A quote from the AAC website;
'There is also the opportunity for all AAC soldiers to apply to train as an Army helicopter pilot, subject to suitability, aptitude and medical status. You must have attained the rank of Lance Corporal and be recommended for promotion to Corporal. Army pilot selection comprises of aptitude tests, a very thorough medical, Flying Grading and finally a selection interview. The earliest that you could expect to start pilot training is some 4 years after completion of your basic Groundcrew training. A limited number of personel may also apply for Aviation Crewman training, where you will be employed as a Doorgunner, Systems Operator or Winch Operator. Selection is similar to pilot training except that you need only be a Class 1 Airtrooper to apply for Avaition Rearcrew, and there is no requirement to undertake Aptitude testing or Flying Grading, however you will still need to pass the medical and interview process.'
Should answer your question.