Mesa Air Lines

NPRM 2009-NM-230-AD Paragraph (g) (2) requires the following “Revise the Airworthiness Limitations Instructions (ALI) of the Instructions for Continued Airworthiness (ICA) by incorporating the inspection requirements contained in Bombardier TR 2A–46, dated July 24, 2009, into Appendix A, ‘‘Certification Maintenance Requirements,’’ of Part 2 of the Bombardier CL–600–2B19 Maintenance Requirements Manual (MRM). The initial compliance times for the tasks identified in Bombardier TR 2A–46, dated July 24, 2009, are specified in Table 1 of this AD.” Table 1 of NPRM 2009-NM-230-AD has the initial compliance of CMR task C30-10-141-01 of “Before the accumulation of 6,000 total flight hours. Within 5 flight hours after the effective date of this AD.” On Page 2A-11 of MRM CSP A-053 Part 2 Appendix A, CMR task C30-10-141-01 has the following description and interval. “Functional Check of the wing anti−ice standby overheat switches and overheat/sufficient heat sensors and associated circuitry has a task interval of 6000 flight hours”. On Page 1-2-35 of MRM CSP A-053 Part 1 Section 2, MRB Report Task No. 30-12-12-01 has the following description and interval. “Functional Check of the wing anti−ice overheat sensors (duplicate CMR C30−10−141−01) 4000 FH Note 15” On Page 1-1-6 of MRM CSP A-053 Part 1 Section 1 has the following definition of Note 15 as the following. “This task has a duplicate CMR requirement. Refer to Maintenance Requirements Manual, CSP A−053, Part 2 Appendix A, for identification of specific requirements regarding handling of Certification Maintenance Requirements (CMRs). Where the CMR interval for an MRB Report task is more restrictive, the CMR interval takes precedence. When the interval for an MRB Report task is more restrictive, the MRB Report task interval will take precedence.” There needs to clarification in the NPRM as to which interval needs to be tracked, 6000 flight hours or 4000 flight hours.