I don't think the (operational) reliability of the Avro's is all that bad. It is not magically going to improve just because another aircraft is of a newer generation. New generation brings new problems. With all digital systems, a bad ground, or a resistance at a dirty connector is going to trigger faults that can ground the aircraft. A new aircraft will break down just as easy as an older one, don't be fooled. It's just the age related problems that you get rid of. But that is because the aircraft is new, not because it is a new generation. And also note that a part or a component is most reliable when it is mid-life, not when it is new.
It's not bad because they're used in a low utilization program, so we don't see delays or cancellations because there's always or almost always an aircraft to swap. However, they require much more work than the A32S and even the Classics. The engines are sensitive and need regular swaps. Having 4 of them gives twice as many reasons to change them. Many preventive engine changes are being done and their amount just don't compare with the CFM's.
The digital generation indeed has its share of problems but they're not frequent and can usually be fixed during the A-checks or on the line with a LRU swap.
A new aircraft will break down just as easy as an older one, don't be fooled. It's just the age related problems that you get rid of. But that is because the aircraft is new, not because it is a new generation. And also note that a part or a component is most reliable when it is mid-life, not when it is new.
The age and philosophy related problems are the biggest problems. The older the aircraft, the more they deviate from their original configuration. There are the natural deviations caused by vibrations and movements and there are deviations caused by maintenance. These deviations cause problems with electrical wiring, hydraulic/bleed/water systems/oxygen/fuel systems and structural, the typical day to day issues.
The most you fix on a new airplane is an occasional LRU swap, a software fault or minor manufacturing errors.
Newer generation aircraft are also better thought-out for maintenance and avoid accessibility problems on zones that need regular attention.
Sometimes just getting access to places for maintenance or troubleshooting takes longer then that, and then the work has to be done as well. Troubleshooting a single problem may drag for days with such short availability, and if the cause then eventually is found, you still need time to get the parts should they not be in store. So, be realistic, stressing a fleet like that will eventually backfire, especially the first year or two, when the maintenance organisation is gaining experience on type.
The Avro's have too many accessibility problems and many too sensitive systems that vacuum time and resources, a result of excessive haste by British Aerospace to get the aircraft certified during the design stage.
Look at the Airbus, most systems are accessible in the turn of a few quick-locks.
If you can't defer an item, you tow the aircraft to the hangar and use a spare aircraft.
Example of what happens if a night charter goes tech before departure.
Aircraft "A" 22:30 scheduled to fly to Bastia, Corsica. Problem discovered, grounded.
Spare aircraft "B" activated, departs 23:00 to Bastia. Takes over the schedule from aircraft "A".
Aircraft "A" fixed between 23:00 and 06:00 to serve as the new spare aircraft, "B" continues flying through the day.
I don't doubt for a moment that the turboprops are capable of operating in such a high-efficiency scheme but I'm far from sure that SN can handle it organisation-wise, at least for sure not under its current structure.
Southwest Airlines achieve a 12.5 hours average daily utilization. Feel free to compare with SN's statistics accessible to all SN staff and you'll see what I mean by low efficiency operation. The problem isn't aircraft maintenance ground time but rather a lot of parking and too many aircraft to operate a light schedule. It's good for operational on-time departure statistics, but it's a hole in the wallet.
So, be realistic, stressing a fleet like that will eventually backfire, especially the first year or two, when the maintenance organisation is gaining experience on type.
It depends on how it's done. If there's always the comfort of 2 spare aircraft while all the other aircraft are either on scheduled maintenance or flying like there's no tomorrow, then it would be fine.
04:30 till 06:30...? That is the worst time to have an aircraft avaliable for mx. The shiftchange is at 6, so, assuming the aircraft comes in on time, which is not certain at all, a delay earlier in the day may cascade till the end of the flight day, and in this case even de next day if the delay is severe enough, but if it comes in on time, you are looking at effectively 30 minutes till 1 hour max downtime for mx. A day!
It doesn't matter because aircraft only need attention if something arises. On the turboprops, you don't even need a daily check. The most you would have is an item that needs to be deferred and otherwise you can activate one of the spare aircraft and immediately start repairing the grounded aircraft to make it ready to act as spare aircraft.
The larger the fleet, the more spares you can have.
If at any given time, SN has 30 turboprops, it can easily have 2 spares and 2 in heavy maintenance.
Line and A checks can be scheduled every 3 to 4 days at night. The night mx program would look like this:
8 aircraft on line check,
1 in A check
2 spares
2 in heavy maintenance
remaining 17 aircraft flying night charters.
Even in a 15 aircraft fleet you can do the same with 4/1/1/1/8, but then it gets riskier on the spare aircraft, so I would reduce the night flight charter potential to 6 or 7 to have additional breathing room.
A Line check every couple of days is not the problem, that is a gloriyfied daily check anyway. But there are more things like wheel and brake replacements, out of phase maintenance tasks, A-checks, troubleshooting problerms, cabin maintenance, prop balancing, etc..
All mentioned tasks can be done in the 3-daily, nightly line checks. You can put as many tasks as you want in the line check, as long as there's no single task that takes more than 7 hours. Even then, you can still use a spare aircraft or if it's not possible, you can weigh a delay, because making money is just as important as flying on-time.
Given the resources freed by the maintenance-friendlier design and absence of daily checks, those resources can be used to aggressively attack the aircraft on every nightly line check or when an aircraft goes tech and a spare is activated.
Interesting comparison ATR72/Q400.
