Summary
We propose to adopt a new airworthiness directive (AD) for the products listed above. This proposed AD results from mandatory continuing airworthiness information (MCAI) issued by an aviation authority of another country to identify and correct an unsafe condition on an aviation product. The MCAI describes the unsafe condition as: The installation of TU250 CS boards, however, has resulted in a few occurrences of erratic engine behaviour, in the form of unexpected N1 variations and/or illumination of the "GOV'' warning light. The conclusions from an investigation by Turbom[eacute]ca are that these malfunctions are due to a lapse of quality control in the varnishing process applied to the boards, and that only boards in a specific serial number range, as defined under "Applicability'' and referred to below as the "suspect batch,'' are affected. We are proposing this AD to prevent loss of automatic engine control during flight due to an uncommanded engine roll-back, which could result in the inability to continue safe flight.