CRJ-200 Fuel system

[Alltheway]

On the CRJ-200 fuel system is it possible to x cross feed fuel from one side to the other (TO both engines) in a unlikely event of lets see…..you right side engine driven fuel pump fails and also your right side electric boost pump. The fuel layout shows there is a connection between the two just after the left and right boost pumps. thx

 

[Stifler's Mom]

Won't the main ejectors continue to operate through motive flow and isn't there a high pressure pump that is not shown on the layout page that will keep the engine running???

I don't have my POH, so I'm going off the top of my head right now.

 

[Alltheway]

I dont think so because from what I understand the motive flow is from the EDP, I guess I should be clearer and say can you have one side of the fuel system provide for both engines?

 

[Rez O. Lewshun]

A. FUEL TRANSFER
1. Under normal circumstances, fuel is transferred throughout the system using motive flow ejectors powered by high-pressure fuel from the engine-driven pumps (see Fig. 7.2.2). Fuel is drawn from the wing tanks equally to feed the collector tanks, which in turn supply the engines. The wing tanks are filled automatically with any fuel that may be in the center tank. When either wing tank’s contents reduce to 94% capacity, the fuel computer activates the transfer ejectors to fill the tanks. This continues until the center tank is empty.
2. Fuel balance is automatically maintained by the Crossflow / APU Pump, with a provision for manual control. Whenever the computer detects an imbalance of greater than 200 lbs. between the main tanks, automatic crossflow is initiated and continues until the contents of the selected tank are 50 lbs. greater than the other. If a failure of the auto-transfer system occurs, manual selections may be made on the fuel control panel using the Manual XFLOW Override and the respective shut-off valve. As a final resort, symmetry may be maintained using the Gravity XFLOW line, selectable on the fuel control panel.





B. FUEL FEED
1. The two collector tanks are kept full of fuel at all times by scavenge ejectors or by gravity flow. Under normal conditions, fuel is pumped from the collector tanks to the engines by two main ejectors. If the main ejectors fail, two DC-powered booster pumps automatically start to provide the fuel to the engines. A connecting line between the left and right boost pump output lines allows both engines to be fed from one collector tank, or one engine to be fed from both collector tanks (see Fig. 7.2.2).
2. Fuel for the APU is provided by the XFLOW/APU pump whenever the APU PWR FUEL switch is selected ON. If the XFLOW/APU pump fails, or under conditions of negative G, fuel is provided by the right engine fuel feed line.

 

[Stifler's Mom]

The EDP is probably the one I am referring to as the high pressure pump. If both main pumps are in STBY (or pushed in) as soon as a low fuel pressure is sensed, both pumps will automatically turn ACTIVE and provide fuel to both engines.

Or in your case, I believe one engine will provide fuel to both engines.

 

[Alltheway]

thx got it

 

[piratebooty]

One boost pump can supply fuel to both engines. On the other hand, one main ejector is only able to feed that side's engine due to a one way check valve that is not shown on the synoptic. My airline (PSA) does a daily check on this check valve on the first flight of the day by turning off both boost pumps once both engines are started. This is done to ensure that you can stop fuel to that engine in the case of fire.

 

[BCpilot81]

Yeah, what he said

 

[Hawker dude]

oh my GOD. Dorks, you must be from Fagship or Mesa (losers)

did you skip ground school? or is it just the 300 hrs. total time you have?

The problem is, to ask that question an open forum just doesn't make since. you must be joking or really stupid.

 

[shamrock]

The problem is, to ask that question an open forum just doesn't make since. you must be joking or really stupid.

Hello Mr. Pot.

 

[DoinTime]

oh my GOD. Dorks, you must be from Fagship or Mesa (losers)

oh my GOD....Cøck Sucker, you must be from Skywest or CHQ.

 

[Rez O. Lewshun]

Alltheway... look up FAR25.

