Boeing is to incorporate a redesign to the landing gear on later production 787-8s to speed gate turnaround operations by improving the thermal performance of part of the braking system.
As Boeing announces it has cleared all 787 equipment for first flight, it has emerged that early 787s will be constrained in some quick turnaround operations if the gate arrival follows a high-energy landing that raises the brake temperature past a certain threshold. Boeing emphasises that the issue lies not with the brakes themselves, but the remote data concentrator (RDC) units on the four 787 main landing gear axles.
RDCs are used to flow digital and analogue data from remote sensors into the 787's Common Core System and replace traditional, dedicated signal wiring, saving weight and allowing increased operator flexibility.
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The landing gear-based RDCs were intended to accommodate the extreme heat, but "did not meet expectations", says Boeing. "Until the new units are installed, airplane dispatch based on a lower brake temperature will be implemented."
Boeing says cooling fans can be used at the gate following a high-energy braking landing to reduce the park time necessitated by brake heat generated during landing.
Brake cooling time would vary based on airport conditions and a specific duration of time would not be specified, though brake temperature would have to return to acceptable levels before pushback.
A high-energy landing would, for example, be undertaken if a higher autobrake setting were selected to reduce stopping distance on a shorter runway.
To improve turnaround time following high-energy landings that would significantly raise brake temperature, Boeing along with partner GE Aviation, who supplies the RDCs, is developing a more robust installation that will relocate the unit and improve thermal performance.
The design change will maintain the functionality of the landing gear RDCs, but Boeing will have to revise the brake control monitoring system software to maintain compatibility with the new component package.
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© Jon Ostrower/flightglobal.com |
The software is developed by Crane Aerospace and Electronics and was previously cited as a key pacing item for the 787 programme.
Boeing expects production incorporation to tentatively occur in late 2010, which when matched up against the airframer's proposed production ramp-up, could be part of the blockpoint changes expected for aircraft number 20. Boeing adds that the fix will be implemented as soon as it is available and the company is still working out the exact timing of the change.
Meanwhile, Boeing says "all equipment for first flight has been cleared" as it prepares for the twinjet's maiden sortie in the second quarter. Boeing Commercial Airplanes chief executive Scott Carson says Airplane One, which has been delayed by fastener problems and design changes, is "essentially factory complete".
He cites several visible "mini-milestones" expected in the coming weeks, including a trip to the paintshop and the start of gauntlet tests to verify and validate systems integration, as well as flight line ground and ship power testing to ensure the aircraft's self-sufficiency.
Source: Flight International
