CRJ Hydraulic Question...

[h25b]

Could someone fill me in on what the CRJ Checklist says for a total hydraulic failure, and hydraulic leak... Does the checklist guide toward a landing as soon as possible or land as soon as practical... ? ... etc... Was on a flight the other day that we diverted for a hydraulic problem and was just curious about the system.. Thanks...

 

[Rottweiller]

If at any time you get a low hydraulic pressure message and after selecting the B pumps on if hydraulic pressure and or quanities are not normal the QRH calls for landing at nearest suitable airport.

A total and complete hydraulic failure would ruin everyones day, the RJ is a hydraulic aircraft with no manual reversion.

 

[DoinTime]

Could someone fill me in on what the CRJ Checklist says for a total hydraulic failure, and hydraulic leak

I don't believe there is a checklist for a total hydraulic failure. Your just about dead if that happens and there won't really be enough time left read the checklist. I've tried it a couple of times in the sim and almost came close to surviving once. Pitch can still be controlled with trim and roll can be influenced with differential thrust but it is a delicate process. Spliting the workload between both pilots (one on pitch and one on roll) makes it a lot easier.

 

[h25b]

Did I read that correctly, A HYDRAULIC A/C WITH NO MANUAL REVERSION ??? OUCH!

 

[CRJ puppy]

In a "nutshell", yes.

 

[resistance]

That's very interest about the CRJ. The jungle-jet has a very simple hydraulic system with manual reversion fail-safe. I can't believe that the Canadians didn't put in a cable backup....

Does the CRJ 70 have the same hydraulic flight control system as the 50?

 

[Rottweiller]

The 70 and 90 have basically the same flight control system. The only cables are those from the yoke and rudders which run out to the PCU's just forward of the control surfaces and then hydraulics take over.

 

[JJJ]

There are 3 hydraulic systems on the CRJ. Even if you lost 2 of the 3, you could still land safely. All of the primary flight controls have at least 2 hydraulic systems powering them. The rudder has all 3 and elevator has all 3 to both sides, in case you have to pull the pitch dissconect. The flaps and pitch trim are electric.

There is something buried in the QRH in regards to a total hydraulic failure.

ABNORM 6-18(b):

TOTAL HYDRAULIC FAILURE:

NOTE: Sorry guys, your number is up. It's you day to go.

End of checklist

 

[SkyWestCRJPilot]

Imagine some kind of explosion in the aft equipment bay like the APU exploding and not being contained in it's firebox. The three hydrualic systems have lines back to the elevator and you could have something akin to the DC-10 accident in Sioux City (or was it Sioux Falls?), Iowa, except the RJ doesn't have very good roll control (if any) with engine power only since the engines are fuselage mounted, not wing mounted like the DC-10.

 

[ICU]

Hi

Now you've given me something else to worry about.
The CRJ is equipped with three inderpendant hydraulic systems. I guess Bombardier figured that would surfice any emergencies.

However the earler posted point about what would be the effect on an uncontained fire or explosion in the arft equipment bay had not crossed my mind, nor I fear the manufactor. But with all fail safe devices in aircraft to day there is a limit to what is pratical.

I would have to say yes if all three lines are ruptured then you'd be screwed big time, but then there are other factors to consider if you have enough fluid to still get down, and of course if the explosion is that big that it blows apart a titanium fire box your probally aready dead anyway. Back to just a fire, and lets face it, the only thing that going to burn back there is fuel and oil, in flight as soon as a fire is detected the apu shuts down cutting off fuel and you still have a fire bottle to extinquish the fire.

So yes its possible but until that happens the cause of the hydraulic failure is probally worse than the result.
At least thats my take. The 70 does not have the titanim box around the apu as its mounted in the tail like a real jet (Just ask General Wing Commander, Lee) so that's probally a hirer risk of explossion.
Also and I'm not sure about this point, but I think where the hydrulic lines come through the Aft equipment bay the lines are individually shielded.
Good Question Dude

 

[sstearns2]

....

There may be 'hydraulic fuses' in the system. The fuse looks at the flow rate which is normally pretty small. The flow rate goes way up if you break a line and the fuse senses this and closes the line before all the fluid is gone.

I beleive most airbus's and the newer 777s are all hydraulic with no manual reversion.

I just read somewhere that the FAA is looking at an AD to have hydraulic fuses put in the DC-10 because of the Sioux City accident and some accident down in south america.

