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Engine Problem - Aborted TO


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  • Commercial Member
Posted

Hi,Before I start this post, I'd like to stress that I am certain this is not a bug with the PMDG 747.. But it was the weirdest thing I've seen (and kinda fun because I wasn't expecting it)..So.. what happened? Well I was about to start a long haul flight from Heathrow to Singapore.. as QANTAS.. I'd done all my pre-flight prep.. weights etc.. programmed my route, SID.. setup my performance parameters.. did my push and began taxiing to the hold, flipped on autothrottle ready for TO/GA.. 9R in this instance.. Got to the hold, strobes on landing lights on as I lined up... (LNAV, VNAV armed, TO/GA, TO/GA set as current modes.. F/D on etc etc.. flaps down 20 Green) everything was perfect.. as usual.. everything was going fine..So.. time to go.. given clearance.. engines slowly advance to 70% N1.. hold them there... everything stable.. heading just to the left of the centreline.. perfect.. TO/GA switches pressed.. THR REF on PFD.. levers advance to TO Thrust (in this case full thrust, no de-rate as I was very heavy).... 80knots.. and HOLD on the PFD... then I heard an engine spooling down.. looked at my upper EICAS.. and sure enough engine 3 was ramping down to idle.. HOLD still active on the PFD... I wasn't going to get the speed required for T/O now.. and V1 hadn't been called so it was abort time..Pulled off onto the taxi way.. checked everything over.. it looked ok.. nothing unusual... so I made sure I was good to go again.. and taxied back to the holding point for 9R.. As before.. going well.. THR REF.. then HOLD.. 80 knots.. 100knots.. 120knots... engine 3 then began to spool down.. another abort required!.. Rolled off the high speed exit.. and checked it over.. Now I'd got a brake overheat and wasn't going anywhere this time.. so it was a very.. gentle limp back to the nearest ramp..I had no idea what caused it.. some funny glitch in MSFS I was sure.. perhaps a rogue signal here or there.. I've never EVER seen it before it was quite odd... could only conclude MSFS sent a signal to the A/C saying I'd moved my throttles and therefore moved the throttles to idle..I subsequently took off without issue.. I've been flying with these same settings since getting this A/C for FS9 with my throttles for a good few months now.. will keep an eye on it in future..But overall is was quite good fun.. a problem was the last thing I was expecting because I never have failures set ON... Having one during the TO roll was something I was not expecting at all..Just thought I'd share that with you guys.. Like I said.. I'm not asking for "support" on this issue.. I am pretty sure after reflection I can guess what the culprit is (not PMDG).. Just thought you'd like to hear the story..CheersCraig

Craig Read, EGLL

Posted

I guess if it were a Speedbird flight you'd just keep going on three, unless they've re-evaluated their procedures since that KLAX-EGLL flight.I've had a few odd things happen that I could never reproduce or isolate. I've suspected something like the panel state so I never create a new flight from the panel of an other saved flight and the oddities have decreased. If I create a flight I make a new panel state.. even if it is "exactly" just another cold and dark one.

Dan Downs KCRP

  • Commercial Member
Posted

Dan,Must say your post did make me chuckle.. As captain in command I decided flying on 3 wasn't a good idea.. lol... Yeah normally I have no problems, I've not managed to reproduce it since actually.. it's all a bit strange but all good fun.As for my failure settings Tom.. they are set to off.. I think it's got something to do with a funny signal from my throttles.. Although I'm not entirely sure because I didn't move them during the takeoff after the TO/GA switch was pressed..Like I said.. it's not an issue for support to clear up.. It's not an A/C fault.. it's one of those strange things that MSFS does.. or perhaps it's just my PC..CheersCraig

Craig Read, EGLL

Posted

You may have the old 'noisy controller' input problems. If you have 'controls override' checked in the PMDG options, AFDS section, you will get weird behavior with both the A/T and A/P. My 747 was doing PARTIAL, no alarm (silent) disconnects of both the A/P and A/T during the takeoff phases. One of these glitches showed up as an engine going to idle during takeoff. Real exciting to say the least. It occurred with either engine 2 or 3 (or both) mostly in my case.You can either uncheck both of those boxes in the PMDG AFDS menu or set a larger dead zone for your controllers to filter out any input spikes.Kim

  • Commercial Member
Posted

Yeah I think it is the noisy controller issue.. just one of those things.. I have a bit of a sensitive rudder too so I've totally re-calibrated things and everything it a lot smoother..CheersCraig

Craig Read, EGLL

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