FRANKLY, you have gone off on a tangerine.
(How's that for a malapropism)
Any aircraft accident that is caused by pilot error is, by definition, an "act of stupid".
You mentioned negligence not me.
Although that is a subjective term and the insurer may well be liable.
hangar Indemnity is somewhat different, and does cover faulty work.
Although my insurer made noises about releasing private aircraft with On Condition piston engines.
They saw you coming!
As the Bishop said to the Pope