coded F-15 (Luke Arizona) leaving on 26 September 1995 when the 550th Fighter Squadron inactivated, 21 years after the first TF-15A arrived at Luke. With the transfer of the Eagles, additional F-16 training units were assigned to the 56 OG, all tail-coded "LF" (Luke Falcons): 61st Fighter Squadron, 1 April 1994 (formerly at MacDill AFB) 62d Fighter Squadron, 18 March 1994 (formerly at MacDill AFB) 63d Fighter Squadron, 1 April 1994 (formerly at MacDill AFB) 308th Fighter Squadron, reassigned from 58th OG 309th Fighter Squadron, reassigned from 58th OG 310th Fighter Squadron, reassigned from 58th OG 425th Fighter Squadron, reassigned from 58th OG (joint USAF-RSAF unit) The 21st Fighter Squadron was activated on 8 August 1996 to train Taiwanese Republic of China Air Force F-16A/B crews at Luke AFB. Empty hangars were refurbished and aircrews were pulled in from other units on base. By January 1997 several ROCAF F-16A/B block 20s had been delivered and the first training flights began for their crews. Despite being A/B models, the aircraft were new construction from General Dynamics, with modern avionics and engines, and were considered to be more advanced than the F-16C/Ds being flown from Luke AFB. The aircraft carry USAF markings and serial numbers, and also the "LF" tail code. On 20 September 1999, an F-16D crashed at Luke AFB, marking the 56th Fighter Wing's seventh Class A mishap in FY99. In all cases, the pilots ejected safely. Engine problems caused most of the mishaps. The 56th Fighter Wing commander, Brig. Gen. John Barry, grounded the wing's F-16s after the second mishap. Maintenance personnel discovered that engine augmentor ducts had failed in both cases. They developed a new inspection procedure to identify cracks, which was subsequently used throughout the Air Force. A manufacturing defect in turbine blades was responsible for many of the mishaps, and General Barry grounded the fleet a second time to allow maintainers to upgrade the turbine blades, which improved safety. On 8 March 2000, it was noted that the 50,000th fighter pilot had graduated from Luke AFB, Arizona, since the Army Air Forces started training at this location in July 1941. After the 11 September 2001 terrorist attacks, Luke suspended routine flying training operations, as the Federal Aviation Administration shut down the nation's airways to all but select military flights. Aircraft of the 56th Fighter Wing were deployed to fly combat air patrols over New York City