Anders Mjos wrote:

The conductance check on the electrical check was found to be outside of accepted values for the TBHT at 7.0 mOhm. A successful attempt to reduce the conductance was made by re-tightening the bolts on the TGHT legs in the SHC. Grant operated the manipulator and torqued the bolts to about 1/8 of a turn with the air ratchet. The conductance across the TGHT (A-B) could be improved from 7.0 mOhm to 6.2 mOhm by re-tightening the bolts. The value is still somewhat higher than usual, but was deemed to be acceptable. Measurements attached.

1. TGHT leg bolts were loosened, and resistance was measured very high, as expected.

2. TGHT leg bolts were then tightened, loosened, and tightened again, and the resistance improvement was then measured (from 7.0 mOhm to 6.2 mOhm).

3. Another attempt was then made to loosen and tighten to see if there would be further improvement.  The right bolt was loosened, but the left bolt was found to be quite stiff and was left as-is (not fully loosened) for fear of breaking the supporting insulator.  Both bolts were then re-tightened, and resistance was checked to be about the same as achieved during the previous loosening / tightening attempt (step 2 above).

To tighten the bolts in all cases: the air ratchet was used first to turn the bolts "air tight" (air pedal only, no manual force) and then with the air pedal held down, manual torque was applied to turn no more than 1/8th of a turn.