I'm guessing the 70 hours comes from a supeficial look at the requirements for upgrading a PPL(H) - which can be done in 40 hours + 5 hours in an FNPT - with the 30 hours CPL(H) modular course.
However, that calculation misses the additional experience required of the PPL(H) holder which, for a CPL(A) holder is 105 hours in helicopters - so we are back to our 135 hours! Fancy that
