On a visit to Boeing Aerostructures Australia (BAA) in Melbourne last week I heard how the manufacturer is working with the Seattle-based Boeing Commercial Airplanes design team to look at extending the use of advanced resin infused composite parts used on the 787-8 trailing edge to other elements of the stretched 787-9.
The material, which does not require curing in a high-pressure autoclave, is also expected to feature on the 737 replacement says BAA managing director Mark Ross. Pioneered for the 787 trailing edge by BAA, resin infused composites are as light as alternatively made pre-preg composites, but are made by laying up plies of dry composite prior to resin infusion.
A flap test article - now used for trailing repair techniques (Guy Norris)
The process is used for the inboard and outboard flaps, flaperon, aileron and spoilers on the 787-8. Melbourne Center director Dong Yang Wu says the resin-infusin process is being considered for wider application on other parts of the -9, as well as being retained for the current parts. As well as saving cost, resin infusion has potential for greater weight savings than pre-preg made composites because it can be used more easily to make integrated structures. While declining to put a specific number on the potential savings Ross says "the weight advantage is enough to buy itself onto the aircraft."
Further improvements are also being studied for later block upgrades of the 787-8, with the possible evolution of the current rib and stiffened flap structure to a fully integrated unit with fewer parts.
BAA is in the process of ramping up 787 shipset production in lockstep with Boeing's rate increase in Everett, Wash. As parts from Australia are shipped by sea, the rate is around 45 - 50 days ahead of that in the U.S. The Melbourne line is currently running at 3.5 per month, while targeting four in the immediate future and 10 per month in the longer term Production line changes to accommodate the higher rate will be complete by year-end says Ross. On a visit to the site last week I noted trailing edge sections being prepared for final assembly and shipment for Line numbers 21 to 27. Shipments were poised to resume as Boeing prepares to restart assembly at Everett following a roughly month-long break to allow the supply chain to catch up.
In a nearby Boeing Australia Component Repair facility by Melbourne Airport, I later saw the remnants of an original flap section static test article which – having fulfilled its primary strength test role – is now being used to prove out repair techniques. Open sections and missing skin provided a rare peek into the internal structure and revealed obvious areas where Boeing is looking at possible enhancements such as integrated structure using the full potential of the resin infusion process.
Test section takes a hammering (Guy Norris)
Jason Braganza, director of the repair facility also gave a classic graphic demonstration of the strength of the raw structure by banging it with this hammer. (see above).
A rare glimpse inside the flap structure. (Guy Norris)
In the latest flight test developments meanwhile, ZA002 is busy undergoing ground tests in Victorville, Calif associated the fuel tank inerting system. The aircraft was last viewed still sporting a gold object beneath the nose. Boeing says this is a device that was used to characterize cloud droplet size for the recent natural icing tests, while the other closely-mounted unit in the belly is used to determine the liquid water content of the environment.
Close up of moisture monitor under nose of ZA002 (Joe Walker)
Two sensors under ZA002 for natural icing tests. (Joe Walker)
ZA001 remains in lay-up at Boeing Field undergoing an engine swap, and around the end of the month is expected to resume test work with low speed aerodynamic validation, and a flight to Edwards AFB for take off and landing validation, plus Phase 2 of stability and control tests. The engine swap replaces the original Trent 1000s with similar standard units, as the improved “Package B” configuration is set to be flight tested on ZA004 just prior to type certification later this year.
ZA003 continues to be used for engine maintenance and interiors test work and is currently running airflow balance tests in areas such as the crew rest compartment plus water waste system evaluations. The aircraft is also expected to perform a flight test over the coming weekend looking at cargo and cabin heating and cooling characteristics, plus evaluations of the interior for noise and vibration and performance measurements of the avionics datalink system.
ZA004, also at Victorville, is being instrumented for the flight loads survey which is expected to kick off into flight tests around the end of the month. ZA005, the first GEnx-1B powered aircraft, is gearing up towards first flight which is expected within the next two weeks. The aircraft is set to undergo a long set of tests this weekend covering evaluation of the electronic engine controls, engine indication and crew alerting system and primary flight control system. Parallel testing is also scheduled for flight test-specific systems such as the on-board gross-weight processor.