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747-8i Engines cutting out.

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747-8i Engines cutting out.

Postby gray1 » Sat Jul 11, 2020 10:12 am

Hello once again,
I had great advice on my previous post regarding the 747-8i banking & crashing to the ground. The advice rectified this perfectly.
So guess what?
New problem, the engines just shut down as I get to within approx 30 nm from touchdown. Now, as I would be at the level to catch the localizer (eg: 6,200 ft) , this gives me no time to restart & yep, I crash.
I have plenty of fuel, A/P is on, aircraft properly configured, ready for an ILS landing.
I try starting the APU, it just won't start. I've tried cutting the fuel off, packs all off, & tried the APU as you do when starting up.
Anybody have an idea?

Thank you,
Gray.
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Re: 747-8i Engines cutting out.

Postby WoodSTokk » Sat Jul 11, 2020 12:05 pm

I dont know the 747, but check fuel quantity and fuel pumps.
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Re: 747-8i Engines cutting out.

Postby gray1 » Sat Jul 11, 2020 8:46 pm

Hello WoodSTokk,
The fuel quantity is always enough, but I do add extra just in case I need to do a go around. This is usually 10% extra.
When the engines stop I do lose pumps 1 & 4, also the hydraulics shut down. Yet fuel pumps 2 & 3 remain operational.
So i try the APU, but it's like a non starting car.
So I have fuel, 2 engine pumps, but no response from restarting the APU for engine ignition.
Very strange.
Thank you for your reply.
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Re: 747-8i Engines cutting out.

Postby tikibar » Sat Jul 11, 2020 9:17 pm

Here's a typical fuel management strategy:
1. At the beginning: all fuel pumps ON, all cross-feeds ON
2. Center tank will be consumed down to 80,000 lbs, then any fuel in the horizontal stabilizer (-8i only) will be transferred to the center tank automatically.
3. Center tank will be source for all engines until it is empty, then its pumps will shut off automatically, and
4. Engines 1 and 2 supplied by inboard left wing tank (Main #2), and engines 3 and 4 by inboard right wing tank (Main #3).
5. When the quantity in the the inboard mains (Main 2 and 3) is about equal to the quantity in the outboard mains and reserves (Main 1 and 4, Res 1 and 4), shut off the outboard cross-feeds and the inboard OVRD pumps. Now each engine is supplied by its corresponding main. Outboard reserves gravity feed into the outboard mains. This will be the configuration for the remainder of the flight.

Depending on the length of your flight, you may not have any fuel in the center or horizontal stabilizer tanks, so you'd start at step 4. On very short flights, you may already start at step 5. Steps 2 and 3 happen automatically, so you don't have to worry about those once you turn the pumps and cross-feeds on. If you go to the 747-8i (or 747-8F) menu and go to "Control Panel," you can check the "In-Flight Tank Management" box; then your first officer will take care of step 5.

There's a document included in the 747-8i package that describes the fuel system in a bit of detail. (see https://github.com/dogsaysmoo/747-8i/bl ... system.pdf)
Boeing 747-8 (rename folder to 747-8i)
Boeing 757-200/300 (rename folder to 757-200)
Boeing 767-300/ER (rename folder to 767-300)
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Re: 747-8i Engines cutting out.

Postby gray1 » Sun Jul 12, 2020 7:48 am

Hi Tikibar,
That's a very good explanation, easy to follow & just the advice I was looking for.
I thank you for the PDF also.
This is the 2nd time you've helped me, you are very kind & patient with those who don't have your depth of knowledge.
I will read this advice until it becomes natural to me.
Thank you my friend,
best regards,
Gray.
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Re: 747-8i Engines cutting out.

Postby gray1 » Mon Jul 13, 2020 2:53 pm

Tikibar,
Yet again you've come to the rescue. The PDF was invaluable too.
I now no longer bank into the floor as in the previous post, & today the engines worked as they should. Gatwick to Barcelona, smooth as silk.

I'm indebted to you once again.
Thanks my friend.

Graeme. UK.
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Re: 747-8i Engines cutting out.

Postby tikibar » Tue Jul 14, 2020 6:41 pm

Hi Gray,
I'm glad I could help! It's been fun developing the model for this aircraft and learning a lot of details about it. I'm glad you're enjoying it!
Cheers,
John
Boeing 747-8 (rename folder to 747-8i)
Boeing 757-200/300 (rename folder to 757-200)
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