Incidents Moteurs présumés

Inspections on [Vous devez être inscrit et connecté pour voir ce lien] engines have found three additional powerplants with a fault in the oil pipe tube, indicating that the manufacturing defect behind the uncontained engine failure on a Qantas Airways [Vous devez être inscrit et connecté pour voir ce lien] was not a one-off occurrence.

• "Dans ces incidents, il ne faut jamais perdre de vue les trois grandes catégories de réflexion à explorer, sans privilégier aucune des trois : (i) "one off" , (ii) "petit lot" ou (iii) "problème après une intervention d'entretien" ; ce sont les deux premières qui risquent de faire l'objet de ces réflexions et analyses d'usage, parce que les moteurs sont trop peu nombreux à ce stade, et trop jeunes pour avoir subi des interventions en MRO approfondies, sous accord TotalCare, ou sans accord TotalCare" !
  

• All three engines with faulty oil tube pipes "were removed from service for further examination," the Australian Transport Safety Bureau (ATSB) says. The three engines were on a Qantas A380 due for delivery this month, an in-service Singapore Airlines (SIA) A380, and a third unidentified powerplant understood to be with [Vous devez être inscrit et connecté pour voir ce lien].
  The oil tube pipe faults were found after inspections on 45 engines deemed "relevant", the ATSB says.

  
  Bon a savoir. C'est le but des inspections. Sachez que le terme employé fut "potentially faulty oil-tubes" !
  

  The ATSB could not be reached for comment on what made those engines "relevant" of all Trent 900 powerplants. There are 92 Trent 900s in service in addition to spare engines and powerplants on aircraft awaiting delivery, according to Flightlobal's ACAS database.

  
  Les 92 + le reste .... ; ça doit représenter les bons chiffres.
  

  Of the 45 inspected engines, 29 were on operating aircraft, eight were not installed on aircraft, four were due to be delivered on a new aircraft and four were on a flight test aircraft, the ATSB says.

  
  On apprécie les faits.
  

  A Qantas spokesman says "there was an anomaly with one of the stub pipes on one of the four engines" on an aircraft due to arrive in the coming weeks. He could not confirm the variant of the Trent 900 involved, but says "it wasn't a 'C mod'".

  
  RR le dira.
  

  Industry sources have said the problem affects only the "A mod" and "B mod" variants of the Trent 900, and not the latest variant, the "C mod".

  
  Il y en a qui disent que le Mod. B n'est pas concrné . A voir. De toutes façons, ... je patiente avant d'écrire quoi que ce soit sur les "nuances" entres les 3 versions (rien d'étonnat dans les circonstances). Il convient de se rappeler ce qu'a dit RR officiellement :
  [quote] "It is not true that we knew about a problem in the A and B versions of the engine and went on to correct it in the C version. There has been no design change relevant to this failure between A, B and C versions of the engine." [/quote]
  Déclaration déposée, et consignée . RR ne donne jamais dans le mensonge, .... le 'parjure', ni par cpmmission ni par omissions ; RR laisse cela aux autres. Nous l'avons assez vu.
  

  Qantas' spokesman says the stub pipe defect is unrelated to the carrier's announcement last week that 16 of its Trent 900 engines require "modification to the latest standard or full replacement".

  Le "Qantas spokesman" est 'hors-jeu', car il n'a aucune autorité qui l'habilite à faire cette remarque !
  Si le "Mod C", par exemple, est le "latest standard", et qu'il soit "non incriminé", .... ce porte-parole n'a rien à dire sur le besoin de modification.
  A ce stade, il reste à RR et à l'ATSB de déterminer cela !
  Aussi, pour le moment, il est clair qu'on n'appelle pas cela, à ce niveau de l'enquête, "un manufacturing defect", sans en donner quelques éléments d'explication, si possible. La seule conclusion d'étape au sujet de la pièce en question, dans le contexte de la recherche dela "root cause" porterait sur le "process" de production, de fabrication, et / ou de l'assemblage / l'insertion. Il ne s'agirait pas d'un défaut de design ou de conception, nécessitant une modification !
  Il ne faut pas raconter des absurdités, surtout à ce stade, même si ces éléments finissent par nécessiter, plus tard, une modification, quand les certitudes se cristalliseront, le cas échéant, dans ce sens !
  Il serait, sans doute, plus approprié de dire "manufacturing process defect".
  
