Why is that not the case now i.e. why is it not necessary to upgrade the gearbox and transmission now? Surely the increased available torque from the Makila engine will require these changes more so today with a much older airframe.
Very simple. It makes it unaffordable. Upgrading the gearbox would be a capability enhancement. The Puma is not being 'upgraded', it is being extended. Any hint of capability enhancement will be rejected at the first hurdle. A better transmission would be fantastic, with higher MAUM etc etc, but it is not
necessary to upgrade the transmission, the aircraft will work just fine with the old one. The IPTs and requirements managers have to justify every aspect of every single requirement in an entire program to pass scrutiny, necessary will (usually) make it through, fantastic to have will not. It is a vast amount of work. And no, I have never been a requirements manager!
To answer your next question, the Makilas are not going in because they are more powerful, they are going in because they are the most economical option to provide Puma with engines with anticipators. The extra power is a bonus. The extra power will really make itself felt H&H where the 3C4s currently run out of puff. If it was just about power, we could go for 4C4s, but they don't have anticipators either. Elsewhere, where the performance is not limited by the engines, but by the transmission, there will be a torque limit, and a torquemeter to measure it on, just like any other helicopter. It will remain the pilot's responsibility not to exceed it.
Why do we have to go for these "making a purse out of a sow's ear" programmes which as we all know will result with a far greater bill than going for a modern replacement aircraft.
Because we do not have the extra upfront money
now that a new airframe would cost. It will be cheaper (allegedly, I share your pessimism on this point!) over the planned 10 year life of the Mk2 than buying something new. By the time we need to start funding a Mk2 replacement by 2022, the money will be available (again, allegedly...). So we have to somehow keep going with what we have got. Yes, we
should have a modern replacement. We
should also have enough money to buy and own outright sufficient modern AT to sustain current ops, and we
should have enough money to stop our quarters falling down, but we don't. Until we are funded better, we can complain all we like about what we
should have, we still can't afford it.
Sorry, rambled on a bit, I'll stop there.