The FAA is calling for operating limitations on the traffic collision avoidance system (TCAS) used in Collins FDSA-6500 flight display systems installed on certain Bombardier Challenger 604, Cessna Citation CJ3, and Beechcraft King Air models. Earlier this week, the agency issued an airworthiness directive requiring the limits, warning of a potential conflict between TCAS display indications and aural alerts that can occur during a resolution advisory (RA).

The issue surfaced during testing of a full flight simulator on a development program, the FAA said, noting a TCAS fly-to/avoidance cue indication on the primary cockpit displays conflicted with other TCAS system information, such as aural cues, during an RA scenario. “While the aural alert will provide the pilot with accurate information to resolve the RA, that information is not accurately represented by the TCAS fly-to/avoidance cue display,” the FAA said. “Specifically, the TCAS fly-to/avoidance cue is displayed relative to the aircraft horizon line instead of the aircraft symbol.”

Collins determined that the TCAS was incorrectly translated by the FDSA-6500 software. Collins is developing a software fix, but in the interim, the FAA issued the AD to address the potential conflict. The agency issued the AD as a direct final action instead of first issuing a proposed action. However, the agency will still accept comments on the airworthiness directive through August 22.

Separately, the agency recently issued a Special Airworthiness Information Bulletin (SAIB CE-19-14) to inform owners and operators of an issue that may cause certain versions of the Rockwell Collins Pro Line Fusion flight management Systems (FMS) to fly a wrong turn direction when deleting a waypoint. Covered systems include Fusion Equipment Type Part Number MSA-6010 810-0163-2B0004; FMSA-6010 810-0163-3B0001; and FMSA-6010 810-0163-1F 0001.

According to the notice, if the crew uses DELETE to remove a waypoint in a departure, standard terminal arrival route (STAR), or approach, it is possible for the FMS to make the longest turn (more than 180 degrees) onto the following leg. This can occur if both of these conditions are true: The following leg is Track-to-Fix (TF) and the database codes a required turn direction for turning onto the TF, and after the deletion, the shortest turn is a different direction than when turning from the original, deleted waypoint.

“This can occur for DELETE selections on any format, such as ROUTE or graphical flight planning on the map,” the FAA said. “The issue can also occur for Left Turns and Right Turns coded in Departures, STARs, and approaches, including missed approaches.” Consequently, the agency recommends using an alternative method to delete waypoints rather than the DELETE selection. Refer to Rockwell Collins Operators Bulletin OPSB 0194-19 for further information.

At this time, the FAA doesn’t believe the safety concern warrants an AD.