Indian security establishment has gone in a tizzy with the discovery of a defused grenade inside an Air India aircraft kept standby in Delhi for Prime Minister Narendra Modi's recent trip to the US.The Boeing-747 was kept on standby at IGI Airport, which means it was fully ready to fly out for the PM in case the Jumbo Jet being used by him developed a snag. According to sources, the aircraft was released for commercial operation when Modi landed here on Thursday night.