Introduced in 1964, it was Learjet's first model and created a new market for fast and efficient business aircraft. Production ended in 1966 after 101 aircraft had been delivered. Production began on the first Model 23 Lear Jet on February 7, 1962. The first flight took place on 7 October 1963 with test pilots Hank Beaird and Bob Hagen.[2] Although the prototype crashed in June 1964 the Lear Jet 23 was awarded a type certificate by the Federal Aviation Administration on 31 July 1964. On October 13, 1964, the first production aircraft was delivered. Production ended in 1966 after one hundred and one aircraft had been delivered. In 1998, thirty nine Model 23s were estimated to remain in use. Twenty seven are known to have been lost or damaged beyond repair through accidents, the most recent being in 2008. In 2013, the FAA modified the FAR Part 91 rules to prohibit the operation of jets weighing 75,000 pounds or less that are not Stage 3 noise compliant beyond December 31, 2015, with the Lear Jet 23 listed in the Federal Register. This meant that any Lear Jet 23's without modified Stage 3 noise-compliant engines - or an approved hushkit - were no longer permitted to fly in the contiguous 48 states after that date. The ruling noted that appropriate hushkits were not currently available for the Lear Jet 23.
