EASA requires operators of certain ATR-42/72 airplanes to inspect the cockpit forward side windows for damage/absence of repair.
A recent event occurred during which the LH forward side glass window of an ATR 72-212 aeroplane blew out while performing a ground pressure test.
The investigation revealed some anomalies on the forward side window at the level of the z-bar on the windows external side and at the level of the inner retainer on the windows internal side. These anomalies are considered as precursors of this failure.
Air or water leakages between the z-bar and the outer glass ply, or between the inner retainer and inner glass ply indicates the presence of deteriorating structural components in the window.
It must also be noticed that neither ATR nor PPG Aerospace authorizes repairs on the window Z-bar / Z-bar sealant.
Any attempted repairs on these forward side window Z-bars/Z-bar sealants could lead to a similar event that has originated this AD. (EASA)