Originally Posted by S_Ellzey

As one of the authors of the regulation I can say that the intent was for there to be a shutoff valve, just stopping the pump was discussed and ruled out.

You have to remember that at the time this was written JPXs where still flying (and may still be) and they had a servo operated shutoff valve, and most of the newer engines of the day had solenoid valves. So the regulation was written to allow these to operate and set a standard for future engines. The wording was left somewhat open to allow for new technology. Had the regulation said “solenoid valve”, if someone came up with, say a piezoelectric valve, it would not be compliant.

As to run away fuel pumps, I saw one at the Mississippi event many years ago. It resulted in a fire ball in the sky. There was no ECU operated shutoff valve, so the pilot could do nothing about it. This event is one of the contributors to the regulation.

Steven