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HELP WITH A TOLD QUESTION


VIPER1616
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I AM A LT COL IN THE COLOMBIAN AIR FORCE. I JUST FINISHED MY INITIAL COPILOT TRAINING IN THE C130. I HAVE A QUESTION THA NOBODY HAS BEEN ABLE TO ANSWER: WHAT DOES AN 100, 98 OR 95 % ENGINE MEAN???? HOW DO I KNOW IF MY ENGINE IS IN THE 100. 98 OR 95%????

THANKS IN ADVANCE

LT COL CARLOS LANDINEZ

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100% best performance (for TOLD calculations)

98% not as good, a reduction in engine performance equals a reduction in overall aircraft performance.

95% Minimum allowed

Check with your maintenance department. They should have the performance number for each engine in the logbooks. Then you can use the lowest of the engines to calculate you’re TOLD. Your (actual) aircraft performance will be better so you have a "margin of safety" if you calculate that way.

You can check the performance of the engines when you set takeoff power. (calculate torque for the TIT you will use for takeoff power setting) not a true performance "number" but a valid check of the actual engine performance under your current conditions.

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What you are asking for can be obtained by performing "Engine Performance Check-Percent Efficiency". This precise power run-up normally carried out by maintenance whenever the engine instruments appear to be indicating abnormal values while performing the Takeoff Power Check, or whenever there is reason to suspect the engine will not produce takeoff power.

The procedures to perform this check in our technical manuals is located in TM 382C-2-3 section 9 (Engine Operational Checkout Procedures).

And as "NATOPS1" state the minimum excepted is 95%.

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WHAT DOES AN 100, 98 OR 95 % ENGINE MEAN????

-associated number is the efficiency of the engine. Compressor and turbine degrade over time cause a drop in efficiency, normal mechanical wear. More abrupt loss of efficiency may be associated with FOD, loss of air somewhere in the engine, and a burned up turbine. Flip that coin, and an engine with a new compressor and turbine may be 105% efficient.

HOW DO I KNOW IF MY ENGINE IS IN THE 100. 98 OR 95%????

- there is a lot to this.....and it's generally left to the maintainers. First thing first is the torque calibration...the gauge is adjustable. Maintainers use a calculator, input LSGI RPM, field elevation (PA) and OAT...calc spits out a number.....I've always got between 700-750, but have not done it in extreme PA or OAT. One adjuted, they can run up the engine to power, record Torque, TIT, FF. Using a programmed calculator, and after inputting the varialbes...it'll spit out a number thus determining efficiency. Not something aircrew does everyday...in that fashion anyway.

-from the CP seat, it would be wise to know what the min efficiency required for your Air Force is....assuming 95%. Your Flight Engineer will use the number to determine performance. So, if the FE posts 17500/1077 and you're only getting 16000...you may have a problem with an engine (lower than 95% efficient) Anything above and you're OK. However the performance book does have a chart to determine where TIT should be if you max out the torque before TIT (ie cold weather). This is good to know and often overlooked, but it taps into the realm of bad thermocouples...a whole other story. I've found that, from my charts..., there is about a 800 in/lb difference between 100 and 95 % efficiency

there is a bit to it and I may have gone to far...but I like this stuff...engine mechanic for 10 yrs turned FE last 5....and like previously mentioned, ask the maintainers, probably the eaiest way!

Stay safe flying and enjoy!

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