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-   -   Apu inop (https://www.airlinepilotforums.com/air-wisconsin/135016-apu-inop.html)

puddlejumper 09-15-2021 01:31 PM

70% N2 is about 48% N1.

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dremaldent 09-15-2021 01:43 PM


Originally Posted by dremaldent (Post 3295481)
Take about 500 lbs extra fuel and then increase thrust on the right engine. It only takes about 70% N2 to deliver the maximum PSI to the PACK. The only downside is that you can't do this while you're moving. I've successfully cooled the cabin to 24 degrees using this technique. Not the most comfortable but at least a safe temperature, and better than canceling the flight by a long shot.

No APU really isn't that big of a deal. Obviously a little more work, but it is still possible to run flights safely unless the temperature outside is over 100 F.

I'm an idiot. Don't do this. Combination of misremembering things and being very tired. Sorry y'all

squib 09-15-2021 05:57 PM


Originally Posted by dremaldent (Post 3295594)
I'm an idiot. Don't do this. Combination of misremembering things and being very tired. Sorry y'all

Must be the side affects from operating without an apu to complete the mission.

Pedro4President 09-15-2021 06:18 PM

So I’m assuming you are talking about the 145. No APU is kinda an iffy one. It only really sucks on the taxi out and does fine once you are in the air. The thing is you have to have a good PCA to cool it down and leave it on as long as possible. If no PCA then I’m not taking it.



It’s the pack1 inop that is an absolute no go item when it’s hot and sunny out there. The flight deck gets north of 45 at times. I have taken them without a pack1 when it wasn’t too hot but sunny. Big mistake. The avionics heats up the flight deck pretty good too.

Sasquatched 09-15-2021 06:45 PM


Originally Posted by Pedro4President (Post 3295692)
So I’m assuming you are talking about the 145. No APU is kinda an iffy one. It only really sucks on the taxi out and does fine once you are in the air. The thing is you have to have a good PCA to cool it down and leave it on as long as possible. If no PCA then I’m not taking it.



It’s the pack1 inop that is an absolute no go item when it’s hot and sunny out there. The flight deck gets north of 45 at times. I have taken them without a pack1 when it wasn’t too hot but sunny. Big mistake. The avionics heats up the flight deck pretty good too.

You’re in the Air Whiskey forum Pedro. Safe to assume they’re referring to the Deuce.

Pedro4President 09-16-2021 04:25 AM


Originally Posted by Sasquatched (Post 3295711)
You’re in the Air Whiskey forum Pedro. Safe to assume they’re referring to the Deuce.

It just goes to show how little I keep up with everything.

pitchtrim 09-16-2021 07:39 AM

Doesn't the book say the cabin can't reach 30c with pax on board? Makes the decision pretty easy to refuse the plane when you can't maintain what's in the book.

RJ4LIFE 09-18-2021 01:29 PM


Originally Posted by dremaldent (Post 3295481)
Take about 500 lbs extra fuel and then increase thrust on the right engine. It only takes about 70% N2 to deliver the maximum PSI to the PACK. The only downside is that you can't do this while you're moving. I've successfully cooled the cabin to 24 degrees using this technique. Not the most comfortable but at least a safe temperature, and better than canceling the flight by a long shot.

No APU really isn't that big of a deal. Obviously a little more work, but it is still possible to run flights safely unless the temperature outside is over 100 F.

You took a lot of flak for this being unsafe but I'd contend that it can be done perfectly safely once you're away from the ramp, especially at outstations where there's usually nobody taxiing directly behind you. The problem is that as the cabin cools down, your brakes will quickly heat up and you might even end up having to delay your takeoff to let them cool, which defeats the whole purpose. Ask me how I know ;)

JohnnyBekkestad 09-18-2021 01:34 PM


Originally Posted by RJ4LIFE (Post 3297125)
You took a lot of flak for this being unsafe but I'd contend that it can be done perfectly safely once you're away from the ramp, especially at outstations where there's usually nobody taxiing directly behind you. The problem is that as the cabin cools down, your brakes will quickly heat up and you might even end up having to delay your takeoff to let them cool, which defeats the whole purpose. Ask me how I know ;)

If you are at at outstation and can be airborne within a few minutes of starting to taxi then this wouldn't be a problem. Try to do that in O'Hare on a warm summer pre covid day...
I made the mistake to take a 200 in ORD early in the morning, first flight of the day to MKE and back. BIG mistake, and swore never to do that again. The problem is not the flight time, its the taxi time, you cant or shouldn't taxi with enough power to cool the cabin without the APU.

TiredSoul 09-18-2021 01:58 PM

Is that why y’all taxi at 70mph?


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