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767 Fuel Pump Issues Force Boeing To Redesign  
User currently offlineEI321 From Iraq, joined Jul 2009, 0 posts, RR: 0
Posted (7 years 10 months 1 week 23 hours ago) and read 7031 times:

From Flight International:

''FAA AD on original design prompts airframer and airline to evaluate improvements

Boeing is evaluating the results of recently completed flight tests conducted with American Airlines that tested an improved fuel pump for the 767, following performance issues with the current pump design.''

http://www.flightglobal.com/Articles...ng+flight+test+new+design+for.html

19 replies: All unread, jump to last
 
User currently offlineDfwRevolution From United States of America, joined Jan 2010, 984 posts, RR: 51
Reply 1, posted (7 years 10 months 1 week 22 hours ago) and read 6970 times:

Slow news day I suppose...

User currently offlineZeke From Hong Kong, joined Dec 2006, 9149 posts, RR: 76
Reply 2, posted (7 years 10 months 6 days 7 hours ago) and read 6485 times:

Does anyone know if these pumps are inside or outside the fuel tank, and what the parts that become loose role is within the tank/pump ?


We are addicted to our thoughts. We cannot change anything if we cannot change our thinking – Santosh Kalwar
User currently offline474218 From United States of America, joined Oct 2005, 6340 posts, RR: 9
Reply 3, posted (7 years 10 months 6 days 7 hours ago) and read 6432 times:

El321;

Your title is very misleading. Boeing is not redesigning the 767 fuel pump. The fuel pump supplier Hamilton Sunstrand is developing a redesigned fuel pump. All Boeng is doing is flight testing the new pump. If the redesigned pump is acceptable, Boeing will then issue a service bulletin allowing the operators to install the redesign Hamilton Sunstrand pump.

Quoting Zeke (Reply 2):
Does anyone know if these pumps are inside or outside the fuel tank, and what the parts that become loose role is within the tank/pump ?

What aircraft has the fuel pumps outside the fuel tank? Please ask the second part of your question again, as the way it is written makes no sense.


User currently offlineQantas744ER From United States of America, joined Jun 2005, 1286 posts, RR: 4
Reply 4, posted (7 years 10 months 6 days 6 hours ago) and read 6396 times:

Quoting Zeke (Reply 2):
Does anyone know if these pumps are inside or outside the fuel tank, and what the parts that become loose role is within the tank/pump ?



Quoting 474218 (Reply 3):
El321;

Your title is very misleading. Boeing is not redesigning the 767 fuel pump. The fuel pump supplier Hamilton Sunstrand is developing a redesigned fuel pump. All Boeng is doing is flight testing the new pump. If the redesigned pump is acceptable, Boeing will then issue a service bulletin allowing the operators to install the redesign Hamilton Sunstrand pump.

Quoting Zeke (Reply 2):
Does anyone know if these pumps are inside or outside the fuel tank, and what the parts that become loose role is within the tank/pump ?

What aircraft has the fuel pumps outside the fuel tank? Please ask the second part of your question again, as the way it is written makes no sense.

I think hes saying if the pump is directly in the tank or outside of the tank..

BTW dont forget Zeke is a commercial pilot  Wink

Cheers Leo



Happiness is V1 in Lagos
User currently offlineXv408 From United Kingdom, joined Nov 2006, 52 posts, RR: 0
Reply 5, posted (7 years 10 months 6 days 6 hours ago) and read 6385 times:

Quoting 474218 (Reply 3):
What aircraft has the fuel pumps outside the fuel tank?

Just about all of them - each engine usually has 2 - a low pressure pump and a high pressure one.


User currently offlineZeke From Hong Kong, joined Dec 2006, 9149 posts, RR: 76
Reply 6, posted (7 years 10 months 6 days 6 hours ago) and read 6339 times:

Quoting 474218 (Reply 3):
What aircraft has the fuel pumps outside the fuel tank?

Heaps and heaps......I think the first 40+ aircraft types I have flown have had external pumps. I do not know the 767 systems.

