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 January 25, 2011 (76 FR 4264). That NPRM proposed to correct an unsafe condition for the specified products. The MCAI states:
There have been two reported cases of failure of the MLG [main landing gear] piston axle, P/N [part number] 49203-3 or 49203-5, resulting from fretting between the inboard axle sleeve and axle thrust face, damage to the protective coating and consequent stress corrosion. In both cases, the MLG did not collapse.
In order to avoid future axle failures, which could potentially result in gear collapse and collateral damage, this [Canadian] directive mandates repetitive visual inspection [for damage and corrosion of the protective coating] and repair, as necessary, of the MLG piston axles, P/N 49203-3 and 49203-5.
The unsafe condition is failure of the MLG, which could adversely affect the airplane's safe landing. 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.
Request To Include Additional Piston Axle Part Numbers
Comair, Inc. (Comair) requested that we revise paragraph (g) of the NPRM (76 FR 4264, January 25, 2011) to include MLG piston axles having P/Ns 49263-1 and 49263-3. Comair explained that it has been in contact with Goodrich regarding these part numbers. Comair expressed that Goodrich's response supports what Comair surmised from the Goodrich component maintenance manual (CMM) for P/N 49000, which was that P/Ns 49263-1 and 49263-3 are a next higher assembly (NHA) part number consisting of a piston axle with a metering pin assembly installed. Comair stated that the Goodrich CMM for P/N 49000 uses the following nomenclature, ``Piston/Axle/Metering Pin Assy (Pre SB 32-45).''
Comair also explained that there have been several instances where Comair has sent Goodrich Landing Gear Services a piston/axle having P/N 49203-3 for repair. Comair stated that while the piston/axle was at Goodrich, a metering pin was installed.
Comair expressed that when the piston/axle was returned, the authorized release certificate (Form One) only contained P/N 49263-1, and that Form One does not list the part number for the piston/axle and metering pin, only the higher assembly part number. Comair further explained that when they received the piston/axle back into stock, the part number had changed from 49203-3 to 49263-1, during the receiving process. Comair stated that, consequently, when the piston/axle is installed on the airplane, it shows that P/N 49263-1 is installed; therefore, as the NPRM is written, Comair asserted that the NPRM would not apply by part number. Comair suggested that if P/Ns 49203-3 and 49203-5 exhibit anunsafe condition, then P/Ns 49263-1 and 49263-3 should be considered to have the same fretting concern and the same unsafe condition.
We agree, for clarification, to include MLG piston axles having P/ Ns 49263-1 and 49263-3, in a note in the final rule. It has also come to our attention that several operators failed to do the inspection because the MLG rework paperwork (Form One) from Goodrich only annotated piston/axle/metering pin assembly NHA having P/N 49263-1 or 49263-3, while the NPRM only proposed to require inspection for MLG piston axles having P/N 49203-3 or 49203-5. While neither this AD nor Canadian AD CF-2010-15, dated May 13, 2010, require inspection for MLG piston axles having P/N 49263-1 or 49263-3, we want to avoid the possibility of an operator overlooking the intent of this final rule simply because the operator's overhaul paperwork is the only document that references the NHA part number. This change has been coordinated with Transport Canada Civil Aviation. We have revised this final rule to include new Note 2 to inform operators that MLG piston axles having P/N 49203-3 or 49203-5 that are installed on the airplane could be identified as having P/N 49263-1 or 49263-3. We have re-identified subsequent notes accordingly.
Request To Extend the Proposed Compliance Time
Mesa Airlines (Mesa) requested that we revise the NPRM (76 FR 4264, January 25, 2011) to extend the proposed compliance time of 12 months for the initial inspection specified in paragraph (h)(1) of the NPRM to 24 months. Mesa explained that its request is due to the number of applicable components, the size of its fleet, repair vendor capacity, and the turn time for the piston axle if needed.
