Tail delamination from hydraulic fluid
I guess A300/A321 vertical stabs are the same in principle and this leak has been clearly visible on several years of photos of EI-ETJ even in July 2015 despite being repainted since the prevous pic in May 2015 so delamination is possible?
Flaw Found In Airbus Rudders: NTSB Orders Inspection Of AA 587 Aircraft | March 31, 2006 | www.rockawave.com | Wave of Long Island
NTSB ordered an "urgent" check on the rudders of all A 300-600 aircraft in the wake of the discovery that the material that holds the rudder to the aircraft may delaminate when corroded by hydraulic fluid.
The rudders on those planes are made of composite plastic that appears prone to disintegrating, the NTSB said.
The flaw in the aircraft came to light last November, when a mechanic working on an Airbus A300-600 operated by Federal Express, found a "substantial area of disbonding between the inner skin of the composite rudder surface and the honeycomb core, which is located between two composite skins," the NTSB said in a prepared report.
"Further examination of the disbonded area revealed traces of hydraulic fluid." That contamination can lead to progressive disbonding, which compromises the strength of the rudder, according to the report.
In the wake of the mechanic's discovery, Airbus Industries, the company that manufactures the aircraft, issued mandatory instructions ordering airlines to check the rudders of their A300-600 aircraft for "deterioration of composite surfaces."
"Further tests on the damaged rudder revealed that a rapid propagation of the disbonding damage could occur during flight."