early on in our deliberations we contacted hawker hunter repair ltd ( hhr ) who sent a couple of their design team hot foot over to assist us , and quickly we all agreed that the basic f6 airframe and the rolls royce avon engine were outstanding , so no major changes there , but the radios , instruments , and various 1950s era electrics were definitely passing their sell by dates , so would inevitably be letting me down on a fairly regular basis .