Boeing - What does AH/SC Valve stand for

[RMC]

On the 787 each of the four cabin air supply lines has an AH/SC valve. Any one able to tell me what does AH/SC stand for?
On the maintenance page it shows as 0.98 when the compressor is deactivated (I assume this means closed)...in flight it seems to normally show around 0.5.

There is also an AH/SC flow mass.

Thanks in advance

[eckhard]

According to the DDG, it could refer to Add Heat/Smoke Clearance.

There are entries for Add Heat valves and Smoke Clearance valves but I can’t find any combination of the two.

Maybe it’s one valve with two different functions?

[RMC]

Can't find a schematic of the 787 anywhere....but as the maintenance page has AH/SC Flow Mass indication it looks like some kind of flow control valve (but is obviously not a Pressure Regulating Shut Off Valve PRSOV). I am not sure but think the Add Heat and Smoke Clearance are (as you say two separate valves with different functions).

[MATMAX]

dunno about the B787 , but other aircrafts AMMs are having a list of abbreviations/acronyms at their beginning , did you have a look at it ?

[RMC]

Thanks....Good to know abbreviations are at the start of AMM ....I am a pilot and don't have access to the 787 AMM. Can anyone have a look at this pls?

[MATMAX]

better ask your Maintenance/Engineering then ...

Add Heat Valve / Surge Control : 0° air temp AHV opens to prevent icing.

[MATMAX]

RMC , check your PMs ...

[RMC]

Matmax.... owe you one :-)

[yotty]

From the SDS manual.

During operations in cold ambient temperatures, the cabin air compressor (CAC) add heat valve (AHV) opens to put warm air back into the inlet of the CAC to increase the temperature of the air at the CAC outlet, as necessary. The AHV also does secondary surge margin control when the variable diffuser can not control the surge margin.