Quoting 474218 (Reply 3):
Please ask the second part of your question again, as the way it is written makes no sense.

Typical of me, my two finger typing cannot keep up with my thought process. The only computer I could ever keep up with was the 744 FMC.

The "reported loose screws in the pump assembly that "could have resulted in some loose steel parts in the pump"", what do they cover/support ? What was their designed role in the fuel system ?



We are addicted to our thoughts. We cannot change anything if we cannot change our thinking – Santosh Kalwar
User currently offlineWingnut767 From , joined Dec 1969, posts, RR:
Reply 7, posted (7 years 10 months 6 days 5 hours ago) and read 6301 times:

Quoting Xv408 (Reply 5):
Quoting 474218 (Reply 3):
What aircraft has the fuel pumps outside the fuel tanks

None. All fuel tank boost pumps are inside the tank on Boeing, Airbus and McD Aircraft. Some can be accessed by going into the tank (older models) or from the exterior on the for or aft spar. The wing tanks have boost or feeder pumps and the Center wing tank usually has a little stronger pump called an override pump.



Just about all of them - each engine usually has 2 - a low pressure pump and a high pressure one.[/quote]

you are talking about a different part. You have fuel tank pumps and engine pumps. The article is about fuel tank pumps. On the engines you have various forms of pumps and fuel controls. You either have a fuel pump coupled with a fuel control or an HMU which combines the two.




 bigthumbsup 


User currently offline474218 From United States of America, joined Oct 2005, 6340 posts, RR: 9
Reply 8, posted (7 years 10 months 6 days 1 hour ago) and read 6089 times:

Quoting Wingnut767 (Reply 7):
None. All fuel tank boost pumps are inside the tank on Boeing, Airbus and McD Aircraft. Some can be accessed by going into the tank (older models) or from the exterior on the for or aft spar. The wing tanks have boost or feeder pumps and the Center wing tank usually has a little stronger pump called an override pump.

Thanks for backing me up and you can add Lockheed aircraft to the list with fuel boost pumps in the wings. You have to get that fuel to the engines and gravity just doesn't do the job.

Now I have a question. Do the aircraft that carry fuel in the horizontal stabilizer have boost pumps in the stabilizers? If not how do they to pump the fuel out?


User currently offlineWingnut767 From , joined Dec 1969, posts, RR:
Reply 9, posted (7 years 10 months 6 days ago) and read 6056 times:

Quoting 474218 (Reply 8):
Now I have a question. Do the aircraft that carry fuel in the horizontal stabilizer have boost pumps in the stabilizers? If not how do they to pump the fuel out?

I believe on the B747 they have boost pumps in the Horizontal.


User currently offlineZeke From Hong Kong, joined Dec 2006, 9149 posts, RR: 76
Reply 10, posted (7 years 10 months 5 days 19 hours ago) and read 5920 times:

Q1 : Just like to know where you guys read it was a fuel boost pump, that term seems to have entered the thread in reply 7 ?

Q2 : Does the 767 have any fuel pumps outside of the fuel tank ?



We are addicted to our thoughts. We cannot change anything if we cannot change our thinking – Santosh Kalwar
User currently offlineJetMech From Australia, joined Mar 2006, 2699 posts, RR: 53
Reply 11, posted (7 years 10 months 5 days 10 hours ago) and read 5810 times:

G'day Zeke  Smile,

Glad to see you back  bigthumbsup .

Quoting Zeke (Reply 2):
Does anyone know if these pumps are inside or outside the fuel tank

I actually did the fuel boost pump check on the 767 many times, so I should be able to answer your questions. With reference to the following picture of a 767 boost pump (sorry for the shocking quality)  blush !


http://www.safeflightinc.com/assets/images/5006003.jpg

Yes, the 767 boost pumps for the left and right main tanks are outside the tank, in that you do not need to enter the tank to get to them. There is a small, oval shaped panel on the bottom wing skin of the 767 about 2 or 3 metres outboard of the root. You remove this panel to get access to the boost pumps. Removing the panel under either the left or right wing will reveal two boost pumps. The boost pumps are orientated as you see in the photo, thus you see the bottom of the two pumps when you remove the panel.

