I recall that in the Mid 1970s a C-141 crashed after straying into a thunderstorm in England. The aircraft had rolled into 30 degrees of right bank in an effort to escape the thunderstorm, adding to the stress on the airframe already induced by the storm. At the crash site, number 4 engine and the vertical stabilizer were found together in an open field, hundreds of yards away from the main wreckage. That showed a historical correlation between engine separation and either stress on the vertical stablizer, or perhaps the engine actually striking the vertical stabilizer as it separated from the wing during. Of course, weather was no factor in the AA crash.