Enfin la VERITE ... selon Guy Norris de AviationWeek !
Et j'ai tendance à le croire, c'est précis et circonstancié, oil fire suspected !
Rupture d'un arbre du T100O, suite à un incendie dans le moteur ???
Ouf, pour en finir avec trop de choses lues, pendant 8 jours, et qu'il vaut mieux oublier !
Quelques inquiétudes à suivre pour les T900 bizarre, à lire ??
--------- Va pour tout l'article Av.Wek ---------http://www.aviationweek.com/aw/generic/story_channel.jsp?channel=comm&id=news/awx/2010/09/01/awx_09_01_2010_p0-251440.xml&headline=Oil%20Fire%20Suspected%20In%20Trent%201000%20Failure
New details of last month’s Rolls-Royce Trent 1000 uncontained
failure are emerging that have impacted the Boeing 787 delivery schedule
Indicators point to a fault with the oil system which led to a fire
developing inside the engine and damaged not just the engine, but also
the infrastructure involved in the trial.
The Aug. 2 incident on a ‘Package A’ configuration engine later
prompted Boeing to push back first 787 deliveries to launch customer All
Nippon Airways to February 2011; the aircraft maker had planned to hand
over the first aircraft by year-end under the latest of several
Boeing says “the delivery date revision follows an assessment of
the availability of an engine needed for the final phases of flight test
this fall,” and subsequently confirmed that the affected shipset had
been due to power 787 Line No.9, an aircraft added to the extended
twin-engine operations performance standards (ETOPS) test effort.
Rolls says the failure specifically concerned the intermediate
pressure turbine (IPT) but refuses to comment further on the incident
which caused substantial damage to the engine maker’s ‘Bed 58’ indoor
test site in Derby, U.K.
However, industry sources say an oil fire broke out within the
engine during high-power runs. The heating is believed to have
‘softened’ the intermediate pressure (IP) shaft which subsequently
failed. The unconstrained IPT then reached an over-sped condition and
ultimately disintegrated; parts thrown loose penetrated the casing.
By coincidence, the FAA is poised to ratify a European Aviation
Safety Agency airworthiness directive (AD) for the Airbus A380’s Trent
900 engine IP shaft which, if not performed, could result in similar
issues to those experienced by the closely derived Trent 1000. The AD
says wear beyond normal limits has been identified on the abutment faces
of the splines on the Trent 900 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 through of the splines
would permit the IP turbine to move rearwards, it adds. This rearward
movement “would enable contact with static turbine components and would
result in loss of engine performance with potential for in-flight shut
down, oil migration and oil fire below the LP turbine discs prior to
sufficient indication resulting in loss of LP turbine disc integrity.”
Although the AD, which requires inspection of the IP shaft coupling
splines, appears to bear an uncomfortable resemblance to the Trent 1000
issues, industry sources maintain the two are unconnected.
The engines installed on the first four 787s are configured with
‘Package A’ improvements, devised to tackle part of the 4-5% specific
fuel consumption shortfall identified in early development tests.
However, a further series of improvements developed during the
subsequent two-year program delay will be introduced in the so called
Package B, which will be retrofitted to test aircraft ZA004 later this
year. The delay to the start of 787 flight tests in 2009 meant some of
the later ‘B’ improvements were sufficiently mature to be introduced
during initial flight tests with units which Rolls described last year
as “a hybrid version of the Package A” and “a robust engine to support
the flight test program.”
Rolls-Royce’s Trent 1000 built to the improved ‘Package B’ standard
is designed to bring performance to within 1% of Boeing’s original
specification. Package B includes enhanced aerodynamics in the six-stage
low pressure (LP) turbine, improved cooling flow for the IP turbine and
changes to the secondary air system to take off sealing and cooling air
at a lower pressure stage. The root-to-tip twist of the fan blade is
also slightly altered to match changes in the pressure ratio caused by a
concurrent reduction in nozzle area. Rolls has run at least three
Package B performance engines and, when last reporting on progress, says
all were in line with expectations. In March Rolls was flight testing
the first Package B engine on its company 747 flying testbed ahead of
delivering finalized engines to Boeing for installation on ZA004.