Runway From United States of America, joined Jun 2005, 0 posts, RR: 0
Reply 5, posted (14 years 1 month 3 weeks 5 days 9 hours ago) and read 1188 times:
The weight for a given volume of Jet A changes with temperature. At 15.6C Jet A-1 is 1.78lbs/l, however if the temperature were to rise above this the fuel would expand. In this case 1/l of fuel is going to weigh less than 1.78lbs/l.
This is called the specific gravity of the fuel. It is a measurement taken whenever needed to let the flight crew know how much their fuel weighs. If for example an aircraft took on 40,000L of fuel at 1.6390lbs/l the total weight of fuel is 65,560lbs. If the SG for the fuel was 1.8040lbs/l the total fuel weight would be 72,160lbs. That's a difference of 6600lbs.
This is important for crews when calculating balance fields, or V speeds etc. Hope this answers your question.
FDXmech From United States of America, joined Mar 2000, 3251 posts, RR: 34
Reply 6, posted (14 years 1 month 3 weeks 5 days 9 hours ago) and read 1187 times:
Just as NKP S2 wrote. The nominal weight of Jet A is 6.7 lbs per gallon. This is the average weight when calculating gallons pumped versus pounds indicated or performing a known quantity on a fuel tank with an inop fuel quantity system. Normally at the beginning of the work shift we'll call the fuel tank farm to get the most accurate specific gravity. It varies usually 6.7 - 6.8 lbs per gallon. But as previously said, 6.7 is nominal.
Buff From Australia, joined Mar 2007, 0 posts, RR: 1
Reply 8, posted (14 years 1 month 3 weeks 3 days 13 hours ago) and read 1150 times:
When discussing "gallons", it is important to discriminate between US Gallons and Imperial. In Europe and of course the UK, a gallon is 160 ounces and known as an Imperial Gallon. Because of this potential for confusion, the whole world delivers fuel in Litres, unless of course it is the USA or a protectorate!! Roughly, there are 3.785 litres in a US Gallon at standard temperatures (15 C/59F).
Our company uses metric measure for fuel calculations. It is so much easier!