We disagree to extend the compliance time specified in paragraph (h)(1) of the final rule. In developing an appropriate compliance time for this action, we considered the urgency associated with the subject unsafe condition, the availability of required parts, and the practical aspect of accomplishing the required inspection within a period of time that corresponds to the normal scheduled maintenance for most affected operators. According to the manufacturer, an ample number of required parts will be available to modify the airplanes identified in the Applicability section of this final rule within the compliance time. In consideration of these items, we have determined that a 12-month compliance time for the initial inspection in paragraph (h)(1) of this final rule is appropriate. However, under the provisions of paragraph (l) 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 new compliance time would provide an
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acceptable level of safety. We have not changed the final rule in this regard.
Request To Add a Compliance Time for Proposed Terminating Action
In its request to extend the proposed compliance time for the initialinspection, Mesa added the following statement, ``6,000 hrs. to terminate.'' Mesa did not provide any explanation for this request.
From this statement, we infer that Mesa requested that we include a compliance time of 6,000 flight hours after the initial inspection for the terminating action required by paragraph (j) of the final rule. We disagree with adding a compliance time to paragraph (j) of the final rule. Mesa has not provided any justification for this request. Further, including an additional compliance time would necessitate additional rulemaking, and we do not consider that delaying this action until that time is warranted, since the actions required by this AD are adequate to ensure continued safety of the affected fleet. We have not changed the final rule in this regard.
Request To Add a Provision for Piston Axles That Require Overhaul
Mesa also requested that we revise the NPRM (76 FR 4264, January 25, 2011) to add a paragraph to paragraph (h) of the NPRM to allow for a provision for MLG piston axles which are scheduled for overhaul. Mesa suggested the following wording: ``(4) For any piston axle that has been in service more than 48 months, of the effective date of this AD and is due to be overhauled within 36 months of the effective date of this AD, must be complied with at schedule overhaul.''
We disagree to include a provision for MLG axles which are scheduled for overhaul. Mesa has not provided any technical justification for this request. However, affected operators may request to allow for a provision for MLG piston axles which are scheduled for overhaul, under the provisions of paragraph (l) of this final rule by submitting data, substantiating that the change would provide an acceptable level of safety. We have not changed the final rule in this regard.
Request To Clarify Paragraph (i) of the NPRM (76 FR 4264, January 25, 2011)
Mesa also requested that we clarify paragraph (i) of the NPRM (76 FR 4264, January 25, 2011). Mesa has not specified what aspect of the requirement it wants clarified, nor has it provided any reason for this request.
We agree to clarify paragraph (i) in this comment section of this final rule. Paragraph (i) of this final rule states the compliance time for doing the inspections specified in paragraph (h) of this AD for airplanes that have the mark ``32-45'' in the MOD STATUS field on the piston axle nameplate, or for airplanes that have done one of the repair engineering orders listed in the service information in paragraph (i) of this AD; within the compliance times required in paragraph (i) of this AD, these airplanes do the inspection and repeat the inspection as required by paragraph (h) of this AD. We have also added paragraphs (i)(1), (i)(2), and (i)(3) to the final rule to clarify the compliance times for paragraph (i).
Clarification
We have revised paragraph (g) of this final rule to clarify that the compliance times for doing the inspection requiredby paragraph (g) of this final rule are the same as the applicable compliance times specified in paragraphs (h) and (i) of this final rule.
We have also added Note 3 to this final rule to clarify that the MCAI specifies to inspect only airplanes having certain serial numbers that are part of the MCAI applicability. Because the affected part could be rotated onto any of the airplanes listed in the applicability, this AD requires the inspection be done on all airplanes.
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 change described previously. We determined that this change 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 foundit 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 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 will affect 380 products of U.S. registry. We also estimate that it will take about 22 work-hours per product to comply with the basic requirements of this AD. The average labor rate is $85 per work-hour. Based on these figures, we estimate the cost of this AD to the U.S. operators to be $710,600, or $1,870 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 docket on 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 (76 FR 4264, January 25, 2011), the regulatory evaluation, any comments received, and other information. The street address for
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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.