Factual Report: Flawed Fan Blades Afflict Two Learjets
Bombardier Learjet 60, Palm Springs, Calif., March 31, 2007–N244X, operated by Jet Solutions, suffered a loss of power in its left engine while cruising at 41,000 feet msl. The pilots told investigators they heard a loud bang and the twinjet began to vibrate. They shut down the left engine, declared an emergency and diverted to Palm Springs Airport. No one was injured.
Investigation revealed that the left Pratt & Whitney Canada (P&WC) PW305A turbofan engine had lost its upper and lower cowlings, and that one fan blade had fractured, while all the remaining blades exhibited nicks and gouges. Further examination revealed that 16 of the remaining 23 fan blades had cracks near the blade root platform, while the right engine fan showed similar damage on five of the 24 blades. Subsequent testing by P&WC showed that a number of blades associated with the same batch lot were below the minimum thickness in the area where the fractures and cracks occurred. The blade producer, Blades Technology of Israel, believes the thin airfoil condition was the result of an improperly aligned forging die.
At the time the blades were produced P&WC did not have a dimensional inspection requirement. According to P&WC, all of the remaining fan blades from that production lot were recalled and removed from service.
Bombardier Learjet 60, Salt Lake City, Utah, Aug. 12, 2007–As the aircraft was climbing through 38,000 feet after taking off from Salt Lake City International Airport (SLC), the pilots heard a loud bang coupled with a loss of power in the left engine as the twinjet began to shake and the cockpit quickly filled with smoke and fumes. The pilots donned their oxygen masks, declared an emergency and made a safe overweight single-engine landing at SLC. Examination of the left PW305A engine revealed fan blade damage similar to that found in the March 31, 2007, Learjet emergency landing. The fan blades were from the same batch lot as those implicated in the previous incident.