AD 97-16-05

This amendment supersedes an existing airworthiness directive (AD), applicable to all Gulfstream Model G-159 (G-I) airplanes, that currently requires repetitive inspections to detect corrosion in the wing planks under the bottom wing center fairings, and repair, if necessary. This amendment requires the installation of a protective paint system which, when accomplished, will allow the inspections to be conducted at longer intervals. This amendment is prompted by the development of a modification that will improve the corrosion resistance of the subject area. The actions specified by this AD are intended to detect and prevent corrosion in the lower skins of the wing center section. If corrosion in this area remains unchecked, it could reduce the integrity of the wing-to-fuselage fitting, and consequently could lead to separation of the wing from the airplane.

Final rule

97-16-05 GULFSTREAM AEROSPACE CORPORATION: Amendment 39-10096. Docket 97-NM-18-AD. Supersedes AD 67-04-01, Amendment 39-1234.

Applicability: All Model G-159 (G-I) airplanes, certificated in any category.

NOTE 1: This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been otherwise 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 (d)(1) 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 detect and prevent corrosion in the lower skins of the wing center section, which could reduce the integrity of the wing-to-fuselage fitting and consequently could lead to separation of the wing from the airplane, accomplish the following:

(a) For all airplanes: Within 4 weeks after July 3, 1971 (the effective date of AD 67-04-01, amendment 39-1234), remove the bottom wing center fairings having part numbers (P/N) 159W10400-121 and 159W10401-121, or use an FAA-approved equivalent method, to perform a visual inspection to detect corrosion of the wing planks under these fairings.

NOTE 2: Paragraph (a) of this AD merely restates the actions previously required by AD 67-04-01, amendment 39-1234. As allowed by the phrase, "unless accomplished previously," if those requirements of AD 67-04-01 have already been accomplished, this AD does not require that those actions be repeated.

NOTE 3: Care must be exercised when removing the fairings, since the attaching rivets go into the pressure vessel. Use caution not to enlarge rivet holes when removing rivets. When reinstalling the fairings, an adequate type fastener and sealant must be used.

NOTE 4: Grumman Service Newsletter, Volume 166, dated August-September 1966, pertains to this subject.

(b) For airplanes on which a protective paint system has not been installed in accordance with Grumman Gulfstream I Aircraft Service Change No. 190, dated June 28, 1971: Accomplish paragraphs (b)(1) and (b)(2) of this AD. As of the effective date of this AD, the inspections required by this paragraph shall be accomplished in accordance with Grumman Gulfstream I Aircraft Service Change No. 190, dated June 28, 1971.

NOTE 5: The repeated inspection referred to in this paragraph is the same inspection previously required by AD 67-04-01. Paragraph (b)(1) of this AD merely restates the requirement of AD 67-04-01 to repeat the inspection at intervals of 6 months. Paragraph (b)(2) permits the reinspection interval to be extended to 18 months once the specified protective paint system is installed.

(1) As a result of the inspection required by paragraph (a) of this AD:

(i) If no corrosion is detected, repeat the inspection thereafter at intervals not to exceed 6 months (26 weeks) until the actions specified in paragraph (b)(2) of this AD are accomplished.

(ii) If any corrosion is detected, prior to further flight, either repair the corroded part with an FAA-approved repair; or replace the corroded part with a new or serviceable part of the same part number; or replace the corroded part with a part approved by the FAA. Thereafter, continue to perform the inspection at intervals not to exceed 6 months (26 weeks) until paragraph (b)(2) of this AD is accomplished.

(2) Within 12 months after the effective date of this AD, install the protective paint system in accordance with Grumman Gulfstream I Aircraft Service ChangeNo. 190, dated June 28, 1971. After installation, continue to perform the inspection required by this paragraph at intervals not to exceed 18 months.

(c) For airplanes on which a protective paint system has been installed previously in accordance with Grumman Gulfstream I Aircraft Service Change No. 190, dated June 28, 1971: Accomplish paragraphs (c)(1) and (c)(2) of this AD. As of the effective date of this AD, the inspections required by this paragraph shall be accomplished in accordance with Grumman Gulfstream I Aircraft Service Change No. 190, dated June 28, 1971.