  Les Autorités, à cette date, avaient émis un AD dite de "non-modification" ! Il serait absurde d'adopter les dires du "Spokesman" de Qantas, qui contredit l'AD en place actuellement !
  
  Il faut comprendre les règles et procédures qui s'appliquent dans le contexte de ces Enquêtes Officielles ! A ce stade, ce genre de dire de ce porte-parole ne vaut pas plus que les fictions et délires de Agités de Service que nous pouvions lire sous d'autres cieux !
  

  "That is not related to the stub pipe issue," the spokesman says. "The only stub pipe [fault] we have found is on this aircraft awaiting delivery." He declines to specify why the 16 other Trent 900s require change.

  Pourquoi ? Problèmes liés à l'absence ou à l'insuffisance des inspections que Qantas aurait dû faire ? Possibilité d'éventuel non respect (respect non systématique) du cahier des charges, par les pilotes / certains pilotes lors des décollages, par exemple ? Possible !
  Et si des défauts ou anomalies commençaient à 'naître', de manière visible, il est clair qu'il pourrait y avoir un avantage à remplacer des pièces ou modules de RR Trent 900, avec adoption de "Mod C", le cas échéant ! Mais cela est une autre histoire, avec une "root cause" ailleurs que dans le moteur, ou devant la porte de RR !
  

  The airline does not expect the oil pipe fault to have a significant impact on the aircraft's delivery. "We will take delivery of the aircraft in the next ten days," the spokesman says.

  Là, le "Spokesman" peut parler 'avec autorité' ! C'est un aspect commercial, 'hors enquête', qui peut se trouver dans son domaine de compétence et de communication ! Il est dans son rôle !
  

  Qantas also plans to take delivery of another A380 this month and two more early next year.
  SIA changed a "B mod" engine last weekend "as a result of the inspections that were recommended by ATSB", a SIA spokesman says. The engine is now undergoing a detailed inspection, he adds.

  La procédure recommandée, ... voire 'stipulée', est respectée !
  

  Last Friday, the ATSB faulted a "potential manufacturing defect" with the Trent 900's oil tube pipe as the cause of the uncontained engine failure on 4 November. The pipe feeds oil to the high-pressure (HP)/intermediate pressure (IP) bearing structure.

  A noter : l'utilisation du vocable "potential" ! L'ATSB tient à rester méticuleux dans son travail !
  

  ATSB chief commissioner Martin Dolan says Rolls-Royce "has issued a procedure for checking all the relevant engines to determine whether or not the problem that we have identified does exist in any of those engines."

  C'est exactement la manière dont 'ça doit se passer'! Pas autrement !
  

  In its report, the ATSB says the misaligned region of counter-boring within the stub pipe outlet produced a localised thinning of one side of the pipe wall. That led to an oil leak and subsequent fire that ejected the powerplant's IP turbine disc, sections of which penetrated the aircraft and caused structural and systems damage, it adds.

  
  Ceci est une répétition, ... pour la bonne mesure ! "Fair enough" !
  
  Réactions ?
  

• en conformité avec les règles de l'Enquête Officielle, recenser et connaître tous les faits, déterminer ce qui s'est passé, mettre en place les mesures conservatoires, et celles nécessaires à la reprise des opérations le plus rapidement possible, et avec un minimum de dérangement dans les opérations, mais en préservant la sécurité, même en faisant des excès de prudence, le cas échéant,.... avant d'entamer les négociations proprement dites ;
  
• en veillant à ce qu'il ne diffuse aucun commentaire, qui risque d'enfreindre la déontologie applicable, quand on est "sous enquête officielle" , notamment en ce qui concerne les 'codes de communication' (le tandem Alan JOYCE / Qantas s'est déjà mis hors jeu, surtout dans ses fausses allégations dans les media).
  

Qantas Airways has detailed the history of the [Vous devez être inscrit et connecté pour voir ce lien] powerplant variants that power its [Vous devez être inscrit et connecté pour voir ce lien] A380s in the affidavit and claim it filed against the engine manufacturer in Australia's Federal Court.

A Trent 900 engine experienced an uncontained engine failure on a Qantas [Vous devez être inscrit et connecté pour voir ce lien] flight on 4 November. The A380 fleet's return to service after a three-week grounding has been dependent on the engine's three different modification standards.

After the 4 November incident, Qantas and Rolls-Royce agreed the carrier should not operate any engines with an "A mod" high-pressure (HP)/intermediate pressure (IP) support structure, the affidavit says.
Qantas can operate "B mod" and "C mod" engines, the affidavit adds. However, the engines are restricted to performing only 75 72,000lb full thrust take-offs. After that threshold has been reached, the engine requires replacement before being operated at any thrust level.

Prior to the incident, seven of 24 Trent 900s on Qantas' six A380 aircraft had the original "A mod" HP/IP support structure. According to Rolls-Royce's engine manual, the life of the "A mod" HP/IP support structure is 2,000 cycles, the affidavit says.

The Trent 900 engine that experienced the uncontained failure was an "A mod" powerplant, the affidavit says.

In December 2007 Rolls-Royce issued a modification standard, "B mod", for the HP/IP support structure. Prior to the incident Qantas had 16 of these engines. Their life was 14,800 cycles, the affidavit says.

Rolls-Royce issued the latest modification standard, "C mod", in April 2009, the affidavit says. Qantas operated at the time of the incident one such engine, which had an unlimited life cycle.

The affidavit and claim do not specify what changes were made between the modification standards.

Qantas' claim says Rolls-Royce is in breach of thrust specification and payload undertaking agreements.

Rolls-Royce wrote to Qantas during the tender process that the "thrust availability guarantee would provide cover against an engine's inability to achieve full take-off thrust whilst on a normal revenue flight, up to 2,000 cycles", the claim says.
Rolls-Royce also said a Trent 900-powered A380 could be "operated regularly and reliably on Qantas' existing international routes (including the LAX routes) with a profitable payload and without the engines having to be replaced at any point before the end of the projected useful engine life", the claim says.

Last week the Australian Transport Safety Bureau said it was focusing on "A mod" and "B mod" variants for having a faulty stub pipe that feeds oil to the HP/IP bearing structure. The "C mod" variant was not affected.
The ATSB identified a faulty stub pipe with a misalignment causing pipe thinning as the likely cause of the uncontained failure.
As a result of the finding, checks were ordered on 45 "A mod" and "B mod" Trent 900 engines, the ATSB has said. Inspections found three engines with a faulty stub pipe, including one on a Qantas A380 imminently due for arrival.

However, the engines are restricted to performing only 75 72,000lb full thrust take-offs. After that threshold has been reached, the engine requires replacement before being operated at any thrust level.

• cette limitation, n'est qu'une mesure temporaire, remplie d'une extrême prudence, nécessaire dans les circonstances ;
  
• et n'entrâine aucun coût pour Qantas, puisque la dépose du moteur, pour remplacer la composante incriminée (pour remise à niveau du moteur, avec une pièce neuve, de durée de vie illimitée), et la mise sur l'aile immédiate du moteur de remplacement, ... sont à la charge de RR ;
  
• car ces opérations précitées ne coûtent rien à Qantas , le contrat TotalCare & les clauses de garantie d'usage, couvrant tous les éléments de coût, pendant une période prédfinie.
  

• dans les circonstances de l'incident qui a frappé Qantas, et les choses étant ce qu'elles étaient, une inspection sans action n'aurait pas empêché l'accident ;
  
• mais, si les inspections avaient été faites, et l'anomalie détecté ("oil stains" / "hot spot marks"), il eût été impératif, et possible, bien sûr, de procéder en temps voulu au changement de moteur qui s'imposait, .. changement à la charge de RR, bien entendu.
  

The affidavit and claim do not specify what changes were made between the modification standards.

Qantas' claim says Rolls-Royce is in breach of thrust specification and payload undertaking agreements.

Rolls-Royce wrote to Qantas during the tender process that the "thrust availability guarantee would provide cover against an engine's inability to achieve full take-off thrust whilst on a normal revenue flight, up to 2,000 cycles", the claim says.
Rolls-Royce also said a Trent 900-powered A380 could be "operated regularly and reliably on Qantas' existing international routes (including the LAX routes) with a profitable payload and without the engines having to be replaced at any point before the end of the projected useful engine life", the claim says.

Last week the Australian Transport Safety Bureau said it was focusing on "A mod" and "B mod" variants for having a faulty stub pipe that feeds oil to the HP/IP bearing structure. The "C mod" variant was not affected.
The ATSB identified a faulty stub pipe with a misalignment causing pipe thinning as the likely cause of the uncontained failure.
As a result of the finding, checks were ordered on 45 "A mod" and "B mod" Trent 900 engines, the ATSB has said. Inspections found three engines with a faulty stub pipe, including one on a Qantas A380 imminently due for arrival.

• changement de fournisseur dans le Supply Chain (notamment quand il est considéré nécessaire et inévitable d'avoir "dual or multiple sourcing" (car les livraisons, dans le contexte "juste-à-temps" ne seront pas synchronisées ou homogènes en terme des quantités de livraisons individuelles ; et, dans les phases initiales du "ramp-up" de la production, cet aspect peut / pourrait être accentué en faveur d'un fournisseur, plutôt que d'un autre, sans qu'il s'agisse de favoritisme, bien sûr) ;
  
• modification du "process" de fabriacation / d'usinage chez le fournisseur (il est possible que, au moment des livraisons, le juste-à-temps ait nécessité la livraison d'un lot, libelleé 'A', par pure convenance administrative, mais avec l'avantage d'offrir la traçabilité impérative de la composante-- il y a des numéros d'inventaire derrière la lettre 'A' ! -- , et des moteurs dans lesquels elles sont insérées) ;
  
• chez le fournisseur de RR, changement d'un outil de production, qui améliore incontestablement le "process", et qui devrait améliorer, par répercussion, par exemple, le process d'assurance qualité (dans la dynamique des opérations de la production, donc) et la constance du respect systématique des spécifications de la pièce définie ; hélas, il arrive qu'il y ait des lots (petits ou importants) de composantes défectueuses, dans la phase de transition entre les tests / la pre-industrialisation vers l'industrialisation du "'process".
  

An Emirates Boeing 777-300, flight EK-650 from Dubai (United Arab Emirates) to Colombo (Sri Lanka), was in the initial climb out of Dubai when the crew decided to return to Dubai for a safe landing about 20 minutes after departure.

The airline reported the crew returned to Dubai due to some technical problems.

Passengers reported the crew announced they had an engine failure

Koro a écrit:Problème moteur sur B 777-300 d'Emirates ?

[Vous devez être inscrit et connecté pour voir ce lien]

An Emirates Boeing 777-300, flight EK-650 from Dubai (United Arab Emirates) to Colombo (Sri Lanka), was in the initial climb out of Dubai when the crew decided to return to Dubai for a safe landing about 20 minutes after departure.

The airline reported the crew returned to Dubai due to some technical problems.

Passengers reported the crew announced they had an engine failure

Qantas va remettre en service cinq A380


La compagnie aérienne australienne Qantas a annoncé mercredi qu'elle disposera de cinq Airbus A380 en service à la fin de la semaine. Qantas, qui possède six exemplaires du plus gros avion de ligne du monde, avait été contraint de procéder à des vérifications techniques après qu'un A380 de la compagnie avait dû effectuer un atterrissage d'urgence à Singapour en novembre. Le problème portait sur l'un des moteurs fabriqués par le Britannique Rolls-Royce. Alors qu'approche le début de la saison estivale dans l'hémisphère sud, Qantas disposera de quatre de ses anciens A380 en service cette semaine. Un nouvel A380 sera ajouté à la flotte enfin de semaine tandis qu'un autre devrait arriver en janvier. L'un des anciens A380 est toujours l'objet d'inspections.

