Not even a maintenance issue (though it probably wasn't maintained well) - this airplane is 10 years past the safe life span and should have been scrapped long ago. Sure it flies, but metal fatigue builds up over time and eventually something serious will break. Since airplane failures tend to be catastrophic and we cannot know how bad it is on any particular airplane Boeing gives conservative estimates for how long it will last - even in the worst case the 737 is safe to fly longer than the 20 years Boeing gives - but nobody has any idea for how much longer - could be 1 year could be 30 years. Which is why airlines where safety isn't a concern can get by with flying planes well past their end of life date. However this airplane has been living on borrowed time and should not have been on the runway. No amount of maintenance will fix the problem. (only a complete rebuild with all new parts could - cheaper to buy a new airplane from Boeing even at Africa labor rates)