To remove the pumps, you firstly remove the screws securing them to the fuel pump housing casting. The removal / carry handle will be orientated as you see in the photo. You carefully pull this handle down to the vertical position. The cams on the handle will force the pump removal ejector pins to extend, which breaks the seals and moves the pump downward about a centi-metre. The next step is critical.

The downward movement of the pump also drags down a sleeve that surrounds the pump. The sleeve is designed to shut off the fuel inlets and outlets to the pump cavity casting. To lock the sleeve in place, you twist the pump a small amount. This turns the dog latch pin. The dog latch pin rotates a dog latch which locks into the side of the sleeve. Once the sleeve is locked, you slowly and carefully continue to withdraw the pump whilst ensuring that the sleeve does not follow the pump. If you rush this part of the removal and neglect to lock the sleeve, it will come out with the pump and you will get a Jet-A1 shower. If done correctly, you are left with the pump motor / impeller assembly as shown in the photo.

Quoting Zeke (Reply 2):
and what the parts that become loose role is within the tank/pump ?

Looking at the photo, you can see the tube shaped impeller inlet, the four rectangular impeller outlets, and four support posts. Two of these support posts on opposite sides had two countersunk holes drilled in them one atop the other. Two countersunk screws were inserted and screwed into a small metal plate that was fitted to the inside of the support post. This small rectangular plate was about 2cm by 1cm and fitted up closely to the bottom of the impeller. The plate also closely fitted up to the drive shaft.

I am not sure what these two plates did, but the check involved ensuring that the screws and the plates were secure. These were the parts that had the potential to come loose. You also had to reach into the impeller exits and gently push on the bottom of the impeller. IIRC, this was the ensure that the bottom part of the impeller was still firmly attached to the top part. Once these checks were done and provided there was no defects, you re-installed the pumps and did leak and operational checks.

Regards, JetMech



JetMech split the back of his pants. He can feel the wind in his hair.
User currently offlineZeke From Hong Kong, joined Dec 2006, 9149 posts, RR: 76
Reply 12, posted (7 years 10 months 5 days 9 hours ago) and read 5770 times:

Quoting JetMech (Reply 11):
JetMech

Thanks mate, well explained, you put a lot of effort into that.

Much appreciated.

 bigthumbsup 



We are addicted to our thoughts. We cannot change anything if we cannot change our thinking – Santosh Kalwar
User currently offlineRoseFlyer From United States of America, joined Feb 2004, 9665 posts, RR: 52
Reply 13, posted (7 years 10 months 5 days 9 hours ago) and read 5762 times:

I'm surprised that this made the news. Some of my good friends and coworkers at Hamilton Sundstrand have been working on redesigning the 767 fuel pump.

Don't worry, it isn't for safety reasons that it needs to be redesigned. The fuel pump however is not having the service life that is demanded, so a redesign to essentially make it stronger in the pumping element is necessary. Things like this regularly occur.



If you have never designed an airplane part before, let the real designers do the work!
User currently offlineWingnut767 From , joined Dec 1969, posts, RR:
Reply 14, posted (7 years 10 months 5 days 9 hours ago) and read 5705 times:

Quoting JetMech (Reply 11):
Yes, the 767 boost pumps for the left and right main tanks are outside the tank, in that you do not need to enter the tank to get to them

You insert them into the housing which protrudes into the tank thus putting them inside the tank. They are not attached to the exterior of the tank. Most aircraft now have this method but technicaly they are inside the tank in the housing.


User currently offline474218 From United States of America, joined Oct 2005, 6340 posts, RR: 9
Reply 15, posted (7 years 10 months 5 days 4 hours ago) and read 5563 times:

Quoting JetMech (Reply 11):
Yes, the 767 boost pumps for the left and right main tanks are outside the tank, in that you do not need to enter the tank to get to them. There is a small, oval shaped panel on the bottom wing skin of the 767 about 2 or 3 metres outboard of the root.