[Vous devez être inscrit et connecté pour voir ce lien]

Au passage,
La plus mauvaise gestion de crise (PR) que j'aie vu dans ce milieu depuis bien longtemps, en plus !
.......

• son auteur ne connaît pas du tout ce milieu (certes, il "l'aime" à sa façon ; mais il le connaît si peu, en réalité) ;
  
• il donne trop dans le paraître, car l'aéronautique et l'aviation ne se limitent pas à son tournevis ;
  
• il manque de rigueur et d'objéctivité, car il n'aime pas les faits, et préfère au factuel les hypothèses, avis personnels, infondés, non étayés et non étayables, et les polémiques.
  

Qantas is believed to be closer to restarting Airbus A380 service on the Los Angeles to Sydney and Melbourne routes after regulators eased engine inspection rules.

According to The Australian, Qantas is in discussions with Rolls-Royce about how it can lift restrictions on Trent 900 engines that prevent the aircraft flying from the US with a full payload.

EASA this week relaxed its requirement of a Trent 900 inspection every 20 flights, designed to detect oil leaks, to an inspection every 200 flights.

EASA ordered the inspections after the Nov. 4 explosion of a Trent 972 engine on a Qantas A380 after take-off from Singapore. The problem has been traced to fatigue cracks in an incorrectly bored stub pipe that feeds oil into the High Pressure and Intermediate Pressure bearing structure ([Vous devez être inscrit et connecté pour voir ce lien]).
Qantas said it will have five A380s flying by Christmas Day including its seventh, which was delivered last week. The airline will take delivery of a further two A380s next months.

The NTSB released their [Vous devez être inscrit et connecté pour voir ce lien] concluding the probable cause of the incident was:

The engine experienced an uncontained release of high pressure turbine material due to fatigue cracks that occurred on four consecutive blade retainig lugs on the 2nd stage turbine hub.

The cracked lugs resulted in the release of four 2nd stage turbine blades that penetrated the engine's cases and nacelle.

The lugs cracked due to loss of material and resultant increase in stress load on the blade slot serrations due to
excessve grit blasting when the hub was being overhauled by Delta Air Lines.

Contributing to the uncontained incident was the FAA's and Pratt & Whitney's failure to act in a timely manner when another PW2037 2nd stage turbine hub was found to have multiple cracks in the blade retaining lugs.

The captain reported in post flight interviews, that they heard a loug bang and the #2 engine (PW2037) fire indication illuminated just as they were applying power for takeoff.

They rejected takeoff, stopped the airplane on the runway and shut the right hand engine down declaring emergency.

The engine fire indication ceased upon shut down of the engine, so they did not discharge a fire bottle.

Attending fire services then reported seeing a glow inside the engine through a hole in the bottom of the right hand engine's nacelle and discharged a fire bottle through the open pressure relief doors.

After fire fighters had ensured there was no fire, the airplane was permitted to taxi back to the gate.

A subsequent examination revealed that 4 adjacent 2nd stage turbine blades were missing from the 2nd stage turbine hub,
the two blades next to the missing blades had fractured and reduced to about 1/4 and 1/2 of their length,
the other blades were nearly full length though showing rub marks, dents and discolouration.

Further examination reveleased that 4 blade retaining lugs in the 2nd stage turbine hub had fractured between the inner and middle serrations.

According to maintenance documentation the turbine hub had accumulated 29097 hours in 12549 cycles with a lifespan of 15000 cycles.

The hub had done 4932 cycles since major overhaul in 2004.

During that overhaul the hub underwent a four-step chemical descaling process, was grit blasted with 500 grit aluminum oxide, steam cleaned, oven dried, FPIed, steam cleaned again, and then dimensionally inspected.

A dimensional inspection of the 2nd stage turbine hub showed, that the hub conformed to requirements in all diametrical
features.

However, the inspection also showed that the blade retaining lug serrations were 0.0092 inches (0.2millimeters) below minimum tolerance.

The PW2000 engine manual had specified a cleaning procedure named SPOP19.

