AD 97-06-05

This amendment adopts a new airworthiness directive (AD) that applies to Avions Pierre Robin Model R2160 airplanes. This action requires repetitively inspecting the weld area between the strut and the lower plate of the nose landing gear leg for cracks, and replacing the strut when cracks are found. The AD is the result of several reports of cracks in the weld securing the nose wheel steering bottom bracket to the nose landing gear leg on the affected airplanes. The actions specified by this AD are intended to prevent nose landing gear failure caused by cracks in the weld area between the strut and the lower plate of the nose landing gear leg, which could result in loss of control of the airplane during landing operations.

Final rule.

97-06-05 AVIONS PIERRE ROBIN: Amendment 39-9962; Docket No. 92-CE-25-AD.

Applicability: Model R2160 airplanes (all serial numbers), 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) 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 initially within the next 100 hours time-in-service (TIS) after the effective date of this AD, unless already accomplished, and thereafter as follows, as applicable:

1. If the width of the lower plate of the bottom bracket of the nose landing gear leg is 84 millimeters: at intervals not to exceed 500 hours TIS; or

2. If the width of the lower plate of the bottom bracket of the nose landing gear leg is less than 84 millimeters: at intervals not to exceed 100 hours TIS.

To prevent nose landing gear failure caused by cracks in the weld area between the strut and the lower plate of the nose landing gear leg, which could result in loss of control of the airplane during landing operations, accomplish the following:

(a) Inspect, using dye penetrant methods, the weld area between the strut and the lower plate of the nose landing gear leg for cracks in accordance with Avions Pierre Robin Service Bulletin (SB) No. 101, Revision 3, dated March 5, 1992.

(b) If any crack is found during any inspection required by this AD, prior tofurther flight, replace the strut with a new or serviceable strut.

(1) If the replacement strut is not new, prior to further flight after installing the strut, accomplish the inspection specified in paragraph (a) of this AD.

(2) Replacing the strut with a new or serviceable strut does not eliminate the repetitive inspection requirement of this AD.

(c) 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.

(d) An alternative method of compliance or adjustment of the initial or repetitive compliance times that provides an equivalent level of safety may be approved by the Manager, Brussels Aircraft Certification Division, FAA, Europe, Africa, and Middle East Office, c/o American Embassy, B-1000 Brussels, Belgium. The request shall be forwarded through an appropriate FAA Maintenance Inspector, who may add comments and then send it to the Manager, Brussels Aircraft Certification Division.

NOTE 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Brussels Aircraft Certification Division.

(e) The inspection required by this AD shall be done in accordance with Avions Pierre Robin Service Bulletin No. 101, Revision 3, dated March 5, 1992. 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 Avions Pierre Robin, 1, Route de Troyes, 21121 Darois France. Copies may be inspected at the FAA, Central Region, Office of the Assistant Chief Counsel, Room 1558, 601 E. 12th Street, Kansas City, Missouri, or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

(f) This amendment becomes effective on May 16, 1997.

Events Leading to the Issuance of This AD
A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an AD that would apply to Avions Pierre Robin Model R2160 airplanes was published in the Federal Register as a notice of proposed rulemaking (NPRM) on November 13, 1996 (61 FR 58145). The NPRM proposed to require repetitively inspecting the weld area between the strut and the lower plate of the nose landing gear leg for cracks, and replacing the strut when cracks are found. Accomplishment of the proposed inspections as specified in the NPRM would be in accordance with Avions Pierre Robin Service Bulletin (SB) No. 101, Revision 3, dated March 5, 1992.

The NPRM resulted from several reports of cracks in the weld securing the nose wheel steering bottom bracket to the nose landing gear leg on the affected airplanes.

Interested persons have been afforded an opportunity to participate in the making of this amendment. No comments were received on the proposed AD or the FAA's determination of the cost to the public.

The FAA's Determination
After careful review of all available information related to the subject presented above, the FAA has determined that air safety and the public interest require the adoption of the rule as proposed except for minor editorial corrections. The FAA has determined that these minor corrections will not change the meaning of the AD and will not add any additional burden upon the public than was already proposed.

Differences Between This AD, Service Bulletin, and DGAC AD
Both Avions Pierre Robin SB No. 101, Revision 3, dated March 5, 1992, and DGAC AD 83-206(A)R3, dated March 18, 1992, specify repetitive inspection intervals of 25 hours time-in-service if a crack in the weld area is found that is within a certain limit. The limit is "if the crack runs along the circumference and is less than 15 mm long max. or/and radial crack is less than 8 mm max." This AD does not allow continued flight if any crack is found. FAA policy is to disallow airplane operation when known cracks exist in primary structure, unless the ability to sustain ultimate load with these cracks is proven. The nose landing gear leg is considered primary structure, and the FAA has not received any analysis to prove that ultimate load can be sustained with cracks in this area.

Cost Impact
The FAA estimates that 10 airplanes in the U.S. registry will be affected by this AD, that it will take approximately 1 workhour per airplane to accomplish the initial inspection, and that the average labor rate is approximately $60 an hour. Based on these figures, the total cost impact of the AD on U.S. operators is estimated to be $600. This figure does not take into account the number of repetitive inspections each airplane owner/operator will incur over the life of the airplane, or the number of airplanes that could have cracked weld areas and would need the strut replaced. TheFAA has no way of determining the number of repetitive inspections each owner/operator would incur over the life of the airplane or the number of nose landing gear leg struts that could need to be replaced because of cracks in the weld area.

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 copy of the final evaluation prepared for this action is contained in the Rules Docket. A copy of it may be obtained by contacting 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 USC 106(g), 40113, 44701.

39.13 [Amended]
2. Section 39.13 is amended by adding a new airworthiness directive (AD) to read as follows: