Honeywell's Test Program Should Mean
Trouble-Free Service Intro for the AS907
Aviation Week & Space Technology
10/06/2003, page 84
Stanley W. Kandebo
New York
Several thousand hours of exhaustive trials should mean fewer
problems in service
AS907 Test Regime
Honeywell is conducting an extensive test program and applying
experience gained in developing ETOPS-ready auxiliary power units
to ensure a trouble-free service introduction for the company's
6,000-8,000-lb.-thrust AS907, the engine certificated by the FAA
in June 2002, for Bombardier's Challenger 300 business jet.
"By the time entry-into-service occurs later this year, we
will have accumulated over 30,000 test hours and more than 6,000
flight hours with this engine. Twenty years ago it would have been
less than one-fourth of those amounts," said Tim Beatty, director
of sales and marketing for commercial propulsion for Honeywell.
According to Beatty, more than 27,000 engine test hours and 5,000
flight test hours--many flown on a Boeing 720 testbed aircraft--have
been completed. And that comes on top of individual trials run on
engine systems. For example, the AS907's full authority digital
control has been through 47,000 hr. of tests; its Hurel-Hispano
clamshell thrust reverser has been run in more than 4,000 hr.
INDIVIDUAL LINE-replaceable units also are being scrutinized. "Early
on we took 38 of the primary propulsion system's LRUs and tested
them under thermal and vibratory conditions that exceeded what they
would normally encounter in service. That allowed us to uncover
potential failure modes and correct them before entry into service,"
Beatty said. As a result, 20 LRUs have been modified, and testing
on those is ongoing as engineers continue to search for more potential
problems.
Much of this "shake-and-break program," as Honeywell
calls its aggressive test method, is a direct result of experience
gained with the GTCP 331-500 APU, the unit developed with "ETOPS
out of the box" for the Boeing 777.
AS907 service and maintenance activities also are receiving attention,
and Honeywell has been aggressive in those areas too. The company
has targeted a 30% reduction in cost of ownership versus equivalent-thrust
powerplants, and AS907s are being offered with either on-condition
maintenance or hard intervals to meet customer desires, a first
for Honeywell. "Maintenance Steering Group 3, or on-condition
maintenance, will probably be needed by fractional owners who operate
their aircraft more like traditional airlines. Hard intervals will
probably be favored by corporate owners," Beatty said. At entry-into-service,
initial main inspections will probably be needed at 3,500 hr. and
core zone inspections at 7,000 hr.
TO ASSIST MECHANICS, the AS907 is being offered with 39 borescope
ports. LRUs are designed to be replaced in 20 min., and they've
been made so all line-level maintenance can be performed with 13
standard hand tools. Honeywell prides itself in saying that early
in the AS907 program, service center mechanics were invited in to
disassemble and reassemble an engine. "Ninety percent of the
suggestions those maintainers came up with were incorporated into
the engine design," Beatty noted.
As a result of the emphasis on mechanical reliability and simplicity,
Honeywell says that one of its AS907s, with a nacelle, can be removed
with a nominal mechanical crew, and another installed, in about
six hours. "That means you can pull and reinstall an engine
overnight," said Dan Fuller, Honeywell's business and general
aviation manager of customer support.
Besides mechanical features, Honeywell has rigorously considered
the digital data aspects of providing maintenance. AS907 operators
will be able to download any existing faults to a laptop computer
and use "Spotlight" software to diagnose the most likely
root problems. "This should reduce or eliminate removal of
LRUs and improve dispatch reliability of the engines," Fuller
said.
Additionally, interfacing with a Honeywell web site will enable
operators to keep track of their maintenance service program and
accounts. "This means less work for the operator and increased
productivity for their personnel," Fuller observed.