On a side note, I've picked up over the years the reason why on take off the XFlow Auto overide is switched to manual is each engine gets its own fuel souce.. not shared. An accident concerning a multi engine recip crashed because only one tank was contaminated but that contam fuel went to all engines. Not sure of the details or how true... but I believed it created an FAR. Anyone have more info??

Back to your question...... can good fuel in one tank cross over to the opposite side engine. I hate to think there is an engineer that would not allow a pilot to do that.......

Title 14--Aeronautics and Space

CHAPTER I--FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION

Part 25: AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES


Previous Section 25.954 Next Section 25.957 Contents of Part 25 List of all FAR parts


Section 25.955: Fuel flow.

(a) Each fuel system must provide at least 100 percent of the fuel flow required under each intended operating condition and maneuver. Compliance must be shown as follows:
(1) Fuel must be delivered to each engine at a pressure within the limits specified in the engine type certificate.
(2) The quantity of fuel in the tank may not exceed the amount established as the unusable fuel supply for that tank under the requirements of §25.959 plus that necessary to show compliance with this section.
(3) Each main pump must be used that is necessary for each operating condition and attitude for which compliance with this section is shown, and the appropriate emergency pump must be substituted for each main pump so used.
(4) If there is a fuel flowmeter, it must be blocked and the fuel must flow through the meter or its bypass.
(b) If an engine can be supplied with fuel from more than one tank, the fuel system must—
(2) For each turbine engine, in addition to having appropriate manual switching capability, be designed to prevent interruption of fuel flow to that engine, without attention by the flight crew, when any tank supplying fuel to that engine is depleted of usable fuel during normal operation, and any other tank, that normally supplies fuel to that engine alone, contains usable fuel.
​

 

[Alltheway]

ok thanks, I have never flown a jet, but I came across some crj material and just seeing diffrent systems and what not

 

[av8erab]

On the CRJ-200 fuel system is it possible to x cross feed fuel from one side to the other (TO both engines) in a unlikely event of lets see…..you right side engine driven fuel pump fails and also your right side electric boost pump. The fuel layout shows there is a connection between the two just after the left and right boost pumps. thx

If the high pressure engine driven fuel pump fails the engine will not run. Some of this fuel pressure is used for motive flow to operate the main ejector and scavenge ejector.

You had mentioned the "engine driven fuel pump" above.

This may help you prepare www.crjstudyguide.com

 

[atlcrashpad]

oh my GOD. Dorks, you must be from Fagship or Mesa (losers)

did you skip ground school? or is it just the 300 hrs. total time you have?

The problem is, to ask that question an open forum just doesn't make since. you must be joking or really stupid.

What doesn't make sense, is your spelling. Since you don't use spell check, you look like an idiot. Learn to spell or write in Ebonics.

 

[Lear70]

oh my GOD....Cøck Sucker, you must be from Skywest or CHQ.

Exactly. From "Airplane": "What an A*S hole".

One boost pump can supply fuel to both engines. On the other hand, one main ejector is only able to feed that side's engine due to a one way check valve that is not shown on the synoptic. My airline (PSA) does a daily check on this check valve on the first flight of the day by turning off both boost pumps once both engines are started. This is done to ensure that you can stop fuel to that engine in the case of fire.

Absolutely, positively, 100% correct.

If the high pressure engine driven fuel pump fails the engine will not run. Some of this fuel pressure is used for motive flow to operate the main ejector and scavenge ejector.

Also 100% correct.

Rez, I *think* you are trying to imply that the FAR's require that the engine WOULD be able to run in this scenario. If you are, you forgot one thing: the engine is NOT designed to be fed from "more than one tank", reference para. B that is bold typed in your quote. Each engine on the RJ gets fuel from only one tank - all the other tanks motive flow into the collector tank eventually and both the EDP and the motive flow pump supply fuel ONLY from the collector, i.e. ONE tank for each engine.

