I, a newwbee to jet airplanes .. I've flown my P-60 a couple of times today...Noticed that starting the flight I would have an air bubble about the size of a pea in my Header tank / UAT After about 5 mins. of flying I find that bubble has expanded to abou the size smaller than a ping pong ball.... I used Teflon plumbing tape on theads of tank... Looks like good fittings on fuel lines and festo.....Any suggestions ?? I assuming this tank should remain unchanged after a flight

Thanks

BIll