A FATIGUE crack in the fan hub is the likely cause of the uncontained failure of a Pratt & Whitney JT8D-219 powering a Delta McDonnell Douglas MD-88. Two passengers were killed and four injured when the left-engine fan disintegrated, sending debris into the cabin during the take-off run of Flight 1288 from Pensacola, Florida, to Atlanta, Georgia, on 6 July. Three passengers were injured during evacuation after the pilot aborted the take-off. There were 142 passengers and five crew on board.
Initial examination of the disintegrated hub indicates that the fracture started at a 25mm-long fatigue crack in one of 24 tie-bolt holes in the hub. Some 13,000 cycles had been accumulated on the hub since it was delivered new to Delta in 1989. The hub was installed on the incident engine in January during maintenance to replace an oil seal. Delta says that the hub had undergone dye-penetrant inspection before installation. Just over 1,500h had been accumulated between installation and the accident.
P&W says that this is the first fan-hub failure in 47 million flight hours and 32 million cycles operational experience with the JT8D-200-series engine, which powers only MD-80-series airliners. The company has delivered 2,621 -200-series engines since 1980, and "-we have never seen any [fan-hub] cracking of any kind," it says.
Delta instigated daily visual inspections of in-service engines and eddy-current inspections of engines in maintenance, but did not find any other cracked hubs.
Source: Flight International
