Forum: F-16 Procedures

I have a question for the zipper suits out there. Tell me the significance of the FTIT as it pertains to you. Is it something that you rely on, or is it something you have been taught is to rely on?

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or is it something you have been taught is to rely on

What do you mean IDCrewDawq? That we shouldn't rely on it? I'm not following...
There are some max readings on the FTIT (on the ground 965°, transient 1000°,...) When you go above these values something is wrong (engine light will come on when exceeding the 1000° etc). But I suppose you know this.

For the rest It is a gauge you x-check when you're suspecting engine problems, the reading should basically be 'logic'. When doing an airstart you check that it is below 700°, during ground start it shouldn't exceed 680° these kind of things.

See ya

Well from what I understand about GE and PW, and bix can correct me if I am wrong I am sure. The PW uses this to schedule fuel and air, for engine performance, along with a thousand other parameters. What I was wondering is how much do you depend on it during flight.

The engine is a complicated thing and there are only four instruments telling you something about it...I guess the engineers had to make a choice about what is for the pilot the most relevant indicator of engine temperature. (The previous aircraft I flew on used EGT (exhaust Gas Temp) as an indicator)It is needed to have at least one engine temperature indicator to asses engine problems.

See ya

Frodo wrote:

The engine is a complicated thing and there are only four instruments telling you something about it...I guess the engineers had to make a choice about what is for the pilot the most relevant indicator of engine temperature. (The previous aircraft I flew on used EGT (exhaust Gas Temp) as an indicator)It is needed to have at least one engine temperature indicator to asses engine problems.

See ya

Ok, this is where I was headed. The GE engine uses a little tiny probe to gather FTIT. This probe is actually aft of the turbine prior to the afterburner section. So does this meet the term FTIT (fan turbine INLET temprature)? If bix or someone else could help me understand how the GE interperts this indication for engine performance I would appreciate it. I am looking as to the need of the indicator vs a desire for it.

thanks

Bix

Thanks for the explanation of the PW FTIT probes, and I knew they were prior to the turbines (just not sure where exactly is all) I knew that the engine relied on them for engine performance. What I was wondering is if the GE depends on it's sigular probe for some similar performance issues. I am aware that the pilots need an indication of engine performance, and if it is over heating. What I want to know is it needed for proper performance, or if it is there only to give the pilots engine temprature. I know that on the GE 110 it was mostly just for cockpit indication, but I am not sure if it was solely for that.

I knew where you question was headed when you asked so I didn't bite at first. No, it's not really FTIT, but that's what the gauge is still called. In short, I don't care what the temperature is but I do care what it is doing. I monitor FTIT on start to watch for a hot start or perhaps a hung start. It's also useful as a sign of engine light-off, especially during airstarts. It's movement can also indicate stalls or stagnations. It can also help troubleshoot other problems; if it moves with the throttle with the RPM at zero, it can mean alternator failure.

Joined: Feb 01, 2007 - 02:38 AM Posts: 0 Status: Offline

I think the FTIT indicator is only there to give the drivers a warm-fuzzy feeling....... They like know what's going on with the engine even if they can't do much more than move the throttle to change it.......

As for performance, FTIT is used for fuel schedule, stall detection, startup, die-out, etc. Due to the technical details (Security) I can't really go into the PFM concerning how the FTIT reading is used in these calculations, but it is very important to the F100s ability to operate at safe/maximum performance.

The reason for 7 probes is redundancy. We are allowed to operate engines with a specific number of bad probes prior to fixing them, but at every shop visit or phase the syetem is fully checked and repaired. This allows the aircraft to fly on the average of the remaining "good" probes longer than if only 1 or 2 were used.

There is nothing "warm and fuzzy about FTIT, whether it be actual EGT or FTIT. The point is, as pilots we know there is a minimum / maximum and optimal FTIT... During different situations, FTIT can be good or bad. YOU NEED TO KNOW WHAT THEY ARE, WHEN THEY ARE and, what you will do when they are wrong. I don't like the idea of "a guage that means nothing.." If that were true, we'd (pilots) would have it removed. Don't waste my time with guages that mean nothing.

Hell, if you know what you are doing, you can even fly a really good ILS based on FTIT vs RPM (FTIT stabilizes faster than RPM).

Cylon
(a purist of "Set it and Forget it" at heart)

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you can even fly a really good ILS based on FTIT vs RPM (FTIT stabilizes faster than RPM).

Just a small add on question: what do you guys use as a parameter for your initial power setting? I always use the fuel flow because I find it the most stable one...just curious

see you

Frodo wrote:

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you can even fly a really good ILS based on FTIT vs RPM (FTIT stabilizes faster than RPM).

Just a small add on question: what do you guys use as a parameter for your initial power setting? I always use the fuel flow because I find it the most stable one...just curious

see you

During operational check of the engine, I check RPM first, while watching response to throttle movement, with a cordinating FTIT indication. No the FTIT is not a "warm fuzzy" for me, it is just how I apply my knowledge of the system. Since above idle the fuel flow rates differ and above mil there is no set expected reading. I stick to FTIT and RPM along with oil pressure. With these three readings I can anticipate an engine malfuntion before the aircraft anounces it to me via PFL or MFL.

What I mean is on regular base, just normal flying. You know the control and performance concept of the AFMAN, power setting is a control instrument, which one do you use to set a climb, descent...I'm just curious because the RPM and FTIT are to my opinion not that stable to use as a power setting...

FTIT is basically telling you the "health" of the engine. Each engine will perform differently at various FTIT readings... A pacer engine would generally run a lower FTIT than a -200 but be producing more thrust..so as an actual guage of power produced it means nothing.
As far as FF (fuel flow), each engine will be a bit different on FF at any given throttle setting, the only "set in stone" numbers were idle 800-1200 PPH and 5th stage augmentor 54,000 pph minimum.
As a former jet mech on block 25's with many hours logged in the hush house I know these numbers to be correct.

There is really no single engine instrument to go by. There were only RPM (N2), FTIT, FF & nozzle position, all of these used together were needeed to judge your power output (and engine health) without the trim box being hooked up.

Ok, let me explain my question again.
You're sitting in your aircraft, you level off after a descent at 1000ft ground. You want to fly 250kts, the power needs to come in, how much will you initially set, and based on what instrument. In my opinion the fuel flow gives my the most reliable info, I'll just put 2500 PPH. Off course this won't be correct and I'll have to cross-check and make an adjustment to keep the speed as I want it. There are pilots that set an RPM value, some even put a certain FTIT. My question was: what do you guys use and why? Don't come and explain you're using them all four at the same time...

I would gather to venture that indicated airspeed in the HUD would be the best source of info not to mention mechanical feel (position) of the throttle. Instruments are secondary in nature and used primarily (in my opinion) during engine starts by maintenance and pilots, and by pilots prior to takeoff. The idiot lights (eye brow), master caution, and B#@ching Betty will or should alert pilots during flight (however not in all cases). Additionally, dependent on engine trend data, data downloads may indicate potential engine problems identifying a fault. I know I didn't answer your question directly but again I will assume HUD info and mechanical feel of the throttle are probably the main methods used for various modes of flight.

And naturally, if an anomoly is experienced in flight, then the appropriate instruments canned be checked along with performing a pilot data save.

Chickenlegs

Forum: F-16 Procedures

FTIT (Fan Turbine Inlet Temperature)