APU bleed valve fault

[windshearDK 52]

Yesterday I had a fault in my APU bleed valve fault, which I had to cancel in order to start my engines... Since I didn't activate it myself, what could I have done to my plane that made my APU bleed valve to break?

 

 

[Tony747-400 44]

Have you got Service Based Failures or Random Failures enabled in the PMDG options?

[windshearDK 52]

Yes I do have this feature activated, that's why I am curious if I misused my APU?

 

Usually I keep it on the least possible as per real world ops

[Flamin_Squirrel 71]

Service based failures are generated using mean time to failure information. Other than a few items such as brakes and nose wheel balance, failures won't occur because you abused the plane. At least this is my understanding.

[KriVa 307]

Things break. They do so in real life, and they do so in PMDG's 777.

[scandinavian13 5,192]

 

 

Since I didn't activate it myself, what could I have done to my plane that made my APU bleed valve to break?

 

As the others have mentioned, service based failures will make things break occasionally.  Since this one's a lot more automatic than the NGX, I don't think you would've caused it through something like advancing throttles past idle with DUAL BLEED illuminated (something that could cause damage on the NGX - the indication is not on the 777 obviously).

 

The correct course of action next time - in order to avoid delaying your flight or unrealistically just clearing the failure - is to tell your push crew to stop the push and pull you back in.  From there "call maintenance" and have them "defer" the APU (not something you'd actually do, obviously).  Finally, hook up the air start unit using FS Actions.  Start one engine.  Push back.  Start the second engine using the cross bleed procedure.  How you do that, though, is beyond me (in the 777 anyway).  Have a look at the manuals to see if it's in there.  Heck, it might even be in the ECLs.

[windshearDK 52]

That's very interesting... I wouldn't think there would be a random fault already, I mean I've only flown a couple of hundred hours or so.

 

I quickly looked under APU in the ECL, but I couldn't find it, I thought about the airstart unit, but I decided to just reset the fault.

[mazelda 124]

On the real thing no matter what make, faults can occur at any time, doesn't matter how old the aircraft is I've seen brand new aircraft with add's  only a day or so after delivery

I might be wrong on this but I think one of BA's 787 was delivered a day late because of a faulty component.

As for your fault being an apu bleed valve, that's quite common in real life

rgds

[scandinavian13 5,192]

 

 

I quickly looked under APU in the ECL

 

Crossbleed would be more of an engine thing - not APU.  While the APU being INOP would force you to use the procedure, it's not an APU thing.

[Flamin_Squirrel 71]

Start the second engine using the cross bleed procedure.  How you do that, though, is beyond me (in the 777 anyway).  Have a look at the manuals to see if it's in there.  Heck, it might even be in the ECLs.

 

It's in the FCOM under suplimentary procedures.

 

Engine start requires at least 25psi at sea level (subtract 1 psi for every 1,000ft decrease in pressure altitude), so advance the thrust lever on the operating engine to achieve this then start the other engine as normal. IIRC anyways!

[777simmer 117]

That's very interesting... I wouldn't think there would be a random fault already, I mean I've only flown a couple of hundred hours or so.

 

I quickly looked under APU in the ECL, but I couldn't find it, I thought about the airstart unit, but I decided to just reset the fault.

Like Flamin-Squrirel said.

 

FCOM_v1 Supplimentary Srocedures page S.P.7.2 (about 1/3 down the PDF)

[windshearDK 52]

Thanks next time I will try my best to do that! 

Any ideas on why it failed? Would an APU restart help?

[mazelda 124]

In the real world you might try it a couple of times depending on the conditions and if the valve has been cold soaked, as they do occasionally stick but in this I'm guessing it would be a failed part

On ETOPS aircraft it may need repaired immediately but short haul depending on the operator it can go for 10 days, much to the dismay of the crews as they can't get their tea and coffee until the engines are running  (brings a tear to the eye lol)

rgds

[777simmer 117]

Thanks next time I will try my best to do that! 

 

Any ideas on why it failed? Would an APU restart help?

As said before, things fail. It is then the pilots job to press the "Checklist" button. You should have had an EICAS message so the corresponding ECL will open when you press that button. In there it will tell you exactly what to do.

 

There is no such thing as having a failure and just trying again or not checking the ECL!

[Flamin_Squirrel 71]

Thanks next time I will try my best to do that!

Any ideas on why it failed? Would an APU restart help?

It's under pneumatics iirc.

 

APU restart won't help. As I said earlier, failures are not condition based and won't occur more often if you abuse the plane.