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RAT  
User currently offlineZkpilot From New Zealand, joined Mar 2006, 4819 posts, RR: 9
Posted (8 years 4 months 2 weeks 1 day 19 hours ago) and read 2410 times:

Hi all, sorry if this has been posted somewhere before,
just wondering has anyone here been operating, or been travelling on a flight where the RAT (RAM Air Turbine) has been deployed?  Smile


56 types. 38 countries. 24 airlines.
22 replies: All unread, jump to last
 
User currently offlineA319XFW From , joined Dec 1969, posts, RR:
Reply 1, posted (8 years 4 months 2 weeks 1 day 18 hours ago) and read 2403 times:

Not been on a flight with the RAT out, but at XFW for the first flights (or on customer flights if they ask so) of new aircraft, they extend them.
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!


User currently offlineKaddyuk From Wallis and Futuna, joined Nov 2001, 4126 posts, RR: 26
Reply 2, posted (8 years 4 months 2 weeks 1 day 18 hours ago) and read 2398 times:

If you are ever on an aircraft which requires the RAT to be extended, i'd say you were a very lucky person.

On the A346:
The Ram Air Turbine supplies auxiliary-hydraulic power to the Green hydraulic system when there is a loss of hydraulic power.

The automatic function extends the RAT when the aircraft has a speed of more than 100 kts, is in flight and the N2 speed of all engines 1, 2, 3 and 4 is less than minimum idle, or there is a total loss of normal electrical power and the N2 speed of the engines 1 and 4 is below minimum idle, or there is a Blue and Green hydraulic reservoir low level indication and a engine burst wire is cut, or the aircraft has a speed of more than 100 kts, is in flight and there is a total pressure loss on all engine pumps.

It would have to be a pretty serious incident to have the RAT extend (i.e. Loss of ALL engines or Hydraulic Pumps).

I've seen one extend in the hangar on a test, really comes down with a whack!



Whoever said "laughter is the best medicine" never had Gonorrhea
User currently offlineAvionicMech From United Kingdom, joined Jan 2005, 315 posts, RR: 3
Reply 3, posted (8 years 4 months 2 weeks 1 day 18 hours ago) and read 2396 times:

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!

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!!!


User currently offlineA319XFW From , joined Dec 1969, posts, RR:
Reply 4, posted (8 years 4 months 2 weeks 1 day 18 hours ago) and read 2392 times:

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!!!

Yes, I know - they do ground checks on them at XFW in the FAL - a nice big cage around them should anything happen Big grin

As for the A320's - the RAT powers the blue hydraulic system.


User currently offlineSfomb67 From United States of America, joined Dec 2005, 417 posts, RR: 0
Reply 5, posted (8 years 4 months 2 weeks 1 day 12 hours ago) and read 2359 times:

Been on several 767 test flts out of HMV's, in which the RAT was deployed during routine cks. The deplyment is done near the end of the flt, as once it's down, it stays down. Seems like all the hyd press indicators read "0" - scary! Been quite a few years ago.


Not as easy as originally perceived
User currently offlineLowrider From United States of America, joined Jun 2004, 3220 posts, RR: 10
Reply 6, posted (8 years 4 months 2 weeks 1 day 8 hours ago) and read 2316 times:

I did a MX test flight to check the operation of the ADG (RAT) on the CRJ. A noticable increase in drag and a substatial increase in noise.


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User currently offlineN766UA From United States of America, joined Jul 1999, 8232 posts, RR: 23
Reply 7, posted (8 years 4 months 2 weeks 1 day 7 hours ago) and read 2303 times:

Keep in mind most airliners do not have RATs or ADGs. Aircraft like the 737, for example, use windmilling of the engines.


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User currently offlineEMBQA From United States of America, joined Oct 2003, 9364 posts, RR: 11
Reply 8, posted (8 years 4 months 2 weeks 1 day 7 hours ago) and read 2299 times:

Quoting N766UA (Reply 7):
Keep in mind most airliners do not have RATs or ADGs

Most commercial aircraft I can think of have RAT's. Boeing, Airbus, Douglas, Canadair CRJ, Embraer 170/190. I have a co-worker that went on some of the EMB-170 test flights with the RAT deployed. He said it was very loud in the cabin. I've also had the chance to be in the hangar while the RAT was being tested and it screams..!! Even with ear protection on, it's loud.

[Edited 2006-04-16 02:02:54]


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User currently offlineAvionicMech From United Kingdom, joined Jan 2005, 315 posts, RR: 3
Reply 9, posted (8 years 4 months 2 weeks 1 day 6 hours ago) and read 2288 times:

Quoting N766UA (Reply 7):
Aircraft like the 737, for example, use windmilling of the engines.

The reason that the 737 doesn't have a RAT is because the aircraft can be flown without hydraulic pressure unlike most current commercial aircraft.

Most aircraft have hydraulically powered flying controls which means that hydraulic power is needed to move them, whereas the 737 and some older aircraft have hydraulically assisted flying controls which means the hydraulic system just helps to move them.


User currently offlineKaddyuk From Wallis and Futuna, joined Nov 2001, 4126 posts, RR: 26
Reply 10, posted (8 years 4 months 2 weeks 1 day 4 hours ago) and read 2264 times:

Quoting AvionicMech (Reply 9):
the 737 and some older aircraft have hydraulically assisted flying controls which means the hydraulic system just helps to move them.

Include all types of B747 under this as well  Smile



Whoever said "laughter is the best medicine" never had Gonorrhea
User currently offlineZkpilot From New Zealand, joined Mar 2006, 4819 posts, RR: 9
Reply 11, posted (8 years 4 months 2 weeks 1 day 2 hours ago) and read 2250 times:

Hey thanks, is interesting to know!

