Hi,

 

I'm using the 777 since the begining and I flying the real aircraft as well.

 

This aircraft is simply stunning ! I Itried some engine failure during the take-off. Great ideas to have the option to simulate an engine falure at V1, Vr and V2. The aircraft and the systems are reacting like in reality.

 

Now, could you considers those problems :

 

1. When a severe damage is simulated, the TAC should disconnect. The FCOM 9.20.15 said that the TAC automatically disengages if  engine thrust data is lost. I doesn't happen in the sim, the TAC remains engaged.

 

2. I started a topic few weeks ago concerning a "sound problem" with altitude calls : http://forum.avsim.net/topic/419653-loss-of-altitude-alert-during-approach/page-2

 

Thanks to considers those "problems" for the improvements of this fantastic aircraft (the real one and the so well simulated),

 

Regards,

Vincent

 

 

 

1. When a severe damage is simulated, the TAC should disconnect. The FCOM (Page 9.20.15) said that the TAC automatically disengages if  engine thrust data is lost. I doesn't happen in the sim, the TAC remains engaged.

 

Page 9.20.16, for those who wish to evaluate themselves.

 

I think you need to re-read the section.  The whole point of TAC is to adjust for differences in thrust between the two engines.  This is most helpful when an engine fails, so you would want it to stay on with an engine failure.  So, your assertion is incorrect.  TAC should take over and ensure the thrust difference between the two engines is taken care of by the automation.

 

You're getting confused by the sentence you quoted, which states:

TAC is available except when automatically disengaged due to a system malfunction or loss of engine thrust data.

 

Don't miss that very last word.

...or loss of engine thrust data.

 

That would be a failure of the sensor, or a failure of the system to receive data from it.  In your case, it is receiving data: no thrust.

 

No thrust does not equal no data.

 

 

 

2. I started a topic few weeks ago concerning a "sound problem" with altitude calls : http://forum.avsim.n...approach/page-2

 

Seems like that's more a problem with your system or your system config.  If they're working and then they stop, it's gotta be something on your end stopping them from working.

 

So, just like above: not a bug.

 

I'd try making sure your virus scanner doesn't actively scan those folders.

Ensure your sound drivers are up to date, and so on...

Hi,

 

When you said engine thrust data, try this failure and look at the secondary engine page : thrust data is lost. So the TAC is lost. We have this failure each time we go to the real sim, and each time, the TAC disconnect with a severe engine damage situation.

 

Concerning the lost of altitude calls, read correctly the full thread. Some peoples help me to solve the problem, and I even re-install three time the 777.

 

Once again, I should have this problem with other aircrafts, other simulation or other game. This is not the case.

 

More, this is a new computer for 8 months.

 

I have had lot of discussions with people and also beta-tester, and we didn't find any solutions. And I am not alone having this problem.

 

So, I just wait from the PMDG to consider and investigate. Those "could be" bugs;

 

Cheers,

Vincent

 

 

So, I just wait from the PMDG to consider and investigate. Those "could be" bugs;

 

If you really think they're bugs, the proper avenue to have them evaluated is support.precisionmanuals.com

Hey Kyle,

 

He is correct on this, maybe not a bug exactly but something PMDG seems to have left out. They should at least have an option to simulate an engine failure that kicks out TAC, although with that in mind it is pretty pointless in FSX with its poor asymmetric modelling.

 

Just some background on this, I can't speak for every 777 operator but for a while the sim sessions with a few of the big operators did not include failures with a loss of TAC, a big fuss was made about it and it's now included. Funny thing is the first 777 to have an engine failure whilst in passenger service lost thrust data and TAC.

 

 

He is correct on this, maybe not a bug exactly but something PMDG seems to have left out. They should at least have an option to simulate an engine failure that kicks out TAC, although with that in mind it is pretty pointless in FSX with its poor asymmetric modelling.

 

Thanks Rob.  I actually just read the next sentence in the FCOM, which notes that "damage" can result in no/unreliable data, which would then kick it off.  Damage seems to be a pretty broad term, but that's only because I'm probably over analyzing it.  Since the failure is called "SEVERE DAMAGE," I'd say it should simulate the same loss of TAC as mentioned in the FCOM.  Severe damage would be enough damage to cause the system to kick TAC off in my mind.

 

Thanks for the extra info.

Hi,

 

Some more informations.

 

From the maintenance manual AMM 27-11-00 :

 

The TAC function receives thrust data for the two engines from the engine data interface units (EDIU). The EDIUs use N1 rotational speed signals from the EECs to calculate the thrust values. The EECs also send other engine data to the EDIUs to make sure the N1 signal is accurate.

 

The TAC function is active when it is armed and the thrust difference between the two engines is more than 6,000 lbs', about 10% of the maximum rated thrust.

 

Enjoy,

Vincent

And here are some ways it can be disabled.

 

Rudder Trim Failure

Loss of thrust data from 2 of 3 channels of the EDIU

Loss of Left AND Right Engine running data

R/L1/V ACE’s failed/direct mode or the PFC not in Normal mode

TAC Switch OFF or Failed

Hi,

 

This is the answer by the PMDG team :

 

Vincent,

This was discussed in the BETA and based on the input from our Flight Crew Tech team,  we opted not to model the TAC fail on Severe damage as our Severe damage model does not cause loss of the EEC which is what triggers that failure as you discussed.  EEC's are extremely difficult to model in FSX due to the lack of an actual turbine model so a lot of it has to be built from the ground up and has a lot of limitations.   Thanks for the input however.

 

Thank you for this answer.