User avatar
DocLightning
Topic Author
Posts: 19766
Joined: Wed Nov 16, 2005 8:51 am

CRJ Hydraulic Pump Deferral

Fri Mar 16, 2012 7:06 am

Was on N886AS today from PHX to OAK. We taxied out and then taxied back because a hydraulic pump wasn't working. Captain said "we have another perfectly good one, so we can just defer it. It won't take a minute."

So obviously, there was more than one other hydraulic pump aboard, yes? We didn't fly with one working hydraulic pump, correct?

What was he talking about, then?
-Doc Lightning-

"The sky calls to us. If we do not destroy ourselves, we will one day venture to the stars."
-Carl Sagan
 
tdscanuck
Posts: 8572
Joined: Wed Jan 11, 2006 7:25 am

RE: CRJ Hydraulic Pump Deferral

Fri Mar 16, 2012 2:07 pm

Quoting DocLightning (Thread starter):
So obviously, there was more than one other hydraulic pump aboard, yes?

Yes. There were 5 others. A CRJ has three hydraulic systems (1, 2, and 3) with two pumps on each. 1 and 2 each have one engine driven pump and one electrical pump. 3 has two electrical pumps.

Quoting DocLightning (Thread starter):
We didn't fly with one working hydraulic pump, correct?

Correct.

Quoting DocLightning (Thread starter):
What was he talking about, then?

On the system that they deferred the pump, you had one working pump left. Had that pump failed you would have lost that hydraulic system (but had two other perfectly good ones).

Tom.
 
Goldenshield
Posts: 5005
Joined: Sun Jan 14, 2001 3:45 pm

RE: CRJ Hydraulic Pump Deferral

Fri Mar 16, 2012 7:42 pm

Quoting tdscanuck (Reply 1):
On the system that they deferred the pump, you had one working pump left. Had that pump failed you would have lost that hydraulic system (but had two other perfectly good ones).

Exactly.

Redundancy in transport aircraft is pretty crtical. and thus, having different hydraulic systems power different parts of the airplane ensure this redundancy. There's only a couple incidents that I can think of where the plane was not able to manuever due to loss of all hydraulics.

Also, in the case of this CRJ, there's one pump that CANNOT be deferred; that being 3B. This is the emergency pump and it powered by the ADG should the plane lose power.
Two all beef patties, special sauce, lettuce, cheese, pickles, onions on a sesame seed bun.
 
User avatar
DocLightning
Topic Author
Posts: 19766
Joined: Wed Nov 16, 2005 8:51 am

RE: CRJ Hydraulic Pump Deferral

Fri Mar 16, 2012 9:02 pm

Quoting Goldenshield (Reply 2):
Redundancy in transport aircraft is pretty crtical.

Right. Hence my question. I knew that no pilot in his right mind would take off with one working pump. So I wondered how many there were.

At the time, I guessed there were at least two hydraulic systems, probably three. I guessed there were two pumps per system. Apparently, I'm right.  
-Doc Lightning-

"The sky calls to us. If we do not destroy ourselves, we will one day venture to the stars."
-Carl Sagan
 
Woodreau
Posts: 1186
Joined: Mon Sep 24, 2001 6:44 am

RE: CRJ Hydraulic Pump Deferral

Sat Mar 17, 2012 5:36 am

Quoting Goldenshield (Reply 2):
Also, in the case of this CRJ, there's one pump that CANNOT be deferred; that being 3B. This is the emergency pump and it powered by the ADG should the plane lose power.

I was wondering if your company has a different MEL, as ours 1B, 2B, and 3B may not be deferred (-700/900 model MEL) or (not knowing which CRJ 866AS is and based on your "in the case of this CRJ" qualifier) is this a difference between a -200 model and a -700/900/1000 model. Thx.
Bonus animus sit, ab experientia. Quod salvatum fuerit de malis usu venit judicium.
 
