An example I read in a magazine many years ago was the battery shelf on a light SE airplane. If the airplane was limited to 4G, then the battery shelf was likely designed to a 4G limit. Even if the wings could withstand 5G at light gross weights, that battery shelf would break, and may cause catastrophic consequential damage.
I beg to differ Intruder.
AFAIK, nowadays, any components/parts used on or in the aircraft are screened against virbration levels which are equal to or greater than the anticipated load limit of the aircraft. I have worked on several critical components for aircraft and believe me...the vibration screening process is RIGOROUS and far exceeds that of the airframe itself!!!
BTW, load limit is a term used specifically for aircraft STRUCTURE.