ESS AC BUS CB\'s

[Sideshow]

Hello all, I couldn\'t work out why my last topic for discussion was getting no responses. I now know why! New webpage.

Anyway, has anyone ever experienced an engine rollback from a partial or full loss of the ESS AC BUS \'a\' phase circuit breakers (qty - one, two or three) on the 245 bulkhead.

There is a note in our flight manual that talks about if a full or partial loss of the ESS AC BUS circuit breakers will or could cause a four engine rollback in torque by 2000 inlbs through a low voltage to the synchrophaser resulting in the speed bias motor reducing speeder spring tension and decreasing blade angle. It also talks about a low voltage to the TD amp resulting in:huh: the valve to take fuel causing a rollback in LSGI and above crossover.

And if anyone is using the solid state amplifiers for their TD system, could you make comment if any issues have been encountered. Much appreciated.

Cheers,

Sideshow.

[Lkuest]

All I know about this subject is what I read in the BAR report on the King 56 mishap, which crashed into the water due to all four engines flaming out. There were tests done on both the synchrophaser and TD Amp. The tests included many things, and one of the tests was to see how the synchrophaser and TD amp reacts to an interrupted power supply, both DC and AC voltage. What they found was surprising. After power being interrupted to the sync, it pretty much did nothing, or went dead. The TD Amp on the other hand did indeed start to take a lot of fuel, so it is technically possible for a TD Amp to cause a rollback, although I have never seen any issues with this.

The sync is another matter though. If it just goes limp with an AC power interruption, you\'re more likely to get a rollback with the sync fully powered than you are with an interrupted AC power supply. Even if it does rollback on torque, it\'s only going to do so with a maximum of 4% RPM. There are physical stops in the valvehousing that prevent the sync from going any higher than 104% or lower than 94%, so I wouldn\'t worry about losing all four engines to a synchrophaser.

Edit- I had a brain fart. The sync can\'t go above 106% or below 96%, depending on what the valvehousing is set at, so there is a +6%, -4% rpm mechanical stops for the sync input in the valvehousing.

[SEFEGeorge]

I read the King 56 report. I know that they looked at the sync and TD amp issues. But wasn\'t the final opinion the engines failed due to fuel starvation brought on by improper fuel management by the FE? - i.e., all 4 engine pumps off and feeding the engines from the fuselage tank using cabin pressure so when the tank was empty the cabin pressure feed overrode the tank to engine gravity feed.

[herkhealer]

Yes, I have heard of it on one of our EC\'s. The guys were doing transition and while theyw were with tower they expierenced a Ess AC bus off light with loss of power (approx 2000 in lbs) and an inability to obtain max TIT. If I remember correctly they were only able to get about 900 or so. I can ask the FE that was on it when we get back to work. Happy Holidays all...

[cfisher]

Was the atm gen. involved in this problem. I do know if all four engine gen. are on and the atm gen is on and you turn off the atm sw. with out turning off the atm gem.you will loose the essential ac buss for two are three seconds.When the atm gen voltage drops low enought it drop off line and the aircraft gen. will pick it up. That was in the 1960 &70 on the c130e That was a long time ago things may have changeg.

[herkhealer]

No, this was inflight with the ATM off. Good input though, could see how that would be a problem.

[Dan Wilson]

Yep, when you bolox up your checklist like that first indication you will get is you can hear the ATM winding down in your headset. Uh so I have been told - as I have never screwed up any checklist:side:

Dan

[herkhealer]

Yeah, I have never run an after takeoff checklist and realize my ATM and Generator are still on...

[cfisher]

It seems that some of the C130 family on this site are PRIMA DONNAS. They seem to enjoy making fun of other peoples posting\'s. They make nasty insulting remarks indicating we are as dumb as a rock and show how much smarter they are than the rest of us.

I have never bolox up a check list and never screwed up a check list on the electrical panel. Your statements seem to indicate that I have...words like bolox up, screwed up, and UH sounds like you are insulting me.

The remark I made about the atm gen. was just a statement I thought might be of some use. When I gave a check ride I would ask if there is a sw. you can flip and loose the essential ac buss. The question was just a gee wiz question and didn\'t matter if he knew the answer. It was just a way to start asking questions about the electrical system.

