Luftwaffe refuses acceptance of two A400M's

[hairystick]

On 11/17/2019 at 9:34 AM, Corsairfoxfouruncle said:

The USAF keeps rejecting the KC-46’s for shoddy workmanship or trash left in critical areas. 

I see that the USAF has embedded QC staff at the manufacturing plant, to attempt a resolution.

On 11/18/2019 at 7:39 AM, Circloy said:

No one would claim the original windows on the Comet were a success would they?

Well, it was.

Up to the point when fatigue set in due to the design fault!

On 11/18/2019 at 11:28 AM, Rob G said:

And there was I thinking that coal industry maintenance dirty secrets were secret... (Although we do use lashings of high quality Sikaflex).

Some time back I read about the nuclear power industry... The use of a regulation NBA basketball to block a pipe... was not looked on favourably.

On 11/19/2019 at 12:13 AM, EwenS said:

Not to mention the cases of removal of the wrong limb. Tip. If you ever need an amputation make sure you mark your own limb with indelible marker just in case!

Recently there has been the non-english-speaking chap in the USA, who went in for a circumcision operation and left with a vasectomy.

The lawsuit resulted in several million dollars in compensation (which also resulted in the reversal procedure).

[Seahawk]

On 11/19/2019 at 8:13 AM, EwenS said:

Not to mention the cases of removal of the wrong limb. Tip. If you ever need an amputation make sure you mark your own limb with indelible marker just in case!

You might be reassured to know that, when I went in for my cataract operations, one of the first things they did was to draw a big down arrow on my forehead.  Pointing to the correct eye each time, I might add.

[John B (Sc)]

On 11/18/2019 at 7:53 AM, Jamie @ Sovereign Hobbies said:

 

There's a retorque and there's loose though no? On most rotating equipment one might expect new bolts to relax a little and vibration can encourage that hence retorquing will snug them back up at the stretched length of the thread. If things are actually loose then stuff is moving that shouldn't be.

 

The BV234 civvie Chinooks developed a habit of the bolts holding the rotor gearbox crowngears to the shaft flange loosening off. Boeing's "fix" was retorquing. What was actually happening is that the civilian machines were flying near max AUW most of the time whereas Army machines flew full one direction and empty the other - the crown gears were coning under the torque and stretching the bolts. Simply retorquing didn't solve the developing fatigue problem though and at least one US Army higher-time machine and a British Airways Helicopters machine suffered a fracture of the crown gear in flight; in both cases the forward gearbox immediately seized, the rotors desynchronised and aft rotorhead separated from the fuselage. Obviously both crashes resulted in multiple fatalities.

 

So in summary, loose bolts might be something to worry about or not, and it depends on exactly which ones and why they're loose. Without knowing the A400M in detail most of us here are probably unqualified to state which is the case - one hopes the engineers inspecting the aircraft know what they're doing or at least erred on the side of caution.

That is most interesting Jamie, thank you.  A depressingly good example of what may happen if the wrong, or inappropriate, simplifying assumptions are made. A lesson for all engineers there; sometimes a deeper bit of thinking & investigation is needed. I recall the BA crash very clearly, was never aware of the underlying causes.

 

As you say, I hope caution and careful thought are involved, to ensure they understand the real mechanisms at work here.  

 

John B