PV=nRT
It was a hot day in JFK, the plane was delayed several hours on takeoff. The packs (air conditioning system on Boeing Airplanes) are directly below the center wing tank. The area became very hot.
That's why Boeing put an fuel tank inert system in the 787. There have been 4 center tank explosions.
http://en.wikipedia.org/wiki/Inerting_system
“It was a hot day in JFK, the plane was delayed several hours on takeoff. The packs (air conditioning system on Boeing Airplanes) are directly below the center wing tank. The area became very hot. “
I live in AZ. I understand hot.
How many times did this exact plane and/or hundreds like it sit on runways in Saudi/Iraq/Middle East/Las Vegas/Phoenix under almost, if not identical circumstances? Numbers would indicate that in your 4 cases, something else happened.