National AeroSpace Consulting, Ltd.

Dear Sirs, Please find our comments regarding FAA’s request concerning information related to effective air cleaning technology and sensor technology for the engine and auxiliary power unit bleed air supplied to the passenger cabin and flight deck of a pressurized aircraft. We believe that FAA has raised very actual and vital issue. Our opinion is that it is critical to determine nomenclature and quantity of contaminants to be detected, recorded and removed. We think that information about nomenclature and quantity of contaminants in the bleed air supplied to the passenger cabin and flight deck may be obtained from results of special engine tests carried out by OEMto determine quality of engine bleed air to be supplied to aircraft conditioning system.Especially effective may beresults of tests which are carried out by engine manufacturer with simulation of defects during certification.From certification test results it will be possible to receive these data that will be needed to assist in evaluation of the types of air cleaning and monitoring technology that will successfully detect, remove and report on engine produced, oil-based cabin air contaminants. Aviation Authorities approve test reports (see attached). As to proprietary information, one could not indicate the company name and the engine model. Best wishes General Director T. Nurullaev