Jetrader - Spring 2018 - 25

model in the GE9X. Pratt & Whitney have
the TALON X lean burn combustor fitted to the PW1000G and along with CFM
claim the system will reduce NOx emissions by around 50 percent against CAEP/6
(Committee on Aviation Environmental
Protection) standards.
The difficulty in achieving sizeable
improvements from conventional two- or
three-spool engines is only getting harder.
Increasing the bypass ratio to improve the
propulsive efficiency will invariably cause
the low pressure turbine (LPT) to grow in
size and stage numbers. Large turbine
systems tend to be expensive, heavy and
increase the cost of maintenance.
Pratt & Whitney has overcome this issue
with the PW1000G geared turbofan (GTF).
The GTF has a planetary gearbox sitting
between the fan and HPC. The reduction
gearbox transmits the load from the LPT
to the fan allowing the fan to spin three
times slower at its optimal speed. This
allows the fan to grow in size with little
impact to the LPT. In fact, the engine can
reduce in length as fewer LPT stages are
required, allowing the LPT to spin faster
at its optimum speed.
Rolls-Royce has seen the benefit of having
a gearbox. As part of the UltraFan research
program, they have invested around €65M
to build a test bed and facility for their
power gearbox. The gearbox is designed to
operate on widebody engines and reach up
to 100,000 horsepower. To incorporate the
gearbox design, Rolls-Royce aims to remove
the LPT altogether and have an enhanced
intermediate pressure turbine (IPT) to drive
the fan via the gearbox. This reduction in
weight and improvement in efficiency is
claimed to allow UltraFan engines to achieve
25 percent fuel efficiency improvements
over first-generation Trent engines.
Little news has emerged from Boeing with
regards to their New Midsize Airplane (NMA)
program. If it is launched, intense competition will surely follow between many of the
major engine OEMs to supply the powerplant.
Current estimates place the entry into service in the mid-to-late 2020s with the need
for an ultra-high bypass ratio turbofan. This
falls in line with the timeframe that RollsRoyce has stated for technology readiness
of the UltraFan. CFM International, having
also studied an engine with a geared system,
and Pratt & Whitney have both stated an
interest in the program.

Maintenance, Manufacturing,
Monitoring
Material and turbomachinery do not represent the only advancements in the aero
engine industry. Maintenance, manufacturing and monitoring have all evolved.
The advent of additive layer manufacturing (ALM), more commonly known as 3D
printing, has allowed OEMs the freedom
to design and manufacture intricate parts
that would otherwise have been impossible
with traditional methods. For example,
blades with a complex network of cooling
passages that aren't able to be engineered
with traditional techniques can be printed.
GE, for one, has adopted the 3D-printing
capability, having launched its own ALM
division, GE Additive, to supply 3D printers,
materials and consulting services. The LEAP
features 3D-printed fuel nozzles, which are
claimed to be 25 percent lighter than its
predecessors and five times more durable.
In designing the Advanced Turboprop,
GE engineers were able to reduce 855 individual parts to 12 parts. More than a third
of the engine is built using ALM parts,
which enables a five percent reduction in
engine weight. GE also claims the engine
will be able to operate for 1,000 hours longer than its competitors, further extending
the mean time between overhaul. Fewer
parts benefits the operator, in terms of
reduced maintenance cost and downtime.
Systems health monitoring has been
aided by the explosion of activity in the

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big data market. During each flight, data
is recorded and transmitted live. A 787
can generate anywhere in the region of
500 gigabytes of data every flight. Using
analytics, airlines and OEMs can interrogate
the data to monitor the health of their fleet
and schedule maintenance accordingly. This
works particularly well for both the airline
and OEM if the airline is enrolled on a flighthour agreement (FHA). Predictive maintenance can reduce downtime, in-service
delays or flight cancellations benefitting
both parties.
For MROs, the next frontier is to incorporate the use of drones and virtual reality
platforms during maintenance. EasyJet has
been trialling the use of drones for inspections and damage assessments during the
past number of years in a bid to reduce and
eliminate technical delays.
Rolls-Royce and GE are both heavily
involved in robotics research to assist engine
inspections and repairs. With the goal to
reduce costs, the OEM can remotely assist a
local engineer with assessments and repairs
from anywhere in the world rather than fly
to the location and incur hefty costs. In
the same vein, augmented or virtual reality
will allow more qualified engineers to assist
local technicians using wearable technology
to help with maintenance.
Not only is virtual reality useful for
maintenance activities, it can be a powerful tool for training the next generation
Continued on page 66

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2018 25
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Jetrader - Spring 2018

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