So how can the pump be on the outside of the tank if the panel that you remove to access the pump is on the lower wing surface and the pump is above the access panel? The pump is in the tank submersed in fuel and only the access to it is on the outside of the fuel tank.


User currently offlineHAWK21M From India, joined Jan 2001, 31684 posts, RR: 56
Reply 16, posted (7 years 10 months 5 days 4 hours ago) and read 5544 times:

Quoting JetMech (Reply 11):

 bigthumbsup 
Great effort as usual.
regds
MEL



Think of the brighter side!
User currently offlineFDXMECH From United States of America, joined Mar 2000, 3251 posts, RR: 34
Reply 17, posted (7 years 10 months 5 days 2 hours ago) and read 5470 times:

Quoting 474218 (Reply 15):
So how can the pump be on the outside of the tank if the panel that you remove to access the pump is on the lower wing surface and the pump is above the access panel? The pump is in the tank submersed in fuel and only the access to it is on the outside of the fuel tank.

I think this is a matter of semantics saying the fuel boost pumps are outside the tank. To a layman, outside the tank means means external to or not part of the tank. Dependings on manufacturer all boost pumps are mounted to and protrude within the tank.

The part always within the tank are the inlet and outlet ports integral to the boost pump. The fuel is drawn in and forced out under pressure via an impeller.

Some boost pumps such as the 727 & 737 are accessed via large oval panels on the wings lower surface. Remove these panels and you'll see a dry enclosure with the majority of the boost pump exposed as well as the electrical connector. The part you can't see is the end of the assembly protruding into the fuel tank which sucks in the fuel and discharges it in the fuel piping (located in the fuel tank).

The Airbus's I've worked have the entire pump assembly enclosed within the tank with only the end visible on the lower surface of the wing. The electrical connector is on the end with the power supply wiring covered by a fairing on the bottom of the wing.

The DC10/MD11 also have its boost pump mounted flush within the fuel tank but interestingly the electrical connector is not externally mounted on the pump but on the part of the pump inside the tank.



You're only as good as your last departure.
User currently offlineJetMech From Australia, joined Mar 2006, 2699 posts, RR: 53
Reply 18, posted (7 years 10 months 4 days 14 hours ago) and read 5296 times:

Quoting 474218 (Reply 15):
The pump is in the tank submersed in fuel and only the access to it is on the outside of the fuel tank.

I did actually make that qualification when I defined the pumps to be "outside" the fuel tank; albeit, not specifically.

Quoting JetMech (Reply 11):
Yes, the 767 boost pumps for the left and right main tanks are outside the tank, in that you do not need to enter the tank to get to them.



Quoting 474218 (Reply 15):
So how can the pump be on the outside of the tank if the panel that you remove to access the pump is on the lower wing surface and the pump is above the access panel?

It depends if you consider the access panel to be an integral part of the fuel tank boundary. If you do, the pumps, housing casting and the associated wiring are all "inside" the tank. I do not consider the access panel to be part of the tank boundary as it is not wetted with fuel.

Quoting Wingnut767 (Reply 14):
You insert them into the housing which protrudes into the tank thus putting them inside the tank. They are not attached to the exterior of the tank.

I thus consider any part of the fuel pump visible when I remove the panel to be external. The non-visible parts are internal.

Anyway, if I don't have to don static free overalls, a respirator and thread myself through a tank access cutout, the component is as good as external to me  bigthumbsup !

Regards, JetMech



JetMech split the back of his pants. He can feel the wind in his hair.
User currently offlineValcory From United States of America, joined Dec 2006, 89 posts, RR: 0
Reply 19, posted (7 years 10 months 4 days 12 hours ago) and read 5243 times:

The housing is inside the tank if you need to change the housing you have to go inside the tank.The fuelpump/impeller insert into the housing. The fuel pump/impeller can be remone from the outside.I have seen guys take shower's when they remove the pump because they forgot to turn it when pulling it out.

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