Thanks for asking, let be discuss components and the lists in NavigatorV. We do not have a database of all approved aircraft parts, we DO have a list of all components that we publish documents for (i.e. ADs, SBs, manuals). This second list is what you will find in the Navigator dropdowns in Search and Profiles. If a manufacturer or Model is not listed we do not have any ADs, SBs or manuals for that item. We also include a second source of Appliance ADs so that you can verify that Not Listed = No ADs (and not just missing data!). Go to the Forms tab and open ATP Worksheets. You should see an Appliance AD List document. This PDF lists all FAA Appliance ADs, grouped by category, and lists the manufacturer and models. For example all Carburetor Appliance ADs are on page 6.
Hope this answers your question.
Tip – did you know you can type manufacturers and models in the profile page that are not listed in the dropdowns? This allows you to watch for ADs in the future.