A throttle down to 67% may occur prior to fine count if the center engine is failed due to the
incorporation of CR 91042 Second Stage Pitch Gimbal Relief in OI-26. This CR compensates for
potential gimbal saturation due to the super light weight tank (SLWT). The SLWT is about 8,000
lbs lighter and causes the vehicle center of gravity (cg) to move about 6 to 8 inches further up into
the Z-axis at MECO. This higher cg makes controlling the vehicle difficult for press to MECO
cases with the center engine out when the orbiter Zcg is near the top of the entry cg box
Now that's interesting - so the last-second control problem with the center engine gone is actually real.