AD 99-02-18

This amendment adopts a new airworthiness directive (AD), applicable to certain EMBRAER Model EMB-120 series airplanes, that requires removing the thermal insulating blankets from the upper rear nacelle structure; re-positioning the engine exhaust duct; and replacing the engine exhaust bracket with a new engine exhaust bracket, if necessary. For certain airplanes, this amendment also requires installing new stainless steel plates onto the upper rear nacelle structure. 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 fretting of the titanium thermal insulating blankets, which could result in an increased risk of fire in the engine exhaust duct of the tail pipe.

Final rule.

99-02-18 EMPRESA BRASILEIRA DE AERONAUTICA S.A. (EMBRAER): Amendment 39-11012. Docket 98-NM-265-AD.

Applicability: Model EMB-120 series airplanes, serial numbers (S/N) 120003, 120004, and 120006 through 120336 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 (e) 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: Required as indicated, unless accomplished previously.

To prevent fretting of the titanium thermal insulating blankets, which could result in an increased risk of fire in the engine exhaust duct of the tail pipe, accomplish the following:

(a) For airplanes identified in "Part I" of the effectivity listing of EMBRAER Service Bulletin S.B. 120-54-0035, Change 02, dated May 29, 1998: Within 2,400 flight hours after the effective date of this AD, accomplish paragraphs (a)(1) and (a)(2) in accordance with the service bulletin.

(1) Remove the thermal insulating blankets from the upper rear nacelle structure.

(2) Install new stainless steel plates onto the upper rear nacelle structure.

(b) For airplanes identified in "Part II" of the effectivity listing of EMBRAER Service Bulletin S.B. 120-54-0035, Change 02, dated May 29, 1998: Within 2,400 flight hours after the effective date of this AD, remove the thermal insulating blankets from the upper rear nacelle structure in accordance with the service bulletin.

(c) For all airplanes: Prior to further flight following accomplishment of either paragraph (a) or (b) of this AD, as applicable, re-position the engine exhaust duct with the use of shims in accordance with EMBRAER Service Bulletin S.B. 120-54-0035, Change 02, dated May 29, 1998. If it is not possible to re-position the engine exhaust duct with the use of shims as specified in the service bulletin, prior to further flight, replace the rear exhaust duct bracket with a new rear exhaust duct bracket, in accordance with the NOTE in paragraph 1.3.1.1 of the Planning section of the service bulletin.

(d) As of the effective date of this AD, no person shall install on any airplane a thermal insulating blanket having part number (P/N) 120-35411-025, -035, -036, 120-35413-001, or 120-35411-002.

(e) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may beused 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.

(f) 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.

(g) The actions shall be done in accordance with EMBRAER Service Bulletin S.B. 120-54-0035, Change 02, dated May 29, 1998. 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 deAeronautica 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 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 directives 97-11-03, dated December 3, 1997, and 97-11-03R1, dated July 6, 1998. Issued in Renton, Washington, on November 9, 1998.

(h) This amendment becomes effective on March 3, 1999.

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-120 series airplanes was published in the Federal Register on November 16, 1998 (63 FR 63620). That action proposed to require removing the thermal insulating blankets from the upper rear nacelle structure; re-positioning the engine exhaust duct; and replacing the engine exhaust bracket with a new engine exhaust bracket, if necessary. For certain airplanes, that action also proposed to require installing new stainless steel plates onto the upper rear nacelle structure.

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

Cost Impact
The FAA estimates that 171 Model EMB-120 series airplanes of U.S. registry will be affected by this AD.

It will take approximately 9 work hours per airplane to accomplish the required actions on airplanes listed in "Part I" of EMBRAER Service Bulletin S.B. 120-54-0035, Change 02, at an average labor rate of $60 per work hour. Required parts will cost approximately $337 per airplane. Based on these figures, the cost impact of the AD on U.S. operators of airplanes listed in "Part I" of the service bulletin is estimated to be $877 per airplane.

It will take approximately 2 work hours per airplane to accomplish the actions on airplanes listed in "Part II" of EMBRAER Service Bulletin S.B. 120-54-0035, Change 02, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of the requirements of this AD on U.S. operators of airplanes listed in "Part II" of the service bulletin is estimated to be $120 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 were not 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: