AVSIG: JetA freeze concern? wwswsigarch.jpg (7236 bytes)

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AVSIG Discussion Sections >> Training & Proficiency

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Dave Siciliano (ADS)
Top Gun


Reged: 05/17/04
Posts: 8469
Loc: ADS (Dallas, TX)
Re: JetA freeze concern? [Re: Mase Taylor]
      #389278 - 04/10/14 10:33 AM

Of course, Prist doesn't affect the freeze temp of Jet A. It would inhibit any water in the tanks (bladders) from freezing.
Jet A1 freezes at -47 and is used by some airlines when flight through colder air is planned.

Best,

Dave


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Dave Siciliano (ADS)
Top Gun


Reged: 05/17/04
Posts: 8469
Loc: ADS (Dallas, TX)
Re: JetA freeze concern? [Re: Mac Tichenor (DAL)]
      #389279 - 04/10/14 10:39 AM

Thanks Mac! I didn't think about the heated fuel being recirculated and and that didn't come up in systems discussions. Our fuel is heated at the fuel filter going into the FCU. Makes sense that unused fuel is recirculated, but I think that would go into the center tank or nacelle on my plane, not the bladders in the wings. Anyway, I'll look into that. Kinna wondering why we don't have fuel temp gauges. I normally fly low flight levels, so, not as much of a concern, but I could see leaving up north with cold soaked fuel on a -20C day and it being colder higher up.

Best,

Dave


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Dave Siciliano (ADS)
Top Gun


Reged: 05/17/04
Posts: 8469
Loc: ADS (Dallas, TX)
Re: JetA freeze concern? [Re: Dave Siciliano (ADS)]
      #389280 - 04/10/14 11:09 AM

Well, I called my shop and their thoughts are fuel isn't recirculated after being heated. It comes into the fuel/oil heater, goes into the transducer which is your fuel flow meter and then into the Fuel Control Unit. If it was recirculated, the transducer wouldn't be an accurate indication of fuel flow. Scratching my head.

Best,

Dave


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Richard Duxbury (Dux)
Top Gun


Reged: 05/15/04
Posts: 5468
Loc: Minneapolis/Tucson
Re: JetA freeze concern? [Re: Dave Siciliano (ADS)]
      #389282 - 04/10/14 11:25 AM

It's been a long time -but like Randy noted, I think fuel cell temps were sometimes a concern on the long winter flights to Narita.

I also seem to remember from my military flying, that JP-4/5/6 had some different freeze points as well as some other stuff?

All the Boeing birds had various forms of fuel heaters as I remember (not fuel cell heaters).

Regards,

Dux, no frozen fuel in Tucson today at 95 degrees again.


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Geoff Sjostrom - Chicago
Top Gun


Reged: 04/29/04
Posts: 4312
JetA freeze concern? [Re: Dave Siciliano (ADS)]
      #389283 - 04/10/14 11:32 AM

I'd sure like to see Paul Millner get into this thread. I'll bet the fuel
producers are on top of the issue, or at least would have some good,
practical advice for pilots.

Geoff


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Bill Bridges - 9S1
Top Gun


Reged: 05/17/04
Posts: 6008
Loc: 9S1
Re: JetA freeze concern? [Re: Mac Tichenor (DAL)]
      #389291 - 04/10/14 01:54 PM

Quote:

the unused heated fuel is rerouted from the FCU back to the tanks




Mac,

I have a coffee drinking buddy that flies the BD-700 (?) who said that it recirculates the fuel similar to what you are describing (my understanding, anyway) once the temp gets below -25C. He indicated he had seen -70C with out any problems.

the other bill


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Randy Sohn
Gradn Exlated Ordre of teh Fyling Fingres


Reged: 08/31/01
Posts: 23187
Loc: Savage, MN - U.S.A.
Re: JetA freeze concern? [Re: Richard Duxbury (Dux)]
      #389295 - 04/10/14 04:04 PM

Quote:

It's been a long time -but like Randy noted, I think fuel cell temps were sometimes a concern on the long winter flights to Narita




Yup, been a l-o-n-g time ago but I seem to recall casting a nervous eye at the FE's/SO's (whatever you want to call him) panel and worrying about the fuel's "jelling point". And, on-loading around 400,000# of fuel for departure didn't include any Prist, although I think I do recall helping Clay do some of it on his Learjet at HRL once. Only had to divert to a more southerly Pacific track once for it IIRC but also once had to do some fast monkey-motion thinking stuff when one of my outboard tank valves acted up and needed to be thinking about our zero fuel weight and the structural considerations. Guess some think it's all "fun and games" for 12-15 hours and drinking coffee (which, thank God it usually is). At any rate, "it's good to be retired".

(Which reminds me, it's time now to go down to Caribou for afternoon coffee.)

best, randy


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Mac Tichenor (DAL)
Top Gun


Reged: 06/04/04
Posts: 1857
Re: JetA freeze concern? [Re: Dave Siciliano (ADS)]
      #389310 - 04/10/14 09:49 PM Attachment (102 downloads)

Dave -

>>It comes into the fuel/oil heater, goes into the transducer which is your fuel flow meter and then into the Fuel Control Unit.<<

It's in a different order on the TBM...



This is reminding me that I'm due for recurrent soon, too. Normally that's the only time I dig this stuff out.

Mac

Edited by Mac Tichenor (DAL) (04/10/14 09:50 PM)


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Jeff Hartmann CIC
Top Gun


Reged: 05/18/04
Posts: 7323
Loc: Chico,CA
Re: JetA freeze concern? [Re: Mac Tichenor (DAL)]
      #389316 - 04/11/14 07:19 AM

And that is how it is on later King Airs.

--------------------
Jeff

nothing clever to say right now...


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Dave Siciliano (ADS)
Top Gun


Reged: 05/17/04
Posts: 8469
Loc: ADS (Dallas, TX)
Re: JetA freeze concern? [Re: Jeff Hartmann CIC]
      #389328 - 04/11/14 10:59 AM

Thanks. I'll look again this weekend.

Dave


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