs are deploy-only, aren´t they?

Well interestingly Klaus, technically they only really have a restow actuator, although this is only on a 757/767. And it can only be restowed on the ground from a switch behind a small access panel in the R/H main wheelwell. If I remember right it is restowed electrically on the 767 and by the right hydraulic system on a 757, although I stand to be corrected as that was from memory not any books.

When the RAT is deployed it falls out by gravity into the down and locked position.

Avionic Mech

edit: you beat me to it Air2gxs, thats the trouble with having your lunch while you write a reply, it takes a while and someone might get there first. Smile

[Edited 2005-02-19 15:01:18]

Klaus · Sun Feb 20, 2005 2:41 am

It would surely need a reliable re-alignment mechanism in order to be able to restow in flight, that much is certain...

So it´s probably not intended for that; It just looked plausible in case an emergency could be averted by restarting the engines after having deployed the RAT. But that´s probably unlikely enough in cases where even the APU wasn´t available any more...

cheekie747girl · Sun Feb 20, 2005 3:00 am

Just for info....

The B747 has no RAT.

Smile/happy/getting dizzy

Santhosh · Sun Feb 20, 2005 4:25 am

Where in the cockpit of Airbuses is the control to deploy the RAT situated and are all aircrafts equipped with a RAT.

Thanx,
George

HAWK21M · Sun Feb 20, 2005 2:12 pm

Can the RAT be manually operated to deploy the unit in Emergency Situations,or can it be actuated automaticallyon sensing need.
regds
MEL

CRJ200Mechanic · Sun Feb 20, 2005 10:48 pm

The CRJ has a RAT. It can be manually deployed with a lever on the bottom of the center pedestal or it automatically deploys when all main buses go off line. If it blows on the ground you obviously have to replace a squib and there is a hydraulic pump behind a panel just aft of the radome that you pump to retract it

Santhosh · Mon Feb 21, 2005 1:16 am

Quoting CRJ200Mechanic (reply 40):
If it blows on the ground you obviously have to replace a squib and there is a hydraulic pump behind a panel just aft of the radome that you pump to retract it

What is a Squib?

George

dl757md · Mon Feb 21, 2005 2:36 am

Quoting Santhosh (reply 41):
What is a Squib?

It is a small explosive device that when triggered opens a valve or in this case releases a latch. More accurately it is the valve or latch, and its destruction removes the valve or latch allowing flow or release.

Dl757Md

AvionicMech · Mon Feb 21, 2005 4:26 am

Quoting HAWK21M (reply 39):
Can the RAT be manually operated to deploy the unit in Emergency Situations,or can it be actuated automaticallyon sensing need.

The RAT can be deployed manually by momentarily pressing the Ram Air Turbine guarded switch on the overhead panel, you can see it below towards the top centre of the panel, just above the engine start switches.

View Large View Medium
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Photo © superaccipiter

But also the RAT will deploy automatically if both engines are out, I cant remember how this is detected in this system though. And you also need to have air/ground system 1 in air mode and have more than 100 knots airspeed blowing down the lower left hand pitot head which is the alternate 1 pitot system if memory serves me correctly.

All this is referring to our BY 767's, but the 757 has a very similar setup for the auto deploy.

Just as a sidenote it is quite amusing when someone comes into the flightdeck to deploy the RAT on a 'c' check and accidentally press the PASS OXY switch instead, which as you can see above is identical in design and very close by on the overhead panel. This is so funny when you hear the loud bang of all the solenoids in the cabin opening and the 'rubber jungle' all falling out especially on a 767-300 with 326 seats. Big thumbs up

Avionic Mech

CRJ200Mechanic · Mon Feb 21, 2005 11:38 am

Quoting AvionicMech (reply 43):
The RAT can be deployed manually by momentarily pressing the Ram Air Turbine

Do you know if all A/C are like this. I don't recall the CRJ being like that. Not a system I mess with though, my knowledge is very limited

khenleydia · Mon Feb 21, 2005 11:59 am

Quoting Cheekie747girl (reply 37):
The B747 has no RAT.

That is amazing that the 747 doesn't have a RAT. Is that all versions or just early versions?

Quoting AvionicMech (reply 33):
But I know for certain that a RAT is not required for 737NG ETOPS as the ones in our fleet are ETOPS certified and do not have one fitted.

What ETOPS rating can the 37NGs get? Are all of the versions able to get the ETOPS rating?

KhenleyDIA

Santhosh · Mon Feb 21, 2005 5:15 pm

For aircrafts without a RAT are there any other back up equipments onboard in case of an emergency?

George

B747FE · Tue Feb 22, 2005 2:20 am

Quoting KhenleyDIA (reply 45):
That is amazing that the 747 doesn't have a RAT. Is that all versions or just early versions?

I think it's not necessary.
The 747 classic has six AC generators.
Four of these generators are engine driven through hydraulic CSD or IDG for RR engines and two generators mounted on the APU (only one for the SP).
Four separate and independent main hydraulic supply systems to meet the power requirements of the flight control and landing gear, powered by four engine driven hydraulic pumps, four air driven pumps and one AC pump. (Two in the SR)
I don't know the -400, but I am sure it's systems are very similar.

Regards,
B747FE.

HAWK21M · Tue Feb 22, 2005 2:28 am

Why was a RAT not considered on the B737.
regds
MEL

Klaus · Tue Feb 22, 2005 2:44 am

It´s probably a function of changing certification requirements and changing mission profiles as well... I´d expect the A380 to have at least as much redundancy in its systems as the 747, but times have changed, routes are expanding and regulations have further developed, so it´s got a RAT in addition...

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