Piston aeroengine manufacturer Textron Lycoming has launched a programme to retire all hammer-forged crankshafts that still remain in the fleet after a series of costly recalls prompted by failures blamed on improper heat treatment. The plan calls for crankshafts in 5,100 engines not covered by previous service bulletins to be replaced within three years.
In 2002, in response to a series of failures, Lycoming recalled about 950 high-horsepower engines and fitted crankshafts produced by a new supplier using an improved press-forging process. In July last year, after observing the same cracking problem in lower-power engines with hammer-forged crankshafts, the manufacturer issued another service bulletin requiring their replacement within 50 flight hours of six months. The 1,400 engines affected are expected to be completed by August or September, says Lycoming vice-president and general manager Ian Walsh.
The latest service bulletin affects those remaining engines manufactured between 1997 and 2002 that still have hammer-forged crankshafts produced by Lycoming’s original supplier Interstate Southwest.
The retirement is “proactive”, as there have been no incidents involving these engines, Walsh says.
Under the retirement plan, crankshafts must be replaced at the next overhaul, or within three years, with kits available for $2,000 – a “deep discount” of around 70%, Walsh says.
Source: Flight International
