Jump to content

cold start vs high fuel consumption


herky400M
 Share

Recommended Posts

Hello C-130 world, I need your help:confused:!!(T56-A-15)

I have a task looking into a problem: we are struggeling during a few months with:

1) during the latest times we have a lot of cold starts (more than 50% of the fleet) which are starting lower than 750°C TIT or around it (<780°C in several OAT's and hight Levels), but normal start time(<60'').

2) Equal to another problem high FF consumption @ LSGI, HSGI, FI and MAX REV => if I have to plot this, it's out of the charts or in the upper limit.:rolleyes:(try this, it's FF VS TorqueVS TIT)

So what I'm sure of is that the TD-system functions correcttly, thermocouples=>ok, Thermal block => ok, Y cable=>ok!

Everything pionts out to the Fuel Control!

but what causes this problem and what to prevent. (in long therms we can save a lot of turbines)

my mindmap:

Can there be a correlation between the cold starts and the high FF consumption?

is there a malfunction of the cit and or cip? ( belows rupture)

is there a degradation of the acceleration rack in the FCU?

any sugestions?

We are using the TM 382C-2-3 in case ur looking for the chartes (9-2, 9-3, 9-4 & 9-5)

greetz bob:cool:

Link to comment
Share on other sites

Half of your fleet is experiencing it? All the starts are within time limits?

The fuel control will control your fuel flow in order to achieve the start. I am guessing that the concern is because of the warning given by Allison about downstream burning damaging the turbine. I would seriously doubt that half your fleet is suffering from this malfunction. If you suspect that your engines are suffering from this, have someone watch at an angle up the tailpipe during start and see if the turbine starts glowing. If it is really downstream burning, it will be visible from the rear.

As said already, check to see where your TD valve Null Orifice is set to. Also, you really should do your troubleshooting of start TIT problems with the TD system turned OFF first.

You might have room to adjust the TD valves up to get your starts between 750 to 810. (I know that our books says that 780 to 810 is desired.)

You could very well be putting out a whole lot of effort trying to repair a problem that does not exist.

Link to comment
Share on other sites

If it is an ongoing problem with no solid solution, you might want to look at the type of fuel your aircraft are using. The higher quality fuel, the longer your fuel system components will last, and the fewer problems you will have. Definately though, check your null starts like Dave said. The TD system can be very tricky. We had a couple of planes recently have abnormal start TIT's caused by a faulty AC instrument inverter. Also, as with many engine problems, look at all the problems the engines are having. I get cold starts all the time caused by cold TIT gauges, but they might be fine as soon as I'm ready to go to power. Most of the time though, they are a little slow there too, and you will be able to tell it is bad by either swapping gauges or doing the Brake Lock Check to see if it is low along with every other TD check.

Link to comment
Share on other sites

Hi Bob, long time, no chat. I get a rash of these things from time to time.

First thing to determine, is it the whole schedule that has shifted, or only start?

Are you getting this problem in NULL and AUTO?

What is the RICH/LEAN spread?

Are you making 1077°C take-off in AUTO?

What is NULL take-off, will it make 1007°C (minimum), or does it exceed 1083°C?

Let's see if we can beat this one

Cheers

PJ

Link to comment
Share on other sites

In start limiting the TD is already in null and only energizes only to correct an overtemp condition. I guess if the start pot on the TD amp is screwed up, or maladjusted, it may try to control the temp sooner. Start in null and see if its different than what it is in auto. They should both have the same temp reading, if not then the amp may be the problem.

But if its happening to half your fleet and it suddenly started, I would imagine its someone making adjustments and doesn't know exactly what he's doing - equipment on several different planes don't fail or get out of adjustment by themselves all at once, so I would (in addition to fixing the problem) investigate if its an individual misadjusting the system either through inexperience/faulty procedures or perhaps some more nefarious reasons.

