It’s the fourth major delay for the revolutionary, carbon-composite aircraft. It’s now about two years behind the original schedule. The delays are due to late redesigns, underperforming suppliers and a shortage of key parts.In addition Boeing suffered a fifty eight day strike by machinists at its main plants in Seattle in September and October. The delays threaten to seriously damage the company’s finances and reputation. It now says the first test flights should take place before the middle of next year with the first deliveries early in 2010.