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Boeing 787 Dreamliner Reaches First Flight Milestone

December 14, 2009

5 Min Read
Boeing 787 Dreamliner Reaches First Flight Milestone

To the outside world - and muchof the aviation press - the  Dreamlinerstoryline revolves around unmet delivery schedules, broken promises and a veryembarrassing FirstFlight cancellation earlier this year.

To the employees and managersinvolved in the actual creation of the airliner though, the storyline isdifferent. It's about problems solved, objectives met and an incredibly longand detailed testing regime that culminates in the First Flight of Boeing'snewest creation.

Not since John Cashmanpiloted the Boeing 777 on its First Flight in June of 1994 has Boeing fieldedsuch a complex new airliner. The 777 was Boeing's first Fly-By-Wire airlinerwhich meant electrically controlled actuators, under the control of multiplecomputers, operated the flight surfaces.

The 787 retains thosecharacteristics and adds extensive use of compositestructures to the mix. Seen in simplistic terms, the testing roadmap to First Flightappears straight forward. But the devil is in the details and the details forthis extremely complex airplane are extensive.

Legions of tests areperformed on the individual parts and assemblies both in isolation and assub-systems in preparation for integration.

Eventually, all the parts andsub-systems are assembled into a finished airframe and additional extensivetesting is performed. (It was during this rigorous testing regime that smallportions of the wing disbonded last spring resulting in cancellation of thepreviously scheduled First Flight - much to Boeing's chagrin.)

Finally, just before FirstFlight, the airplane is subjected to a systems integration test with an ominousname:  "TheGauntlet."

The Gauntlet is what standsbetween the preliminary tests and First Flight. During this phase, the aircraftis powered up and operating 24/7. Three shifts simulate all normal and abnormalground and flight modes. Single and multiple failures are introduced and thedesigner's recovery procedures are verified.

All of the design assumptionsmade over the several years prior to the creation of an actual airplane are eithervalidated or they are refuted and changed. Sixteen test phases are utilized andeach one consists of single spaced text printed on a stack of paper one inch ormore tall.

The detail is extreme. Anexample:  every path and the reaction of everydevice associated with the tripping and resetting of every circuit breaker isanalyzed. Nothing is signed off until all aspects of each event are understoodand documented. Even if the engineering is understood and has a track recordfrom tests performed on other aircraft, it has to be looked at again.

The Gauntlet is a good namefor the procedure.

Finally, after a few days ofhigh speed taxi tests, First Flight day arrives and the flight crew attends thepre-flight briefing. For months, the pilots have been working with the designand manufacturing engineers to sort out the details of the First Flightobjectives.

The general plan is tovalidate the basic design approach and to determine that the airplane has nobad habits.

The airplane will be a flyingtelemetry platform. Designers and engineers will monitor the progress of theflight and be available for consultation should something unexpected occur.Afterwards, they'll pour over the data in excruciating detail, trying todissect every bit of information.

Take off speeds will havebeen generated by the designers and the cross wind, if there is one, must bewell within the design parameters or the flight will be scrubbed. Once theaircraft rotates, the best rate of climb is established until a predeterminedaltitude is reached. From that point on, the airplane is kept within a block ofairspace, by itself - with the exception of one or two chase aircraft - whilethe test objectives for the flight are ticked off one by one.

Gentle turns are made in eachdirection as well as small pitch angle altitude changes. Bank angles for theFirst Flight will likely be limited to 30-45 degrees since extreme bank anglesincrease the wing loading dramatically. (As an example, at 60 degrees of bank, 2gare generated.)

Power settings vs. fuel flowwill be measured and compared to theoretical values. Power settings vs.airspeed will also be measured and compared to expectations.

The landing gear will becycled and the high lift devices will be deployed to check efficiency, pitchmoments and effect on authority of the other flight control devices.

The chase plane pilots willkeep an eye on the aircraft and report anything suspicious to the Dreamliner'spilots. They will confirm landing gear operation, flap deployment, symmetry offlight control operation and keep an eye out for any hint of hydraulic or fuelleaks.

Back in the cockpit, thepilots will determine if the instrumentation appears to be working correctly - somethingthat will be thoroughly checked against the telemetry by the engineering test group.

Finally, once the objectiveshave been accomplished, the airplane will depart its block of airspace and headback to Boeing Field. The approach and landing speeds it will use are specifiedby the designers for the aircraft's weight, weather and runway conditions.

And after the taxi in andshutdown, everyone will receive high fives.

For the media crowd, it's over,but for the employees and test pilots the testing goes on. Six prototypeaircraft are involved in the testing and a full 24 hour day is used.

Five hours each day are setaside for actual flight tests with the balance being used for maintenance andto make changes needed as a result of discoveries made in flight test.

The objective istwofold:  1) to discover all problemsbefore the first customer takes delivery of the airplane and 2) to reach themagic day when the Federal Aviation Administration gives Boeing its covetedpermission to begin manufacture of the airliner.

And when that day comes, thedesigners, pilots and test employees move on to another project. Somewherealong the way, they might pause for a moment to congratulate each other forwhat they've accomplished. Then it's back to work.
John Loughmiller is an Electrical Engineer, CommercialPilot, Flight Instructor and a Lead Safety Team Representative for the FAA.

The test roadmap leads from design to First  Flight, but there are many stops along the way. Photo:  John Loughmiller

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