Mechanical issues are more of a question of when not if. I've already experienced repeated failures of certain systems to have my own stats on how long some components go between failures.
For this poll, only base it on failures in operation (in the air or on the ground). Not, preemptive replacement or failing a checking at maintenance and being replaced. For in-flight failures, share your stories.
For electrical system, vote based on any failures that entirely or partially hindered electrical system operation. So, not a radio failure but a master switch failure, alternator failure, wiring failure, voltage regulator, etc. Not a dead battery and won't start failure. But, if you had an electrical problem in flight because the battery stopped working.
For vac system include any vac systems from the vac pump to the actual vac driven instruments.
For powerplant, it doesn't have to be a full engine stop or necessarily even power loss. Vote based on a failure that affected power production, that you can feel in the cabin or at the controls, necessitated an urgent landing, or prevented further engine operation without maintenance after the failure. You can be more specific in the discussions.
I'm particularly interested in hearing the number of hours of Mooney operation for pilots who've experienced the same failure at intervals (not the same thing breaking again immediately after being fixed). Basically take an average based on the number of Mooney hours flown divided by the number of times you've experienced a failure in that category.
Don't include pilot error things like fuel starvation or exhaustion, turning something off accidentally, etc.
The numbers aren't particularly exact, just round to the nearest category.