FlyASAGuy2005
Posts: 3965
Joined: Sun Sep 23, 2007 4:55 am

RE: CRJ Hydraulic Pump Deferral

Sun Mar 18, 2012 5:52 am

Quoting woodreau (Reply 4):

886AS is a CR2..
What gets measured gets done.
 
User avatar
DocLightning
Topic Author
Posts: 19766
Joined: Wed Nov 16, 2005 8:51 am

RE: CRJ Hydraulic Pump Deferral

Sun Mar 18, 2012 6:54 am

Quoting FlyASAGuy2005 (Reply 5):
886AS is a CR2..

Out of curiosity, did you look it up or do you know it by heart?
-Doc Lightning-

"The sky calls to us. If we do not destroy ourselves, we will one day venture to the stars."
-Carl Sagan
 
Goldenshield
Posts: 5005
Joined: Sun Jan 14, 2001 3:45 pm

RE: CRJ Hydraulic Pump Deferral

Sun Mar 18, 2012 11:07 am

Quoting woodreau (Reply 4):
I was wondering if your company has a different MEL, as ours 1B, 2B, and 3B may not be deferred (-700/900 model MEL) or (not knowing which CRJ 866AS is and based on your "in the case of this CRJ" qualifier)
is this a difference between a -200 model and a -700/900/1000 model. Thx.

Well, the MMEL aside, everyone's going to have slight differences. Yes, in the -200, you can have 1B and 2B deferred, as long as the all 3 hydraulic systems have a way to pressurize. With the 7/900, you are correct that none of the Bs can be deferred. Also, Neither 1A or 2A can be deferred at the same time.

Quoting DocLightning (Reply 6):
Quoting FlyASAGuy2005 (Reply 5):
886AS is a CR2..

Out of curiosity, did you look it up or do you know it by heart?

Airlines (at least here in the US) have number ranges for different aircraft types and/or versions (with a few exceptions) to help differentiate them to those who work with them.
Two all beef patties, special sauce, lettuce, cheese, pickles, onions on a sesame seed bun.
 
tdscanuck
Posts: 8572
Joined: Wed Jan 11, 2006 7:25 am

RE: CRJ Hydraulic Pump Deferral

Sun Mar 18, 2012 7:55 pm

Quoting DocLightning (Reply 6):
Quoting FlyASAGuy2005 (Reply 5):
886AS is a CR2..

Out of curiosity, did you look it up or do you know it by heart?

I can't speak for FlyASAGuy2005, but I looked it up on airfleets.net and it also says CRJ-200.

Tom .
 
FlyASAGuy2005
Posts: 3965
Joined: Sun Sep 23, 2007 4:55 am

RE: CRJ Hydraulic Pump Deferral

Mon Mar 19, 2012 1:07 am

Quoting DocLightning (Reply 6):
Out of curiosity, did you look it up or do you know it by heart?

Knew it by heart.

Former EV bird. All ASA CR2s (prior to aquiring the ACA a/c (600BRs)) are numbered 800AS or 900EV. All CR7s (prior to the Comair and QX transferes) are numbered 700EV (one given an IND reg).
What gets measured gets done.
 
VC-10
Posts: 3546
Joined: Tue Oct 26, 1999 11:34 am

RE: CRJ Hydraulic Pump Deferral

Mon Mar 19, 2012 1:15 am

Assuming it wasn't a nil dispatch why did they return to the gate? In out MEL is says 'The MEL applies to all defects that occur up to the point of dispatch, and comes into effect again when the a/c next comes to rest at the end of its flight' - EASA regs
 
Goldenshield
Posts: 5005
Joined: Sun Jan 14, 2001 3:45 pm

RE: CRJ Hydraulic Pump Deferral

Mon Mar 19, 2012 1:58 am

Quoting VC-10 (Reply 10):

Assuming it wasn't a nil dispatch why did they return to the gate? In out MEL is says 'The MEL applies to all defects that occur up to the point of dispatch, and comes into effect again when the a/c next comes to rest at the end of its flight' - EASA regs

Restrictive MELs need to be complied with before takeoff regardless of whether they are at the gate or taxiing, per the FAA.
Two all beef patties, special sauce, lettuce, cheese, pickles, onions on a sesame seed bun.
 
apodino
Posts: 3027
Joined: Mon Apr 04, 2005 2:11 am

RE: CRJ Hydraulic Pump Deferral

Mon Mar 19, 2012 4:31 pm

On the CRJ-200 the 1B, 2B, and the 3A pumps can be deferred. Those are all Electrical driven pumps. Though it is very rare, the two engine driven pumps can be deferred as well.

