AD 98-11-30

This amendment adopts a new airworthiness directive (AD), applicable to certain EMBRAER Model EMB-145 series airplanes, that requires inspection of the main landing gear (MLG) bushing seats to detect cracks, and repair of the bushing hole or replacement of strut bushings with new bushings, if necessary. This amendment also requires replacement of the plain bearings of the MLG shock absorber with new bearings. This amendment is prompted by issuance of mandatory continuing airworthiness information by a foreign civil airworthiness authority. The actions specified by this AD are intended to prevent structural failure of the MLG due to fatigue cracking of the strut bushing seat.

Final rule

98-11-30 EMPRESA BRASILEIRA DE AERONAUTICA S.A. (EMBRAER): Amendment 39- 10555. Docket 97-NM-279-AD.
Applicability: Model EMB-145 series airplanes, serial numbers 145004 through 145018 inclusive, certificated in any category.

NOTE 1: This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been modified, altered, or repaired in the area subject to the requirements of this AD. For airplanes that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (c) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.

Compliance: Requiredas indicated, unless accomplished previously.

To prevent structural failure of the main landing gear (MLG) due to fatigue cracking of the strut bushing seat, accomplish the following:

(a) Prior to the accumulation of 2,000 total flight cycles, or within 100 flight cycles after the effective date of this AD, whichever occurs later, accomplish paragraphs (a)(1), (a)(2), and (a)(3) of this AD.

(1) Perform a one-time liquid penetrant inspection to detect cracking of the flanged bushing seats of the MLG, in accordance with EMBRAER Service Bulletin 145-32-0012, dated September 1, 1997. If any crack is found, prior to further flight, repair in accordance with a method approved by the Manager, Atlanta Aircraft Certification Office (ACO), FAA, Small Airplane Directorate.

(2) Perform a one-time inspection of the bushing holes using a bore micrometer to determine the dimension of the holes, in accordance with EMBRAER Service Bulletin 145-32-0012, dated September 1, 1997.Prior to further flight, accomplish paragraph (a)(2)(i) or (a)(2)(ii) of this AD, as applicable.

(i) If the dimension of the bushing hole is less than 49.2 mm, perform the applicable corrective actions specified in the service bulletin.

(ii) If the dimension of the bushing hole is greater than or equal to 49.2 mm, repair in accordance with a method approved by the Manager, Atlanta ACO.

(3) Replace the plain bearing of the MLG shock absorber with a new bearing in accordance with EMBRAER Service Bulletin 145-32-0009, dated September 1, 1997.

(b) As of the effective date of this AD, no person shall install a plain bearing having part number ABC24VG (NMB) on the shock absorber of the MLG of any airplane.

(c) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, Atlanta Aircraft Certification Office (ACO), FAA, Small Airplane Directorate. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Atlanta ACO.

NOTE 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Atlanta ACO.

(d) Special flight permits may be issued in accordance with sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the airplane to a location where the requirements of this AD can be accomplished.

(e) The actions shall be done in accordance with EMBRAER Service Bulletin 145-32-0012, dated September 1, 1997, and EMBRAER Service Bulletin 145-32-0009, dated September 1, 1997. This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from Empresa Brasileira de Aeronautica S.A. (EMBRAER), P.O. Box 343 - CEP 12.225, Sao Jose dos Campos- SP, Brazil. Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the FAA, Small Airplane Directorate, Atlanta Aircraft Certification Office, One Crown Center, 1895 Phoenix Boulevard, suite 450, Atlanta, Georgia; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

NOTE 3: The subject of this AD is addressed in Brazilian airworthiness directive 97-10-02, dated October 13, 1997.

(f) This amendment becomes effective on July 8, 1998.

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an airworthiness directive (AD) that is applicable to certain EMBRAER Model EMB-145 series airplanes was published in the Federal Register on April 2, 1998 (63 FR 16170). That action proposed to require inspection of the main landing gear (MLG) bushing seats to detect cracks, and repair of the bushing hole or replacement of strut bushings with new bushings, if necessary. That action also proposed to require replacement of the plain bearings of the MLG shock absorber with new bearings.

Comments
Interested persons have been afforded an opportunity to participate in the making of this amendment. No comments were submitted in response to the proposal or the FAA's determination of the cost to the public.

Conclusion
The FAA has determined that air safety and the public interest require the adoption of the rule as proposed.

Cost Impact
The FAA estimates that9 airplanes of U.S. registry will be affected by this AD, that it will take approximately 1 work hour per airplane to accomplish the required inspections, and that the average labor rate is $60 per work hour. Based on these figures, the cost impact of the inspections required by this AD on U.S. operators is estimated to be $540, or $60 per airplane.

The FAA estimates that it will take approximately 6 work hours per airplane to accomplish the required replacement of the plain bearings, at an average labor rate of $60 per work hour. Required parts will be provided by the manufacturer at no cost to operators. Based on these figures, the cost impact of the replacement required by this AD on U.S. operators is estimated to be $3,240, or $360 per airplane.

The cost impact figures discussed above are based on assumptions that no operator has yet accomplished any of the requirements of this AD action, and that no operator would accomplish those actions in the future if this AD werenot adopted.

Regulatory Impact
The regulations adopted herein will not have substantial direct effects 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. Therefore, in accordance with Executive Order 12612, it is determined that this final rule does not have sufficient federalism implications to warrant the preparation of a Federalism Assessment.

For the reasons discussed above, I certify that this action (1) is not a "significant regulatory action" under Executive Order 12866; (2) is not a "significant rule" under 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. A final evaluation has been prepared for this action and it is contained in the Rules Docket. A copy of it may be obtained from the Rules Docket at the location provided under the caption "ADDRESSES."

List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.

Adoption of the Amendment
Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration amends part 39 of the Federal Aviation Regulations (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.

39.13 [Amended]
2. Section 39.13 is amended by adding the following new airworthiness directive: