No bond as such, its within your training contract that you complete the line training also, so you cannot just leave as there is then the three months notice requirement.
Also, if you start to perform badly on the TR YOU have to pay for extra sessions, if you do not improve you are gone, No TR and NO refund, if you fail the first base check, FR pays for some extra sim and covers another attempt in the aircraft, if you fail this you are gone, again, no refund and no TR.
Ive not known anyone fail the line training so I cannot comment, but im sure it happens, I found the line training the hardest!
YYZ