Twin engine feeder box

[Just another student]

It seems with half the questions you come across, if you read the same question in two different places the answers differ!

What does the feeder box of a twin engine aircraft do?

a. prevent cavitation

b. collects fuel prior to being sent to the engines

I can not find reference in my book, so that's why I thought i'd check with you guys.

Cheers

[My names Turkish]

I couldnt find a specific reference to the feeder box in either of two schools notes, so I'm wondering if its an old fashioned or obsolete item? Anyway saw the same question today, the one I have for what its worth is:

In a twin jet fuel system what is the function of a feeder box?

a) To equally distribute the fuel to each tank during refuelling

b)To prevent cavitation

c)To control the amount of fuel remaining during fuel dumping

d)To feed fuel to the volumetric top off unit

The answer I have is (b) which seems to make sense. (a) is wrong as its the crossfeed valve that does that. (c)A seperate system controls fuel dumping and (d), well I have no idea what that means...:p So that would leave b as the "most correct".

These are my thoughts, but I am hoping that someone out there who actually knows what they are talking about will confirm my guessing. It must be pointed out that I am studying for the re-take as we speak:{

[Just another student]

Just showing me the version of the question you have got, has answered the question for me:D

To prevent cavitation.

Cheers

[Keygrip]

Now - follow it up.

Many people have read those messages and ask themselves...."What's cavitation?"

[My names Turkish]

Cavitation:The sudden formation and collapse of low-pressure bubbles in liquids by means of mechanical forces, such as those resulting from rotation of a marine propeller.

Again, couldnt find a definition in my books so heres www.dictionary.com, where would we be without cut and paste. Still waiting for a Factual answer from an expert, rather then a chancer like me!

[Keygrip]

Then let's move it to where the brainy people go!!

[A and C]

In the best part of thirty years in aviation including ground engineers full type courses on A320 , B732 and BAe1-11 I have never heard this term.

Is it something the JAA have made up for the exams ?.

[Voidhawk]

According to my notes, the fuel system booster pumps are fitted inside a feeder box (or collector tank) which always holds a certain amount of fuel, to keep the booster pumps submerged. This prevents the booster pumps becoming uncovered, thereby preventing pump cavitation.

There's a good description of pump cavitation in centrifugal pumps (like the booster pumps) here (http://www.gewater.com/library/tp/785_Understanding_Pump.jsp).

[My names Turkish]

A and C:Is it something the JAA have made up for the exams ?.

It wouldnt surprise me, at all.

[Tinstaafl]

Shouldn't that be "...something else the JAA made up..." :hmm:

[fruitloop]

Voidhawk, I think that you have nailed it !!Collector (feed box)keeps pumps submerged and primed.and available for both engines (crossfeed) Ref.F27-all series,also F50 (F27-Mark-50)and Fairchild notes (yank version) Nasty accident not long ago where the supply switch was left off and the engines stopped a few minutes after take-off.(Jeez I'm getting old)
Cheers