Delta maintenance had found it increasingly hard to clean the engines using SPOP19.

The PW2000 manual also specified an alternate procedure called SPOP10 using 500 grit aluminum oxide dry grit blasting in case the hubs could not be adequately cleaned employing SPOP19.

Delta subsequently adopted SPOP10 as their standard procedure, Pratt&Whitney ultimately revised the engine manual to delete SPOP19 in favour of SPOP10.

Tests showed that using SPOP10 on materials used as the 2nd stage turbine hub only minimal material was removed from
the surface.

However, if the blasting gun was held too close, was allowed to dwell in one spot or was held at an angle of 45 degrees,
significant amounts of materials were removed.

In June 2007 another PW2037 had been identified with cracks in the blade retaining lugs.

The FAA was aware that this occurrence had been reported to P&W.

At the time of the uncontained engine failure in Aug 2008 however P&W had not yet determined the cause of those cracks.

A subsequent dimensional inspection revealed similiar deviations from the blade slot serration profiles that were found on the engine of Aug 2008.

Documentation of the Jun 2007 engine showed that the engine had undergone multiple grit blasting cycles before the inspector accepted the part for inspection.

• 80% des clients, et 60% des volumes !
  

LOUPO a écrit:Retour sur un incident P&W 2037 ayant affecté un B 757 de Delta en aout 2008

Release du NTSB repris sur Avherald :

[Vous devez être inscrit et connecté pour voir ce lien]

The NTSB released their [Vous devez être inscrit et connecté pour voir ce lien] concluding the probable cause of the incident was:

The engine experienced an uncontained release of high pressure turbine material due to fatigue cracks that occurred on four consecutive blade retainig lugs on the 2nd stage turbine hub.

The cracked lugs resulted in the release of four 2nd stage turbine blades that penetrated the engine's cases and nacelle.

The lugs cracked due to loss of material and resultant increase in stress load on the blade slot serrations due to
excessve grit blasting when the hub was being overhauled by Delta Air Lines.

Contributing to the uncontained incident was the FAA's and Pratt & Whitney's failure to act in a timely manner when another PW2037 2nd stage turbine hub was found to have multiple cracks in the blade retaining lugs.

The captain reported in post flight interviews, that they heard a loug bang and the #2 engine (PW2037) fire indication illuminated just as they were applying power for takeoff.

They rejected takeoff, stopped the airplane on the runway and shut the right hand engine down declaring emergency.

The engine fire indication ceased upon shut down of the engine, so they did not discharge a fire bottle.

Attending fire services then reported seeing a glow inside the engine through a hole in the bottom of the right hand engine's nacelle and discharged a fire bottle through the open pressure relief doors.

After fire fighters had ensured there was no fire, the airplane was permitted to taxi back to the gate.

A subsequent examination revealed that 4 adjacent 2nd stage turbine blades were missing from the 2nd stage turbine hub,
the two blades next to the missing blades had fractured and reduced to about 1/4 and 1/2 of their length,
the other blades were nearly full length though showing rub marks, dents and discolouration.

Further examination reveleased that 4 blade retaining lugs in the 2nd stage turbine hub had fractured between the inner and middle serrations.

According to maintenance documentation the turbine hub had accumulated 29097 hours in 12549 cycles with a lifespan of 15000 cycles.

The hub had done 4932 cycles since major overhaul in 2004.

During that overhaul the hub underwent a four-step chemical descaling process, was grit blasted with 500 grit aluminum oxide, steam cleaned, oven dried, FPIed, steam cleaned again, and then dimensionally inspected.

A dimensional inspection of the 2nd stage turbine hub showed, that the hub conformed to requirements in all diametrical
features.

However, the inspection also showed that the blade retaining lug serrations were 0.0092 inches (0.2millimeters) below minimum tolerance.

The PW2000 engine manual had specified a cleaning procedure named SPOP19.

Delta maintenance had found it increasingly hard to clean the engines using SPOP19.

The PW2000 manual also specified an alternate procedure called SPOP10 using 500 grit aluminum oxide dry grit blasting in case the hubs could not be adequately cleaned employing SPOP19.

