FAA and Transport Canada have codified requirements for operators of Boeing 737s with older LiveTV in-flight entertainment (IFE) radomes to inspect the units for cracks, mandating a program that the vendor and operators have had in place for several years.

The airworthiness directives, issued Feb. 25, target inspections to detect cracks in LiveTV’s so-called “legacy” radomes. The radomes are installed on both 737s and Airbus A320s, but—for reasons never fully understood—the cracking phenomenon only affected those on 737s. United and WestJet Airlines aircraft include the affected aircraft/radome combination.

The cracks stemmed from what LiveTV terms “a lack of dimensional controls” during manufacturing. The affected radomes developed pre-load stress, which led to cracks forming. Analysis has determined that the cracks could propagate, which could allow pieces to separate and strike the tail.

“The full core section of the radome weighs 10.5 lb. and there is no data available to substantiate that a section larger than 8 lb. could not separate,” LiveTV explains in a service bulletin that helped shape the directives.

“When the first surface crack was discovered about three and a half years ago, we worked in collaboration with the FAA and airlines to ensure the highest levels of safety were maintained and, in an abundance of caution, implemented a proactive, voluntary inspection program that removed all radomes with cracks,” explains LiveTV’s vice president of quality, certification and product support engineering, Nick Drivas. “We have inspected the fleet three times now, and have not detected any additional radome cracks since the initial inspections.”

Operators found a total of 26 cracked radomes, but none of the damage resulted in pieces separating from the domes.

LiveTV revised the engineering drawings in September 2010, and the change went into effect with radome serial no. 499. None of the domes built according to the new drawings have shown signs of cracking.

The affected series of domes is not the same model that LiveTV recently put into service to bring broadband Wi-Fi to customers. That dome, the first to pass FAA’s clarified certification protocol calling for bird-strike tests, is critical for JetBlue Airways’ FlyFi-branded inflight Internet offering.