A320 FCOM wording: cross-bleed
Hello, need help untangling the semantics of this sentence from FCOM.
"Adjust thrust of supplying engine to obtain 30 PSI at start air valve before start initiation and at least 25 PSI during the start" [FCOM 2008].
"Adjust thrust of supplying engine to obtain an engine bleed pressure of 30 PSI before start initiation, and at least 25 PSI during the start sequence." [FCOM 2025 edition]
Which side are we looking at here, Hoskins? The receiving bleed or the supplying one?
I have always understood the requirement is for the bleed pressure at the RECEIVING engine:
a) It feels just normal to check the required min press at the delivery not at the source (the drop across the tubing is around 6 psi);
b) Naturally following the guidance of ENG START w/ EXT PNEUMATIC, where ground unit performance is requested - "The minimum recommended starter air supply pressure is 30/25 psi when the start valve is open" (FCOM 2008 through 2025) - which is only visible on the receiving side, clearly.
But if I am honest about "trusting the instruments", the present (2025) FCOM language does not really justify checking on the receiving side - if you had to choose exclusively, one or the other.
Awkward. Is anyone trained to check the supplying side? Why the odd wording?
thanks a lot.