Ground test vehicle

[tejas]

dear friends
1)is it neccesary to do overspeed runs in ground test vehicle that is clamped to the ground before pilots could try in flight for a single engine helicopter.
2)FAR27/FAR29 doesn't say anything on overspeed run on ground test vehicle clamped to the ground.
3)DEFSTAN and MIL-T-8679 standards say something like 120% of normal operating speed can be done on GTV.
How many hours it should be done, there is no clarity.
Please clarify