Why not go straight from the Squirrel to the Chinook?
As I have opined in the past.....Folks...a helicopter is a helicopter is a helicopter.
The real difference is the operational use of the machine and training for that.
Young, fresh, keen as mustard, new co-pilots can quickly learn to fly the bigger machine and with not a lot of training can fit into an experienced crew with not a lot of bother.....assuming the experienced crew is willing/required to mentor the new guy.
The hard part of learning how to fly the Chinook is understanding how small it is.....along with how big it is.
I realize in a shrinking military organization....there is going to be some Turf protecting going on....but sometimes commonsense has to used. The RAF certainly has figured out a way to complicate matters at the expense of efficiency and cost it would appear....but at least it justifies all those manning points I guess.
Before you squawk....the US Army is pretty good at doing the same thing.
A young BlackHawk pilot friend of mine told me of all the "Qualifications" she has to achieve before flying in Afghanistan......the process was to the point it would make the Australian CAA blush and I used to think they were the most extreme in the World.