Attached

Comments on FAA NPRM 2006-NE-24-AD published in the Federal Register on January 21 2009 (document ID FAA -2006-25173-0013) FAA has published an NPRM on January 21st 2009 proposing the existing FAA AD #2006-NE-24-AD. The proposed changes would effectively mandate the provisions of McCauley SB #255A, affecting the McCauley C1101/1102/1103/1104 propeller fitted to the BAe Jetstream 41 aircraft. This document requests the FAA to look deeper into the root cause of the problem the cracks so as to restore the original expected service life of the blade . Since 1995 SA Airlink has operated up to 16 J41 aircraft. This airline has experienced the majority of the cracks found in the blades of the above mentioned propellers. The Propeller OEM maintains the cracks in the propeller are caused by operation of the propeller in the restricted RPM for extended periods of time. Over the years several blades have been test by BAe metallurgist and questions have been asked in respect to changes in the manufacturing process. In May 2008 SA Airlink had an independent test carried by the CSIR. Mr. TJ Carter carried out the tests and he concluded that the cause of the cracks is due to changes in the manufacturing process and the material used. His findings are the same as BAe Systems conclusions. His report is also attached as supporting evidence. Reducing the life of the blade to 3500 hours does not address the root cause of the problem and only adds additional expenses to airlines and operators and the OEM is the only one to benefit from increased sales of blades. BAe have introduced SB J41-61-014 Propeller Speed Warning System to assist flight crews in complying with the propeller limitation which restricts operation between 82% and 90% RPM. Airlink is in the process of installing the system on our fleet. For many months now Airlink has been monitoring Crews for compliance by DFDR down loads and we find that the crews are fully compliant. Random samples of these DFDR down loads and forwarded to the SACAA. Airlink has given the undertaking to BAe Systems that they will continue to do the DFDR monitoring even when the PSW is installed. If the Metallurgic analysis is ignored and the OEM explanation that the blade cracks are only caused by operations in the prohibited range then the question has to be asked why the blade life is reduced if SB255 is carried out at the interval required and no cracks are found and DFDR down loads are carried out to monitor crews and the BAE Propeller Speed Warning System is fitted. With all of the above provisions the present life of 5000 hours can be justified whilst retaining an acceptable level of safety.