Here are some comments Chris made in a recent discussion about this:Right now the maintenance costs of an aircraft are based on a percentage of its market value. This can produce some unrealistic numbers especially when dealing with older out of production where the real world market value is very low compared to current production aircraft. Often these aircraft have a very low market price because the maintenance costs are so high, where flynet reverses this, where the newest aircraft with the lowest maintenance costs are penalized because of there high purchase price. I would therefore propose the following change to the maintenance calculation.
Instead of using the market value to calculate maintenance cost, we would calculate a 'maintenance value' that would be based on the dry weight of the aircraft (larger the aircraft the larger the cost) the formula would be.
500v$ per KG of the aircraft's dry weight
+10% per engine.
+5% per engine if piston powered (not turbines).
+10% if no longer in production (alternate +1% for each year since production stopped).
Some examples, for two aircraft of about the same weight)
A320, current production two engines, market value is 61m, using this formula the maintenance value would be 25.3m and an A level check would be 759.000v$ rather than the current 1.830.000v$.
B727-200, not in production three engines, market value 40m, using this formula the maintenance value would be 63.5m and an A level check would be 1.9m rather than the current 1.2m.
Another comparison would be the DC-3, current market price 300.000v$ an A level check is 9.000v$. Using this formula
(8030kg * 500v$ * 1.4 two piston engines plus out of production) a maintenance value of 5.621.000v$ so 168.630v$ for an A level check. Of course this could lead an airline to conclude its cheaper to scrap an airplane than fix it, which happens some times in real life.
So some additional comments and questions I have:CAPFlyer wrote:Joe, I still think we need to go to a time based maintenance system with a percentage based failure system is the way to go. Percentage based maintenance just doesn't work as well since your maintenance can be too easily minimized by maintaining it before you go through the threshold for the next level of maintenance.
Also, I think we still need to have 4 levels of aircraft - jet, turboprop, helicopter, and piston. Those levels would trigger modifiers that would (in that order) progressively increase cost to account for level of difficulty to maintain (and thus cost). Beyond that, your original proposal still holds the same merit I said before.
- Turbo props: Are they more or less costly to maintain that jet engines.
- Helicopters: Would probably add 10% or 20% to the cost to maintain, is that enough?
- How would a time based maintenance system work. Right now its percentage based, and the percent decreases by how many hours you fly and how hard your landings are. If we did implement an hour based maintenance system, we would still have to have some way to deal with damage done to the aircraft.
No decisions have been made and everyone's input is welcome.