Besides that, something strange is happening if you are experiencing BOTH cold starts AND High fuel flow in all beta range functions, it really looks like multiple things as low TIT and high FF would seem to be opposed to each other.

Hope you guys can figure this one out, I for one am very interested in what you find is the cause.

Dan

Link to comment
Share on other sites

"....it really looks like multiple things as low TIT and high FF would seem to be opposed to each other."

Dan,

Bad thermocouples or torching nozzles can cause the exact symptoms you just described. (And a degraded hot section.) The question is where are tach and torque?

Being a dual element T/C there is possibility he has a bad signal going to the cockpit while the TD is good. EXCEPT for the fact that this is occuring on multiple aircraft.

This had led me to another question. (Maybe I should have posted it else where.)

How often do the old TiT indicators go bad? And are they prone to do so in colder weather?

Anybody who can answer that one let me know. There have been some questions here about the need to test the TiT indicators to 40 below zero during repairs.

Link to comment
Share on other sites

Bad thermocouples or torching nozzles can cause the exact symptoms you just described. (And a degraded hot section.) The question is where are tach and torque?

Being a dual element T/C there is possibility he has a bad signal going to the cockpit while the TD is good. EXCEPT for the fact that this is occuring on multiple aircraft.

True Statements. I've seen that happen. One side of thermocouple(s) bad the other good.

This had led me to another question. (Maybe I should have posted it else where.)

How often do the old TiT indicators go bad? And are they prone to do so in colder weather?

Well, I'm not sure what you're describing as 'old' TIT indicators, but the ones in the Es and Hs I worked for over 10 years didn't seem to be affected by environmental temperature changes. The TIT indicators didn't seem to break as often as other engine indicating systems. A H261 Temp tester can tell you if there's a problem from the T-block up to and including the TIT indicator in short order.

Anybody who can answer that one let me know. There have been some questions here about the need to test the TiT indicators to 40 below zero during repairs.

I'd have to do some digging, but testing a TIT indicator to below zero don't ring any bells and right off hand don't sound very useful, but don't hold me to that just yet.

325X1

Link to comment
Share on other sites

I agree if your talking about a specific engine but what I was thinking was this is on multiple engines on multiple planes.

Dan

I was just replying to jetcal1's comment...not to mention the original post said this: "So what I'm sure of is that the TD-system functions correcttly, thermocouples=>ok, Thermal block => ok, Y cable=>ok!"

That rules out a LOT when it's also happening on the entire fleet, or half the fleet.

I would start thinking like you did, training of one individual or fuel composition, or something not on the airplanes. Hmmm, what fuel is being put in these in Belguim? Jet A-1? That would change the equasion a bit.

325X1

Link to comment
Share on other sites

True Statements. I've seen that happen. One side of thermocouple(s) bad the other good.

Well, I'm not sure what you're describing as 'old' TIT indicators, but the ones in the Es and Hs I worked for over 10 years didn't seem to be affected by environmental temperature changes. The TIT indicators didn't seem to break as often as other engine indicating systems. A H261 Temp tester can tell you if there's a problem from the T-block up to and including the TIT indicator in short order.

I'd have to do some digging, but testing a TIT indicator to below zero don't ring any bells and right off hand don't sound very useful, but don't hold me to that just yet.

325X1

Well, as some of you know, I have no C-130 background, just some Navy T56 minor maintenance accumulated over 20 years.

For full dsclosure I work for the company that builds the H261, H394, and H395 which are all testers used on the C-130. Working with the guys in the field on maintaining the gear and working with the development of the H395 has been the sum total of my exposure to the C-130 world. (BTW, Thanks to everyone here who has given help. Not only have the folks here been happy to help, but the gouge has always been good!)

We have a customer flying the older BH183 series indicators on their P-3's, the Dutch took the old NavAir manual and put in a requirement to freeze the unit to -40. The current customer wants us to repair to that standard. I know that some C-130 operators still have them. (Mostly FMS, and these indicators were built from 1963 to 1979.)

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...