AD 97-14-10

This amendment supersedes an existing airworthiness directive (AD), applicable to certain Gulfstream Model G-159 (G-I) airplanes, that currently requires modification and repetitive inspections for cracks in the main landing gear (MLG) retract cylinder attachment fittings. This amendment requires installation of improved attachment fittings which, when accomplished, terminates the requirement for the repetitive inspections. This amendment is prompted by the development of a modification that positively addresses the identified unsafe condition. The actions specified by this AD are intended to prevent failure of the MLG retract cylinder attachment fitting due to fatigue cracking. This condition, if not corrected, could result in the inability to retract the MLG.

Final rule

97-14-10 GULFSTREAM AEROSPACE CORPORATION (formerly Grumman): Amendment 39-10068. Docket 97-NM-16-AD. Supersedes AD 67-31-08, Amendment 39-515.

Applicability: Model G-159 (G-I) airplanes; serial numbers (S/N) 1 through 12 inclusive, 14 through 112 inclusive, 114 through 148 inclusive, 322, and 323; on which main landing gear cylinder attach fitting assemblies having part number (P/N) 159WM10276-1 and -2 and balls having P/N 159WM10277-1 are not installed; 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 (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 prevent failure of the main landing gear (MLG) retract cylinder attachment fittings due to fatigue cracking, which could result in the inability to retract the MLG, accomplish the following:

(a) Accomplish the actions specified in paragraphs (a)(1) and (a)(2) of this AD, at the times indicated in those paragraphs and in accordance with Grumman Gulfstream Customer Bulletin No. 172, dated September 6, 1963.

(1) Beginning November 7, 1967 (the effective date of AD 67-31-08, amendment 39-515), and prior to each flight, conduct a visual inspection to detect cracks in the MLG retract cylinder attachment fittings on the lower surface of the right-hand and left-hand wings in the vicinity of the aft end of the fitting.

(2) Within 25 hours time-in-service after November 7, 1967, accomplish the actions specified in paragraphs (a)(2)(i) and (a)(2)(ii) of this AD:

(i) Conduct a dye penetrant inspection, in conjunction with at least a 10X magnifying glass, to detect cracks in the MLG retract cylinder attachment fittings on the lower surface of the right-hand and left-hand wings in the vicinity of the aft end of the fitting. Repeat this inspection thereafter at intervals not to exceed 25 hours time-in-service. And

(ii) Modify the aft end edges of the fitting by rounding them off to approximately 1/32" radius.

(b) If any crack is found during an inspection required by paragraph (a) of this AD, prior to further flight, accomplish either paragraph (b)(1) or (b)(2) of this AD:

(1) Replace the cracked part with a part of the same part number that has been modified and inspected in accordance with paragraph (a) of this AD, in accordance with Grumman Gulfstream Customer Bulletin No. 172, dated September 6, 1963. Thereafter, continue the inspections required by paragraph (a) of this AD. Or

(2) Replace the fitting assembly with an assembly having part number (P/N) 159WM10276-1 or -2, and balls having P/N 159WM10277-1. After accomplishing this replacement, the repetitive inspections of that fitting required by paragraph (a) of this AD may be terminated.

(c) Within 400 hours time-in-service after the effective date of this AD, replace the MLG retract cylinder attachment fitting assemblies with assemblies having part numbers (P/N) 159WM10276-1 and -2, and balls having P/N 159WM10277-1. This replacement constitutes terminating action for the inspection requirements of this AD.

(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 67-31-08, amendment 39-515, are approved as alternative methods of compliance with this AD.

NOTE 2: 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 Gulfstream Customer Bulletin No. 172, dated September 6, 1963. 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 August 7, 1997.

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) by superseding AD 67-31-08, amendment 39-515 (32 FR 16201, November 28, 1967), which is applicable to certain Gulfstream Model G-159 (G-I) airplanes, was published in the Federal Register on March 6, 1997 (62 FR 10228). The action proposed to supersede AD 67-31-08 to continue to require repetitive inspections and modification of the MLG retract cylinder attachment fittings, and replacement, if necessary. It also proposed to require that the attachment fitting assemblies eventually be replaced with assemblies made of steel. Once this replacement is accomplished, the previously required modification and inspections may be terminated.

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 (G-I) 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 actions that are currently required by AD 67-31-08 take approximately 3 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 currently required actions on U.S. operators is estimated to be $12,960, or $180 per airplane, per inspection.

The replacement action that is required by this AD action will take approximately 45 work hours per airplane to accomplish, at an average labor rate of $60 per work hour. Required parts will cost approximately $5,400 per airplane. Based on these figures, the cost impact of the requirements of this AD on U.S. operators is estimated to be $583,200, or $8,100 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 39-515 (32 FR 16201, November 28, 1967), and by adding a new airworthinessdirective (AD), amendment 39-10068, to read as follows: