tolerance could be there for pressure loss with minimal impact on performance for launch to go ahead?
usual question that comes up: "Schedule is a schedule, hit da switch?"
I assume this 350Bar HELIUM tank is relatively small (must be very heavy otherwise) and is intended to displace the toxic explosive propellant with inert Helium as it is pushed out into the pumps, before being REALLY pressurized and injected into the engine combustion chamber. When propellant is all gone, you just have a bit of inert helium inside.
So the question is: WHY is there a leak? Is it saying that
(a) a pipe fitting is faulty (minor) or
(b) that there is a crack in a weld of the 350-atmosphere tank?
What happens in either case when the engine fires up and the vibration shakes the whole vehicle? I don't think there is any question of taking that risk. In one case the flow of propellant to the pumps cannot be regulated (or may stop), so getting to the right orbit is impossible, and in the other case, more immediate catastrophe during launch itself.
The NOTAM suggests that they have found and fixed it, but are now checking in more detail. One faulty fitting, then what about the others? I assume that they can test the tank pressure-holding without filling the propellants. Case (b) must have been thoroughly checked and tested per SOP, so it must be a huge relief to find that it is (a).
I wonder seriously if much deeper gyan about precise equipment specs etc is a good idea to share here to impress each other.