Cessna 310 RentalRent Cessna 310
So if the landlord just wants him to land where he would be financial, whether you are flying or not, everything that needs to be charged over and above the price of petrol has to be his running costs per hour without any contributions from you for the solid material such as hangar rental, assurance (you would still have to pay any rise in premiums due to your use), loan management, data base upgrades and periodic inspections (minus repairs).
They should cover things like motor and propeller reconditioning reserve, equipment service reserve, tyres and brake, change of fuel (maybe you could do the work) and something for unplanned upkeep. In an NA 310, I would suggest something like $35-40 for engine/props, $5 for supplies ($2 if it has boots), $5 for tires/brakes, $10 for changing oils, and another $20 for unplanned service. For a $75-80 per hour low price.
Perhaps another $20-25/hr tossed onto the public debt for general erosion would be good enough for te CF write-off etc fetching the rates at a cute even $100/hr. However, if the user actually wants to make some money savings by contributing to the fix cost, it will be hard to find a reasonable number of lessons as this would strongly correlate with the number of lessons per year and the sum of the fix cost (which varies greatly).
Incidentally, I think that it is far overstated to base such a number on the expense of the petrol used. On the one hand, if petrol rises by 25% due to the riots in the Mideast, this should not affect the remaining operational expenses. Secondly, right now you can anywhere from $3. 80 to almost $7. 00 paying for a gal of Gas and I can't see how you would even select a petrol prize to multipolate by a multiplier.
Using your real income from gasoline, the owners would be suffering if you were good at locating inexpensive gasoline and seeing a wind fall if you were paying through your nose for gasoline. Eventually, for a damp installment, a variation in the fuelling charge does not come close to making such a big mistake in the overall costs, since the fuelling charge is such a big part of it, but to get a drier installment, the mistakes are a much bigger percent of the non-fuelling charge.
Conclusion is that if petrol costs are steady and relatively constant, there is a fairly large correlations between petrol costs and running costs, especially if the petrol is included in the overall amount rather than paid for individually, but if this is not the case (e.g. broad petrol margin and/or calculation of a drying rate), this relation contains too many errors to be of use.