QANTAS A380 Uncontained failure.

[DERG]

Basic Designs

TURBINE D

"I should add, the newer combustors utilize twin swirlers that perform better to mix the air with the fuel creating a leaner burn, lower temperatures, improved fuel burn and longer combustor life."

So we have a cool end where the big intake fan is, and a hot end where the exhaust gas is released. We have your analogy of the central shaft running from fornt to back...about 7 feet..in the case of the T900 upon which all of the various twirlers and compressors are affixed. Then we have the ancillaries the power take off shaft down to the gearbox and another shaft to start the engine. Much appreciate your input..thank you!

OPEN FORUM

Deduction 1.

Looking at the latest GE design we see that the big intake fan is made from carbon fibre. GE also use a fibre case to house the engine. So I think I am correct is assuming the GE products are using carbon fibre technology where as RR are using advanced metallurgy for the blades and old technology for the case.

Deduction 2.
Because the intake fan is lighter in the GE engine it is easier to balance and has inherently less kinetic energy to be lost in vibration. So the big mass at the front end is now "tamed".

Deduction 3.
Running temps. The 180C and 196C max temp of the T972 that failed is higher than other civil aviation engines to date. We have read the data in the Oxford University document and it is noted that 10% or more of RR engines fail the final passing out test due to imbalance. And a higher rejection rate is detected when the engines are overhauled at the RR appointed agents. The high running temps are cause by vibration inherent to this design.

Deduction 4.
Manufacturing tolerances. The RR design is difficult to manufacture beacuse of the nature of the concentricity of the drive shafts and the fact that is has three distinct compression stages. GE, I believe, use two stages.

Deduction 5
Given that the RR product is inherently difficult to balance it is clear that the existing in service methods of detecting an inbalance are inadequate.
On one drawing I see only one vibe detector noted but this was a schematic and there may be more than one.

Deduction 6
RR agents themselves cannot detect vibration or allow engines that are outside the norms back into service.

Deduction 7
RR are aware that the 3 spool design has inherent flaws but are unwilling to adopt a new design because the costs would be to high.

Deduction 8
As we see the fractured oil feed pipe as published in the ATSB report we must assume that the quality checks on parts from outside suppliers is poor.

Deduction 9
Communication failure. As the fractured oil pipe is clearly of poor manufacture we must deduce that the department which does the invigilation does not realise the importance of that part. In other words they have no concept about the vibrations inherent within the machine.

Deduction 10
Management Character. The commercial managers were easily persuaded that the monitoring system using the probablility model was robust. Because the work was done by assumed experts they did not apply rigour in seeking confirmed evidence. As far as we know they did not hire MIT for instance.

We know that a company called Schaeffer with the brand names FAG and INA were given the contract to build the entire bearing set and support structure. This was the first time this company had built this..the entire assemble with supports... a complex and critical part for a civil avaition aerospace gas turbine.

Deduction 11
The failure to be able to shut down the #1 engine on the stricken Qantas A388 was unforseen.

All repiles most welcome.