Boeing pays PIA $3 million for BGY.

[Moin]

I forgot to mention that Boeing has paid PIA $3 million owing to the rigorous use and stress they put the a/c through, including one hard landing and the number of hours that the airframe has accumulated. The a/c had completed 500 cycles by the time it left Seattle for Pakistan.

Every a/c has a limit to the number of hard landings it can tolerate as it puts a great amount of stress on the airframe and if for example, the LR has a tolerance level of 25 hard landings, Boeing carried out 1 which now leaves it with 24. As a result, PIA got $3 million from Boeing as compensation.

I guess its not always a very good idea to get the first a/c off the assembly line as that a/c is the one that the company puts through the grind. Had this been say the 10th or 20th a/c off the line, chances are it would not have been put through its paces as much as #1 and would have had most bugs ironed out by that time. Sometimes its wise to observe a new type a/c in service with other carriers for a while and judging by the feedback received, act accordingly, an example being QR and the 777. They operate an all Airbus fleet and now they're looking at the 777 which is probably because its currently Boeings best seller and airlines that operate the type are extremely satisfied with its performance.

I've also heard that the A380 is having problems with its wing stress tests. SIA may be the first to fly them but they may also be the first to encounter teething problems.

[flyingsystem]

I've also heard that the A380 is having problems with its wing stress tests. SIA may be the first to fly them but they may also be the first to encounter teething problems.

For precision this failure occured during the final stage of the test (at 98%of the goal). And this wing is designed to support 50% more strenght than it can support in traffic. That means the failure happened very close to the goal that airbus established .

[AP-BGL]

Can anybody tell me whats Hard Landing? Heard about it for so many times but still could't able to know what that acctually is?

[R.F.]

When the Rate of descent during landing flare exceeds 600 feet per minute or +2.5 g's and above it's considered a 'HEAVY' landing, after which the aircraft goes through certain checks related to stress.

A positive touch down could be mis construed as a hard landing which is basically of no consequence as long as it's within the defined parameters as stated above.

[Adnaan786]

Do PIA have performance monitoring equipment on their aircraft like BA do?? It's like a live feed from the aircraft to the airlines Ops department. Every single thing you do is relayed back to Ops.

It's their way of monitoring pilot performance, to make sure you handle the aircraft efficiently. In the case of a hard landing they would know exactly when it happened and who the pilot flying was.

[cheetah]

In case of a heavy landing i am sure the wheels would overheat and lead to a deflation. Cant go unnoticed.

[Adnaan786]

It wouldn't necessarily cause the wheels to overheat.

[R.F.]

The wheels never overheat it's the brakes that do once the temperature of the hydraulic fluid crosses a predetermined threshold and may even cause fire, however the fuseible plugs tends to deflate the tyre as a precaution or rather prevention against tyre burst.

A tyre failure is when the tyre limitation speeds are exceeded which is generally 225 mph or 195.5 kts.

[Adnaan786]

I could be wrong, but I'm pretty sure the hydraulic fluid used in commercial aricraft is inflammable.

It's the friction between the brake pads and the brake disc that cause it to catch fire.

The break limit speed (called Vmbe - velocity maximum break energy) can also be exceeded if the aircraft weight is too high.

[R.F.]

Correct Vmbe is a factor however the hydraulic fluid has a threshold beyond which it is susceptible to fire due to the immense heat generated, especially if a reject takes place close to Vef.

However what you're referring to is steel brakes where as the commonly used are the Messiers or carbon brakes which tend to absorb far more energy compared to the steel or Bendix brakes.
The advantage of the carbon brakes are that their wear is propotional to the number of applications therefore a single steady application is required to prolong the life and consequently with selection of idle reversers saves engine life and fuel.

[Adnaan786]

I don't think it is susceptible to overheating. All the heat is felt by the break disk and break pad, the hydraulic fluid just provides a constant pressure to the breaks. Once again I could be completely wrong, but it's something I've never heard of, but I'll look into it.

Btw do commercial aircraft have temp. indicators for the hydraulic fluid?

If so then I guess you're right, but I don't think they do. I can only remember them having hydraulic pressure indicators.