Airworthiness Directive 2021-17-08
one-timeAirworthiness Directives; The Boeing Company Airplanes
What this AD requires
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.
Which aircraft AD 2021-17-08 applies to
Applies only to airplanes with ViaSat In-Flight Connectivity (IFC) System Antenna Provisions installed in accordance with Astronics Armstrong Aerospace Supplemental Type Certificate ST04096CH.
Whether AD 2021-17-08 actually applies to your aircraft (by serial and installed parts) and whether it’s already complied with comes from that aircraft’s records.
How AD compliance is recorded
A valid compliance record (14 CFR 43.9) states:
Tailplate reads a tail number’s logbooks and matches every applicable AD — including this one — to its compliance evidence, with recurring next-due dates computed.
Look up a tail number →Read the full directive (Federal Register)Applicability is derived from the FAA directive corpus and is advisory, not a legal airworthiness determination. Compliance is established only from an aircraft’s actual records.