There are lots of issues that could cause serious failures that are generally found before members of the public are aware of them. Some major ones in the past decade are: B737 pickle fork (wing spar attachment) cracks, A32x wing fatigue cracks, A32x nose wheel failures (especially the 90 degree jams that have been happening for 20 years now), B737 check valve corrosion from aircraft storage (could lead to dual engine failure), A32x P&W un-commanded engine shutdowns, A32x windshield frame fatigue cracking, A32x blockage of all AoA sensors, etc.

Both manufacturers tend to have an Emergency Airworthiness Directive related to design, production or engineering issues that could cause a major failure and lead to a crash, about once every year or two.