Jump to content
Aero Precision provides OEM part support for military aircraft operators across more than 20 aircraft

take off tit


rsd653
 Share

Recommended Posts

Take off tit low of T56-A-7B Eng.in nul tit ok. We already change TD AMPS.clalibared with td tester.rpm,torque ok.throttle moment ok ,cordinator new.fuel flow is high 100pph than other eng,where tit should more than other eng, BUT tit still low.can anybody help me pl.

Link to comment
Share on other sites

From your short description, I'd say that you have yellow boxed the new amp, have checked out the response of your TD valve, and still have a problem. Did you use your yellow box to check to see if the TIT indicator in the flight deck is accurate? It could be that, in null, you are running higher than you think but it only appears to be good. You may actually be running at the correct TIT, but your indicator makes it only seem to be running too cold.

If your indicator is good, I would next use an ohmmeter and check the potentiometer inside the coordinator to make sure it is still good. If it is not good, many other problems would appear to rise up and you'll spend a lot of time chasing things that aren't there.

If you still have the problem, look for a reason for the amplifier thinking your TIT is one thing while the indicator thinks it is another. Now you are getting into the area of faulty thermocouples, t-blocks, wiring, and harnesses.

Link to comment
Share on other sites

Take off tit low of T56-A-7B Eng.in nul tit ok. We already change TD AMPS.BUT tit still low.can anybody help me pl.

There isn't much information here that we can use as many things can cause this problem.

The temperature indication system is not very reliable. Is Fuel Flow and Torque the same as the others at the lower TIT, or is Fuel Flow and Torque higher than the other three at the same TIT? After you let the aircraft set for 12 hours or more, does your bad engine TIT indicator read lower than the other three engines? Is the crossover TIT low? Do you get a cold start in Auto only? All of these things can point to a bad Temp Indicator. Swap indicator with another that you know is good to verify.

When you installed a new TD Amp, did you use a TD Amp Test Set to check calibration? If not, you may have a bad co-ordinator causing the TD amp to read a low "desired" TIT. There is a way to check the co-ordinator with a multimeter.

What TIT does your TD Valve break lock check break? If it breaks at the lower TIT, your indicator and TD Amp are not reading the same thing, and your problem is in the indication system somewhere, such as thermocouples, thermocouple harnesses, T-block, Y-lead, or most likely the Temperature Indicator.

Does your temp controlling check function properly? If not, you could have a stuck TD Valve or a bad J3 lead (going from the amp to the valve).

The TD Amp test set can also be connected to the firewall thermocouple c/p with an adapter cable to test all the wing wiring and indicator. You just dial in a temperature, say 971, and the indicator has to read within 6 degrees of that temperature.

If your maximum TIT is about 830 to 850, you could have a bad 94% switch in the Speed Sensitive Control.

Some things that can aid us in helping you further troubleshoot this problem:

Did you swap with a known good indicator?

Did you perform a TD Amp Test Set?

How low is the TIT at the wall?

How is your rich/lean check?

Cold start in auto only?

What are the other three engine Torques and Fuel Flows at Takeoff?

Link to comment
Share on other sites

first!....coffee!!........then we do a ground run. We take readings .....after that, we can begin to think about it. The guy in charge has got to stay cool or else, he's gonna start running around like crazy!!.........................John

"It is a "Take" or "put" proposition!!........LOL!!!

Link to comment
Share on other sites

65% and 66% switches in the coordinator....

Check your Bias and Slope settings as they control temperature between 66 and 90 degrees of throttle travel (at coordinator)...

You may have a bad TD test set...

Also as stated use an Ohmmeter to check the resistance values your coordinator is supplying your TD amp (desired TIT).

Acceptable Ohm (range) readings are listed in your engine manual.

What is the "correction" at crossover? From what TIT to what TIT? Does your TIT go up or down?

Link to comment
Share on other sites

Kind of a loaded question... If all is working correctly yes....

High actual TIT (more than 4.5 degrees F) from the thermocouples as compared to the "desired" TIT of 820 +/-20 will cause a decreases fuel flow signal to equalize the two temperature signals. (gives you desired TIT... Throttle setting)

Yes, the switch can cause some issues. (The switch is set at 66 +/- 2, as per our books....)

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...