Australian authorities believe that incorrectly installed engine brackets may be contributing to the cause of in-flight engine shut-downs on Cessna 208 Caravans and are recommending immediate inspections to help guard against the problem.
Australia's CASA is recommending that Caravan operators inspect an engine mount bracket on the plane's Pratt & Whitney Canada PT6A 114s to ensure it is installed correctly. Operators also should check the accompanying oil transfer fitting for fatigue cracking that may result from improperly installed brackets.
CASA and the Australian Transport Safety Bureau have been probing a "spate" of PT6A shutdowns, CASA noted in an airworthiness bulletin (.pdf)
recommending the maintenance checks. Preliminary findings indicate that incorrectly installed brackets may be causing fatigue cracking on the oil transfer fitting.
As far as can be determined at this point of the investigation, the evidence suggests that there is a possibility that the fatigue failure of this fitting may be caused by unusual vibration caused by the incorrect installation of the upper vibration isolator, for example, the aft portion installed inverted or up-side down.
CASA recommends the checks be done "before further flight."