A pair of lithium ion batteries on the Boeing 787-8 – which should have been risk-assessment afterthoughts compared to the overall electrical system – became unexpected safety problems. Luckily, nobody was hurt and the aircraft escaped heavy damage. Why?
Despite three overlapping investigation reports issued earlier this year by Boeing jointly with the Federal Aviation Administration, the Japan Transportation Safety Board, and lastly the National Transportation Safety Board on 1 December, there has still been no clear root cause found for the internal short circuits that destroyed two batteries on separate 787-8s in January 2013.
While not definitively traced to the battery failures, NTSB investigators found GS Yuasa’s production techniques for the 787 batteries had flaws that could lead to quality defects that the supplier’s inspection processes were unable to detect. How could that happen? As the Boeing/FAA report last April and most recent NTSB report make clear, the 787-8 suffered a failure of management. The original outsourcing model – which Boeing has since renounced – distributed design and quality assurance authority to levels of the supply chain unaccustomed and ill-equipped to perform it.
Most often, the consequences of that lack of quality assurance at subcontractor level manifested itself on the 787-8 in the form of chronic reliability problems, especially with the flight control software and the uniquely powerful electrical system.
The aviation industry uses a failure-tolerant certification process. A reliability problem should never lead to a safety crisis. A glitch-prone component should simply be a maintenance headache until fixed. In at least two incidents, however, design and quality problems at the sub-tier level are linked to safety incidents.
The FAA does not have resources to verify the safety of the design and production of every component on a modern widebody. It must rely on manufacturers to self-certify and monitor the integrity of on-board systems. It is clear the 787-8’s original outsourcing plan strained this arrangement to breaking point.
The problem, however, is not outsourcing, but its execution. Boeing has reclaimed major elements of the 787 supply chain, but long-term trends favour continued outsourcing of yet more work. As a result, final assembly manufacturers must become more vigilant of sub-tier suppliers. And sub-tier suppliers must become more sophisticated. The 787’s battery woes show what can happen if the industry fails to adapt.
Source: Flight International
