Chad and I leak checked the heat shield circuit after uc#3target installed. It took 5minutes to pump down the circuit to the leak detector bottom scales.   All the vacuum lines and connections are leak checked by spraying helium. Chad sprayed helium to each vcr fittings for 2 seconds. There is no any response on leak detector . The test repeated one time and the result is same. The heat shield circuit is leak tight at this stage . We will move TM4 to conditioning station and pressure helium test the circuit.