"Uhhh, ladies and gentlemen, we're experiencing some slight
mechanical difficulties" The words strike fear into the hearts
of the most coach-hardened frequent flyer. Boeing and partner
airlines-initially, Air France and American-are working on ways
to make them heard less often, using advanced mathematics.
Boeing's Airplane Health Management (AHM) program uses the data
that is already gathered by the central maintenance computer (CMC)
fitted to the 747 and 777. The CMC receives data from built-in
test (BIT) equipment attached to all the systems on the airplane,
and was originally designed to give maintainers a single access
point for that data. "But we learned in working with the
CMC that we knew more than we thought we did," comments VP
for maintenance and engineering Rich Higgins.
The CMC was originally designed to compare BIT signals with pre-set
thresholds and alert the crew to "something that is on the
verge of failure or has failed," says Higgins. But buried
in millions of flight hours' worth of CMC data is what Higgins
calls "microdata-tiny effects, patterns in data that appear
long before a failure."
Mathematics specialists in Boeing's Phantom Works are developing
tools that comb the data archives for such patterns and correlate
them with actual failures. That knowledge will be built into a
fleet-wide database. CMC data from each individual aircraft will
be compared with the database to predict failures before they
occur, and a suspect part can be replaced at a time that fits
the schedule.
AHM will have other benefits, including the ability to analyze
an airplane's condition before it goes in for maintenance. "75%
of maintenance is unplanned," says Higgins. "We want
to make that 25%." With AHM, "we can stabilize the time
for major checks, rather than having to plan for the lowest common
denominator."
Boeing is developing AHM in a gradual process. The first step
will be to add a datalink to the CMC so that the failures and
near-failures that it logs today will be transmitted to the ground.
"It's an improvement over ACARS [Aircraft Communications
Addressing and Reporting System]," says Higgins. Release
2.0, available late in 2004, will dispatch periodic 'snapshots'
of data for analysis; by late 2005, with Release 3.0, Boeing expects
to be analyzing a continuous stream of data from every airplane
in the air. In the process, Boeing hopes to build up an ever increasing
database of information and knowledge, related to each individual
aircraft in each fleet. Future improvements, says Higgins, could
include sensors that sample the air inside the aircraft for indicators
of corrosion.
