Discussion
We issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 to include an AD that would apply to the specified products. That NPRM was published in the Federal Register on May 10, 2010 (75 FR 25788). That NPRM proposed to correct an unsafe condition for the specified products. The MCAI states:
At present, the Wing Anti-Ice System (WAIS) sufficient heat switches/sensors on CL-600-2B19 aircraft are located at the inboard end of each wing and require a simultaneous low-pressure signal to generate a L or R WING A/ICE amber caution. However, there have recently been several in-service occurrences that have highlighted the inability of the existing system to detect a low-heat condition in the wing leading edge at all times, with the potential consequence of unannunciated asymmetric ice build-up on the wing. These have included partial failure of several piccolo ducts [ref: Airworthiness Directive (AD) CF-2008-30] and partial (not fully closed or open) failure of a modulating and shut-off valve, the latter resulting in unannunciated asymmetric ice build-up on the wing leading edge. Such a condition, in combination with maneuvers close to stick shaker activation, could possibly result in reduced controllability of the aircraft.
This directive mandates:
(a) Revision of the Airplane Flight Manual (AFM) to notify the flight crew that, following installation and activation of the low- heat detection switches, certain WAIS mode selection changes may result in a two-minute inhibition of the wing anti-ice message, if posted;
(b) Revision of the approved maintenance schedule to include one revised and three new functional checks that are required following activation of the low-heat detection switches;
(c) Replacement of the Data Concentrator Units (DCUs) with DCUs incorporating a software update that caters for the new outboard low-heat detection switches and generates the appropriate anti-ice messagefor the flight crew when a low-heat condition is detected;
Note: Although not related to this directive, the software update also corrects the sampling rate of two previously non- compliant Flight Data Recorder (FDR) parameters, normal acceleration and pitch attitude.
(d) Installation of the low-heat detection switches in the wing outboard leading edges, the wing A/ICE box assembly and associated wires; and
(e) Activation of the low-heat detection switches.
You may obtain further information by examining the MCAI in the AD docket.
Comments
We gave the public the opportunity to participate in developing this AD. We considered the comments received.
Support for the NPRM
Air Line Pilots Association, International (ALPA) stated that it agrees that all reasonable steps should be taken to avoid reduced controllability while operating in icing conditions. ALPA stated that it supports the NPRM, but also encouraged the FAA to implement it as soonas possible to enable full compliance before winter.
Requests To Revise Costs of Compliance
Limited Brands and Air Wisconsin requested that we revise the costs of compliance. Limited Brands disagreed with the estimate of 21 work- hours and the cost of $1,785 per product to comply with the proposed AD. Limited Brands stated that the modification of the data concentrator unit (DCU), as required by paragraph (g)(3) of the NPRM, costs $1,200, the installation required by paragraph (g)(4) of the NPRM costs $3,300, and additional labor costs are $25,000, which brings the actual cost to $30,000 per airplane. Air Wisconsin stated it calculated that the costs are $600 for each of the two upgrades, $2,570 for other required parts, and 70 work-hours--for a total of $9,720 per airplane.
We agree to revise the Costs of Compliance section of this AD. We have based our cost estimate on the service information and information from the manufacturer, and have calculated the costs for complying with the AD as follows: 2 work-hours for revising the Limitations section of the AFM and the ALI; 3 work-hours for replacing the DCU; 72 work-hours for installing the switches, assemblies, and wires; and 4 work-hours for activating the switches. We also calculated $4,500 for parts. We revised the Costs of Compliance section of this AD accordingly.
Request To Clarify the Modification to the Wing Leading Edges
Air Wisconsin requested clarification regarding the modification of the wing leading edges. Air Wisconsin noted that the effectivity is against the airplane models but Bombardier Service Bulletin 601R-30- 031, Revision D, dated February 3, 2010, specifies modifying the leading edges, which was not addressed in the NPRM. Air Wisconsin noted that, if a non-modified spare leading edge is installed, there could be cause for confusion.
We agree to provide clarification. The actions required by paragraph (g)(4) of this AD include modifying the leading edges.