I don\'t claim to be the smartest FE, I am far from that. However, I do have some knowledge and experience on the C130. Like most FE from the 1960\'s, I flew three years in Vietnam. I was a IFE in the school sq at Sewart and Little Rock. I taught class room to pilots and FE for a month or two, then taught simulator for two weeks, then flew for two weeks, then started the whole process all over again.

I was in the 17th TAS in Alaska for three years. The sq OPS officer had me teach pilots and FE systems on some of the days they were not flying. I was also chosen to teach class room and simulator to my wing commander when we changed from A models to E models. I have started engines with a piece of safety wire in remote places of Alaska when the speed sw failed, and yes I pulled the wire out when the engine came on speed. I have been a IFE and stand EVAL FE for years. I have flown the A, B, D, and E models. I have dropped the big bomb in Vietnam and made a jato takeoff on the Greenland ice cap.

I know the things and the experiences that I have is nothing great, because many before me has done the same thing. I am not bragging. I just wanted you to know I have been there and done that. I don\'t post messages trying to belittle anyone. Some of your comments I take as a personal insult. I thought us C130 people were a band of brothers and would not run one another down. Let us be courteous with all are C130 family. I posted this message because I don\'t know if you know how you come across to people, or you just don\'t give a darn.

[DC10FE]

Mr. cfisher,

I think you need to thicken up your skin a little if you want to survive on this board. As I read Dan Wilson\'s & herkhealer\'s posts, I got the distinct impression that they seemed to be poking fun at themselves & not you & your checklist expertise. I\'ve never met Dan Wilson in person, but from reading his posts -- a PRIMA DONNA he ain\'t!!

I\'m impressed with your credentials, but, even after my 24,000+ hours, I still embarrassed myself at times. Usually, when you do something that embarrasses you, you do it only once (or maybe a second time). I\'m living proof of that!!!

Don Rogers

[Dan Wilson]

cfisher wrote:

It seems that some of the C130 family on this site are PRIMA DONNAS. They seem to enjoy making fun of other peoples posting\'s. They make nasty insulting remarks indicating we are as dumb as a rock and show how much smarter they are than the rest of us.

I have never bolox up a check list and never screwed up a check list on the electrical panel. Your statements seem to indicate that I have...words like bolox up, screwed up, and UH sounds like you are insulting me.

Wow, all I can say is I have a long resume too but I don\'t feel the need to post it to show how important I WAS

Now listen to this YOU ASS, I was referring to myself OKAY, I have embarassed myself MANY times over twenty some odd years (and I can admit it too). I think you have a inflated sense of importance to make a reply like that. You are not flying these anymore so your importance is the same as mine as an EX FE!

God I cant believe I am even replying to this.

Now if you not the \"Prima Donna\" that you post makes me think you are then I am sorry but show me the FE that has NEVER screwed up a checklist and I will show you someone that is pathetically self deluded.

Dan

[SEFEGeorge]

Amen Dan......

[cfisher]

Mr. Wilson. I guess we are not helping the man out with the ess ac buss problem. Like Don Rogers said i need to have thicker skin. I took your comments wrong i thought you were making a personal attack on me.I was wrong and i hope you will except my apology. I have PTSD and when i get angry it gets worse and i say things i should not say so please forgive me. Charles Fisher

[Dan Wilson]

has anyone ever experienced an engine rollback from a partial or full loss of the ESS AC BUS \'a\' phase circuit breakers (qty - one, two or three) on the 245 bulkhead.

YES

…will or could cause a four engine rollback in torque by 2000 inlbs

Rollback can be by more than 2000 per engine (regardless what “avoid litigation Lockheed†says, mine was probably more like 4k per engine (it’s been awhile) but first indication was very large swings of torque on all four engines stabilizing (sorta) very low.

It also talks about a low voltage to the TD amp resulting in the valve to take fuel causing a rollback in LSGI and above crossover.

Personally I never had any serious problems with the solid state amp; hell only had minimal problems with the old analog amps, usually nothing more than potentiometer adjustment problems.

And if anyone is using the solid state amplifiers for their TD system, could you make comment if any issues have been encountered.

Well your asking several questions here but that’s okay, regardless whether your more interested in Partial Loss of Ess AC Bus or 4 engine rollback they all pretty much tie into each other and its really hard to talk about one without involving the other.

