March 6, 1999
Following the in-flight airframe failure of a Beech Model 45 (T-34A) in April, the FAA issued Priority Letter Airworthiness Directive 99-12-02, which places a 152-knot speed limit and a flight load limit of 2.5 Gs on the airplanes. Aerobatic maneuvers are also prohibited per the temporary restrictions that will be in place until the FAA and Raytheon agree on a fix.
Two pilots were killed when one of three T-34s owned by Sky Warriors of Atlanta, Georgia, suffered an in-flight failure of the right wing. The airplane entered a rapid spin to the right and crashed. Examination of the accident airplane revealed evidence of fatigue cracking at the location of the fracture on the T-34’s aft wing spar. The airplane, which was originally delivered to the Air Force in 1954 or 1955, reportedly had a total of 8,200 flight hours, 4,000 of which were with Sky Warriors.
Sky Warrior pilots were not supposed to exceed a company-imposed limit of four positive Gs, despite the airplane’s 6-G limitation. In a videotape of the flight, however, the pilot is heard telling the pilot-passenger that they had just performed a 4.5- to 5-G turn. Another of Sky Warriors’ airplanes reportedly exceeded 12 Gs during one mission.
In its recommendation to the FAA prior to the release of the AD, the National Transportation Safety Board (NTSB) said that it “has found no other examples of possible wing structure fatigue cracking in the long history of the T-34.” However, the NTSB believes that air combat flights, with their higher number of wing-loading events per hour, caused the fatigue cracking that led to the wing’s failure. The NTSB recommended grounding all T-34s that had been or currently were in use for air-combat simulation flights. The NTSB also called for recurrent inspections of the wings and other critical structures on the T-34.
Raytheon went one further and recommended, in a May 19 safety communiqué to T-34 owners, that all YT-34, T-34A, and T-34B airplanes be voluntarily grounded until a final determination of the action required is made by the FAA. The Raytheon letter mentioned another T-34 that crashed in Venezuela as a result of an in-flight wing failure during aerobatic maneuvers. AOPA, which had recommended that the FAA place temporary limitations on the airplanes, applauded the FAA’s decision to allow the airplanes to continue flight while the investigation continues.
June 3, 1999
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