Pack3 Off (PMDG 747)

[Guest RoniisH]

Hi guys. I recently took a flight with the PMDG 747 and used the "pack 2+3 off" before startup, but after the start-up, I cannot turn Pack 3 back on. Pack 2 works fine to turn back on, but pack 3 remains off, even though it's on "NORM" on the overhead.Thanks, Ron.

[downscc 1,327]

Check the EFIS environmental screen to verify it's on then just cancel the annunciation, use the cancel button on the EFIS panel.

[FLEX1978 373]

A picture of the ECS page on the Lower EICAS would help.Rob

[Guest RoniisH]

>A picture of the ECS page on the Lower EICAS would help.>>Robdownscc; Unable to cancel such "white" messages.

[tcas_climb 45]

have you tried the pack reset button, or cycling the switch from NORM to OFF?Bryan

[Qavion 19]

Have you accidentally armed one of the cargo fire switches?Cheers.Q> Ян

[Guest RoniisH]

>Have you accidentally armed one of the cargo fire switches?>>Cheers.>Q> ЯнI might just have! How could that be the cause of it?tcas_climb: Yes, tried them all, didn't make any difference.

[Qavion 19]

"I might just have! How could that be the cause of it?"Boeing airplane logic... Arming the cargo fire switch shuts down the #3 Pack. Never could make sense of this.... as it also forces the other two packs into hi-flow (in cruise). Surely lots of fresh air means lots of oxygen to fan the fire(???).Cheers.Q> Ян

[Ralgh 43]

Just a quick thought before digging into the 747 systems manual. Does the cabin air go into the cargo compartment? I fly the 737 and no pack air goes into the cargo compartmets on that. Driving the packs to high could be done to get any potential smoke that is in the cabin out quickly. In the 737 the first step in the Smoke/Fumes Removal checklist is to set the packs to high.

[Qavion 19]

"I fly the 737 and no pack air goes into the cargo compartmets on that. Driving the packs to high could be done to get any potential smoke that is in the cabin out quickly."True.. Pack air usually only goes to the lower cargo area on 744 freighters, however, normal flow on the 744 is about 2/3rds of high flow, so you basically end up with the same amout of air with 2 packs at high flow as 3 packs at normal flow. Perhaps it's the distribution that varies? Although the air from the three packs goes into a common plenum, similar to the 737NG, Pack #1 air has a preference for the cockpit area (baffles in the plenum direct the air towards the cockpit). Upper/Lower Recirc Fans are shut down also. This would mean that the cabin and cockpit will be getting roughly the same amount of air as a whole, but fresher. Seems to me, that the pilots would be getting the most benifit, however :(Cheers.Q>