The FAA plans to order inspections of LiveTV in-flight entertainment system radomes on certain Boeing 737NGs, after 26 reports of radomes being cracked due to mishandling during installation or maintenance.

In a draft directive published Aug. 5, the FAA says a “lack of dimensional controls” on manufacturing drawings can lead to preload stress on a radome during assembly with the fairing that surrounds it on top of the fuselage.

Combining preload stress with more stress during flight or maintenance—such as by stepping on the fairing—is thought to be causing the cracks.

LiveTV addressed the issue by changing the manufacturing drawings, starting with radome serial number 498. 

The agency’s draft airworthiness directive (AD) proposes inspections of radomes with part numbers (P/N) 5063-100-V3 or 5063-101-V2, and serial numbers up through 497. The checks would be required within 1,250 flight hours. 

The FAA says 165 U.S.-registered 737s require the inspections. Replacement of a cracked radome would cost about $24,000, but the agency says it can not determine how many aircraft would need new parts. The FAA’s draft AD is based on a LiveTV service bulletin issued in March.