PW1100G

The flight tests, due to begin by June on one of Pratt's two Boeing
747SP flying testbeds, will be critical to assessing not only fuel
consumption, but also operability and overall performance in advance of
flights on the first reengined A320 late next year. The PW1100G is the
first of the new-generation mid-thrust turbofans to fly. The competing
CFM Leap-1A from the alliance of General Electric and Snecma, is not due
to begin ground trials until September, and will start test flights in
2014.

The mood at Pratt is optimistic as it begins mating the first engine
to a strut developed by L-3 Communications for attachment to the 747 at
the Mirabel Aerospace Center in Quebec. Confidence stems from favorable
results during ground tests that were completed on the first engine at
the company's facility here in early April. The engine, rated at 33,000
lb. thrust, accumulated 120 hr. in trials that began in early December
and ended with acoustic tests on April 10.
Pratt & Whitney
President Dave Hess says performance evaluations to date are positive.
“We feel we're on the mark, and meeting the projections we made,” he
says. Pratt originally targeted the PW1100G at a 12% better fuel burn on
the A320 than the CFM56-5B and now believes it has a 16% advantage. “In
the development program, we're where we need to be. In fact, we're
right on the mark for delivering on fuel burn on all three of the
platforms,” he adds, referring to the geared-turbofan-powered A320NEO as
well as the Mitsubishi Regional Jet (MRJ) and Bombardier CSeries.
A
second PW1100G engine is undergoing structural trials and is poised for
crosswind evaluations. The tests will assess fan characteristics and
flutter margin before the engine moves on to other low-pressure system
stress tests. The fan blade is a larger version of the same bi-metallic
blade developed and tested for the CSeries that has proven highly robust
in testing, says Bob Saia, vice president of Pratt's Next-Generation
Products Family. “We hit a home run with this new fan blade,” he says.
The
blade had greater flutter margin than predicted, which enabled Pratt to
discard the variable area fan nozzle (VAFN) from the CSeries's PW1500G
engine late last year. The feature dynamically alters exit nozzle area
for different phases of flight to maintain blade stability It remains
part of the baseline on the Pratt-powered A320NEO and will be certified
in this configuration. On larger engines, such as the PW1100G, the VAFN
offers the potential for additional fuel savings as well as maintaining
flutter margin. For smaller engines, like the PW1500G for the CSeries,
the specific aim is to safeguard the fan, and Pratt says fuel efficiency
will be better without the feature

A third NEO engine will begin high-pressure spool tests next month,
while a fourth PW1100G has begun endurance testing for certification at
Pratt's Manitoba icing facility. The first four engines are expected to
collectively amass 1,000 test hours in the run-up to full certification
testing, which is due to get underway in “two to three months,” Saia
says.