The FAA has issued an airworthiness concern sheet regarding latent failure of the FreeFlight Systems ADS-B unit model No. FDL-987-XVR. The issue was initially reported to the Fort Worth Aircraft Certification Office and it was determined that while some units failed completely, others were failing intermittently. No indication of failure was given to the pilot and attempts to upgrade the equipment or update settings did not resolve the issue.
Failure of these units results in the loss of ability to see traffic on the display and the aircraft will no longer be visible to other aircraft. Users of the FDL-987-XVR who have experienced failures are asked to contact FAA Aerospace Engineer Jacob Fitch at firstname.lastname@example.org or 817-222-4130.
Read the concern sheet here.