We've all heard the news about an engine valve sticking open after parking for a week or more. Here is the full text of the AD
https://rgl.faa.gov/Regulatory_and_Guidance_Library/rgad.nsf/0/ec0e5875b315e9e5862585ae007cd448/$FILE/2020-16-51_Emergency.pdf
https://rgl.faa.gov/Regulatory_and_Guidance_Library/rgad.nsf/0/ec0e5875b315e9e5862585ae007cd448/$FILE/2020-16-51_Emergency.pdf