Request To Revise the Compliance Time for Requirements of Paragraph (g)(2) of the NPRM for Task C30-10-141-01
Mesa Airlines requested that we clarify the requirements of paragraph (g)(2) of the NPRM for Task C30-10-141-01. Mesa Airlines stated that on page 2A-11 of Appendix A of Part 2 of the Bombardier CL- 600-2B19 Maintenance Requirement Manual (MRM), Task C30-10-141-10 provides the functional check of the wing anti-ice standby overheat switches and overheat/sufficient heat sensors and associated circuitry with an interval of 6,000 flight hours. Mesa Airlines stated that page 1-2-35 of Section 2 of Part 1 of the Bombardier CL-600-2B19 Maintenance Review Board (MRB) Report, Task 30-12-12-01, ``Functional check of the wing anti-ice overheat sensors (duplicate Certification Maintenance Requirements (CMR) C30-10-141-01),'' provides a compliance time of 4,000 flight hours. Mesa Airlines also stated that page 1-1-6 of Section 1 of Part 1 of the Bombardier CL-600-2B19 MRM states the following in Note 15: ``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 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
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MRB report task interval will take precedence.''
Mesa Airlines asked that we clarify the NPRM as to which interval needs to be tracked--6,000 flight hours or 4,000 flight hours.
We agree to clarify. The intent of the AD is to introduce the CMR tasks that are associated with the new switches. CMR Task C30-10-141-01 was inadvertently mandated in Canadian AD CF-2009-37 and was carried over into the NPRM. The MRB group is currently looking into harmonizing these task intervals. Therefore, we have removed CMR Task C30-10-141-01 from Table 1 of this final rule.
Request To Clarify Required Service Information
Air Wisconsin requested that we clarify the name of the service information in paragraph (g)(2) of the NPRM. Air Wisconsin stated that paragraph (g)(2) of the NPRM refers to ``Airworthiness Limitations Instructions.'' Air Wisconsin asked if it should instead be ``Bombardier CL-600-2B19 Maintenance Requirements Manual (MRM), Appendix A, Certification Maintenance Requirements (CMR).''
We agree with the commenter's suggested service information citation. We have changed paragraph (g)(2) of this final rule accordingly.
Request To Revise Compliance Time in Table 1 of the NPRM
Air Wisconsin requested that we revise the compliance time in Table 1 of the NPRM. Air Wisconsin stated that under the column heading ``Initial Compliance Time (whichever occurs later)'' for Tasks C30-10- 141-03, C30-10-141-05, and C30-10-141-07 in Table 1, the compliance time under that column heading should read ``Before the accumulation of 6,000 flight hours, or if previously accomplished, within 6,000 flight hours since last accomplishment, whichever comes first.'' The commenter did not provide a reason for these suggestions.
We agree with the commenter's suggested change. The intent of Table 1 is to establish the initial compliance times for accomplishment of the specified tasks because only repetitive intervals are specified in Bombardier TR 2A-46, dated July 24, 2009. However, we acknowledge that some operators might have previously accomplished the initial tasks and could be doing those tasks repetitively. The commenter's suggested language would provide credit for earlier accomplishment of the tasks for those operators. We have revised Table 1 to include the language suggested by the commenter.
Request To Remove Note 3 of the NPRM
Air Wisconsin requested to remove Note 3 from the NPRM. Air Wisconsin stated that the inspection requirements in Bombardier Temporary Revision (TR) 2A-46, dated July 24, 2009, are already contained in the generalrevision of the MRM, specifically, Revision 9, dated December 10, 2009. Air Wisconsin stated that this updated general revision makes Note 3 irrelevant and, therefore, the note should be removed.
We disagree. The note is necessary to keep operators in compliance when the TR is incorporated into general revisions. Operators that have a revision of the MRM that contains the information in Bombardier TR 2A-46 are in compliance. We have not changed the final rule in regard to this issue.
Request To Remove Note 4 of the NPRM
Air Wisconsin requested we remove Note 4 from the NPRM. Air Wisconsin stated this note is not pertinent to the content of the NPRM because Task 30-11-41-820-801 is not part of Bombardier Service Bulletin 601R-30-031, Revision D, dated February 3, 2010, and should be removed.
We disagree. Task 30-11-41-820-801 is pertinent to this AD because it is part of the Bombardier CRJ Series Regional Jet Aircraft Maintenance Manual, and it provides guidance to correct alignment of the piccolo ducts since a small number of cases have been reported in which they were found to have been installed in the opposing wing, resulting in the incorrect orientation of the bleed holes. One of the requirements of this AD is to install the low-heat direction switches in the wing outboard leading edges. This task requires particular attention to the correct alignment of the piccolo ducts after the installation of the low-heat detection switches. We have not changed the final rule in regard to this issue.
