PPRuNe Forums - View Single Post - What is the reason for turning off fuel pumps after shutdown.(a320)
Old 9th Jun 2020, 21:42
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jettison valve
 
Join Date: Sep 2002
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Dear tdracer,
As was pointed out already, on A330/A340s (I think A380 is the same) the ENG master switch closes also the LP valve on the front spar. Unless... itīs assembled wrongly, as a hidden failure.
This lesson was learned when during a maintenance activity (for whatever reason!) an engine was to be shut down using just the ENG Fire P/B (which interestingly only moves the LP valve, but does not trigger the HMU or anything else in ATA 73). The engine kept on running for many minutes, when the engineers finally killed the engine with the ENG master switch.
Side facts: The incident took place on an A340 whose "operator" at that time was, well, a big aircraft manufacturer in Seattle. Secondly, we replicated the same scenario (eng shutdown via fire P/B) on a different airplane, and it took more than 60sec before the EGT started decreasing after P/B activation; I still wonder why it takes so long...
(Official documentation: https://ad.easa.europa.eu/ad/F-2003-360R1 - On reading the AD more than 15 years later, I am still amazed about the long compliance times set by the DGAC - for such a simple task, 12.000FH / 39 months (we pushed this through much quicker)).

Now, and the real reason to start typing: A big thank you for all your comments and insights! I really appreciate your contributions. No political nonsense or guesses, but always solid technical statements, presented understandibly, even for a maintenance person.

Thank you very much!
J. V.


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