B737 Bleed press. differentials
 

Hi ,
Can anybody tell me (technically speaking) about the maximum allowable differential L and R needle of bleed pressure ? On my recent flight with 735 the L -49 psi & R-12 psi on CLB thrust, and L-46 & R-28 on CRZ thrust, on DES relatively equals at 26 psi. No light illuminates, and pressurization is normal.
Thanks.

Usually there is no differences between tle L and R needles.The duct pressure change with thrust change,but it doesn't affect the pressurization.The system is automatic,and it's no use to check this indicator except on engine start.
"Differences between L and R duct pressure on the bleed air duct pressure indicator are considered normal as long as there is sufficient air for cabin pressurization" OM 2.
So ,just check the cabin altimeter/differential pressure indicator,if you feel something is wrong.
No other specification on the technical man.
Al


:ok:

OK...so you've heard about Bleed Splits from an operational standpoint. From a maintenance standpoint, that bleed split is unexceptable. Off the head, I believe the limit for splits is 8 psi.

But that engine bleed system (R) definitely has a problem.
You've got a regulation problem (doubtful) or a temperature problem (most likely).

"From a maintenance standpoint, that bleed split is unexceptable. Off the head, I believe the limit for splits is 8 psi."

Is this any different from the NG, B73567AMT? I'm currently looking at a 737NG simplified bleed pressure diagram (N1 Vs Bleed Pressure, for sea level to 5000') in the Maintenance Manual D&O and, at N1's above 65~70, the pressure can be 42psi +/-8 psi (as modulated by the PRSOVs). This gives a possible range of 34 to 50psi. Even so, Arba's 12psi is well outside this range.

Regards.
Q.

Let me correct myself. Technically, there are no limits for splits between the L and R sides.
But yes, that aircraft needs attention.