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Another boring P7 question!!

Posted: Thu Aug 20, 2015 9:07 pm
by vololiberista
What is/was the P7 reading for an engine at idle at SL on an ISA day? Was it just a little more than ambient pressure or a lot more? I know the max was just under 74

Re: Another boring P7 question!!

Posted: Fri Sep 04, 2015 11:24 pm
by 1103
Next time we run 150 I'll try to remember to make a note

Re: Another boring P7 question!!

Posted: Sat Sep 05, 2015 8:47 am
by vololiberista
1103 wrote:Next time we run 150 I'll try to remember to make a note
That's very kind of you. If you could also remember to record the QNH and ambient temperature at the same time. I hope I'm not asking too much.

The reason for this query has arisen from the Minimum acceptable P7 graph which only goes up to 8,500ft asl. When one tries calculations for a hot and high airport such as El Alto SLLP the numbers don't appear to work very well. So your input would give a genuine base line which for the moment I'm only guessing at!

Re: Another boring P7 question!!

Posted: Sat Sep 05, 2015 9:15 am
by bobisqueen
On a standard ISA day the P7 gauge would be reading approx 29 In/Hg. After engine start, when conducting your post run checks, you would be looking to see an increase of about 1 In/Hg on the gauges at idle.

Hope that helps.

Re: Another boring P7 question!!

Posted: Wed Nov 25, 2015 6:21 pm
by 1103
I finally remembered to take note when we ran ZA150 today- all 4 engines were showing 32 In/Hg

Paul

Re: Another boring P7 question!!

Posted: Thu Nov 26, 2015 2:42 pm
by Jelle Hieminga
If you want the ambient conditions, have a look at this site: http://www.ogimet.com/display_metars2.p ... &send=send
I've used Farnborough here as a relatively close position, temperatures and pressures wouldn't have been all that different.

Re: Another boring P7 question!!

Posted: Mon Dec 21, 2015 7:38 pm
by vololiberista
Sorry for the late reply. I'm busy on a special project .Thanks to all. The info was very useful.