Originally Posted by
tdracer
Perhaps the standards are different for turboshaft engines used on helicopters,
No difference in standards between the two, but more a point of when those engines were certified. There was a revision to the Part 33 turbine engine containment rules in the 1980s which were after the certification date of most turboshaft engines of that time. In the case of the S-76 C30 engine mentioned above, when the AD was released as a result of that incident, those engine models were upgraded to meet the newer containment rules with the installation of an improved internal containment ring. The “BBQ plates” or protective shields, were the initial temporary fix of the issue. One positive outcome from using those external plates/shields was that as the engines were upgraded with the permanent rings, any mechanic who wanted got a free set of custom Inconel rivet bucking bars.