Answer: Jet fuel is refined kerosene. Airliners use "Jet A" kerosene and the military uses "JP 4" kerosene. Regardless, neither grade burns hot, or it would melt the inside of a jet engine.

Jet A is the same stuff burned in conventional steel wall heaters. In an open-air office fire such as that at WTC (called a "dirty burn") kerosene or any hydrocarbon will burn at around 500-700degrees Fahrenheit. The FEMA report on 911 said that the jet fuel burned off after a few minutes and the fires from the office furniture and carpets were about 560 degrees. The special structural steel of the WTC has over 98% of its strength at those temperatures, and the WTC was built to hold 5 times its load.

In a "controlled burn" (where oxygen and fuel are regulated in an optimal mix), jet fuel will reach a maximum temperature of 1800 degrees Fahrenheit, which is still not anywhere near the temperature required to weaken the steel girders of a building to the point that the entire building plummeted to the ground.  Yet molten steel was reported below the towers, suggesting that a very powerful "fuel" was used, set to burn or explode BELOW the building, not at its top. Thermite, an HTA (high-temperature accelerant) typically used in military operations, would have been able to liquefy the steel.  Thermite can reach a temperature of 4500 dF in 2 seconds, and steel begins to melt at 2750 dF.

Professor Steven Jones (Google him), a physicist at Brigham Young University, came forward in November 2004 with a published paper on the possibility of thermite having been used at the WTC on 9/11.  His research continues, and he has now found not only solidified drops of molten metal in a dust sample from the WTC, but evidence of sulfuric granulation (a "eutectic reaction") on the structural steel, which suggests that thermate, an enhanced form of thermite, was involved in the destruction of the towers.