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A320 APU Fire Test with APU already running
Hi all
Is there anything somewhere in the books that specifically prohibits this during Cockpit Preparation? The APU fire test does not shut down the APU on ground and as far as I am able to interpret the procedures, crew has to perform the APU fire test even if it is left running by previous crew/maintenance. What's your take on this? Regards What's y |
We do it every day. I don’t believe their is any prohibition as it’s necessary to follow the Preliminary cockpit preparation in most cases. |
My company check pilot asked why I did the APU FIRE TEST as the APU is already running. I looked it up on the A320 FCOM there is not restriction saying that we shouldn't do it. Any take on this?
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test the APU, no mention if it is running or not, so just test the APU
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I had the test once aborting an APU start cycle, but that might have been a fluke or coincidence, apart from that, no problem whatsoever with testing it while the APU is running.
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The APU AUTO EXTG test button on the overhead maintenance panel will cut off the APU if running. The regular fire test has no effect at all, and should be done even if it is already running! |
Asked several times over the years, and all the answers are already provided above. Once a a line engineer told me the only issue is with a in-depth MX / warning system troubleshooting procedure , when a C/B gets pulled.. The system logic would err on the conservative side and fire the squib. :\ Just a story. |
Maybe I'm missing something but I don't understand why you need to perform the APU fire test. If you arrive at the aircraft and APU is already running, it means the maintenance has turned it on and has done the APU fire test already.
In the company I work for, we only do that test if the cockpit crew arrives at the aircraft and APU is not running. |
Originally Posted by pineteam
(Post 10361234)
Maybe I'm missing something but I don't understand why you need to perform the APU fire test. If you arrive at the aircraft and APU is already running, it means the maintenance has turned it on and has done the APU fire test already.
In the company I work for, we only do that test if the cockpit crew arrives at the aircraft and APU is not running. Our SOP is that when you pick up an aircraft, you test the APU fire detection, running or not. It has to be tested every day and maybe it was left running from the previous evening and the test is required again (we operate 24/7). |
Doing less is inherently safer, in this respect reduced amount (of unnecessary) decision making is better.
If the FCOM suggestions work unaltered, it is easier just to follow them - same as Hans'. For us new crew = new start, irrespective of what has been left running. pinteam: it is my personal belief the reason for the BAT check split between PM and PF during the cockpit prep is to cover for one of the guys actually not doing the job at all. On what is a survival-critical system in case of a larger failure inside the electrics. Good SOP would have such "recovery" features embedded. That's where your company's way - whilst perfectly reasonable under the assumed state of things - falls short of the (slightly ignorant) FCOM regime, me thinks. |
Ok, I get your points. Thank you guys. |
Thanks guys. Interesting feedback.
Regardless of individual company SOPs, it is clear now that there is nothing in the Airbus procedures prohibiting it. @pineteam It often happens that an aircraft arrives within a few minutes of the next departure; in such cases, the previous crew leaves the APU running to save APU start cycles. Therefore, we cannot assume whether they left it ON or the engineering switched it ON. Even if its engineering that did it, it's still a part of FCOM procedure and a change of crew definitely necessitates a fire test. The point of asking this question was due to the fact that I was recently confronted by a Captain who asked me to prove where its written. I pointed out there's nothing prohibiting it, and with back to back flights with crew change, sometimes the APU remains ON continuously. Apparently some people have their own interpretations of the FCOM. Not everything is mentioned nor can be mentioned explicitly for every situation. Thats how it works. |
do you fly the entire 320 family of aircraft? if so you might want to research what happens if you perform the APU fire test in other models, and see if performing the test while the APU is running has a negative effect on those models...one possible reason for you company' SOP......in any event, the SOP should be sufficient reason for you to not perform the test....no?
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Originally Posted by ironbutt57
(Post 10362706)
do you fly the entire 320 family of aircraft? if so you might want to research what happens if you perform the APU fire test in other models, and see if performing the test while the APU is running has a negative effect on those models...one possible reason for you company' SOP......in any event, the SOP should be sufficient reason for you to not perform the test....no?
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Is there anything that forbids APU test when it's running? The answer is NO. Rather if you are not sure if the test was done you should do it.
Below from FCOM PRO NORM SOP FIRE APU FIRE pb-sw.......................................................... .........................................IN and GUARDED AGENT lights ............................................................ ............................................................ ..... OUT If the APU is already running, ensure that the following check has already been completed. If not, perform it. APU FIRE TEST pb.......................................................... ......................................................PRESS Check : ‐ APU FIRE warning on ECAM + CRC + MASTER WARN light (if AC Power available). ‐ APU FIRE pb-sw lighted red. ‐ SQUIB light and DISCH light on |
If you arrive at the aircraft and APU is already running, it means the maintenance has turned it on and has done the APU fire test already |
Originally Posted by Check Airman
(Post 10362739)
I've flown the 319, 320 and 321 for 2 different airlines. Neither has specified APU on or off for the test.
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Originally Posted by Black Pudding
(Post 10362823)
Not necessarily so. That’s like requiring you to do and APU fire test as you taxi in before you switch it on before engine shut down. You wouldn’t. Why would you presume engineers will always do a test. Your preliminary cockpit procedure requires you to do it on YOUR first flight of the day. |
The FCOM Regarding the cockpit preparation assumes the APU was not running. It’s not very clear IMHO that we are supposed to test the APU if already running. pineteam, it is very clear. I have produced airbus FCOM SOP. It just checks the circuitary. There's no problem what so ever. |
I think Airbus are very clear. First two lines under the title GENERAL - PRELIMINARY COCKPIT PREPARATION. Items marked with an asterisk are completed for a transit stop with no crew change. Otherwise complete all items. |
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