Quoting Kaddyuk (Reply 10):
Include all types of B747 under this as well

It does have a RAT also  Smile



56 types. 38 countries. 24 airlines.
User currently offlineKaddyuk From Wallis and Futuna, joined Nov 2001, 4126 posts, RR: 26
Reply 12, posted (8 years 4 months 2 weeks 23 hours ago) and read 2229 times:

Quoting Zkpilot (Reply 11):
It does have a RAT also

Negative, the B747-400 at least does not have a Ram Air Turbine.



Whoever said "laughter is the best medicine" never had Gonorrhea
User currently offlineZkpilot From New Zealand, joined Mar 2006, 4819 posts, RR: 9
Reply 13, posted (8 years 4 months 2 weeks 23 hours ago) and read 2227 times:

Quoting Kaddyuk (Reply 12):
Negative, the B747-400 at least does not have a Ram Air Turbine.

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.



56 types. 38 countries. 24 airlines.
User currently offlineHAWK21M From India, joined Jan 2001, 31679 posts, RR: 56
Reply 14, posted (8 years 4 months 2 weeks 19 hours ago) and read 2197 times:

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.
regds
MEL



Think of the brighter side!
User currently offlineVC-10 From United Kingdom, joined Oct 1999, 3701 posts, RR: 34
Reply 15, posted (8 years 4 months 2 weeks 18 hours ago) and read 2185 times:
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Quoting Kaddyuk (Reply 10):
Quoting AvionicMech (Reply 9):
the 737 and some older aircraft have hydraulically assisted flying controls which means the hydraulic system just helps to move them.

Include all types of B747 under this as well

Wrong. 747 Flight Control are not Hyd assisted


User currently offlineAvionicMech From United Kingdom, joined Jan 2005, 315 posts, RR: 3
Reply 16, posted (8 years 4 months 2 weeks 18 hours ago) and read 2178 times:

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.

You are not wrong there Mel, if you are on a flight where the RAT has to be deployed start praying to whatever God you pray to.  

The RAT on the 757 if I remember correctly powers the Centre system whereas the HMG is powered by the Right system, so if you were down to the RAT you would also be down to standby power. 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.

[Edited 2006-04-16 15:03:49]

User currently offlineHAWK21M From India, joined Jan 2001, 31679 posts, RR: 56
Reply 17, posted (8 years 4 months 2 weeks 17 hours ago) and read 2170 times:


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.

True.Amazing set of Backups on the B752.

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regds
MEL

[Edited 2006-04-16 15:10:21]


Think of the brighter side!
User currently offlineReidYYZ From Kyrgyzstan, joined Sep 2005, 536 posts, RR: 0
Reply 18, posted (8 years 4 months 1 week 4 days ago) and read 2049 times:

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. I spent a whole shift lubing the t/e flaps and the whole time watching the tech (a severe tool) stare at the underspeed light. For 8 straight hours, he f*&%$d around with it, and asked NOBODY for any clues. The arrogant prick never did get it right:

25 years worth of training: $250,00.00
A years salary: $61,000.00
Knowing where the $1.00 worth of jumper wire goes: priceless


User currently offlineA/c train From United Kingdom, joined Jun 2001, 501 posts, RR: 4
Reply 19, posted (8 years 4 months 1 week 3 days 20 hours ago) and read 2025 times:

isnt the 757 with HMG only for ETOPS aircraft ?

User currently offlineDH106 From United Kingdom, joined Jun 2005, 626 posts, RR: 1
Reply 20, posted (8 years 4 months 1 week 3 days 20 hours ago) and read 2020 times:

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.

There was a tragic Japan Airlines crash back in 1985 I think where all 4 hydraulics systems were lost. The aircraft was rendered very laterally unstable due to losing most of it's fin, but as I recall the pilots had NO mechanical recourse after the hydraulics failures, but managed nonetheless to keep the aircraft aloft for sometime using differential engine power only.



...I watched c-beams glitter in the dark near the Tanhauser Gate....
User currently offlineAvionicMech From United Kingdom, joined Jan 2005, 315 posts, RR: 3
Reply 21, posted (8 years 4 months 1 week 3 days 19 hours ago) and read 2007 times:

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.

Yeah I have installed this link a few times but I also can't remember the panel number, but I know it is the right hand panel round the back of the E1 rack. We have a special lead made up that fits in-line with the existing wiring which makes it nice and easy for the not so electrically minded airframe guys to fit it.  

But saying that I have seen an airframe supervisor not know which hydraulic system to turn on to retract the RAT. First he tried it with the CTR pumps still running, then he tried the Left system then finally he turned the Right system on.

Quoting A/c train (Reply 19):
isnt the 757 with HMG only for ETOPS aircraft ?

There are at least 2 different HMG's on the 757, one for ETOPS aircraft and one for non-ETOPS aircraft. The difference between then is the kVA output, the ETOPS aircraft have a higher output, that is on our fleet here at BY.

[Edited 2006-04-20 13:47:01]

[Edited 2006-04-20 13:47:47]

User currently offlineHAWK21M From India, joined Jan 2001, 31679 posts, RR: 56
Reply 22, posted (8 years 4 months 1 day 15 hours ago) and read 1829 times:

Quoting A/c train (Reply 19):
isnt the 757 with HMG only for ETOPS aircraft

Not necessary.
Non ETOPS Aircraft can be Equipped with one too.
regds
MEL



Think of the brighter side!
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