The Gogo/Intelsat 2Ku radome mount is causing troubles again. This time it is the Airbus 220 family of aircraft affected, but the problem is not a new one. Air vortices generated by the antenna radome are generating excessive vibrations of the Emergency Locator Transmitter (ELT) antenna. Over time this can cause the ELT antenna to separate from the fuselage or cracks resulting in cabin depressurization.
The issue is nearly identical to troubles with the A330/A340 2Ku installations reported in 2018. Those installations were halted and the certification adjusted to account for the challenges.
The line-fit installation certification for the A220s remains valid today, but airlines will be required to inspect the systems regularly to ensure structural integrity of the aircraft.
Transport Canada issued an Airworthiness Directive (AD) addressing the issue, describing multiple incidents that triggered the airworthiness directive:
Two ELT antenna failures have been reported, including one case where the antenna departed the aeroplane causing minor damage to the vertical stabilizer skin. The investigation revealed that these ELT antenna failures were caused by vibration loads induced by air vortices shed by the Gogo 2Ku antenna radome. Uncorrected, this situation can lead to the loss of the ELT antenna and the development of fuselage cracks that can result in an inability to maintain cabin pressure.
To mitigate the risks associated with the loss of the ELT antenna and inability to maintain cabin pressure, this AD requires replacement of the ELT antenna with a new ELT antenna at a specified interval and a repetitive inspection of the exterior fuselage skin around the ELT antenna attachment area.
Under the airworthiness directive airlines are required to replace the ELT and inspect the fuselage skin surrounding the mount point. The timing of that replacement is on a sliding scale but no more than 850 flight hours from the issuance of the AD. Following the initial replacement a repeat inspection and replacement is required every 2,500 hours to ensure the system remains reliable.
At least 65 A220s are potentially affected by the AD. These include 48 at Delta Air Lines (41 of the –100 model, 7 of the –300 model) and 17 of the –300 model at Air Canada. Both carriers have additional A220 deliveries pending that are expected to also carry the 2Ku system.
An Intelsat spokeswoman confirmed the issue with the line-fit installations, noting, “When it comes to linefit, the OEM – rather than Intelsat – designs how the avionics are integrated to the aircraft. This is one of the big differences between STCs and linefit for service bulletins. Of course we work together to rectify any issues and that’ll be the case in this situation as well.”
Presumably an STC-based installation post delivery would include an alternate installation option that mitigates the vortices effect, should an airline choose that option.
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