Merci Poncho, la liste pourrait être longue pour Airbus ... on en parlait !
Et l'EASA va les aider à faire le tri, s'ils trainent les pieds chez Airbus !
Encore des Mécréants qui ne croient pas au : U.N.R.E.L.A.T.E.D chez AviationWeek Ouarf !
Ben juste noter que le soft "Anti -survitesse", devrait être vite implanté, JL en parlait ce matin, et qu'il doit déjà l'être sur le T1000 depuis 1 mois, dommage d'avoir loupé le coche avec Qantas !
Pour les boites à roulements, on va voir, faut descendre le bloc MPT, juste espérer qu'ils ont vraiment trouvé lé "Mère" de toutes les Root Cause ! Hum ...
Ailleurs Qantas commente un arrêt pour qq jours plutôt que qq semaines !
Tiens, qq shémas, courtoisie de A.net ! Merci JamBrain !
Allez j'ouvre un petit bout de la page 2
Signs of a rapid disc burst are important clues to potential failure mechanisms. The Trent 900 IPT disc is thought to be a life-limited part (or life cycle fatigue-limited), which is designed with a high burst margin. In the event of a failure of the IP shaft, and a subsequent disc overspeed, the unit is designed to withstand substantial damage—including the loss of blades—without exceeding this margin.
However, given the breakup of the disc, speculation is focusing on potential mechanisms that could reduce this margin, one of which is an oil fire. In such a situation, the fire would heat up the shaft, just as is believed to have occurred in the Trent 1000 test failure in August, weakening shaft strength and leading to almost simultaneous shearing of the shaft and disc failure.
Although Rolls says the Trent 900 and Trent 1000 events were unconnected, and that “it is now clear this incident is specific to the Trent 900 engine,” the IPT and oil system are implicated in both cases. Rolls sources indicate the Trent 1000 test incident was linked to issues with the specific oil system in the test setup rather than in the production-standard engine. This may be why the company can claim the events are unconnected, even though the results are startlingly similar.
Following these clues, EASA also identifies the oil system as the prime suspect in the A380 investigation and will likely, at the very least, make the oil system a watch item on the Trent 1000.
Historically, Rolls has had to combat oil system issues with the A340-500/600’s Trent 500, on which the Trent 900 is heavily based.
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Longer-term actions, such as redesigning part of the oil system, are being considered. The Trent 900 oil system is made up of one main pressure pump, plus seven scavenge pumps feeding the accessory, step-aside and lower-level gearboxes, front bearing housing, internal gearbox, tail bearing housing and the suspect HP/IP bearing chamber. The system also includes a 15-micron scavenge filter as well as a 125-micron pressure filter, and various magnetic chip detectors.
Leakage in the oil system, leading to the potential for oil fires below the LP turbine disc, was identified in EASA’s original AD issued this year for the Trent 900 engine IP shaft (AW&ST Sept. 6. p. 41). The AD followed the discovery of wear beyond normal limits on the abutment faces of the splines on the IP shaft rigid coupling on several engines during strip. As the shaft-to-coupling spline interface provides the means of controlling the turbine axial setting, the wear would permit the IP turbine to move rearward, it says. This movement “would enable contact with static turbine components and would result in loss of engine performance with potential for inflight shut down, oil migration and oil fire below the LP turbine discs prior to sufficient indication resulting in loss of LP turbine disc integrity.”
As part of the latest inspections, Rolls therefore told operators to check for any anomalies in the HP turbine gas path, as well as the platform at the front of the IP turbine for evidence of contact with the IP nozzle guide vanes. It also instructed a repeat of the intermediate coupling spline inspection AD if the time since the last inspection is greater than one-third of the 150-cycle inspection interval.
In addition to fixes that will almost certainly need to be identified, developed, tested and certificated for the Trent 900, the commonality between the IPT events on the A380 and 787 engines is expected to result in additional reviews of the hardware and software improvements already in train for the Trent 1000 following the August ground-test failure.