I think 100 hours a year, as a watermark, is a bit low. The rule of thumb I came up with, is 20 hours per month (and that's a LOT of recreational flying)..
I've crunched the ownership numbers, every way imaginable.. and ended up being part owner in a club airplane, soley for defering insurance, and flying at the owner's, hourly rate. Anyway.. here are some rough numbers for a $100,000 C182.. all numbers are monthly:
- Interest paid on $100,000 loan (or income not earned if you tie up $100,000).. = $500
- Insurance (Hull and liability) .. = $300
- Hangar and misc. ground expenses .. = $300
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- Cost to just stand next to it and say, "look what I own" .. = $ 1100 /month (nearly six hour of rental, right off the bat)
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Numbers for 20 hours of flying:
- Fuel @ $6/gal @ 14gph ... = $1680
- Engine wear @ 2000hr TBO / $25,000 engine ... $250
- Airframe/avionics, wear/depreciation ... $300
- Average annual-inspection cost (for a $100,000 C182 /12) .. $300
- Oil / tires / untimely equipment failure (ie. DG quits) ... $ $200
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Total operational only, cost per month @ 20 hours ... $2730
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Cost for first 20 hours of flying per month.. $3850 .. or .. $191/hour (aprox. a wet rental)
Of course 20 hours/per month, every month, is a LOT of flying.. commiting you to nearly $4,000/month, just to break even on a per hour basis.
I you fly a reasonable (but still tough) 10 hours a month.. the fixed cost per hour doubles.