Request To Revise Compliance Time for Requirements of Paragraph (g)(5) of the NPRM
Air Wisconsin, Mesaba Airlines, and Mesa Airlines requested that we revise the compliance time for activating the outboard low-heat detection switches, as proposed by paragraph (g)(5) of the NPRM. Air Wisconsin requested that incorporating the procedures specified in Part F of the Accomplishment Instructions of Bombardier Service Bulletin 601R-30-031, Revision D, dated February 3, 2010, should be performed at the next heavy maintenance visit, provided that parts (kits) are available. Air Wisconsin stated that it has scheduled these tasks to be completed by the end of December 2011. Mesaba Airlines requested that the compliance time in paragraph (g) of the NPRM be revised from 11 months to 5,000 flight hours after the effective date of this AD. Mesaba Airlines stated that the 11-month compliance time for the modification will result in extended downtime and cause interruptions. Mesa Airlines stated that it agrees with Mesaba Airlines' request to change the compliance time from months to hours.
We disagree. In developing the compliance time for this AD action, we considered not only the safety implications of the identified unsafe condition, but the average utilization rate of the affected fleet, the practical aspects of an orderly modification of the fleet during regular maintenance periods, the availability of required parts, and the time necessary for the rulemaking process. The proposed compliance time, which is based on the effective date of the final rule, was determined to be appropriate. However, under the provisions of paragraph (h) of the final rule, we will consider requests for approval of an extension of the compliance time if sufficient data are submitted to substantiate that the change would provide an acceptable level of safety. We have not changed the final rule in regard to this issue.
Clarification of Changes to This AD
We have revised paragraph (e) of this AD by removing some text and retaining only the text that applies to the Reason section of this AD.
In addition, we have removed paragraph (h)(3) of the NPRM because this AD does not contain a reporting requirement.
Conclusion
We reviewed the available data, including the comments received, and determined that air safety and the public interest require adopting the AD with the changes described previously. We determined that thesechanges will not increase the economic burden on any operator or increase the scope of the AD.
Differences Between This AD and the MCAI or Service Information
We have reviewed the MCAI and related service information and, in general, agree with their substance. But we might have found it necessary to use different words from those in the MCAI to ensure the AD is clear for U.S. operators and is enforceable. In making these changes, we do not intend to differ substantively from the information
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provided in the MCAI and related service information.
We might also have required different actions in this AD from those in the MCAI in order to follow our FAA policies. Any such differences are highlighted in a NOTE within the AD.
Costs of Compliance
We estimate that this AD affects 599 products of U.S. registry. We also estimate that it takes about 81 work-hours per product to comply with the basic requirements of this AD. The average labor rate is$85 per work-hour. Parts cost $4,500 per product. Based on these figures, we estimate the cost of this AD to the U.S. operators to be $6,819,615, or $11,385 per product.
Authority for This Rulemaking
Title 49 of the United States Code specifies the FAA's authority to issue rules on aviation safety. Subtitle I, section 106, describes the authority of the FAA Administrator. ``Subtitle VII: Aviation Programs,'' describes in more detail the scope of the Agency's authority.
We are issuing this rulemaking under the authority described in ``Subtitle VII, Part A, Subpart III, Section 44701: General requirements.'' Under that section, Congress charges the FAA with promoting safe flight of civil aircraft in air commerce by prescribing regulations for practices, methods, and procedures the Administrator finds necessary for safety in air commerce. This regulation is within the scope of that authority because it addresses an unsafe condition that is likely to exist or develop on products identified in this rulemaking action.
Regulatory Findings
We determined that this AD will not have federalism implications under Executive Order 13132. This AD will not have a substantial direct effect on the States, on the relationship between the national government and the States, or on the distribution of power and responsibilities among the various levels of government.
For the reasons discussed above, I certify this AD:
1. Is not a ``significant regulatory action'' under Executive Order 12866;
2. Is not a ``significant rule'' under the DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and
3. Will not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act.
We prepared a regulatory evaluation of the estimated costs to comply with this AD and placed it in the AD docket.
Examining the AD Docket
You may examine the AD docketon the Internet at http://www.regulations.gov; or in person at the Docket Operations office between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The AD docket contains the NPRM, the regulatory evaluation, any comments received, and other information. The street address for the Docket Operations office (telephone (800) 647-5527) is in the ADDRESSES section. Comments will be available in the AD docket shortly after receipt.
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.