THE US FEDERAL Aviation Administration will issue an airworthiness directive (AD) calling for detailed inspection of Pratt & Whitney JT8D turbofan engines overhauled by Turk Hava Yollari (THY), an FAA-certificated aircraft and engine-maintenance shop in Turkey.
The AD results from an investigation of the 8 June uncontained failure of a JT8D power plant on a ValuJet McDonnell Douglas DC-9 during a take-off from Hartsfield International Airport at Atlanta, Georgia. Engine fragments penetrated the cabin and started a fire, which destroyed the aircraft. The engine was one of 23 JT8Ds, which ValuJet acquired in its purchase of nine DC-9s from Turkish Airlines.
The US National Transportation Safety Board (NTSB) says that the seventh-stage high-pressure compressor disc on the No 2 engine failed. The disc failure was caused by a fatigue crack in an area, which cannot be inspected without disassembling the engine.
As recommended by the NTSB, the FAA's AD will require inspection of JT8D high-pressure compressor steel discs overhauled by THY before reaching 3,000 cycles since the last overhaul and inspection.
Source: Flight International