Delta subsequently adopted SPOP10 as their standard procedure, Pratt&Whitney ultimately revised the engine manual to delete SPOP19 in favour of SPOP10.

Tests showed that using SPOP10 on materials used as the 2nd stage turbine hub only minimal material was removed from
the surface.

However, if the blasting gun was held too close, was allowed to dwell in one spot or was held at an angle of 45 degrees,
significant amounts of materials were removed.

In June 2007 another PW2037 had been identified with cracks in the blade retaining lugs.

The FAA was aware that this occurrence had been reported to P&W.

At the time of the uncontained engine failure in Aug 2008 however P&W had not yet determined the cause of those cracks.

A subsequent dimensional inspection revealed similiar deviations from the blade slot serration profiles that were found on the engine of Aug 2008.

Documentation of the Jun 2007 engine showed that the engine had undergone multiple grit blasting cycles before the inspector accepted the part for inspection.

Bon alors, "Maintenance issue" ou " Manufacture issue" ...?

• 80% des clients, et 60% des volumes !
  

La compagnie aérienne angolaise TAAG a décidé de suspendre les vols de ses Boeing 777 suite à un nouvel incident de moteur, a annoncé vendredi un responsable de la compagnie à la radio nationale angolaise (RNA).

Un Boeing 777-200ER de la TAAG qui avait décollé de Luanda pour Dubaï jeudi soir avait dû retourner à l'aéroport suite à "une défaillance détectée dans le moteur droit", a déclaré Rui Carreira, administrateur de la TAAG, à la RNA.

"Face à 2 incidents similaires en 17 jours, pour des raisons de sécurité internationale et de prudence, la TAAG a décidé de suspendre tous les vols de sa flotte de Boeing 777-200ER", a ajouté Rui Carreira en précisant que [Vous devez être inscrit et connecté pour voir ce lien] et Boeing, fabricants respectifs du moteur et de l'avion, seront interrogés.

Le 6 décembre dernier, un Boeing 777 de la TAAG qui devait faire la liaison Lisbonne-Luanda avait dû atterrir d'urgence à Lisbonne après avoir perdu des pièces métalliques.

La TAAG, inscrite sur la liste noire des transporteurs interdits de vols dans l'Union Européenne pour des raisons de sécurité en juillet 2007, a repris ses liaisons avec le Portugal en juillet 2009 avant d'être à nouveau autorisée à voler dans toute l'Europe en mars dernier.

.......an oil fire in the HP/IP turbine area..... to be the cause of the uncontained failure in the RR Trent 900 engine of the Qantas A380 on Nov. 4 last....... This is an outcome that was expected by experts.

But why does an oil fire lead the IP turbine disk to disintegrate? Let's go through, in simple language, reasonable detail, what probably happened, step by step :

• The buffer cavity / "bearing-box buffer cavity" between the HP and the IP becomes contaminated with oil. Why this happened is pure speculation at the moment. It could have been a bearing that leaked, it could have been oil lines that leaked or failed or something else...

• During the take-off and climb phases temperatures in the cavity are rising extremely swiftly and high enough to make the oil ignite.
  
• With this "spontaneous ignition", and the sudden surge of brutally excessive heat, the bearing-box shatters, its "red-hot / white-hot" fragments flying around in a small, tight environment ; the IP shaft, too, gets hugely overheated in no time at all, and fails, with extreme suddenness, just like that of the shattering of the bearing-box.
  
• In the same, tiny fraction of a second, the IPT disk, with equally unexpected and brutal suddenness runs free without the IP compressor there acting as a brake, and accelerates in milliseconds while fuel is still pumped into the combustor.
  
• The bore of the disk is designed to withstand speeds up to, say, 40%-to-60% higher than the speed at takeoff, whilst the airfoils are designed to fail earlier, at possibly 120%-130% of "base-line design speed".
  
• But the oil fire also caused the bore to heat / overheat sharply, thereby decreasing ("eating up") the so-called "overspeed burst margin".
  
