Mr Spaceman
Topic Author
Posts: 2723
Joined: Thu Mar 15, 2001 5:09 am

A 747's Instrument Panel Question?

Thu Jul 25, 2002 2:25 am

Hi guys.

I have a great poster at home of the cockpit of KLM's 747 named "Wilbur Wright" (PH-BUI).

I was looking at it today, and started wondering about the gauge in the middle of the panel that's titled "FF". What does it stand for? My amateur educated guess tells me it means Fuel Flow, but I would like to know for sure.

Here's some photos...the first one is very interesting because of the #4 engine failure.


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Click here for bigger photo!

Photo © Mulder



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Photo © Patrick Lutz


Chris  Smile
"Just a minute while I re-invent myself"
 
FDXmech
Posts: 3219
Joined: Sun Mar 19, 2000 9:48 pm

RE: A 747's Instrument Panel Question?

Thu Jul 25, 2002 2:44 am

Correct!
FF stands for Fuel Flow in Pounds Per Hour (PPH)X 1,000. In other words the 1 = 1,000 pounds per hour or 12 = 12,000 PPH. 1 gallon of jet A weighs approx 6.7 lbs. I've seen this vary from 6.7 - 6.8 lbs per gallon.

FF can also be measured in Kgs.
You're only as good as your last departure.
 
Guest

RE: A 747's Instrument Panel Question?

Thu Jul 25, 2002 2:47 am

Dear Spaceman -
FF means fuel flow, calibrated in lbs/hour or kg/hour (airline option)...
KLM uses kg for weight and fuel units...
The picture shows the "tape gages option" as well as was found in airplanes of the KSS group (KLM, SAS and Swissair) which agreed on common equipment and configurations for their aircraft. The "standard configuration" of the 747 is quite different (i.e. "round gages")...
(s) Skipper
 
Mr Spaceman
Topic Author
Posts: 2723
Joined: Thu Mar 15, 2001 5:09 am

RE: A 747's Instrument Panel Question?

Thu Jul 25, 2002 2:59 am

Thank You Gentlemen.

I've had this poster of PH-BUI's cockpit since I was 14 and now I'm almost 36. I figured it was about time I asked what those letters "FF" stood for.

Thanks Again.

PS, How's the weather in your part of the world? Here in Toronto it's +25 C, with a nice sunny sky dotted with broken heap clouds. It's a beautiful day today.

Chris  Smile
"Just a minute while I re-invent myself"
 
Guest

RE: A 747's Instrument Panel Question?

Thu Jul 25, 2002 4:08 pm

Hi Spaceman -
Weather here Argentina is winter, drizzle and wind, near freezing at night... but we revenge ourselves from DEC through MAR, we have barbecues at the beaches for Xmas...
Since you are a metric guy obviously, the weight of a liter of jet fuel is 815 grams at the temperature of 15C. We never think about fuel in terms of gallons or liters, except when I sign the fuel bill from the supplier, we think about it as weight (kilos outside USA)...
(s) Skipper
 
wardialer
Posts: 1141
Joined: Fri Sep 14, 2001 1:08 pm

RE: A 747's Instrument Panel Question?

Wed Jul 31, 2002 1:09 pm

Let's say I filled my car to 10.5 Gal. of gasoline, how many pounds would that be? But I think gasoline differs in weight compared to jet fuel though. But I just want to be sure.
 
Guest

RE: A 747's Instrument Panel Question?

Wed Jul 31, 2002 3:07 pm

Dear Wardialer -
Each liquid or solid (or gas) has a specific gravity...
Water is 1... some liquids are heavier, some are lighter than water...
Jet fuel (Jet A, Jet A-1) has specific gravity of .813... meaning that the weight of jet fuel is lighter than water... .813 % of the weight of water...
Gasoline, aviation or car gasoline has specific gravity of .69... so, it is lighter than water, and jet fuel...
Since you ask me for lbs and gallons (the above is easier with metric units), a gallon of gasoline is 6 lbs, and a gallon of jet fuel is 6.75 lbs... So if you put 10.5 gallons of gasoline in a car or airplane, it weighs about 63 lbs...
xxx
The cooler the gasoline (or jet fuel gets) the heavier it becomes for that gallon of volume... and the warmer it gets, the lighter it gets as well... As an example, jet fuel weighs only some 6.68 or 6.7 lbs per gallon when hot on a summer day...
xxx
An advise to you and all those who read this... you buy gas by volume (litre or gallons) but your engine only knows its weight... so buy fuel when it is cold such as early in the morning... you will save, a little, if you do so...
xxx
A 747 may need a lot of fuel (we think by weight, we burn it by weight) yet, we pay the bill by volume, can make a difference when we get the fuel...
All the best...
(s) Skipper
 
PW4084
Posts: 287
Joined: Tue Mar 06, 2001 7:31 pm

RE: A 747's Instrument Panel Question?

Wed Jul 31, 2002 3:15 pm

Gasoline is lighter than kerosene (Jet Fuel)...
the general relationship is 6 LB/Gallon.

So I'd say you have 63 Lb of Gasoline


PW4084

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