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ecagan

APU Fault for RFP 747-200 V2

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Hi all,

I decided to pull this aircraft out of the hangar for a bit of retro flying. That came to a screeching halt though after attempting to start the APU. I found some videos online about starting it up, but they pretty much follow what I'm doing. Here's what I am doing. Please let me know if I'm missing something in my checklist:

1. For external power I go to the overhead panel and click on the GRD Crew Call button and select Request External Power.

2. On the electrical panel, when the EXT PWR 1 AC CONN lights up, I close the breaker next to it and the green light shows PWR ON BUS. I do this for the EXT PWR 2 lights. I then close all the BUS TIEs and turn on Galley Power.

3. Turn on the Battery

4. Question based on videos vs. manual. Do you need to turn on any of the boost pumps or open any crossfeed valves prior to attempting to start the APU? I tried both ways, but it didn't seem to help.

5. Keeping the Bleed Air Closed, I put the APU to ON and waited until the APU Door light extinguished.

6. I put the APU button to Start, but immediately got an APU Fault light and no start up. 

 

Can anyone help?

Thanks,

Eric

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Not looking at it and not having flown it in a while, I could be wrong, but did you turn the boost pump on for fuel tank number two? Also make sure you actually have fuel in that tank.

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That was what I did in step 4. I tried it according to the manual's tutorial flight (which didn't include turning on any boost pumps or crossfeed) and then watched the video and turned it on and then attempted APU start. Neither worked. Got the APU Fault both times.

Eric

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Did you confirm you actually have fuel in fuel tank number two. If you don't have fuel in that tank, you aren't getting it to start. I tried it earlier and was able to get it to work just fine.

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Kevin,

To follow up with you, I'm not sure exactly what I did wrong, but now seem to have things sorted out. I was able to get the APU started and even flew a couple flights. Now I'm going back through my checklists and updating them.

I had an additional question regarding fueling. Do you just zero out your fuel and use the loader to fill up appropriately?

Thanks for your help.

Eric

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I usually just use the simulator's fuel loader. The problem with zeroing out the fuel and using the fuel loader to fill it is that it fills tanks 1 and 4 first before it fills 2 and 3, so if you're on a short enough flight where you don't carry that much fuel, you might wind up in a situation where tanks 2 and 3 don't get loaded with fuel at all. If that happens, you won't be able to start the APU at all since you don't have fuel in tank 2. That said, normally, you would want tanks 1, 2, 3, and 4 to contain the same amount of fuel to the extent practical, so that each tank is feeding fuel to their respective engines. With tanks 2 and 3 being larger than tanks 1 and 2, it's obviously not possible to do that if you're flying a very long flight, but once you burn off enough fuel, you would adjust the crossfeeds accordingly, so that each tank is feeding fuel to their respective engines.

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