From newer skymasters to old?

[Kevin McDole]

Richard,

I didn't realize the 67 did not have the pop-off valve.

However, the pop-off valve does not replace the variable controller. They serve very different functions. The controller adjusts the position of the waste gate to maintain a constant "delta" in the upper deck pressure, while the pop-off valve is for overboost protection.

If the 67 doesn't have a pop-off valve, how is it protected from overboost?