AD 59-12-07

59-12-07 WRIGHT: Applies to R-1300-1A Engines Installed in North American T-28A Aircraft. Compliance required by July 1, 1959, or within the next 10 hours of operation, whichever occurs first. There is a possibility that a small number of R-1300-1A engines were released by the military for civil sale and use with crankshafts that had undergone a chrome plating salvage repair operation during the last military overhaul. This operation was found to render the crankshaft unsafe and accordingly was discontinued. Engines with these salvaged crankshafts have a note to this effect in the records and log sheets kept for the engine. No other identification of such engine was provided. A re-examination of the military records of these engines must be made and if any indication is found that the crankshaft has been salvaged by chrome plating it is mandatory that the engine be removed from service consistent with the above stipulated compliance provisions and prior to reuse of the engine in civil aircraft the affected crankshaft must be replaced.