BLEED OVHT advisory

[ASCTU744]

AMM's mention a BLEED X OVHT advisory message (No, not the STATUS message).

Some manuals say that the BLEED OVHT or OVHT/PRV advisory pop-up during an overheat, others say that PW4000's only have the BLEED X OVHT and not the OVHT/PRV message. The new LH tech training manuals mention both simultaneously, all rather confusing...

Is this an IDS thing and do the two eicas messages (OVHT and OVHT/PRV) coexist in one airplane? And most importantly is this message still present in the current 744's?

Btw, the FCOM's and QRH's do not mention this message at all.... this seems to happen in more EICAS related instances: https://aerowinx.com/board/index.php/topic,7283.0.html

Thank you in advance!

Edit, JAL training manual from '92 and China airlines AMM from 2018:

[ASCTU744]

Just saw the BLEED OVHT advisory again in an old SIA manual, no mention of the BLEED OVHT/PRV. Has anyone that currently works on the airplane ever seen this advisory msg?

[John H Watson]

In the MAS FIM, the BLEED X OVHT/PRV message has a note saying "as displayed", whatever that means.

The description varies slightly

BLEED x OVHT: Bleed air overheat causing engine x PRV and HPSOV to be commanded closed.
BLD x OVHT/PRV: Engine x PRV failed closed [when bleed pressure is less than 65psig] or bleed air overheat causing PRV and HPSOV to be commanded closed.

Sounds like different logic to me.

Our GE DDG (2012) listed the BLD X OVHT/PRV version and the BLEED X OVHT version.

I don't have a QRH for this aircraft.

[Jeroen Hoppenbrouwers]

I guess that there may have been a desire to add a new message and there was no budget for an extra one.

Original: "BLEED x OVHT".
Desired: both "BLEED x OVHT" and "PRV x".
Compromise: use the same lamp for both and adjust only the label.

EICAS messages need to be seen as lamps ... there are only so many slots available and installing a new lamp needs adjustments to multiple avionics boxes. Changing the label is only an EIU ("display") adjustment and something further upstream, but not a complete bus redefinition programme.  And with the message still covering the previous case as well, probably less recertification impact, too.

Docs ... always a problem ... maybe they list both "so we cover the transition period."

Again, just a guess...

Question: is the crew response to both messages essentially the same?


Hoppie