The 2B pump is the biggest pain in the neck to defer though. Hydraulic system 2 controls the Landing Gear and the Anti Skid system on the airplane, so when 2B is deferred, the restriction also assumes that you are without an Anti Skid system as well. What that means is at sea level, you need at least a 9,000 foot long runway (For landing, not takeoff) to avoid a serious weight restriction (And more than likely to even be able to launch, which is one reason why the plane is never sent to LGA or DCA with that MEL in place).

The 3A pump also has a slight performance hit on takeoff, but it never causes the problems that a deferred 2B pump causes.
 
Woodreau
Posts: 1186
Joined: Mon Sep 24, 2001 6:44 am

RE: CRJ Hydraulic Pump Deferral

Mon Mar 19, 2012 6:32 pm

Quoting Goldenshield (Reply 7):
Yes, in the -200, you can have 1B and 2B deferred, as long as the all 3 hydraulic systems have a way to pressurize. With the 7/900, you are correct that none of the Bs can be deferred.

Thanx for the info. Surprised that the -200 can defer the B pumps, I wonder what changed.

Quoting VC-10 (Reply 10):
Assuming it wasn't a nil dispatch why did they return to the gate? In out MEL is says 'The MEL applies to all defects that occur up to the point of dispatch, and comes into effect again when the a/c next comes to rest at the end of its flight' - EASA regs

Sometimes you can defer without returning to the gate if you can crew placard. If mx has to placard the deferral and the crew is not permitted to defer the inoperative item, then you have to go back to the gate.
Bonus animus sit, ab experientia. Quod salvatum fuerit de malis usu venit judicium.
 
DashTrash
Posts: 1266
Joined: Mon Aug 21, 2006 8:44 am

RE: CRJ Hydraulic Pump Deferral

Mon Mar 19, 2012 7:36 pm

Quoting Goldenshield (Reply 7):
With the 7/900, you are correct that none of the Bs can be deferred. Also, Neither 1A or 2A can be deferred at the same time.

Slats on the B system. or both?
 
Goldenshield
Posts: 5005
Joined: Sun Jan 14, 2001 3:45 pm

RE: CRJ Hydraulic Pump Deferral

Mon Mar 19, 2012 8:01 pm

Quoting woodreau (Reply 13):
Surprised that the -200 can defer the B pumps, I wonder what changed.

Everything changed on the -700 (including the -900/1000)---for the better. Better bleed air configuration and automation, better anti-ice, hydraulic reversers, etc. I could go on.

Quoting DashTrash (Reply 14):
Slats on the B system. or both?

Erm, no. Electrically driven via two motors and a torque tube.
Two all beef patties, special sauce, lettuce, cheese, pickles, onions on a sesame seed bun.
 
wingscrubber
Posts: 806
Joined: Fri Sep 07, 2001 1:38 am

RE: CRJ Hydraulic Pump Deferral

Mon Mar 19, 2012 8:01 pm

http://www.smartcockpit.com/pdf/plan...r/CRJ-100-200-SERIES/systems/0015/

Smartcockpit has some good material describing the CRJ hydraulic system.
Resident TechOps Troll
 
User avatar
DocLightning
Topic Author
Posts: 19766
Joined: Wed Nov 16, 2005 8:51 am

RE: CRJ Hydraulic Pump Deferral

Mon Mar 19, 2012 10:05 pm

Quoting woodreau (Reply 13):
Sometimes you can defer without returning to the gate if you can crew placard. If mx has to placard the deferral and the crew is not permitted to defer the inoperative item, then you have to go back to the gate.