Scott

 

[cl-65link]

If the explosion from an uncontained APU fire destroys the fire box, the tail is gone, and you are dead. End of story.

 

[CRJ Driver]

If the explosion from an uncontained APU fire destroys the fire box, the tail is gone, and you are dead. End of story.

Why would the APU be running at cruise altitude anyway? It destroys the APU box, I dont think so.
There's pump 3B if everything goes to $hit.

 

[cl-65link]

Who said anything about cruise. What about ice in IMC in the terminal area? We have that in MSP, about 6 months out of the year. Unpressurized landings are a pain in the ass, uncomfortable for the pax, and unnecessary with a functioning APU. How's that for aliteration.

 

[anon]

I've set up and flown the total hydraulic failure in the simulator several times.

The CRJ is controllable in pitch and roll via electric stab trim and differential thrust.

If you establish a relatively long final, you can get established on a fairly normal descent rate and attitude at flaps 20. The problem I experienced was in the last 10 seconds of the approach. Any attempt to flare resulted in pitch instability and a resulting crash. Also, if you find yourself 100 feet left of the runway at low altitude, you don't have time to correct it.

IMHO, I found the following procedure to be fairly consistent and workable IN THE SIMULATOR.

Flaps 20
LONG final
Configure EARLY
Don't attempt to flare, just take the 700-800 fpm descent
No lateral corrections below 200', just keep wings level

I'm no super pilot by a long shot, but it was workable. The plane is gonna be trashed, but I believe there is a chance of survival if you can get out before it burns.

Just my $.02 worth.

 

[SmackYourPappy]

Why would the APU be running at cruise altitude anyway? It destroys the APU box, I dont think so.
There's pump 3B if everything goes to $hit.

Mr. CRJ Driver....

I assume you have never flown or accepted an a/c that has had a GEN deferred? It occurs every now and then although I haven't had to do it in a while. The procedures in the MEL spell out the need to run the APU continuously in flight to provide another GEN source and they also state that the fuel burn should be compensated/increased for the APU usage in cruise.. No need to tansfer bleeds, just electricity.

Also, Pump 3B wont do jack if the lines are severed.... I can just see you switching it to ON and easing the seat back to finish off the Starbucks and Comics....

Tailwinds

 

[ICU]

Why would the APU be running at cruise altitude anyway? It destroys the APU box, I dont think so.
There's pump 3B if everything goes to $hit.

Please tell me this was a joke, or you were drunk when you wrote this? There could me small children reading your stuff in first grade who might all assume we are all a bunch of idiots.

 

[CRJ Driver]

Ok boy and girls I guess YOU all need a review or a PC.

System 3

Description:

System 3 components are in or near the main landing gear bay. The main components are: an accumulator, a reservoir and two alternating current motor pumps (ACMPs 3A and 3B) System 3 services the largest demands of the three systems.

Hydraulic System 3 powers:

Rudder and Elevator
Left and right aileron
Left and Right Spoileron
Landing Gear
Nosewheel steering
Nose Door
Inboard Brakes

 

[SmackYourPappy]

Ok boy and girls I guess YOU all need a review or a PC.

System 3

Description:

System 3 components are in or near the main landing gear bay. The main components are: an accumulator, a reservoir and two alternating current motor pumps (ACMPs 3A and 3B) System 3 services the largest demands of the three systems.

Hydraulic System 3 powers:

Rudder and Elevator
Left and right aileron
Left and Right Spoileron
Landing Gear
Nosewheel steering
Nose Door
Inboard Brakes

Not to get picky, but the original hypothesis stated that the APU has an uncontained explosion (kinda like what happened to an AMR F100 at ORD last winter when the de-ice crew decided to squirt some type 1 into the intake for good measure.) If the explosion is of the force to rip open the box, then there is a pretty good chance that it might sever the lines.

And before you go quoting from the manual, yes I have seen with my own two eyes how the line from SYS 3 is located physically apart from 1 & 2. Either way if there's that much damage, then you can still bleed 3 dry through the broken line since it does power the rudder & elevator.

Besides... why would we be cruising with the APU on?

Tailwinds

 

[CRJ Driver]

How do you know that the lines for system 3 run thru the aft equipment bay?

 

[DoinTime]

How do you know that the lines for system 3 run thru the aft equipment bay?

How else are they going to get from the wheel well to the rudder and elevator?

 

[CRJ puppy]

Did you forget about "PFM"?

 

[ICU]

I'm going to find my happy place