Here are some helpful tips on how to find an addon here on YSFHQ!
1.YSFlight Addon Database
A google sheet with links to most of the available YSFlight aircraft, ground object, and map addons with links.
2.YSFHQ Forum Search
Search for keywords of YS addons you are looking for, or by username. Choose the "Addon Releases" forum in the forum selection list to search our vast amount of addons here on YSFHQ. You can also search for when keywords were posted by date, and display results as individual posts or topics.
If all else fails, Google search may be able to help you. Search for keywords you are looking for and be sure to include "YSFlight" in your search. Hopefully it may be able to find aircraft or addons that you may not be able to find with the other resources above.