Air Wisconsin Airlines Corporation

Air Wisconsin does not contest the need to modify the seals in order to maintain the highest level of safety. However, Air Wisconsin also believes that the justification stated in the NPRM is a gross misrepresentation of the situation (and the events) which lead up to the referenced accident. The failure of these engines to restart after the flame out event was a direct result of the flight crew failing to properly follow in-flight engine restart procedures. Every engine is tested during the aircraft certification test flight process to ensure it meets the requirements of FAR 25.903. The NPRM should be reworded to indicate the desired reason for the modification is to enhance safety and not as a result of the accident as stated. Otherwise the implication is that the CF34 engine does not meet the certification requirements which is inaccurate. Additionally the compliance requirements in the NPRM are not entirely clear. This is a non-serialized part as is the case with the #5 rotating seal as referenced in GE SB 72-0109 and AD 2001-12-06, which is difficult to track and manage. I have personally observed a situation where an MRO overlooked the requirement to incorporate this particular modification because of an interpretation of what constituted "piece part exposure". Fortunately Air Wisconsin caught the oversight and drove compliance before the engine was returned to service. If the desire is to ensure modification at first exposure, then the requirement should indicate to accomplish SB72-0238 at "piece part exposure" which is defined as "removal of the combustion liner" but no later than the first LLP shop visit since this is when the HPT Life limited Parts (and typically the liner) are removed.