We were back at the gate for maybe ten minutes tops. All in all, we were less than 25 minutes late on arrival into OAK.

Quoting apodino (Reply 12):
The 2B pump is the biggest pain in the neck to defer though. Hydraulic system 2 controls the Landing Gear and the Anti Skid system on the airplane, so when 2B is deferred, the restriction also assumes that you are without an Anti Skid system as well. What that means is at sea level, you need at least a 9,000 foot long runway (For landing, not takeoff) to avoid a serious weight restriction

Wasn't 2B then, because the weather at OAK was absolutely rotten.
-Doc Lightning-

"The sky calls to us. If we do not destroy ourselves, we will one day venture to the stars."
-Carl Sagan
 
apodino
Posts: 3027
Joined: Mon Apr 04, 2005 2:11 am

RE: CRJ Hydraulic Pump Deferral

Tue Mar 20, 2012 5:21 am

Quoting DocLightning (Reply 17):
n

Wasn't 2B then, because the weather at OAK was absolutely rotten.

It still could have been the 2B. IIRC runway 11-29 at Oak is nearly 11,000 feet long, which is plenty long enough to handle a 2B pump. The fact that the visibility was down is irrelevant to the length of runway needed for a safe landing.
 
Goldenshield
Posts: 5005
Joined: Sun Jan 14, 2001 3:45 pm

RE: CRJ Hydraulic Pump Deferral

Tue Mar 20, 2012 9:25 am

Quoting DocLightning (Reply 17):
Wasn't 2B then, because the weather at OAK was absolutely rotten.

I know what it was, but I've already said enough...

Quoting apodino
It still could have been the 2B.

It's already been fixed. That is all.

[Edited 2012-03-20 02:26:24]
Two all beef patties, special sauce, lettuce, cheese, pickles, onions on a sesame seed bun.
 
DashTrash
Posts: 1266
Joined: Mon Aug 21, 2006 8:44 am

RE: CRJ Hydraulic Pump Deferral

Tue Mar 20, 2012 1:03 pm

Quoting Goldenshield (Reply 15):
Erm, no. Electrically driven via two motors and a torque tube.

Far out. I thought they were hydraulic.
 
Alias1024
Posts: 2231
Joined: Mon Oct 25, 2004 11:13 am

RE: CRJ Hydraulic Pump Deferral

Tue Mar 20, 2012 7:47 pm

Quoting apodino (Reply 12):
The 2B pump is the biggest pain in the neck to defer though. Hydraulic system 2 controls the Landing Gear and the Anti Skid system on the airplane, so when 2B is deferred, the restriction also assumes that you are without an Anti Skid system as well. What that means is at sea level, you need at least a 9,000 foot long runway (For landing, not takeoff) to avoid a serious weight restriction (And more than likely to even be able to launch, which is one reason why the plane is never sent to LGA or DCA with that MEL in place).

Ugliest weight penalty I've ever seen was with 3A deferred and an inop APU in freezing fog. Unpressurized takeoff so we could use the bleeds for wing and cowl anti-ice, and the 3A deferral requires single engine performance to be calculated with the landing gear remaining down. Even with 11,000 feet of runway we were limited to 26 passengers.  Wow!
It is a mistake to think you can solve any major problems with just potatoes.
 
DashTrash
Posts: 1266
Joined: Mon Aug 21, 2006 8:44 am

RE: CRJ Hydraulic Pump Deferral

Wed Mar 21, 2012 1:03 am

Quoting Alias1024 (Reply 21):
Ugliest weight penalty I've ever seen was with 3A deferred and an inop APU in freezing fog. Unpressurized takeoff so we could use the bleeds for wing and cowl anti-ice, and the 3A deferral requires single engine performance to be calculated with the landing gear remaining down. Even with 11,000 feet of runway we were limited to 26 passengers.

That would make one hell of a hit on second segment climb!

Who is online

Users browsing this forum: Google [Bot] and 23 guests