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MD80 Systems question

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flx757 said:
enigma is in the basic ballpark, but not exactly right on a couple of the points he made.

ART (Automatic Reserve Thrust) is a fuel control function that keeps 850 lbs of thrust in reserve for use after an engine failure on takeoff, provided you are making a NORMAL power takeoff (TO selected on TRI; ART switch in AUTO). For a max power or flex power takeoff, the ART switch is off, therefore this reserve thrust is not available, since you are already making a max power takeoff. (A flex power takeoff is a max power takeoff at a given assumed temperature, which provides for a lower EPR setting than a normal power takeoff at the current ambient temp.)

For the ART to be "ready" (green ready light illuminated):
1) The system must be operational (self-test satisfactory)
2) The ART switch must be in AUTO
3) Slats not retracted
4) A valid N1 signal from both engines indicating the engines are operating.

The ART system then is ARMED when both engines are above 64% N1.

The ART activates (amber ART light illuminated) when:
1) A 30% N1 differential in sensed (indicating an engine failure).
or
2) Windshear is detected by the WAGS
or
3) The DFGC is switched or loses power


The ATR (Automatic Thrust Restoration) is a function of the Autothrottle system. It also provides for an increase in power following an engine failure on takeoff (and if the ART is also armed, will only increase the power up to a point that will allow for the additional 850 lbs of thrust that the ART provides to prevent overboosting the engines).

For the ATR to activate, the Autothrottles must be on, the Flight Directors have to be in the Takeoff mode, and engine power at less than G/A thrust. If the system detects an engine failure ABOVE 350 ft RA (and this system defines an engine failure as BOTH a 7% N1 and .25 EPR differential in the same direction OR a vertical speed of zero or less for 5 secs on takeoff), the autothrottles will drive to G/A thrust.


**Disclaimer** I am at home with no reference material. So I may not have this completely correct...but I think I got most of it. I'll double-check it tomorrow to be sure.:)

what he said:)
 
{shiver} Thank you Boeing for transport aircraft with a real FMC and a throttle quadrant/ECU combination which won't overboost the engine(s). ART and ATR are probably still one of the favorite systems questions designed to terrorize MD-80 guys. One of a dozen or more hideous laundry lists of "what is needed to arm/actuate 'X' "

Need more power? Push the throttle to the stop and get full rated power without blowing up the engine. What a bizarre concept!:rolleyes:

And yes I know Boeing owns McD-D, but they didn't design the beast.
 
I don't think any 70's era designed Boeings had the capablility of which you speak, either. I know the 727s and 737s that I flew from that era didn't.

Boeing didn't design the 717 either, but it can do exactly what you speak of with it's FMC/ECU combination.

No one has a monopoly on old technology or new. Surely you are not so clueless or naive to believe otherwise now are you?

What a concept.
 

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