After briefly suspending Rockwell Collins TDR-94/94D modifications on October 25, Duncan Aviation has resumed offering the upgrade to these transponders so they meet the FAA DO-260B standard for ADS-B Out. The work started again on November 13 at Duncan’s Lincoln, Nebraska headquarters.

The reason for suspension of the modification was not related to the ADS-B upgrade but had to do with “a software fix to address a minor TSO non-compliance” issue, according to Duncan. The FAA has issued a waiver to Duncan for this issue, and by the end of December, Duncan will release a service bulletin for the software fix. Customers with affected transponders will be able to have the service bulletin complied with during an upcoming shop visit, but the bulletin is optional and no cause for suspending flying activities.

“We’d like to reassure our customers that the recent software issue with the TDR-94/TDR-94D has no flight deck effect and in no way affects flight safety,” said Mark Cote, v-p of component services, parts sales, and satellites. “The fix will be an optional service bulletin that Duncan Aviation can perform during a scheduled maintenance event or as a quick turn in our avionics component shop. There is no reason to put down an aircraft for this modification.”

Duncan Aviation’s Battle Creek, Michigan, Provo, Utah, and 27 satellite shops and workaway stations can do the software upgrade in conjunction with the company’s Lincoln facility.