I think that may be true for flying schools only i.e. an owner (or his family, IIRC) can still train in his aircraft even if the engine is past TBO. Worth a check if this affects anyone.
IMHO the saving in the per-hour DOC by running an engine “on condition” is miniscule.
Peter wrote:
IMHO the saving in the per-hour DOC by running an engine “on condition” is miniscule.
I think you must mean for a commercial operation doing many hours per year? It may be true for them but the 12 year calendar time limit being inapplicable to my Part 91 operations has meant that my aircraft has so far avoided four unnecessary major overhauls or about $72,000 at 2020 US overhaul prices for a small Lycoming. If engine operating time were instead the applicable issue, then running an extra 200 hrs past manufacturer TBO would allow me to avoid an overhaul for about 3-4 years at my rate of use. That’s about $4K cost of money saved. Also, when operating on condition it is not ever necessary to completely overhaul the engine, only to IRAN indefinitely based on condition, which is a huge issue for owners if for example their certified plane has a six cylinder Franklin engine instead of a more common type that is in current manufacture.
Yes I meant the TBO, not the 12 year time limit. Do European schools have to comply with the 12 years?
Time on condition makes a big difference to us. O200 engines often get an extra 1000+ hours with little extra maintenance.
Peter wrote:
IMHO the saving in the per-hour DOC by running an engine “on condition” is miniscule.
On the average, we saved €12/hour, compared to an overhaul at TBO. Every little bit helps…
@Peter:
As a private operator (including non-commercial ATOs) you don’t have to comply with any form of TBO, whether it is expressed in flight hours or calendar time.
You still need an individual maintenance programe if you want to go beyond any TBO.
With our self-declared maintenance programs, we are able to run each aircarft, including the ones used for training, on condition (propeller and engine).
Depending on the aircraft, we get 500-1000h beyond TBO on the engines and propellers. In some cases this means years of extended use.
In that case I wonder if the UK CAA is running its own scheme? Perhaps it is the SDMP which they don’t allow. Here ya go.
There are different ways of calculating the effect of going past TBO. I found one previous discussion – here. Some may find some of the posts amusing 
I obviously don’t know a thing about the situation in the UK, but I was under the impression (based on this forum’s content) that non-profit ATOs/DTOs are very uncommon in the UK.
The above-mentioned does only work because we are private ops. This in turn is only possible because we are strictly non-profit, not paying anyone (including the instructors, technicians and various post-holders) a salary not charging more than the operating costs of the planes.
If we were a commercial, for-profit ATO, we’d be subject to the fixed TBOs.
Non profit “anything” is very uncommon in the UK
Joking aside, and not starting the old discussion yet again about any cash-negative “nonprofit” entity necessarily going bust eventually this must be a definitional issue. If the CAA defines every training operation (where people obviously pay – it can’t be done for free unless you go to communist-era Yugoslavia) as a profit entity, but exempts it from needing an AOC, as the UK CAA does, then you end up with the UK situation.
The UK certainly does have a “club” category for accounting and taxation purposes. Maybe in the UK this cannot be used for flight training or, if it is, it doesn’t carry any weight with the CAA.
You can certainly form a syndicate, which owns any number of planes, and they can go over TBO, etc, while receiving flight training. But a syndicate isn’t good for a scenario where most people drop out almost right away. Also AFAIK this structure cannot be used for ab initio PPL training.
Give me one last try to make clear what I’m talking about 
, I’ll stop after this one!
I wasn’t talking about anything being “cash-negative”, because, for the reasons you posted above, anything out of the ordinary will have no funds to cover it.
What I was talking about is a legal entity where
Maybe this should be moved to somewhere else? I get the feeling we’ve had quite a thread drift…
