SDR 510022349

Bombardier CL604 DC generation system—IDG faulty. 
At cruise level the GEN 1 OFF CAS message was posted. Initial visual inspection of the LH integrated drive generator found the generator had lost oil and was had produced a lot of heat. There was delamination on the adjacent cowl, also bubbled paint. After removing the IDG it was observed the shaft was not sheared, but had no resistance if turned. It seemed there was an internal failure in the IDG. The failure may have been caused by a loss of oil, which then caused the IDG to overheat and fail; or something inside the IDG failed which caused an oil leak, and the IDG then overheated. P/No: 731579C