Boeing and the US Federal Aviation Administration (FAA) on 19 March jointly blamed the 787’s “teething issues” and battery crisis on a failure of both parties to monitor and communicate with a newly-empowered supply chain.
But the aircraft’s “novel” technologies – a more-electric architecture and composite structures – escaped direct fault in a sweeping report commissioned by former Secretary of Transportation Ray LaHood on 11 January 2011, or four days after a battery fire erupted on a parked Japan Airlines 787 at Boston Logan airport.
The report – signed by seven Boeing and six FAA employees – describes the FAA certification model for the 787 as “antiquated”, applying the same certification rules for the 787 as for a less complex, small aircraft lacking a globalised supply chain.
The FAA’s certification system also fails to account for Boeing’s move to a distributed supply chain on the 787, which assigned design authority for components to Tier 1 suppliers and moved manufacturing to Tier 2 suppliers and below, the report says.
As a result, the FAA is changing how it overseas the commercial aircraft manufacturing process, using risk-based tools to focus resources on areas with the greatest risk rather than a “one-size-fits-all” approach.
“We were actually heading in this direction well before the review,” says FAA administrator Michael Huerta. “The team’s recommendations have given us a clear path forward.”
When LaHood commissioned the review, the FAA and Boeing were just coming to grips with the faulty lithium ion battery system that triggered two fires within eight days, which remain under investigation.
The FAA said the review would scrutinize the entire certification process, but focus especially on the 787’s electrical and power distribution system.
Boeing designed the 787 to use electrical power to de-ice the wings and pressurise the cabin, replacing a pneumatic system driven by siphoning compressed bleed air from the engine compressors.
The electrical system introduced several new components and design features with reliability problems that have damaged the 787’s reputation.
The jointly authored report, however, defends the 787’s overall reliability, comparing the 787’s roughly equivalent dispatch rating with the 777’s record.
It also suggests the 787’s electrical system issues have been inflated by how airlines troubleshoot problems. Boeing’s design assumed that airlines would inspect components identified as faulty by an onboard diagnostic system. Instead, according to the report, airlines often remove the component and replace it with a spare to minimise delays caused by trouble-shooting.
But the report also takes a “deep-dive” into several key technologies that have generated the most reliability complaints. In each case, the review found that the basic technology was sound, but the design or manufacturing was compromised by a failure to monitor the suppliers properly.
For example, the power distribution system includes a power panel that has been the source of several in-flight overheating incidents. The report says the panel’s supplier – ECE – did not follow industry design standards.
Another system cited by the report is the variable frequency starter generator mounted on the engines. It includes an air-oil heat exchanger circuit, which is comprised of parts from different suppliers. Boeing, however, had not identified the owner of the integrated assembly, leading to a poor design.
The battery investigation last year revealed that Boeing’s testing standard for triggering a short-circuit in a lithium ion battery was inadequate.
Similarly, the FAA-Boeing review review team also concluded that 787’s testing procedures sometimes relied on assumptions that no longer worked with the aircraft’s more advanced electrical systems.
Boeing has since overhauled how it designs and develops new commercial aircraft. In 2010, the company rolled out a “gated” development process, which prevents the design from moving forward if there are any issues at designed points.
The new process was used to design the 737 Max family, the KC-46A tanker and the 787-9.
The FAA, meanwhile, is still working to change how it plans to regulate the process of introducing new commercial aircraft with a more complex and distributed supply chain.
Source: Cirium Dashboard
