c hang, for my best knowing, most rocks of TQCS were came from II SQN (they rotate form SQN to SQN each 4 yrs)
to joining the QCS, they must be completed first 4yrs service in any field Sqn in the Regt. and joining the selection course (training flight of TQCS), if pass > transfered to TQCS / if failed > RTU