Horrific 747 Crash - Bagram, Afghanistan

[Guest Maj Millard]

would the -400 use fuel in the horiz stab for GC adjustment like some others...maybe that was a factor ?......................................................Maj...

 

 

[ben87r]

Not really sure what you mean with most of that

I was commenting mostly on post #42 #43. I agree that no stable flight would have been able that wasn't where i was going with it, my comment about the elevator wasn't saying that it was recoverable, just the opposite that nothing apart from bringing the W+B back into the envelope could recover. As for the drag, I had been told that there is a design feature built in so that if was in a fully stalled state that there was a rearward drag center that would create a pitch down effect. I had thought that this would explain how the AC landed quite level. I also think that there would have been a load shift

 

 

[Guest Maj Millard]

Many of the big intercontenental jets carry quite a bit of fuel in the fixed horiz stab. They adjust this for GC movement, as fuel burns off in the foward sections and wings....I recall talking to an MD-11 Captain once and he told me they lost control of the transfer abilty to/from the stab tanks, and almost lost the aircraft in the process (San Jose California to Osaka japan...early 80s MD-11 run) ........................Maj...

 

 

[Billzilla]

Many of the big intercontenental jets carry quite a bit of fuel in the fixed horiz stab.

Some of the -400 passenger ones do, none of the -400 freighters do though. Nor the converted ones.

 

 

[cooperplace]

Some of the -400 passenger ones do, none of the -400 freighters do though. Nor the converted ones.

pardon my ignorance, but why are the pax vs freight aircraft different?

 

 

[Mriya]

Many of the big intercontenental jets carry quite a bit of fuel in the fixed horiz stab. They adjust this for GC movement, as fuel burns off in the foward sections and wings....I recall talking to an MD-11 Captain once and he told me they lost control of the transfer abilty to/from the stab tanks, and almost lost the aircraft in the process (San Jose California to Osaka japan...early 80s MD-11 run) ........................Maj...

It's been a few years now since I last used my 747-400 maintenance licence, but here we go anyway...

 

747-400 (pax version in the very least) do not use fuel to trim in the way many Airbus aircraft do. In simple terms the fuelling manual calls for fuel in the tail only once other tanks are to be filled to capacity. Once in flight the engines draw fuel from the centre wing tank until a single point sensor (which sense when enough room exists in the CWT) triggers the transfer pumps which then pump all fuel from the tail to the CWT. The tail tank will then empty, fuel then keeps being drawn from the CWT till it is almost empty at which point the fuel starts being drawn from the wing tanks. A CWT scav pump then slowly pumps whatever remains in the CWT into #2main tank so it can be used also.

 

I can't verify claims of others that freighter versions don't use tail tanks as I never played with fuel systems on freighter versions, however I note on the Boeing website that the fuel capacity specs are idential for PAX and freighter versions of the -400, so my gut feeling is that the tail tank does exist, but someone may be able to prove me wrong on this one .

 

Hope this info is helpful...

 

 

[Billzilla]

I can't verify claims of others that freighter versions don't use tail tanks as I never played with fuel systems on freighter versions, however I note on the Boeing website that the fuel capacity specs are idential for PAX and freighter versions of the -400, so my gut feeling is that the tail tank does exist, but someone may be able to prove me wrong on this one .

The purpose-built freighters don't have the tail tank and the converted ones leave the tank in place but deactivated.

 

 

[Mriya]

The purpose-built freighters don't have the tail tank and the converted ones leave the tank in place but deactivated.

Can you point me to evidence that shows this? When I looked on the Boeing website the fuel capacity for the PAX and Freighter versions of the -400 were the same. I'm not claiming to know the answer, but the evidence I found from a quick search of the web last night does not agree with what you say. I am trying to stretch my memory back to some limited work on Atlas / Polar Air Cargo Freighter -400 work I did a while back, but I really can't remember any significant differences (apart from a big swing open nose, less seats, galleys & toilets).

Could just as easily be a faulty memory on my part.

 

 

[Billzilla]

Just from watching the 747 crash thread carefully in Pprune and talking to various 747-400 drivers over the years. All of them have said the freighters don't have tail tanks.

 

I'm not rated on the -400 but I've got about 5,000 hours on the -100,-200, and -300's

 

 

[Billzilla]

Edit - I had a look on the Boeing site and found the same numbers on the Wikipedia site.

 

On Wikipedia there's some brief information and it shows the difference though -

 

747-400 - 216,840 L

 

747-400ER - 241,140 L

 

747-400F - 216,840 L

 

http://en.wikipedia.org/wiki/Boeing_747-400#Specifications

 

And

 

http://www.boeing.com/boeing/commercial/747family/pf/pf_400er_prod.page

 

http://www.boeing.com/boeing/commercial/747family/pf/pf_400f_prod.page

 

 

[Billzilla]

Oh that's interesting, Boeing got the MTOW weights wrong on the 747-200 and 300.

 

They show the MTOW as 833,000 lbs but got the kilograms incorrect at 374,850 kg. It's actually 377.8 tonnes.

 

 

[Mriya]

Edit - I had a look on the Boeing site and found the same numbers on the Wikipedia site.On Wikipedia there's some brief information and it shows the difference though -

747-400 - 216,840 L

 

747-400ER - 241,140 L

 

747-400F - 216,840 L

 

http://en.wikipedia.org/wiki/Boeing_747-400#Specifications

 

And

 

http://www.boeing.com/boeing/commercial/747family/pf/pf_400er_prod.page

 

http://www.boeing.com/boeing/commercial/747family/pf/pf_400f_prod.page

I saw the figures you have listed and they support my proposition that the -400 (pax version with tail tank) and the -400F (dedicated freighter) all have the same fuel capacity. The -400ER which is listed with a higher fuel capacity has AUX tanks in the fwd cargo hold in addition to the tail tank, which it also has accounting for the higher capacity. To my knowledge Qantas was the only customer to purchase the -400ER.

 

When I googled I did note some pprune references, however without firm evidence from an official source, I am yet to be convinced that any difference exists. You have got me curious though, and I will need to contact some of my previous QF colleagues to seek confirmation one way or another.

 

As I said before, I have not done enough work on -400F aircraft to remember, but all the evidence that I see, including the links you have given me suggest to me that the -400F does have a tail tank.

 

Having said all that, it is very possible that most/all freight operators opt to deactivate the system if it is an option, sacrificing range for payload, which probably makes sense for that type of operation. In fact I did find evidence that Boeing have made that decision for the 747-8F.

 

 

[Admin]

An update:

 

http://www.recreationalflying.com/threads/bagram-investigation-suggests-cargo-shift.63749/

 

 

[Gnarly Gnu]

Hmm loadmaster a local?

 

 

[Guest Maj Millard]

Hmmm a possibility I suppose...the aircraft was not loaded there apparently, it was just a refuelling stop..........Maj...