Maintenance is the one cost that you cannot predict. For a Cessna 172
type aircraft it is $5-$15 per hour. It will be more toward $15 if you
have a lot of instuments and radios as gyros, vacuumn pumps and radios
go out periodically.

Our flying club has found that for an Archer or Tomahawk we average about
$25/hour, and for an Arrow about $35. This includes the annual (both the
actual inspection and all of the items that require repair) but does not
include avionics, or allowance for engine overhaul reserve. We do a lot of
training in all of the planes, so this probably increases our expenses for
tires, brakes, and landing gear.