NOTE 6: The repeated inspection referred to in this paragraph is the same inspection previously required by AD 67-04-01. Paragraph (c)(1) of this AD merely restates the requirement of AD 67-04-01 to repeat the inspection at intervals of 12 months. Paragraph (c)(2) permits the reinspection interval to be extended to 18 months.

(1) As a result of the inspection required by paragraph (a) of this AD:(i) If no corrosion is detected, repeat the inspection thereafter at intervals not to exceed 12 months until paragraph (c)(2) of this AD is accomplished.

(ii) If any corrosion is detected, prior to further flight, either repair the corroded part with an FAA-approved repair; or replace the corroded part with a new or serviceable part of the same part number; or replace the corroded part with a part approved by the FAA. Thereafter, continue to perform the inspection at intervals not to exceed 12 months until paragraph (c)(2) of this AD is accomplished.

(2) Within 18 months since the last inspection accomplished in accordance with paragraph (c)(1) of this AD (i.e., the last inspection accomplished in accordance with AD 67-04- 01), repeat the inspection specified in paragraph (c)(1) of this AD.

(i) If no corrosion is detected, repeat the inspection thereafter at intervals not to exceed 18 months.

(ii) If any corrosion is detected, prior to further flight, repair in accordance with the service change. After repair, continue to perform the inspection at intervals not to exceed 18 months.

(d) (1) 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.

(2) Alternative methods of compliance, approved previously in accordance with AD 67-04-01, amendment 39-1234, are approved as alternative methods of compliance with this AD.

NOTE 7: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Atlanta ACO.

(e) 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.

(f) The actions shall be done in accordance with Grumman Gulfstream I Aircraft Service Change No. 190, dated June 28, 1971. 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 Gulfstream Aerospace Corporation, Technical Operations Department, P.O. Box 2206, M/S D-10, Savannah, Georgia 31402-2206. Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the FAA, Atlanta Aircraft Certification Office, Small Airplane Directorate, Campus Building, 1701 Columbia Avenue, Suite 2-160, College Park, Georgia; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

(g) This amendment becomes effective on September 5, 1997.

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) by superseding AD 67-04-01, amendment 39-1234 (36 FR 12688, July 3, 1971), which is applicable to all Gulfstream Model G-159 (G-I) airplanes, was published in the Federal Register on March 6, 1997 (62 FR 10224). The action proposed to continue to require the repetitive visual inspections, specified in AD 67-04-01, to detect corrosion of the wing planks under the bottom wing center fairing assemblies, and repair, if necessary.

For airplanes on which a protective paint system had not been installed previously, the action proposed to require that the inspection continue to be repeated at intervals of 6 months (26 weeks), until a protective paint system is installed within 12 months. Once the paint system is installed, the repetitive inspections were proposed to be required to continue, but the repetitive interval would be extended to 18 months.

For airplanes on which aprotective paint system was installed previously, the action proposed to extend the currently-required repetitive inspection interval of 12 months to 18 months.

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
There are approximately 146 Gulfstream Model G-159 airplanes of the affected design in the worldwide fleet. The FAA estimates that 72 airplanes of U.S. registry will be affected by this AD.

The inspections that are currently required by AD 67-04-01, and those that are required by this action, take approximately 40 work hours per airplane to accomplish, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of the required inspection actionson U.S. operators is estimated to be $172,800, or $2,400 per airplane, per inspection.

The installation of the protective paint system that is required by this AD action will take approximately 30 work hours per airplane to accomplish, at an average labor rate of $60 per work hour. Required materials will cost approximately $100 per airplane. Based on these figures, the cost impact of this requirement of this AD on U.S. operators is estimated to be $136,800, or $1,900 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 removing amendment 39-1234 (36 FR 12688, July 3, 1971), and by adding a new airworthiness directive (AD), amendment 39-10096, to read as follows: