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Rzouga

throttles misallignment bellow crossover

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hello HERKY people,

we have torque, fuel flow and TIT high bellow crossover which make throttle misalligned bellow crossover.

i read some conversations about this issue that are concerned about null start vallue and rich\lean check.

null start was not verified but rich\lean check shows 975 deg in null then correct back to 890 deg in auto( -7B engine).

my question is this fuel control was shifted rich? if so, correction will be made from temperature compensating bellows at fuel control(CIT)?

 

 

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i know that but it is not comfortable as i see it all over the flight.

for information fuel control was changed but the problem is the same.

any idea what should i do?

 

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Posted (edited)

what is NULL start TIT? what is TIT before correction light out? what

is rich/lean? where is NULL orifice set?

 

I need exact numbers .....

Edited by pjvr99

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 Hello again,

NULL start TIT is 800 deg same as in AUTO

LSGI TIT is 665 deg and NGI TIT is 610 deg

TIT before correction light out is 865 deg then correct back to 780 deg

null orifice is set at two graduation below zero mark

rich\lean check values are 975 deg with TD NULL then correct back to 890 deg when placing TD to AUTO.

 

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Cool. Ok start is perfect. LSGI looks like like a low time, very strong engine, but

thats where things get hazy. NGI should be 580 to 600.

 

After lights out TIT should be 740 to 780. It does look look like the FCU may have

shifted rich, but you may also have a TD system cutting back too much fuel. Before

messing with FCU, remove and inspect all thermocouples - replace as required. Make

sure engine rigging is spot-on. Carry out  yellow box check.

 

CIT bellows can be adjusted on flight line (if lead seal is still present on FCU) - 1 flat

decrease (clockwise) is +- 25°C. This will affect the fuel flow across the entire

schedule, so it may be necessary to reset NULL orifice.

 

 

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I will try to do that next time, but what is the yellow box check, do you mean TD test set??

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1 hour ago, Rzouga said:

I will try to do that next time, but what is the yellow box check, do you mean TD test set??

yes

 

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