For reviewing costs, consider doing an annual meeting where everybody agrees on how much balance to keep for reserves and what rates to use in building those reserves.
Excellent post! You'll probably never get everyone to agree on things like that, though.
The trick to running a club well is to have a board of directors that is empowered to do things like this, and elect people to that board who are willing to listen to everyone at the annual meeting and the rest of the year and take actions that are good for the club as a whole. You'll never make everyone happy, but if you do things well and your decisions are backed up by real numbers, 90% of people will be happy. The rest are generally the folks that don't fly, and it's fine to let them leave, or do what we did - Have a reduced-cost or free social membership level with no flying privileges.
Reserves aren't really that difficult. Engine reserve: Take the overhaul cost (engine shop cost), add the removal and reinstallation cost (it was about $6K the last few times I did it, but probably more like 8-10 now), divide by TBO. Multiply the result by the number of hours since overhaul and that should be how much you have - If you don't, best to start catching up sooner than later.
Avionics reserves can be more variable, but they also depend greatly on the makeup of the club. Some clubs have dozens of members per airplane and they're largely only flying a handful of hours a year in a trainer class airplane and probably don't care much about fancy avionics. Other clubs have only a few people and probably (a) faster airplane(s) and are more interested in avionics that can make long IFR cross country travel easier. There's also the matter of whether people would rather add a few bucks to the hourly rates or the dues and put that in reserve for future upgrades, or just fork it over when the time comes.
Maintenance tends to be more constant - You're always doing it, and you should always be billing for it. Cost of an annual (just the inspection) should be in the fixed/dues cost bucket. If your club is subject to 100-hours (you have instructors), take the cost of that and divide by 100 to put it on the hourly rate. Everything else, you'll figure out over time and should be billing for as part of the hourly rate. For predicting future costs, it's a good idea to track not just dollars but also labor hours as noted above.
Last is whether any owner is inactive, or barely active. This person might prove interesting and look to keep monthly dues artificially low from the perspective of not getting value for the money. Doing this for too long is a death cycle as it will eat reserves and lead to special assessments or continually refinancing the plane. This trap is not fun.
Oddly enough, though I was managing a club of pretty active flyers with very nice airplanes, I know of quite a few clubs that are able to keep their dues low because they have so many members that don't fly. There's a bunch of older guys out there who have lost medicals or just stopped flying because it's too expensive but if the dues are low enough they'll just hang on to the membership as a way to keep ties to aviation. There are clubs out there with sub-$50/mo dues and dozens of members where only maybe 25-35% of the members actually fly. It's great to have others subsidize your flying, it's just a lot harder to keep the fleet up to date.
