Page 72 - World Airnews September 2020 Edition
P. 72
HANGAR
TALK
TRENT XWB HIGH-TIME
WEAR ISSUE
By Guy Norris
olls-Royce has discovered cracks
Rin the intermediate pressure com-
pressor blades of higher-time Trent XWB-
84 engines during scheduled overhaul but
said early detection will enable the speedy
development of a fix.
The issue does not threaten the long-
term reliability of the engine built to power
the Airbus A350-900, Rolls Royce said.
The cracks were found in the roots of a
limited population of first-stage IP com-
pressor blades of engines undergoing their
first overhaul since entering service on the
A350 in 2015 and 2016.
However, unlike the well-documented
wear and corrosion issues experienced
on the Boeing 787’s Trent 1000, the XWB
problem “is much more benign, and we
have found it before it found us,” Rolls
Royce chief engineer for large engines
Frank Haselbach said.
Rolls-Royce announced earlier this year been no abnormal operation, no vibration, comprised of solid blisks (integrated blades
an exceptional charge of (US) $1.77 billion and no in-flight shutdowns. It’s a case of and disks), rather than the XWB-84’s more
or £1.50 billion related to the ongoing fixes ‘we have a problem and we need to find conventional blade and disk configuration.
for the Trent 1000, and is moving pro-ac- out where it’s coming from’. Now we have The issue on the Airbus engine was
tively to re-assure A350 operators that found it, we’ll have to make sure that we unexpected because “fundamentally the
the wear issue discovered on the XWB is are effectively doing the right thing and aerodynamic forcing of the IP compressor
insignificant by comparison. scanning the fleet in the appropriate age in the XWB is much weaker than on the
The engine-maker, which expects EASA and actually go to a repeat inspection Trent 1000,” Haselbach said.
to make the IP compressor inspections regime.” “We’ll have to see what the investigation
the subject of an imminent airworthi- Cracks were found in isolated blades in gives us but clearly this is something which
ness directive, meanwhile remains in the 20% of the approximately 100 higher time we’re driving with a lot of speed.”
middle of cost-cutting efforts to combat engines inspected to-date. Rolls Royce The trouble-shooting team aims to
losses associated with the impact of the has so far built around 800 Trent XWB-84s complete a vibration survey and root-cause
COVID-19 pandemic. and accumulated six million hours of flight analysis by year’s end. In the meantime, af-
time in what the manufacturer calls the
Describing the cracks as “clear wear and “smoothest entry-into-service of any wide fected engines will be retrofitted with new
tear in the actual bedding area of the first body engine we have developed.” first-stage blades pending the longer-term
stage rotor blade,” Haselbach said, “We development of a permanent fix.
didn’t expect that to happen on the XWB.” The vibratory issue will not occur on the Compared to the height of the Trent
Similar issues occurred on the first and more powerful XWB-97 variant used in the 1000 crisis in 2018-2019, when Rolls was
second rotor stages of the Trent 1000 IP A350-1000 because the first two-stages hamstrung by limited repair and overhaul
of the IP compressor in this engine are
compressor, and were later traced to capacity, the pandemic has changed
resonance caused by wake interac- the picture for the XWB recovery plan.
tions with upstream stages. “We actually have more capacity
However, when Rolls Royce first around us than we thought we’d have
checked the XWB-84 fleet for similar because of less flying activity and
issues as it tackled the Trent 1000 stretched overhaul schedules. So, we
crack problem, it found none. have parts and we have the capacity to
Underlining the late service life do it,” Haselbach said.
onset of the condition, Haselbach
said “nothing has actually happened Article courtesy:
with any of these engines. There has https://aviationweek.com/
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