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ENGINE 4# FUEL FLOW,TIT AND TORQUE SUDDENLY INCREASE (BELOW XOVER) THEN RPM DROP%80


airman57
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''DURING AIRCRAFT DECENT (LANDING) (FIRST OF ALL) ENGINE 4# FUEL FLOW,TIT AND TORQUE SUDDENLY INCREASE,(THEN) RPM IMMEDIATELY DROP%80 WHILE THROTTLE AT FLIGHT IDLE.(BELOW XOVER) FLIGHT CREW SHUT THE ENGINE AT %80 RPM'' (EMERGENCY)

NOTE: Flight crew said that no change temp.datum valve switch in null position.

WE CHECKED THE ENGINE:

1.Operational Checkout of Throttle Control System------------------------------ (no problem)

2.Operational Checkout of Engine Condition Control System---------------- (no problem)

3.Operational Checkout of Propeller - Static Condition---------------------------(no problem)

4.Inspection of Engine Power Section (with baroscope)------------------------ (no problem)

5.Power section and Reduction gear box mag.plug check----------------------(no problem)

6.Electrical Components Check Using Electrical Components Checkout Test Set----------(no problem)

7.Check of Temperature Datum Control System With Engine Static UsingTest Set--------(no problem)

8.We run the engines for run-up control--------------------------------------------------(no problem,all of indications were normal.)

WE DECIDED TO CHANGE THE FOLLOWING PARTS AND WE CHANGED.

1.Valve Housing

2.Main Fuel Control

3.Fuel Enrichment Valve

(THEN AGAIN) (AFTER CHANGED THE PARTS) WE RUN THE ENGINE FOR CONTROL.(NO PROBLEM)

WE DECIDED TO FLY THE AIRCRAFT (TO CONTROL FLIGHT)

AND AFTER TAKE OFF WHILE CLIMBING. (APPROXIMATELY AFTER 7-8 MINUTES) SAME PROBLEM WAS OCCUR IN FLIGHT AFTER NTS CHECK WHILE ADVANCE THROTTLE FROM FLIGHT IDLE TO XOVER POINT.(APPROXIMATELY ABOVE 1 INCH OF FLIGHT IDLE DETENT)

NOTE:FLIGHT CREW SAID THAT NTS CHECK WAS SUCCESS IN FLIGHT.BUT...(TWO TIMES EMERGENCY)

ANYONE CAN GIVE SOLUTION.

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Just a shot in the dark even though you did the yellow box test have you ohmed out the co-ordinator ? and The J-2 Lead even though you check it while yellow boxing .Maybe disconnect it and ohms ck it out maybe there is a break or some wiring issues in the wing

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This one has the grey matter in a mess (more so than usual). For the numbers to change

that radically, you need the TD and the FCU to work together. I'm wondering if there isn't

a split pulley or tension regulator stirring the pot. Also take a good look (disassemble) the

gimble assy at the coordinator.

Also take a look at the CIP hoses for blockage, both upstream and downstream of the FCU,

blow them out with compressed air

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It looks like the fuel system problem (in my opinion)

But why did RPM drop? (under %80 RPM......) Engine was go from %100 RPM to %80 RPM in flight.then flight crew shut down the engine.

(When failure occure) Engine values firstly indicate torque :15.000, tıt:1050 C , fuel flow :2400 pph.After this situation RPM should not drop when the engine fuel flow,tıt,torque increase.

(because engine's power is very high)

(I don't understand this situation.)

I NEED MORE TECNICAL INFORMATION FOR THIS FAILURE.THANK YOU pjvr99,tenten,DanGothe,

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Problem has to be multiple component and/or wiring. This rig is not airworthy. Take it off the wing. Throwing parts at it, and cannot duplicate on ground with that kind of discrepancy is, in my mind, grounds for R2. Probably cheaper, and surely quicker in the long run. Sending up "I hope its not another IFE" is not in my mind acceptable.

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To my opinion you might have an issue of TD system malfunction accompanied with play on the pump housing due to warn out/looseness of anti-rotation bracket. (Sudden increase of power twists the pump housing…. activating the NTS system …….. leading the RPM to drop.)

But again the value of power increase appeared to me beyond the ability of TD malfunction to produce, unless I am wrong on this understanding.

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Couple of things still have me puzzled: in the first post was stated problem occurred during

descent. That would mean a pretty serious yaw when then miscreant engine suddenly increased

power. The second thing that worries me is the 80% - bleed valves would have opened, and

flameout would be the result

This is really wacky .............

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I wish I had my hands on that plane so I could poke around, but my shoot-from-the-hip instinct says it's a propeller malfunction. If the propeller causes the RPM to drop, the fuel control will think it's still trying to accelerate up to ground idle RPM, and start putting a lot of fuel. We've had at least three cases that I can think of on the top of my head where the Valve Housing caused the engine to go to full takeoff power (fuel flow, TIT, torque all went up) upon upspeeding the engine. The bleed valves opening up below 94% could also partially explain the high TIT without massively overtorquing.

Again, this is shooting from the hip, so I make no claims that I know exactly what's going on. I'm just saying that I wouldn't be suprised one bit if a prop change fixed the problem.

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............good day guys!!!!!!!!.............but!!.........if something increases fuel!!!............you're gonna get an increase of TIT and Torque!!!

" The bleed valves opening up below 94% could also partially explain the high TIT without massively overtorquing."

......yes but!!!......what about the fuel flow increase!!!!

FCU or TD system!!!.................maybe!!!!!!!!!!!!

How's the hardware in the system!!...........For sure............something is increasing fluel flow!...............Well!!! let's keep on thinkin' about it!!

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