Serviceability is defined as the amount of effort it takes to perform a maintenance task.
So when a unit reports x% of its aircraft serviceable, how much effort does that represent? Your definitions of serviceability and reliability are at an individual aircraft level. Serviceability and reliability as I am using the terms above is at the unit level, what % of the force can be usually expected to be available day to day, how many abort missions because of faults.
Your example on troubleshooting a radio WOULD NOT be considered scheduled maintenance!!!
Agreed, I was actually but unclearly pointing out how you can cost and effort shift depending on what is important, dropping a new radio in as a time saver if you want to turn the aircraft around, as is sending aircraft away and receiving new ones to keep the load down on the unit but serviceability up. Everyone has encountered the better way of doing things that has been stopped because it costs shifts onto someone powerful enough to resist the change. The fighter pilot congratulating himself on returning his badly damaged fighter met with the maintenance crew pointing out that means they have to fix it instead of receiving a new one.
Again, repairing damage, be it from combat, wear and tear or operational damage is different matter.
Wear and tear is damage, versus being part of routine maintenance? Apart from damage there is what a squadron can expect to take care of during routine operations and what happens in an emergency. The Battle of Britain was an emergency situation but all we have is data showing the numbers of damaged aircraft repaired by the combat units or taken away to be repaired in a situation where the operational airfields were taking damage, degrading their ability to perform maintenance, and risking the safety of leaving aircraft there to await maintenance, with aircraft taking all sorts of damage amounts, where it seems Hurricane squadrons were on average bigger than Spitfire ones and probably other factors as well.
And again you're 100% incorrect.
Can you please reread my words? And note you are essentially agreeing with me while saying I am wrong? In particular my second sentence? I was pointing out giving a definition do not help finding what resources are required and therefore the ability to find one type was more reliable, rugged, better nose art or whatever.
Now anything found outside of SCHEDULED maintenance would be considered a REPAIR (in certain organizations referred to as "non-routine" or "over-and-above" tasks). All of this includes scheduled maintenance at the line and depot level.
Why add the mention of repair, which by definition tends to be non scheduled, in "line servicing and depot servicing"? So something unexpected, the need for a repair, can be scheduled?
Again, I don't know if you have any experience in this area,
Will this help?
All machines have regular scheduled maintenance making it easy to compare the costs, ultimately in money but also the times between maintenance and the time required for the work. Sometimes the scare or more valuable commodity is time, others money.
Next is damage repair, which in this case is about Hurricane versus Spitfire, with only anecdotal evidence about damage to specific parts of the airframe. Before you even start on the repairs accounting you need to check whether one type or the other could make it back with on average heavier damage than the other. Something which tends to be called rugged.
I am not sure what the RAF used but it wouldn't surprise me if their processes were similar
Apart from similar forms/checklists. The RAF went to planned flying, which was efficient in its use of maintenance personnel at the expense of breaking the direct link between them and an individual aircraft which had its costs.
The USAAF has far more detailed figures published on issues like accident and loss rates, serviceability and abort rates than the RAF. So 1,018 out of 4,228 8th Air Force B-17 losses on operations were Category E, 24.1%, while 544 out of 1,562 8th Air Force B-24 losses on operations were Category E, 33.4%. On that basis the B-24 was more rugged, more chance of returning with write off levels of damage.
When it comes to accidents they include things like being hit while parked, the ground crew setting the aircraft on fire as well as take off accidents, collisions, etc. The USAAF usually classified the damage taken between 1, minor, and 5 salvaged/write off. As far as I can tell some level 3 and most level 4 damaged aircraft were scrapped. The B-17 accident list I know of has 4,021 accidents, 3,632 of which have a 1 to 5 damage level recorded, 27% level 4, 23% level 5. For the B-24 3,653 accidents, 3,288 of which have a damage level recorded, 35% level 5, 30.4% level 4. So 50% of B-17 accidents probably meant scrapping versus 65.4% of B-24 accidents.
That says the B-24 was at least more likely to sustain greater damage in an accident. And heavily damaged aircraft returning tend to make crash landings or be abandoned in the air if the landing risk was judged too great. So how much of the higher percentage B-24 of making it back with write off damage is actually due to on average taking more damage during the landing? Accidents percentage B-17 50.0, B-24 65.4, 8th AF category E percentage times two B-17 48.2, B-24 66.8
On this evidence, which was the more rugged? That is able to take more damage but make it home? To remove the effects of the 1943 losses, for 1944 only 20.4% B-17 losses were write offs, 28.7% B-24, loss rates B-17 2.0%, B-24 1.8% of credit sorties.