The U.S. aircraft register, updated daily
Parts

Bottom Directional

No failure report names the bottom directional. 2 FAA approvals let 2 companies make a replacement bottom directional, Ryan International CORP holding the most (1).

Approved replacement parts 2 parts manufacturer approvals

A parts manufacturer approval (PMA) lets a company other than the aircraft's maker make a bottom directional and sell it as an approved part for the models named. These are the companies holding such approvals for a bottom directional:

For these models most: Cirrus SR20 (2), Cirrus SR22 (1).

MakerPartReplacesFitsGrantedStatus
Avidyne CorporationBottom Directional Antenna Doubler DWG1029-041DWG1029-041Cirrus Design Corporation SR20 SR222009-01-19current
Ryan International CORPBottom Directional Antenna Doubler DWG1029-041Modification PartCirrus Design Corporation SR20, SR222004-08-09current

Sources: the FAA's service difficulty reports since 1995 (a report is a part that failed and was fixed, as filed by an airline, repair station or owner; the count shows reporting as much as reliability) and the parts manufacturer approvals in the FAA's Dynamic Regulatory System. The part name is the reporters' and the approval holders' own words, reduced to the first plain words so that spellings meet.