Air Wisconsin Airlines Corporation

COST OF COMPLIANCE: SB 601R-28-055 does not discuss any warranty considerations for the distribution of kits to accomplish this modification. All operators will have to purchase kits. The current cost is $427 per aircraft. Please amend the cost for compliance. SERVICE BULLETIN REVISION STATUS: Air Wisconsin incorporated this modification on all 70 aircraft in their fleet between June 04 and November 06. The Original issue of SB 601R-28-055, as well as rev A and B, were used dependent upon what latest revision was available at the time of accomplishment. While it was Revision D that paragraph B “Procedures”, was amended to include a statement to ensure both the left and right sides of the aircraft were modified, it is inconceivable that any aircraft would not have both sides modified if an earlier revision was used. All issues of the SB called for 1) circuit breakers to be pulled for the LH and RH sides, 2) access panels to be removed from the LH and RH sides, 3) a quantity of parts were supplied sufficient for the LH and RH sides, and 4) several figures in the SB contain information specific for the LH and / or RH sides. Never the less, when Transport Canada issued AD CF-2007-34 against SB 601R-28-055 Revision D, Air Wisconsin initiated verification for compliance for both the LH and RH sides on aircraft as they had their “heavy checks” accomplished, as this was a convenient opportunity. To date (September 08, 2008) 19 aircraft have been checked with no discrepancies noted. We will continue verification for all 51 remaining aircraft. While we prefer that all issues of SB 601R-28-055 be allowed to show compliance for the modification, the US AD should at least recognize Revision D as an acceptable method of compliance, as it was at this revision that the statement to ensure compliance for the LH and RH sides was made and Air Wisconsin initiated the verification inspection. Please amend the rulemaking to recognize 601R-28-055 Revision D as an acceptable method of compliance. I have attached a copy of the Air Wisconsin Engineering Order used for the verification inspection and copies of the Summary of Results for the 19 aircraft already inspected.