In the wide-ranging investigation, Boeing failed a check that dealt with the component that blew off the jet, known as a door plug, the report said, citing an FAA presentation viewed by the publication. The plane maker passed 56 of the audits and had a total of 97 instances of alleged noncompliance, according to the presentation. The FAA also conducted 13 product audits for the part of the inquiry that focused on Spirit AeroSystems, and six of those audits resulted in passing grades, while seven resulted in failing ones, the presentation said. MOODY'S REVIEWING BOEING'S CREDIT RATING: On March 26, Moody's placed the Baa2 senior unsecured rating and Prime-2 short-term rating of Boeing on review for downgrade. The rating outlook was previously stable.