AD 2021-17-08 Prompted By Reports That Several Of The Fittings That Provide Attachment Between The Radome And Fuselage Were Cracked

The FAA is adopting a new airworthiness directive (AD) for certain The Boeing Company Model 737-800 and -900ER series airplanes.

This AD was prompted by reports that several of the fittings that provide attachment between the radome and fuselage were cracked to the point of failure on airplanes modified in accordance with a certain supplemental type certificate (STC). This AD requires demodification of the STC installation on the airplane by removing the external equipment installed during the STC modification (including the radome, antenna, and associated structure), installing doubler and fasteners, and system deactivation by pulling and collaring associated circuit breakers if installed. This AD also requires inspecting the external and feed-through doublers, intercostals, skin, and frames in the area around the removed external equipment for cracking, and repair if necessary. The FAA is issuing this AD to address the unsafe condition on these products. This AD is effective August 17, 2021.

Supplementary Information: The FAA has received reports indicating that several of the fittings that provide attachment between the radome and fuselage were cracked to the point of failure. The radome to fuselage fittings were part of the ViaSat In-Flight Connectivity (IFC) System Antenna Provisions installed in accordance with FAA STC ST04096CH on Model 737-800 and -900ER series airplanes. This failure of the attachment fittings, if not addressed, could result in loss of the radome and antennae, and consequent damage to the tail and damage to the fuselage in the vicinity of the radome, which could reduce the ability of the flightcrew to maintain safe flight and landing of the airplane. The FAA is issuing this AD to address the unsafe condition on these products.

FMI: www.regulations.gov