A little background on 4 eng rollback, they don’t know what or how it’s caused, they didn’t know what or how it was caused when I started flying in 85 and they still didn’t know what or how it was caused when I retired in 04. Over the years Partial loss went from like 10 or 12 steps, down to 4 or 5 and it’s probably back up to 10 or 12 steps again. This just shows they don’t know what is causing the problem, over the years they thought they eliminated this or that so dropped it from the procedure just to have to add it back on after later on. Especially after that IDIOTIC B.A.R .after the HC crash!

But I do know Sync problems and TD problems tie together with a loss of ESS AC bus failure and four engine rollback. Personally there really is no problem is you have a TOTAL loss of the bus, the problem happens when you have low voltage on a phase of the buss with or without loss of the other phases of the buss, from that point, to this day,

Following the HC crash into the Pacific, Lockheed came right out and said there was no such thing as a four engine rollback (lets do the litigation avoidance dickdance) then after everybody shows Lockheed the pubs that Lockheed has talked about this issue for the last god knows how many decades they finally admitted to it. BUT Lockheed also said that the change from tube type to solid state syncrophasers did decrease the amount of rollbacks BUT that when they did occur they were more severe!!

The TD system will fall into the equation when you get low voltage across one or more of the phases for the amp, I would tend to think that solid state will act worse with low voltage than any analog circuit will, computerized systems do all sorts of stupid things when you don’t feed them right. But as to how much more a solid state will contribute to the rollback problem vs. an old analog amp. I don’t really think they attribute a much larger problem with the solid state TD amp than with the old amp during a rollback or any other TD system problem.

We would always know if we had a solid state or analog syncrophasers, they each had separate procedures but with the TD amp the change is transparent and you would have to open the cowling to tell which one you have, emergency procedures were exactly the same as well and I don’t even think the flight manual split out the difference between the two in systems description. I don’t think this really answers your questions completely but for an operator, chances are slim if you ever know which TD amp you had after you’ve had a problem.

Mr. Fisher, sorry if I was a little sharp as well. That’s been specialty of mine for decades – overreaction!! Sorry, and yes your right my comment did nothing to answering the mans question, guess I am getting lazy(er) lately.

Dan

[pjvr99]

Dan Wilson wrote:

.....

The TD system will fall into the equation when you get low voltage across one or more of the phases for the amp, I would tend to think that solid state will act worse with low voltage than any analog circuit will, computerized systems do all sorts of stupid things when you don’t feed them right. But as to how much more a solid state will contribute to the rollback problem vs. an old analog amp. I don’t really think they attribute a much larger problem with the solid state TD amp than with the old amp during a rollback or any other TD system problem .....

Dan

Dan, you\'ve said something here that is much closer to the truth than you think. I worked for an electronics company in the R&D lab. We had a number of problems with our devices initially, due to bad/low power supplies. Some of the devices were fitted to cars and trucks and were extremely unstable until we redesigned the power circuits for ESD problems, and more importantly brown-out.

Brown-out is a low voltage condition where a circuit is still active but the voltage is too low for a clear signal/data to be transmitted and interpretted. Then, as you say, it does all sorts of stupid things. When I get back to work I will try to locate schematics for the TD amps and see if there is a brown-out reset function installed.

It would appear from what you say, that in a low voltage condition the amp thinks there is too much fuel going in and therefore, starts cutting back. The problem may be that the comparators in the amplifier are incorrectly referenced .....

..... this may become an interresting project

[herkhealer]

Sorry all,

I wasn\'t poking fun at anybody. I felt the ATM input was a very valid point and stated so. I was merely making fun of myself and my inability to complete a checklist. I assure all I am far beyond poking fun at someone\'s post here but merely trying to add valid input.

Brandon

[Dan Wilson]

herkhealer wrote:

Sorry all,

I wasn\'t poking fun at anybody. I felt the ATM input was a very valid point and stated so. I was merely making fun of myself and my inability to complete a checklist. I assure all I am far beyond poking fun at someone\'s post here but merely trying to add valid input.

Brandon

I don\'t think I could point to a single flight in twenty some odd years that there was a flight that I didn\'t forget or miss something!

Only forgot the Nose gear pin once though:blush:

Dan

[Hunter]

You bet that would happen. The ATM has a time delay relay that will allow the ATM to stay on line even if the the Freq is below 365 CPS if the motor is shut off prior to turning the ATM gen off first.The Ess Ac Bus for a few seconds falls off line until it is regained by a operating Generator.

