B747F, Pressure test, BANG!!!...:-(
 

I'd liked to have been a fly on the wall when this one went off....:} :eek: :ouch: :(

This from Flight International...

"Boeing is investigating the causes and the costs of a botched pressurisation test that resulted in severe damage to a new 747-400F destined for an unidentified Asian operator. The manufacturer, which says the mishap occurred during a routine pre-delivery pressurisation test inside the Everett final-assembly building on 3 March, says “two teams have been set up, one to investigate the causes and the other to assess the repairs that will be needed”. Reports say the build-up in internal pressure caused the aircraft’s hinged nose cargo door to suddenly release from its locking mechanism. The door pivoted so rapidly around the upper hinges that it reportedly broke the flightdeck windows and caused structural damage to the fuselage skin. The radome is also thought to have been dislodged during the incident, which Boeing says did not result in any injuries."

© Flight international

Wow- anything up to 8 psi over that area of opening, which is enormous- it must have gone with a wallop! Deformation of the nose area- I would think a complete change of everything in front of the forward passenger door area. With all the electronics bay area around the nose gear well......probably easier to use as spares and build a new one! (that is a joke if anybody takes it too seriously)

But is it really a joke?. Would you want to pay for a brand new aircraft that must have suffered secondary, tertiary damage after a pressure failure? Repairs like this can cause the aircraft to become a regular "Hangar Queen" for it's entire life:\

So should Boeing now carry out a full re certification of the 747F? This sort of failure would be catastrophic in flight and similar to an A380 wing breaking?

If I was the airline that was due to get this aircraft I would want a new aeroplane and compensation for the delayed delivery.

Boeing routinely carry out a pressure test up to (IIRC)12psi on new build and also after extensive major repairs. Called the 'blowtest' it is used to improve the fatigue life of the structure and skins. We have carried out this test after a major repair and it is impressive to watch.......from a distance:ooh: with the skins looking like a quilt, especially noticeable around the cargo doors.

This doesn´t sound good at all.
I still believe those 3 747´s from Air India, over the Atlantic, the TWA off the U.S. Atlantic coast and the 747 from Lockerbie where also hull damages and not a fuel pump, nor a bomb.
Just imagine BOEING would have said:
Yes our planes fall apart. No one would have a bought a Boeing jet from this day on. I still believe in a cover up for economic reason. But this was the old 100series.
The hull design of the 747 is just not ideal. it should be a tube and round and not assymetrical, this oval design brings a lot of problems.
But I also take seat in 747´s and I am not afraid :D
to "surely not" : By the way, read the thread about the A380 wing, it didn´t break, but had a crack at 150% and this at a test assembly. That is something a little different then at a plane, ready for sale !

[QUOTE=Airbus340FO]This doesn´t sound good at all.
I still believe those 3 747´s from Air India, over the Atlantic, the TWA off the U.S. Atlantic coast and the 747 from Lockerbie where also hull damages and not a fuel pump, nor a bomb.


I have deleted what you said after your first sentence in this reply. After all you have completely destroyed your own credibility in that sentence. Suggest you don't tell your employer about your reluctance to believe reality and logic. Otherwise you may keep your "handle" for the rest of your career as common sense should be a requirement for an upgrade. However as an alternative, the Egyptian accident investigating agency may be interested in your help. Guess I just don't think much of conspiracy theorists.

Isn't a monocoque (egg/oval) cross-section the one which imparts the greatest inbuilt strength, expecially over a pure circle?

I thought that's why all Boeing jets have been oval. I can't recall what cross-section Airbus aircraft have but I'd be surprised if it's perfectly circular.

Where are the pictures? :E

Well funnily enough, Airbus seem to think the A380 is OK with an ovalised cross section (as it's a 2 decker....in fact 3 decker)!

I think Airbus340FO has left us all hoping we don't meet him / her professionally? Mind you, I'm sure the nurse will keep the tranquillisers coming just as fast as they are needed in order to keep 340 safe from reality!:uhoh:

The fact is that Boeing aircraft since the Stratocruiser (and BTW the Curtiss C-46 before that) have a dual-lobe cross-section. The upper lobe and lower lobe are each circular, and joined at the cabin floor. All elements (skin & floor beams) are thus in pure tension under pressurization loads. Very efficient structural design! :ok: (Blow up a balloon if you don't believe me)

The departure from this practice is in the nose section (e.g. 747), where the fuselage becomes more slab-sided. Here the formers must be heavier to withstand the bending loads in the non-circular area.

Just because it blew it's nose doesn't mean it's terminally ill :p

Well the article states it was being prepared for delivery to an undisclosed 'Asian' operator....
.... Bird Flu perhaps?:) :)

Barit1,

Small correction:

Not all floor beams/frames in tension since the cargo compartment is pressurized and therefore there are some floor beams and parts of some frames that are compression critical for pressurized loads.

Bird Flu
 

Hey Banana Head - is this it???


http://pip.rubberfeet.org/05/plane.gif

Di

You must be a disciple of that nutcase John Barry Smith.:yuk:

Hull loading
 

I think that double-bubble cross-section is rather popular. The upper and lower frames as well as deck beams in pure tension (with cabin and underbelly equally pressurized), no bending forces anywhere.

There are perfectly circular planes, sure. Airbus 300 series as well as Boeing 777 series.

The advantage of double-bubble is that thanks to pure tension, it is the cheapest way to deviate from circle. Boeing 767 is strongly double-bubble while 777 is not. Reason? The underbelly bulge ensures that 767 underbelly has about as much headroom as 777 underbelly, even though it is narrower. 777 is wide enough that there is adequate headroom for both cabin and underbelly in perfect circle, so a perfect circle it is.

The narrowbodies again are double bubbles in order to get extra underbelly space. Airbus 320 is wider than 737, and very slightly double bubble compared to 737 - but it is not a perfect circle.

380 is triple bubble - again, so as to get the headroom in underbelly and main deck and upper deck.

But the ends are problematic. As are doors.

I think Boeing has had one disaster uncontroversially because a cargo door failed... it was in underbelly - and when it failed, the pressure in cabin broke the cabin floor above, blowing 9 passengers with their seats out of the plane! The rest of the B747 kept flying, though, and eventually landed.

Douglas has had a rather similar disaster - cargo door on a DC-10 failed, 6 passengers above blown out with seats... but the rest of the plane crashed as well with over 300 fatalities.

Well, passenger B747 do not have nose door to blow... but if a B747 nose door slams into the cockpit on climb, what are the chances the plane crashes with those aboard and a lot of people on ground?

banana head Actually, this Bird is still in production and has not yet flown, so cannot be said to have flew ... :=