I got an email from Continental concerning their investigation into the the failed rocker arm in my Performance Engines IO-550.  I sent the broken rocker arm to Continental earlier this year at their request.  The failure was ascribed to high cycle fatigue suggesting many, many hours of use.  The rocker arm had been also been re-machined, and  Continental judged it to be out of limits in several respects.  The  part number on that rocker arm (and the other eleven now strung up in my hangar as a reminder) was superceded in 1966, 44 years ago.    In response to a LOBO inquiry (still ongoing, as far as I know), Performance Engines has responded that the rocker arms in my engine, while  "thirty years old," came from a reputable supplier and were new ("unused?") when installed.    I understand from the FAA office in Atlanta (oversees Teledyne Continental Motors in Mobile,  AL) that the Los Angeles  FSDO is investigating and would welcome any new information.   Fred Moreno