[L382fe]

Hunter wrote:

You bet that would happen. The ATM has a time delay relay that will allow the ATM to stay on line even if the the Freq is below 365 CPS if the motor is shut off prior to turning the ATM gen off first.The Ess Ac Bus for a few seconds falls off line until it is regained by a operating Generator.

It\'s been a while, but I thought the underfreq holding relay was wired through the starter buttons. This allowed the ATM to stay online in an underfreq condition during self contained starts and timed out 4-5 seconds after the starter button was released when the ATM was able to get back on speed. The underfreq time delay should not be a factor if the ATM was turned off with the Gen still on. Haven\'t worked on ATM birds in a while so feel free to tell me if I am full of it.

Mike

[Dan Wilson]

Yep, pretty sure you need a start button in to complete the circuit to the thermal relay on the under freq relay.

Otherwise the ATM will drop off just like any other generator, once it drops below 368cps.

Dan

[KC130FE]

SEFEGeorge wrote:

I read the King 56 report. I know that they looked at the sync and TD amp issues. But wasn\'t the final opinion the engines failed due to fuel starvation brought on by improper fuel management by the FE? - i.e., all 4 engine pumps off and feeding the engines from the fuselage tank using cabin pressure so when the tank was empty the cabin pressure feed overrode the tank to engine gravity feed.

Yes.

[NATOPS1]

Ok let’s try this...solid state components require a specific voltage range to operate correctly. This range would be quite narrow compared to the \"older\" non solid state system components (not just talking sync and TD but all of the newer systems we are installing (more and more digital crap every day!!!)

New components have a smaller tolerance for \"bad\" power and thus we have installed system to prevent \"bad\" power from being supplied...IE power monitor 5 volt range for acceptable power and better yet BSU\'s which select the \"best\" power available, not to mention the AC Bus out light illumination at a higher voltage 96 vice 90... All these are trying to protect our systems from \"bad\" power!

Stick with me and see if this has any merit...

The TD compares the actual TIT(thermocouple{voltage}) to a desired TIT( resistive value) the TD Amp interprets the resistive value and assigns it a reference voltage...then compares the two, develops an error voltage and positions the TD valve to achieve the correct TIT... Therefore any reduction in the operating voltage supplied to the TD amp would be mirrored in the operational outputs from the TD amp....the seemingly higher actual TIT voltage compared to the compromised reference voltage(due to lower input voltage) would resemble a higher than desired TIT and thus require a reduction in fuel to achieve the correct desired TIT (as far as rollback caused by the TD alone is far reaching due to the fact the Prop controls RPM through blade angle so any reduction in fuel should only cause a reduction in blade angle to maintain RPM....

As for the sycnrophaser that is a different story and if the operational voltage were to drop the ability for the sync to maintain the phase relationship and speed would be highly compromised... once the prop is no longer controlling its own RPM any reduction in fuel will cause a further degradation in RPM thus a \"Rollback\" condition...

[pjvr99]

NATOPS, your reasoning is good, but flawed for a simple reason - the opamp comparators in the TD amp generate the reference signal based on the input voltages. So it doesn\'t really matter how the input voltage flux, the reference is always constant. The only thing that can really throw things out of kilter would be digital systems going into a brown-out state by getting too low voltage.

Having said that, most digital systems have brown-out protection, whereby the system is shut off before opamps, etc, start giving out bad data. If the TD system actually got to a point where the was really bad power, it would fail-safe to NULL.

I have been messing around with some engines on the cell, but could never replicate a roll-back.

[NATOPS1]

I think we are talking about brown out due to the fact the Crew had an ESS AC bus off light prior to the event....without the Gen out light being illuminated this points to an older AC.

If it were a newer AC the Bus Off light trips @ 96 and the Gen Out trips @ 95 ... a very small range.

On an older AC the voltage would be as low as 90 volts for the Bus off light and 70 volts for the Gen Out light which would subject the TD Amp to low voltages for an extended period of time without tripping the GCP to remove the Gen from the distrabution system.

As for the ATM the delay is a two part deal one during the start cycle (starter button engaged)and one without... so low bleedair \"not starting\" would cause the ATM to hold until the freqs dropped off plus five seconds via the time delay relay, while during the start the lockout relay will allow the ATM to hold regardless of the freqs,

once the starter button is released the aprox 5 second delay will start.... if freqs recover no issue.