As AV8erAB said: if you lose the EDP (engine-driven pump), you lose the engine. Every turbine engine I've ever flown works like this from the King Air all the way to the 727/737, some because the EDP provides motive flow (Lear, CRJ), and some because the ONLY fuel supply line to the injectors goes through the EDP and a non-moving EDP means the vanes in the pump restrict the flow of fuel.

Most system INSTRUCTORS at PCL didn't understand the line on the synoptic page or the manual drawn between both supply lines on the CRJ fuel system enough to explain WHY it's there and how the check valve works, so about half the pilots flying it don't get it either - I did a LOT of explaining on that one little line to my F/O's who were eventually brave enough to ask why we did the check-valve test on 1st Flight of Day.

 

[n32jk]

It is soo much fun watching a bunch of low time losers bashing each other. What we really need to do is focus on unity in trying to fix a broken industry. When I see posts like these, it makes me glad I only have 10 years left.

Joe

 

[atlcrashpad]

Joe,
It appears you got sum catchin' up ta do. Start postin' bouy... Ten years left? Not much time ta post in order to catch up wif da General.

 

[Thermocouple]

If the engine driven pump fails, that engine quits period. The boost pump cannot deliver fuel pressure high enough to keep the engine running.

Forget about motive flow or anything else. The issue is the fuel control unit and injectors do not have enough psi to keep the engine running. Yes, the boost pump will still be able to supply fuel to the engine and at a more than adequate volume. But, you can still pump 2000 pph of fuel to the engine, but if the engine needs 100psi of fuel to run and the output of the boost pump is 30 psi, then it doesn't matter what volume of fuel you can pump. You are single engine either way.

When the engine quits, who gives a flying f**k about the theory of why it quit and won't restart. If you follow the QRH and then engine is still off, flying the fu**ing airplane safely to the ground.

Does Embry-Ridiculous not teach people how to fly airplanes anymore.

 

[dbert]

The EDP has three pump elements. Perhaps it’s unlikely but it’s possible to lose the one that provides motive flow.

One booshand, one main ejector is only able to feed that side's engine due to a one way check valve that is not shown on the synoptic. My airline (PSA) does a daily check t pump can supply fuel to both engines. On the other on this check valve on the first flight of the day by turning off both boost pumps once both engines are started. This is done to ensure that you can stop fuel to that engine in the case of fire.

I’m good with most of this, but you shut off the boost pumps with “both” engines running? What do you look for?

 

[atrdriver]

I’m good with most of this, but you shut off the boost pumps with “both” engines running? What do you look for?

Don't know that I have ever tried it, but I think all you would get is amber "l(r) fuel pump". You shouldn't get a lo press because the main ejectors would still be providing sufficient pressure.

 

[dbert]

Don't know that I have ever tried it, but I think all you would get is amber "l(r) fuel pump". You shouldn't get a lo press because the main ejectors would still be providing sufficient pressure.

Agreed.
So how do they know their onside motive flow is only feeding itself?

 

[Beanie]

Dbert, they wouldn't if they checked with both engines running.


You check the FUEL CHECK VALVE with one engine running, not both. That is the only way you will get the amber L and R BOOST PUMP INOP caution messages AND the (R or L, depending on which engine is shut down) FUEL LO PRESS caution message when you select the boost pumps off. If both engines are running you should only get the L and R BOOST PUMP INOP message because the Main Ejectors will provide the pressure needed......

The rest sounds pretty right on.

 

[Lear70]

Dbert, they wouldn't if they checked with both engines running.


You check the FUEL CHECK VALVE with one engine running, not both. That is the only way you will get the amber L and R BOOST PUMP INOP caution messages AND the (R or L, depending on which engine is shut down) FUEL LO PRESS caution message when you select the boost pumps off. If both engines are running you should only get the L and R BOOST PUMP INOP message because the Main Ejectors will provide the pressure needed......

All correct.

The operators who do First Flight of Day check valve tests see this pretty reguarly and, once they have it explained to them, have an excellent grasp of the system and what messages you will get when and why.