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ETOPS, Still Air And The APU?  
User currently offlinesmartt1982 From United Kingdom, joined Nov 2007, 225 posts, RR: 0
Posted (1 year 2 months 1 week 6 days 21 hours ago) and read 4034 times:

With regards to ETOPS, what I’ve read talks about still air conditions.

Would I be right in thinking that this time can go up or down depending on what headwind/tailwind conditions you have on the day?

Is it ever a requirement to have the APU running for the entire ETOPS segment at all?

11 replies: All unread, jump to last
 
User currently offlineMender From United Kingdom, joined Feb 2004, 237 posts, RR: 0
Reply 1, posted (1 year 2 months 1 week 6 days 21 hours ago) and read 4024 times:

You can't really make a clear and simple rule is you allow for variables such as wind speed and direction therefore the clearest and simplest definition is to define the time limit for flying in still air conditions.

You can usually depart with an electrical generator U/S if you have the APU running throughout the flight.


User currently offlineTristarsteve From Sweden, joined Nov 2005, 3934 posts, RR: 34
Reply 2, posted (1 year 2 months 1 week 6 days 20 hours ago) and read 3987 times:

Quoting smartt1982 (Thread starter):
Is it ever a requirement to have the APU running for the entire ETOPS segment at all?

The answer is that it depends on the aircraft.
Some aircraft like B777 have enough generators, and a RAT, and can be dispatched with the APU inop.
Some aircraft like B737 have only 2 generators and no RAT and APU must be running.
Some aircraft like A320 have 2 generators and a RAT and the APU must be serviceable but not running.
And these requirements can change for 120mins and 180mins ETOPS.


User currently offlineyeelep From United States of America, joined Apr 2011, 633 posts, RR: 0
Reply 3, posted (1 year 2 months 1 week 6 days 19 hours ago) and read 3949 times:

Quoting Tristarsteve (Reply 2):
Some aircraft like B737 have only 2 generators and no RAT and APU must be running.

As with almost everything, there are exceptions. On the 737NG, on a per airline basis, the FAA allows for the APU to not be running during ETOPS if certain maintenance, operational and reliability criteria are met.


User currently offlineHAWK21M From India, joined Jan 2001, 31580 posts, RR: 57
Reply 4, posted (1 year 2 months 1 week 6 days 17 hours ago) and read 3896 times:

Quoting yeelep (Reply 3):
On the 737NG, on a per airline basis, the FAA allows for the APU to not be running during ETOPS if certain maintenance, operational and reliability criteria are met.

Pls elaborate......Im sure you meant serviceable but not operational APU at that moment.



Think of the brighter side!
User currently offlineyeelep From United States of America, joined Apr 2011, 633 posts, RR: 0
Reply 5, posted (1 year 2 months 1 week 6 days 9 hours ago) and read 3760 times:

There is an operational requirement to cold soak start the APU at cruise altitude. It has to be performed each 30 to 90 days to maintain the APU on Demand status of the plane.

User currently offlineHAWK21M From India, joined Jan 2001, 31580 posts, RR: 57
Reply 6, posted (1 year 2 months 1 week 2 hours ago) and read 3279 times:

Quoting yeelep (Reply 5):
There is an operational requirement to cold soak start the APU at cruise altitude. It has to be performed each 30 to 90 days to maintain the APU on Demand status of the plane.

Isn't the duration of test a bit too long.....was Wondering.



Think of the brighter side!
User currently offlineFabo From Slovakia, joined Aug 2005, 1211 posts, RR: 1
Reply 7, posted (1 year 2 months 4 days 22 hours ago) and read 3051 times:

Since it is not a safety critical thing (no APU before entering ETOPS airspace? Turn around to first alternate, less than 60min away), I guess it is acceptable. I would probably like to test it a bit more often though.


The light at the end of tunnel turn out to be a lighted sing saying NO EXIT
User currently offlineyeelep From United States of America, joined Apr 2011, 633 posts, RR: 0
Reply 8, posted (1 year 2 months 4 days 15 hours ago) and read 3000 times:

Quoting HAWK21M (Reply 6):
Isn't the duration of test a bit too long.....was Wondering.

Its a limit set by the FAA, you would have to ask them. However, I had poorly written the requirement. The check has to be performed within 30 days from the previous check. This can be extended to 60 days or 90 days based on the airlines historical data of these checks and with FAA approval. I don't know what the criteria is to allow the extension.

There are other things that also have to be done to allow APU on Demand, such as a EGT monitoring program/limits, component requirements and a modified maintenance program.

Quoting Fabo (Reply 7):
(no APU before entering ETOPS airspace? Turn around to first alternate, less than 60min away)

With APU on Demand, at no time during the flight including the ETOPS portion, does the APU need to be running.

[Edited 2013-02-18 13:21:02]

User currently offlineFabo From Slovakia, joined Aug 2005, 1211 posts, RR: 1
Reply 9, posted (1 year 2 months 4 days 1 hour ago) and read 2899 times:

Quoting yeelep (Reply 8):
With APU on Demand, at no time during the flight including the ETOPS portion, does the APU need to be running.

Ah, yes. Used to the procedure I had on the NG, APU needed to run in ETOPS airspace.



The light at the end of tunnel turn out to be a lighted sing saying NO EXIT
User currently offlineyeelep From United States of America, joined Apr 2011, 633 posts, RR: 0
Reply 10, posted (1 year 2 months 3 days 19 hours ago) and read 2857 times:

As its a FAA approved program, only US based Airlines that fly 737NG's to Hawaii can benefit.

User currently offlineflybaurlax From United States of America, joined Oct 2008, 637 posts, RR: 0
Reply 11, posted (1 year 2 months 2 days 18 hours ago) and read 2745 times:

Quoting yeelep (Reply 8):
Its a limit set by the FAA, you would have to ask them. However, I had poorly written the requirement. The check has to be performed within 30 days from the previous check. This can be extended to 60 days or 90 days based on the airlines historical data of these checks and with FAA approval. I don't know what the criteria is to allow the extension.

There are other things that also have to be done to allow APU on Demand, such as a EGT monitoring program/limits, component requirements and a modified maintenance program.

The CMP requires 30 days, but can be extended to 120 days. The criteria required to allow the extension is proven reliability of the program, including the 95% start success rate.

Quoting yeelep (Reply 10):
As its a FAA approved program, only US based Airlines that fly 737NG's to Hawaii can benefit.

Other governing agencies follow the FAA requirements, so non US carriers would also benefit. There are currently 2 US operators using APUOD, and another operator across the pond is seeking the program.



Boilerup! Go Purdue!
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