To the outside world - and much
of the aviation press - the Dreamliner
storyline revolves around unmet delivery schedules, broken promises and a very
Flight cancellation earlier this year.
To the employees and managers
involved in the actual creation of the airliner though, the storyline is
different. It's about problems solved, objectives met and an incredibly long
and detailed testing regime that culminates in the First Flight of Boeing's
Not since John Cashman
piloted the Boeing 777 on its First Flight in June of 1994 has Boeing fielded
such a complex new airliner. The 777 was Boeing's first Fly-By-Wire airliner
which meant electrically controlled actuators, under the control of multiple
computers, operated the flight surfaces.
The 787 retains those
characteristics and adds extensive use of composite
structures to the mix. Seen in simplistic terms, the testing roadmap to First Flight
appears straight forward. But the devil is in the details and the details for
this extremely complex airplane are extensive.
Legions of tests are
performed on the individual parts and assemblies both in isolation and as
sub-systems in preparation for integration.
Eventually, all the parts and
sub-systems are assembled into a finished airframe and additional extensive
testing is performed. (It was during this rigorous testing regime that small
portions of the wing disbonded last spring resulting in cancellation of the
previously scheduled First Flight - much to Boeing's chagrin.)
Finally, just before First
Flight, the airplane is subjected to a systems integration test with an ominous
The Gauntlet is what stands
between the preliminary tests and First Flight. During this phase, the aircraft
is powered up and operating 24/7. Three shifts simulate all normal and abnormal
ground and flight modes. Single and multiple failures are introduced and the
designer's recovery procedures are verified.
All of the design assumptions
made over the several years prior to the creation of an actual airplane are either
validated or they are refuted and changed. Sixteen test phases are utilized and
each one consists of single spaced text printed on a stack of paper one inch or
The detail is extreme. An
example: every path and the reaction of every
device associated with the tripping and resetting of every circuit breaker is
analyzed. Nothing is signed off until all aspects of each event are understood
and documented. Even if the engineering is understood and has a track record
from tests performed on other aircraft, it has to be looked at again.
The Gauntlet is a good name
for the procedure.
Finally, after a few days of
high speed taxi tests, First Flight day arrives and the flight crew attends the
pre-flight briefing. For months, the pilots have been working with the design
and manufacturing engineers to sort out the details of the First Flight
The general plan is to
validate the basic design approach and to determine that the airplane has no
The airplane will be a flying
telemetry platform. Designers and engineers will monitor the progress of the
flight and be available for consultation should something unexpected occur.
Afterwards, they'll pour over the data in excruciating detail, trying to
dissect every bit of information.
Take off speeds will have
been generated by the designers and the cross wind, if there is one, must be
well within the design parameters or the flight will be scrubbed. Once the
aircraft rotates, the best rate of climb is established until a predetermined
altitude is reached. From that point on, the airplane is kept within a block of
airspace, by itself - with the exception of one or two chase aircraft - while
the test objectives for the flight are ticked off one by one.
Gentle turns are made in each
direction as well as small pitch angle altitude changes. Bank angles for the
First Flight will likely be limited to 30-45 degrees since extreme bank angles
increase the wing loading dramatically. (As an example, at 60 degrees of bank, 2g
Power settings vs. fuel flow
will be measured and compared to theoretical values. Power settings vs.
airspeed will also be measured and compared to expectations.
The landing gear will be
cycled and the high lift devices will be deployed to check efficiency, pitch
moments and effect on authority of the other flight control devices.
The chase plane pilots will
keep an eye on the aircraft and report anything suspicious to the Dreamliner's
pilots. They will confirm landing gear operation, flap deployment, symmetry of
flight control operation and keep an eye out for any hint of hydraulic or fuel
Back in the cockpit, the
pilots will determine if the instrumentation appears to be working correctly - something
that will be thoroughly checked against the telemetry by the engineering test group.
Finally, once the objectives
have been accomplished, the airplane will depart its block of airspace and head
back to Boeing Field. The approach and landing speeds it will use are specified
by the designers for the aircraft's weight, weather and runway conditions.
And after the taxi in and
shutdown, everyone will receive high fives.
For the media crowd, it's over,
but for the employees and test pilots the testing goes on. Six prototype
aircraft are involved in the testing and a full 24 hour day is used.
Five hours each day are set
aside for actual flight tests with the balance being used for maintenance and
to make changes needed as a result of discoveries made in flight test.
The objective is
twofold: 1) to discover all problems
before the first customer takes delivery of the airplane and 2) to reach the
magic day when the Federal Aviation Administration gives Boeing its coveted
permission to begin manufacture of the airliner.
And when that day comes, the
designers, pilots and test employees move on to another project. Somewhere
along the way, they might pause for a moment to congratulate each other for
what they've accomplished. Then it's back to work. John Loughmiller is an Electrical Engineer, Commercial
Pilot, Flight Instructor and a Lead Safety Team Representative for the FAA.
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