NWA
Topic Author
Posts: 1162
Joined: Fri Jun 22, 2001 2:31 am

Ffrats On The 747-200

Sun Nov 28, 2004 4:01 pm

On my free time, I like to fly "ready for pushback 747-200" in Flight simulator, and one of the main features is the FFRATS. My question is, for anyone that has expirance on it, did you like it? Also, when its set to auto EPR and in TOD mode, it requires you to advance the throttles to a certin EPR, and then it will go to th EPR limit. My question is does the pilot advance the throttles fully and let it limit itself, or just to the point where the FFRATS takes over? Thanks.
23 victor, turn right heading 210, maintain 3000 till established, cleared ILS runwy 24.
 
flymia
Posts: 6867
Joined: Thu Jun 14, 2001 6:33 am

RE: Ffrats On The 747-200

Mon Nov 29, 2004 9:57 am

Well I cant answer any of your questions. Just wanted to added that I fly 747-200 Ready For Push Back all the time. Never got the Ffrats down great or the INS. Great add on. Glad to see someone else have it.
"It was just four of us on the flight deck, trying to do our job" (Captain Al Haynes)
 
air2gxs
Posts: 1443
Joined: Mon Jun 18, 2001 1:29 pm

RE: Ffrats On The 747-200

Mon Nov 29, 2004 12:21 pm

FFRATS, for those who don't know is Full Flight Regime Auto Throttle System. Basically its a modern auto throttle.

In an FFRATS jumbo the flight crew pushes the throttle up until the auto-throttle takes over. The classics don't have throttle by wire (unless you count the cable as a wire). That means the throttle movement is a direct linkage/cable to the jet fuel control. If the pilot pushes the throttle to the stop (as he would on a modern throttle by wire, FADEC system) he runs the very real risk of over-boosting, over-temping or over-speeding the engine.
 
NWA
Topic Author
Posts: 1162
Joined: Fri Jun 22, 2001 2:31 am

RE: Ffrats On The 747-200

Mon Nov 29, 2004 12:44 pm

So they will not push the throttle all the way up then, just far enough for FFRATS to take over?
23 victor, turn right heading 210, maintain 3000 till established, cleared ILS runwy 24.
 
air2gxs
Posts: 1443
Joined: Mon Jun 18, 2001 1:29 pm

RE: Ffrats On The 747-200

Tue Nov 30, 2004 2:31 am

Yes, unlike "modern" (FADEC) airliners, the jet fuel control on a B747-200 (JT9D-7Q equipped) receives its input from a cable. The cable moves the spool valve inside the JFC. If the pilot pushes the throttle to the stops he will be demanding the JFC to give the maximum amount of fuel. This can, and will, easily over-boost, over-temp and/or over-speed the engine. So, he just pushes the throttle up until the auto-throttle system picks it up.

To clarify, on a FADEC engine there is no direct (cable) connection between the throttle and the fuel control. When the throttle is pushed to the stops, the EEC interpets that as a full power command and sends the appropiate commands to the fuel control.

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