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747-400 with non-FADEC engines?

Posted: Mon May 11, 2020 12:13 pm
by AFROBINSON808
Hi,

I am wondering if an aircraft normally powered by FADEC engines (namely, the 747-400) can be fitted with non-FADEC engines if no other engines are available.

Does anyone know if this is feasible?

Thanks

Re: 747-400 with non-FADEC engines?

Posted: Mon May 11, 2020 12:35 pm
by Starlionblue
Everything is feasible with a big enough budget. :)

Lots of modifications to be done.
- Run quite a bit of extra cabling to and from the cockpit.
- Install some more instruments, lights and switches.
- Design and implement interfaces to the existing instrumentation, because the current instruments only speak FADEC.
- Rework the thrust levers, master switches and a few other bits and bobs, because they can't just send electronic signals any more.
- Would you need a flight engineer? Probably not, but the workload for the pilots would still increase I think.
- Break it gently to the beancounters how much more maintenance and fuel burn they'd need to account for.
- A ridiculous amount of paperwork for certification.

So to answer the question. Could it be done? Yes. Should it? Please no...

Re: 747-400 with non-FADEC engines?

Posted: Mon May 11, 2020 12:49 pm
by Woodreau
Is there such a thing as a non FADEC engine in production anymore? I think you’d have to spend money to R&D a new engine that doesn’t have FADEC before you can start to do everything In the post above to get the plane certified to fly with that non FADEC engine.

Re: 747-400 with non-FADEC engines?

Posted: Mon May 11, 2020 1:03 pm
by Starlionblue
Woodreau wrote:
Is there such a thing as a non FADEC engine in production anymore? I think you’d have to spend money to R&D a new engine that doesn’t have FADEC before you can start to do everything In the post above to get the plane certified to fly with that non FADEC engine.


That's a good point. Running a modern engine with its razor-thin tolerances without FADEC would be a tricky proposition.

Re: 747-400 with non-FADEC engines?

Posted: Mon May 11, 2020 2:15 pm
by mxaxai
Starlionblue wrote:
Woodreau wrote:
Is there such a thing as a non FADEC engine in production anymore? I think you’d have to spend money to R&D a new engine that doesn’t have FADEC before you can start to do everything In the post above to get the plane certified to fly with that non FADEC engine.


That's a good point. Running a modern engine with its razor-thin tolerances without FADEC would be a tricky proposition.

You would probably need to use an old non-FADEC engine like those used on the 747-100/-200/-300.

That said, there are engines that had variants with and without FADEC, like the CF6. Did later models of the JT9D ever get FADEC, for example on the 767 and A310?

Re: 747-400 with non-FADEC engines?

Posted: Mon May 11, 2020 4:52 pm
by Tristarsteve
The RB211-524G on the BA B747-400 is not a FADEC engine. It has an EEC (called the FAFC Full Authority Fuel Control) for the fuel system, but the airflow control is all analogue. The VIGVs, and the surge bleed control valves for the IP compressor are controlled entirely by a Fluidic computor, full of engine air, and no electrics.
It worked well on the older RB211 on the B747-200 and the Tristar, and was kept for the B744.
So although it has a motorised fuel valve controlled by the EEC, it is not strictly FADEC.

On the B767. The earliest aircraft had the CF6 and JT9 engines which were non FADEC cable controlled engines. These were superseded by the later CF6 and PW4000 which were FADEC engines. So it may be possible to convert a B767 to non-FADEC as some were built that way. I used to work on the TWA B767-200 which had JT9D-7R4 non FADEC engines.

Re: 747-400 with non-FADEC engines?

Posted: Mon May 11, 2020 5:31 pm
by AFROBINSON808
mxaxai wrote:
You would probably need to use an old non-FADEC engine like those used on the 747-100/-200/-300.

What are you saying there?

Re: 747-400 with non-FADEC engines?

Posted: Mon May 11, 2020 6:15 pm
by mmo
None of the later generations of the JT9 which were certified for the 747 had FADECS. The OP asked about the feasibility of this. I would it is someplace between slim to none. To be honest, it makes absolutely no sense at all. The cost of a midlife 744 is cheap enough where the STC would be more expensive.

Re: 747-400 with non-FADEC engines?

Posted: Mon May 11, 2020 11:14 pm
by Starlionblue
AFROBINSON808 wrote:
mxaxai wrote:
You would probably need to use an old non-FADEC engine like those used on the 747-100/-200/-300.

What are you saying there?


I think he means that those engines at least are suited to the airframe itself, so adaptation might be easier.

Re: 747-400 with non-FADEC engines?

Posted: Mon May 11, 2020 11:35 pm
by LH707330
Some of the late 747-300s were fitted with CF6-80C2 engines that lacked FADEC, so you could notionally get the hardware from that setup and stick it into a 400. That said, no beancounter would sign off on it, so unless you had several (tens of?) millions burning a hole in your pocket, it's not gonna happen.

Re: 747-400 with non-FADEC engines?

Posted: Tue May 12, 2020 3:16 pm
by strfyr51
Starlionblue wrote:
Woodreau wrote:
Is there such a thing as a non FADEC engine in production anymore? I think you’d have to spend money to R&D a new engine that doesn’t have FADEC before you can start to do everything In the post above to get the plane certified to fly with that non FADEC engine.


That's a good point. Running a modern engine with its razor-thin tolerances without FADEC would be a tricky proposition.

the EEC's were installed to limit engine Over-temps on starting and temperature excursions in flight. I have no Idea why anyone would even Want to remove the EEC and so do it manually. The EEC is how they removed the Flight Engineer or I'd still be flying!!

Re: 747-400 with non-FADEC engines?

Posted: Tue May 12, 2020 3:27 pm
by mmo
The EEC/FADEC does a lot more than that. They also control over pressure and over speeds. It is really a radical change from the old mechanical fuel control units/

Re: 747-400 with non-FADEC engines?

Posted: Tue May 12, 2020 3:41 pm
by Albert12
I think you’d have to spend money to R&D a new engine that doesn’t have FADEC before you can start to do everything In the post above to get the plane certified to fly with that non FADEC engine.

Re: 747-400 with non-FADEC engines?

Posted: Fri May 15, 2020 3:02 pm
by 747classic
AFROBINSON808 wrote:
Hi,

I am wondering if an aircraft normally powered by FADEC engines (namely, the 747-400) can be fitted with non-FADEC engines if no other engines are available.

Does anyone know if this is feasible?

Thanks


Short answer regarding the 744 : NO
Because no non-FADEC engine has ever been certified on the 744.
Only if you are prepared to pay Boeing for the re-certification + modification costs + a very healty profit margin.
But that amount will be north of $10.milj for a 744 aircraft with less SFC.