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Morganw487

First NGX failure!

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After many hours flying the NGX, I finally experienced my first failure this morning. Delta Airlines flight 487 non-stop to LAX from DTW (Detroit). I had the APU running, disconnected ground power and air, and began to pushback. After the before start checklist but while we were still rolling back, I turned the engine ignition switch for engine two left one click as I always do. Monitoring the lower EICAS, I noticed nothing was happening, no N2 rotation at all. I thought somehow I had forgotten to turn off the packs or closed the APU isolation valve, but no. Everything was in the proper configuration as it has always been for engine start. I have had this aircraft since release nearly two years ago now; engine start was one of the first things I learned. After another minute of questioning an error on my part, I concluded that the only thing that could be causing the phenomenon was an air leak or loss dealing with the APU. By this point we were fully pushed back from the gate, so I again set the chocks and decided to try out the air start cart. It did enable me to start engine number two. Because I thought I had sufficient air pressure from the engine, I disconnected the cart to start engine one. N2 rotation was very slow and would not reach 25% for starting, so I added power to engine two to generate more air pressure. This worked, and eventually engine one came to life. What got me about the experience was the trouble shooting situation I was forced to go through in the simulator. It got me thinking about aircraft systems and what I could do to complete the task at hand in a non-normal circumstance. On the ground at LAX, I looked at the failures and sure enough, the APU Isolation Valve had failed. I am not sure how or why the device failed unless I am improperly managing the air pressure, but it was really nice to be challenged.

 

All the best,

 

 

Morgan Wiley

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Failure modes certainly sharpen our skills, views and attitudes - and they add to the fun and excitement, as well.

 

I completely agree. The amount of realism goes up 10 fold.

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Looking through the QRH I really can't find anything on how to handle an isolation valve failure. At the time of the flight I didn't have the opportunity to browse the very hefty manuals for help.

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Nice to see someone has had a failure, as I have not yet. But personally I would not have flown with that plane. Mostly because if the isolation valve did fail, there is no telling what else might fail at different periods of flight.

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It gets even more interesting when you encounter a failure that when not dealt with correctly or in a timely manner will result in secondary failures as well, Engine overheat is one example of what i have experienced during cruise. If not dealt with in a timely manner may or may not result in an engine fire, which if not dealt with even quicker may or may not result in loss of hydraulice fluid.

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But personally I would not have flown with that plane. Mostly because if the isolation valve did fail, there is no telling what else might fail at different periods of flight.

 

Excuse me, Joe, but this is grossly non-sense. 

Why do you EVER board a plane with this attitude? 

 

(A long discussion on that you can find here: 

http://forum.avsim.net/topic/402077-loss-of-gen-bus-2-qrh-land-at-nearest-suitable-airport/ )

 

Aircrafts consist of 100s of systems, most of them redundant. Else you could not operate an airline. 

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Nice to see someone has had a failure, as I have not yet. But personally I would not have flown with that plane. Mostly because if the isolation valve did fail, there is no telling what else might fail at different periods of flight.

 

 

Meh, believe it or not, the isolation valve can be added to the MEL (minimum equipment list). Happens quite often. In fact you may be surprised to find out what exactly can and cannot be added to the MEL. As someone pointed out, there are redundancies built into these aircraft.  In real life though, the OP would have to return to the gate briefly for a maintenance check. Just a brief 15 minute inconvenience to his passengers.

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What's funny is that I haven't fixed the isolation valve yet either. Realistically, it would probably take the airlines more than a day to fix something like that, but given its importance for starting the engines it may be higher up on the list of things to fix. I can't get over increasing power to engine two to generate the air pressure to start number one. PMDG has modeled it all, there is no doubt. Currently cruising FL340, again DTW-LAX, isolation valve inoperative.

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Would be interesting to see what would happen in this situation with FS2Crew Failures installed.  Maybe Bryan can advise.

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