180 kias as you will lose control/indications.
Flightsafety diagram 15-19 the only "shuttle valve" that can be seen is the hand pump dump valve. this opens with the first couple pumps with the emergency extension handle, allowing fluid trapped in the uplines to vent back to the power pack. the hand pump then pressurizes the emergency downlines. Oh the slower you are during emergency extension the easier it is to extend the nosegear
Will have to paraphrase the book but
1. reduce speed to 180 kts or less
2. pull landing gear motor relay cb
3. gear handle down
4. pump approx 80-100 strokes until gear indicates 3 green
* if gear will not lock down, pump until additional resistance is felt, do not stow handle, on final/landing continue pumping till pressure felt and down locks can be installed
That said I think we're both on the right track and though we both speak the queen's own, we may not speak the same language. I maybe wrong I've only got 6K on the bird