• The disk bursts (as in this RR Trent 900 / Qantas A380 case) at a speed before the airfoils fail.

So how can RR best prevent recurrence of such a failure ? Or, what measures should RR take to eliminate the possibility of such recurrence, .... or, failing that, at least to alienate the risk thereof ? Or to neutralise the potentially tragic consequences, to which the Qantas A380 came so perilously exposed ?

First of all, prevent the oil leakage. Without oil leakage : no fire, no shaft shear, no disk burst.

Secondly, as one can probably never eliminate with 100% certainty of success, the possibility of an oil leak, a functionality must be incorporated into the engine, in order to detect promptly, virtually immediately, with certainty and sufficient advance-warning, the symptoms of shaft-shear, and to stop sharply all "pumping of fuel into the combustor area" of the engine concerned. Without fuel combustion and the injection of energy into the turbine gas path, the disk will not accelerate.

Rolls Royce said that the Trent 900 and the Trent 1000 uncontained failures are unrelated.

That is doubtless true with respect to the causes of the two incidents.

But I would like to hear what Rolls Royce changed in their design philolosophy between the Trent 900 and the Trent 1000 (and the Trent XWB) to prevent such an overspeed beyond burst limit speeds in case of a shaft shear as it appears that the outcome of the different causes was the same.

To clarify, the story I pictured is my view, on what might happened. I can't assure that it was like I wrote. I hope to hear the "real" story tomorrow from RR.

Taliqua a écrit:Merci pour les précisions ! Et le recadrage....

A Delta Airlines Boeing 757-300, registration N584NW performing flight DL-1921 from Detroit,MI to Phoenix,AZ (USA) with 224 passengers, was enroute at FL360 about 200nm eastsoutheast of Colorado Springs,CO (USA) when the crew reported problems with the right hand engine (PW2040).

The crew shut the engine down, drifted down to FL230 and diverted to Coloroda Springs for a safe landing on Colorado
Spring's runway 35L about 45 minutes later.

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Ramjet2 a écrit:L'équipage d'un B-757-300 de Delta coupe un moteur ( P&W 2040 ) en vol

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A Delta Airlines Boeing 757-300, registration N584NW performing flight DL-1921 from Detroit,MI to Phoenix,AZ (USA) with 224 passengers, was enroute at FL360 about 200nm eastsoutheast of Colorado Springs,CO (USA) when the crew reported problems with the right hand engine (PW2040).

The crew shut the engine down, drifted down to FL230 and diverted to Coloroda Springs for a safe landing on Colorado
Spring's runway 35L about 45 minutes later.

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Qantas CEO Alan Joyce has dismissed the latest Qantas mid-air engine fault as a minor incident.

One of the plane's two General Electric engines began to vibrate and the crew decided to take precautionary measures and return the flight bound for Melbourne back to Perth soon after takeoff.

Mr Joyce said the problem was minor, but he praised the crew for taking exactly the right action.
All 243 people on board were transferred to other flights for their journey to Melbourne.

A Transaero Airlines Boeing 767-300, flight UN-559 from Moscow Domodedovo (Russia) to Hurghada (Egypt) with 214 passengers, was enroute near Rostov (Russia), when the crew needed to shut the left hand engine down because of low oil pressure.
The airplane diverted to Rostov for a safe landing.

TuK a écrit:Chute de pression d'huile sur un moteur de Boeing 767-300 Transaero

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A Transaero Airlines Boeing 767-300, flight UN-559 from Moscow Domodedovo (Russia) to Hurghada (Egypt) with 214 passengers, was enroute near Rostov (Russia), when the crew needed to shut the left hand engine down because of low oil pressure.
The airplane diverted to Rostov for a safe landing.

Il s'agit du CN 25077; LN 385; à moteurs P&W 4060

Mais, au sujet de l'Appel d'Offres des avions ravitailleurs pour l'USAF, quand on pense à l'offre Boeing articulé autour d'un airframe B767 et des moteurs de la famille / série PW2060 de P&W, et à l'offre de la plate-forme A330-200 d'EADS, avec des moteurs GE CF-6, on se gratte plus que la tête !