msfsx .air files report as corrupted

Hi, I tried to run msfs x recently and the engine sound when flying any plane was silent when flying from the left seat but when taking a spot view or outside view the sound was there. Upon looking at the file structure I found that the .air file foo every plane was reported as corrupted and that I should get new files from original author. How do I do that when Aces studio has long gone out of business. How do I get the file for the Cessna 172. 208, Extra sport plane, etc. Anybody able to help me out here?
Regards, Wayne