Sorry to enter this extremely interesting technical discussion but I am rather confused. Looking at my Technical Pilots Notes, revision 1.2 I must presume that the content re the operation of the system and the relevant pressures quoted are incorrect. The pressure expected after a single pump failure is quoted as about 45psi. Now its 5psi or 17psi in another post? It seems, what happened to the missing pressure? Did it ever exist?
If two pumps are fitted to allow redundancy, surly one pump should be able to supply a known psi just below the normal operating pressure hold off the low pressure warning bring on an advisory caution at the lower pressure and be identified on the gauge.
The advisory re a double pump failure and the words “safe operation is still possible for a short period of time” seems a little odd.
Any way hope Technical notes have been amended, will continue to view with interest.
outhouse