Unfortunately, it is usually the owner who gets the bill and it will be an uninsured loss at this stage because it comes to light at maintenance.
What you need is:-
(a). a 'cough' (it woz me guv); or
(b). good supervision and briefing on every flight so that those risk points (throttle shut on start/ SCC/ govenor on prior to lift into the hover and auto-rotations) do not happen.
The confession can be brought on by having a low charge on damage and careful selection of SFH pilots. Charging them £1k to confess (or even no K) is less than £30K for the repairs plus the added insurance premium next time around. When it happens more than once, you can see the case for charge them nothing.
On supervision, I have been concerned how many resellers (flying schools reselling to SFH for a margin) do not brief students on these risk points.
Many people also do not use the check list, which encourges ill discipline in flying.
An owner can try to contract a reseller for any damage that occurs, but then the reseller will probably go and find another mug who does not understand these points and just signs up for a promise of lots of revenue.
So "caveat emptor" as the Romans use to say. Make sure people know where the risk points line; monitor flyers risk profiles; brief each flight; use the checklist; supervise effectively and only resell through reputable organisations that you can trust.
H-R