Discussion
We issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 by adding an AD that would apply to certain Bombardier, Inc., Model BD-100-1A10 airplanes. The NPRM published in the Federal Register on November 29, 2018 (83 FR 61336). The NPRM was prompted by a report that certain split ball bearings used in MLG side brace actuator assemblies are manufactured from material that does not meet the required material properties. The NPRM proposed to require an inspection of the left and right MLG side brace actuator assemblies and, if necessary, replacement of the split ball bearings.
We are issuing this AD to address the non-conforming split ball bearings, which, if not corrected, could result in potentially asymmetric MLG extension or retraction and consequent collapse of the MLG during landing.
Transport Canada Civil Aviation (TCCA), which is the aviation authority for Canada, has issued Canadian AD CF-2018-20, dated July 27, 2018 (referred to after this as the Mandatory Continuing Airworthiness Information, or ``the MCAI''), to correct an unsafe condition for certain Bombardier, Inc., Model BD-100-1A10 airplanes. The MCAI states:
The landing gear supplier has informed Bombardier Aerospace about a quality escape involving Main Landing Gear (MLG) side brace actuators that have been assembled using non-conforming split ball bearings. The affected bearings are manufactured from material that does not meet the required material properties. If not corrected, this condition can result in potentially asymmetric MLG gear extension or retraction and subsequent gear collapse during landing.
This [Canadian] AD mandates verification of the installed MLG side brace actuator assemblies and replacement of the affected parts.
You may examine the MCAI in the AD docket on the internet at http://www.regulations.gov by searching for and locating Docket No. FAA-2018- 0965.
Comments
We gave the publicthe opportunity to participate in developing this final rule. The following presents the comments received on the NPRM and the FAA's response to each comment.
Support for the NPRM
One commenter, Andy Ingwersen, and Flexjet indicated support for the NPRM.
Request for Records Check To Determine MLG Side Brace Actuator Assembly Serial Number as an Alternative Method of Compliance
Flexjet requested that an additional means of verification be allowed for determining the serial number of the left and right MLG side brace actuator assembly part number 40310-103. Flexjet suggested that we add language to paragraph (g) of the proposed AD stating ``A review of airplane maintenance records is acceptable in lieu of this inspection if the serial number can be conclusively determined from that review.'' Flexjet justified this request by pointing out that similar language is used in other ADs. Flexjet explained that 20 MLG side brace actuator assembly serial numbers are affectedby Bombardier Service Bulletin 100-32-30, dated December 18, 2017, and 217 MLG side brace actuator
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assembly serial numbers are affected by Bombardier Service Bulletin 350-32-006, dated December 18, 2017, and reasoned that a logbook review would save time and present less of a financial burden on operators.
We agree with the commenter for the reasons provided. We have determined that a review of maintenance records is acceptable for complying with the actions specified in paragraph (g) of this AD, provided the serial number can be conclusively determined from that review. We have revised paragraph (g) of this AD accordingly.
Request To Shorten Compliance Time
One commenter, Ty Smith, made a request to change the compliance time to verify the MLG side brace actuator assembly serial number and perform applicable on-condition actions, and we infer from the request that the commenter wishes the compliance time to be shortened. The commenter asserted that a compliance time of 48 months leaves a large window of opportunity for the unsafe condition to potentially lead to a malfunction. The commenter conceded that a certain amount of time is needed to address the unsafe condition, but presumed that operators have the means to address the unsafe condition sooner than the 48 month compliance time allows.
We agree to clarify. As noted in figure 1 to paragraphs (g) and (h) of this AD, the compliance time varies depending on the total number of flight cycles accumulated on an airplane, with 48 months being the longest possible compliance time. In consideration of the average utilization rate by the affected U.S. operators, the practical aspects of an orderly modification of the U.S. fleet during regular maintenance periods, and the availability of required modification parts, we have determined that the compliance times specified in figure 1 to paragraphs (g) and (h) of this AD are appropriate. We have not changed this AD in this regard.Conclusion
We reviewed the relevant data, considered the comments received, and determined that air safety and the public interest require adopting this final rule with the changes described previously and minor editorial changes. We have determined that these minor changes:
Are consistent with the intent that was proposed in the NPRM for addressing the unsafe condition; and
Do not add any additional burden upon the public than was already proposed in the NPRM.
We also determined that these changes will not increase the economic burden on any operator or increase the scope of this final rule.
Related Service Information Under 1 CFR Part 51
Bombardier, Inc., has issued Service Bulletin 100-32-30, dated December 18, 2017; and Service Bulletin 350-32-006, dated December 18, 2017. This service information describes procedures for inspecting the left and right MLG side brace actuator assemblies to verify the serial number and replace the split ball bearings. These documents are distinct since they apply to airplanes in different configurations. This service information is reasonably available because the interested parties have access to it through their normal course of business or by the means identified in the ADDRESSES section.
Costs of Compliance
We estimate that this AD affects 468 airplanes of U.S. registry. We estimate the following costs to comply with this AD:
Estimated Costs for Required Actions ----------------------------------------------------------------------------------------------------------------
Cost per Cost on U.S.
Labor cost Parts cost product operators ---------------------------------------------------------------------------------------------------------------- 1 work-hour x $85 per hour = $85............................. $0 $85 $39,780 ----------------------------------------------------------------------------------------------------------------
We estimate the following costs to do any necessary on-condition actions that would be required based on the results of the required inspection. We have no way of determining the number of aircraft that might need these on-condition actions:
Estimated Costs of On-Condition Actions ------------------------------------------------------------------------
Cost per
Labor cost Parts cost product ------------------------------------------------------------------------ 8 work-hours x $85 per hour = $680 per $1,820 $2,500
airplane............................. ------------------------------------------------------------------------
According to the manufacturer, some or all of the costs of this AD may be covered under warranty, thereby reducing the cost impact on affected individuals. We do not control warranty coverage for affected individuals. As a result, we have included all known costs in our cost estimate.
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.
This AD is issued in accordance with authority delegated by the Executive Director, Aircraft Certification Service, as authorized by FAA Order 8000.51C. In accordance with that order, issuance of ADs is normally a function of the Compliance and Airworthiness Division, but during this transition period, the Executive Director has delegated the authority to issue ADs applicable to transport category airplanes and associated appliances to
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the Director of the System Oversight Division.
Regulatory Findings
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 that 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),
(3) Will not affect intrastate aviation in Alaska, and
(4) 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.
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.