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 November 15, 2010 (75 FR 69606). That NPRM proposed to correct an unsafe condition for the specified products. The MCAI states:
The flight crew of a F28 Mark 0070 (Fokker 70) aeroplane received a MLG [main landing gear] unsafe message after landing gear down selection during approach. After cycling the landing gear, only a LH [left-hand] MLG unsafe indication remained. A go-around was initiated and alternate landing gear down selection was performed twice, but the LH MLG did not lock down. During final approach, without further flight crew action, all 3 green lights illuminated and an uneventful landing was made.
Inspection just after landing revealed a lot of ice near the LH MLG downlock actuator. Further investigation revealed that the piston rodof the downlock actuator had failed at the threaded end close to the eye end, which is attached to the lower lock link, and that the piston rod was broken in an overload by bending in the neck close to the threaded end.
Based on the quantity and location of the ice, it is considered highly likely that the ice had formed between the upper end of the downlock actuator and the upper side brace, and was accumulated during taxi on slush-and snow-contaminated taxiways and runway at the departure airport.
Ice in this location prevents the actuator from turning freely relative to the upper side brace during landing gear down selection, likely resulting in failure of the piston rod. This condition, if not corrected, could lead to further cases of MLG extension problems, possibly resulting in loss of control of the aeroplane during landing roll-out.
To address this unsafe condition and prevent the accumulation of water, slush and/or snow, Goodrich, the MLG manufacturer, has introduced a new upper side brace, Part Number (P/N) 41350-3, which has two additional drain holes. Goodrich Service Bulletin (SB) 41350-32-25 describes the modification of the P/N 41350-1 MLG upper side brace, introducing the two additional drain holes and consequent re-identification of the part to P/N 41350-3.
For the reasons described above, this AD requires modification of both (LH and RH [right-hand]) P/N 41350-1 MLG upper side braces, or replacement of the P/N 41350-1 upper side braces with modified P/ N 41350-3 upper side braces.
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 received no comments on the NPRM or on the determination of the cost to the public.
Conclusion
We reviewed the available data and determined that air safety and the public interest require adopting the AD as proposed.
Differences Between This AD and the MCAI or ServiceInformation
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 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 6 products of U.S. registry. We also estimate that it will take about 16 work-hours per product to comply with the basic requirements of this AD. The average labor rate is $85 per work-hour. Required parts will cost about $0 per product. Where the service information lists required parts costs that are covered under warranty, we have assumed that there will be no charge for these parts. As we do not control warranty coverage for affected parties, some parties may incur costs higher than estimated here. Based on these figures, we estimate the cost of this AD to the U.S. operators to be $8,160, or $1,360 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, 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.
Adoption of the Amendment
Accordingly, under the authority delegated to me by the Administrator, the FAA amends 14 CFR part 39 as follows:
PART 39--AIRWORTHINESS DIRECTIVES
1. The authority citation for part 39 continues to read as follows:
Authority: 49 U.S.C. 106(g), 40113, 44701.Sec. 39.13 [Amended]
2. The FAA amends Sec. 39.13 by adding the following new AD: