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Earlier this month EASA issued Airworthiness Directive (AD) 2018-0144 affecting certain aircraft with Gogo‘s 2Ku inflight connectivity kit installed. Air vortices created by the 2Ku radome on certain A330 and A340 installations cause excessive vibration in the ELT antenna. This potentially “shakes” the ELT antenna loose or causes structural issues in the fuselage.
Some cases of high noise level in the aft cabin section of the fuselage were reported. Subsequent inspections of the ELT antenna installation and the surrounding fuselage structure showed cases where the ELT antenna was found loose, with damaged fixations and elongated holes. In addition, cracks were found in the ELT antenna bores and in the underlying fuselage skin and internal doubler. Analysis revealed that the ELT antenna installation can experience oscillating vibration loads, leading to the reported high noise level and also resulting in damage of the ELT antenna and its surrounding structure. This vibration could be explained by a vortex, created by the shape of 2KU-Band antenna radome, installed in front of the ELT antenna by Airbus STC 10062892 (A330) or STC 10064120 (A340) as applicable.
Fortunately the issue was discovered relatively quickly, the number of aircraft affected is low and a revised installation process is expected to be in place in the near future.
The AD only applies to 2Ku installations performed under specific STCs issued to Airbus, not other A330 and A340 2Ku installations performed under different certification.
The Iberia, Air France and KLM A330s are affected given the installation location of the radome between the VHF and ELT antennae on the aft portion of the fuselage.
Iberia’s A340s are also affected and are the only A340s installed under the affected STC.
Virgin Atlantic is in the clear, as its radome installation is further forward on the fuselage.
Extra Inspections
For those aircraft with the system already installed an additional “visual inspection of the ELT antenna, followed by an SDI (rototest) of the six fuselage-to-antenna fastener holes” is now required. This must be performed every 250 flight hours until a Technical Disposition, first defined in early June, is installed. Once modifications are made the inspection timeline extends to every 500 flight hours. Further installations under the affected STCs are not permitted.
It is understood that an adjusted installation process will be in place within a couple months, adjusting the location of the antennae to reduce the impact of the air vortex on the aircraft. A pause in the install is unfortunate, especially coming just as KLM and Air France ramp up installs on their A330s.
It also comes during the summer when such modifications are less commonly performed, owing to the higher usage of the aircraft. As the aircraft utilization decreases the amended STC should be in place, allowing the installations to resume more quickly over the winter months.
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