B-nuts to be specific. The NTSB has released Safety Alert 086 titled Mechanics: Ensure B-nuts Are Properly Secured! You can view the Safety Alert by visiting https://www.ntsb.gov/Advocacy/safety-alerts/Documents/SA-086.pdf.
The Safety Alert starts off saying, “B-nuts are a small piece of hardware that can cause a big problem if they are not properly secured.”
It goes on to discuss “The problem.”