波音公司的一份分析报告指出，１９９９年５月４日“德尔它”Ⅲ运载火箭失事是由Ｐｒａｔｔ公司的ＲＬ１０Ｂ发动机“低劣的制造工艺控制”和“不合适”的质量监督引起的。波音公司的这个结论对美国的空间计划将产生影响，因为这是１９９９年发生的第四次故障，并被列为美国重 An analysis by Boeing pointed out that the crash of the Deltas III launch vehicle on May 4, 1999 was caused by Pratt’s RL10B engine “poor manufacturing process control” and “inappropriate” quality supervision. This conclusion from Boeing will have an impact on the U.S. space program because it was the fourth failure in 1999 and was classified as a U.S. heavy