AD 96-23-09

This amendment supersedes an existing airworthiness directive (AD), applicable to certain de Havilland Model DHC-8-100 and -300 series airplanes, that currently requires repetitive inspections to detect cracks of the upper drag strut trunnion fittings of the nose landing gear (NLG) and to verify tightness of the fitting attachment bolts, and replacement of fittings or fasteners, if necessary. This amendment requires the installation of a modification to terminate 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 upper drag strut trunnion fittings of the NLG, which could lead to collapse of the NLG.

Final rule

96-23-09 DE HAVILLAND, INC.: Amendment 39-9814. Docket 93-NM-194-AD. Supersedes AD 93-08-03, Amendment 39-8550.
Applicability: Model DHC-8-102, -103, -301, -311, and -314 series airplanes; having serial numbers 003 through 395 inclusive, but excluding serial numbers 011, 362, and 391; on which Modification 8/2139 (as described in de Havilland Service Bulletin S.B. 8-53-49, dated June 30, 1995) has not been accomplished; 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) of this AD. The request should include an assessment of the effectof 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 upper drag strut trunnion fittings of the nose landing gear (NLG), which could lead to collapse of the NLG, accomplish the following:

(a) Within 500 landings after May 27, 1993 (the effective date of AD 93-08-03, Amendment 39-8550), unless accomplished within the last 500 landings, conduct a visual inspection of both upper drag strut trunnion fittings of the NLG to detect cracks; and conduct an inspection of the fitting attachment bolts to verify tightness; in accordance with de Havilland DHC-8 Alert Service Bulletin S.B. A8-53-40, Revision `A', dated June 12, 1992; or Revision `B', dated February 24, 1993; or Revision `D', dated June 30, 1995.

(1) If no crack is detected in the upper drag strut trunnion fittings of the NLG, and no looseness is detected in the fitting attachment bolts, repeat the inspections at intervals not to exceed 1,000 landings until the modification required by paragraph (b) of this AD is accomplished.

(2) If any crack is detected on either fitting, prior to further flight, replace both fittings with confirmed crack-free fittings in accordance with the service bulletin. After such replacement, the inspections required by this paragraph must continue at intervals not to exceed 1,000 landings until the modification required by paragraph (b) of this AD is accomplished.

(3) If any fitting attachment bolt is found to be loose during the initial inspection, prior to further flight, replace the fasteners (nut, washer, and bolt) that secure the fitting, in accordance with the service bulletin. After such replacement, the inspections required by this paragraph must continue at intervals not to exceed 1,000 landings until the modification required by paragraph (b) of this AD is accomplished.

(4) If any fastener is found to be loose during any repetitive inspection required by this AD, prior to further flight, tighten the bolt to the value specified in the service bulletin.

(b) Within 6 months after the effective date of this AD, install Modification 8/2139 in accordance with de Havilland Service Bulletin S.B. 8-53-49, dated June 30, 1995. Installation of this modification constitutes terminating action for the inspection requirements of this AD.

(c) Installation of Modification 8/2139, in accordance with de Havilland Service Bulletin S.B. 8-53-49, dated June 30, 1995, constitutes terminating action for the inspections required by this AD.

(d) 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, New York Aircraft Certification Office (ACO), FAA, Engine and Propeller Directorate. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, New York ACO.

NOTE 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the New York 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 de Havilland DHC-8 Alert Service Bulletin S.B. A8-53-40, Revision `A', dated June 12, 1992, Revision `B', dated February 24, 1993, Revision `D', dated June 30, 1995; and de Havilland Service Bulletin S.B. 8-53-49, dated June 30, 1995. The incorporation by reference of de Havilland DHC-8 Alert Service Bulletin S.B. A8-53-40, Revision `A', dated June 12, 1992, and Revision `B', dated February 24, 1993, was approved previously by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51 as of May 27, 1993 (58 FR 25549, April 27, 1993). The incorporation by reference of de Havilland DHC-8 Alert Service Bulletin S.B. A8-53-40, Revision `D', dated June 30, 1995; and de Havilland Service Bulletin S.B. 8-53-49, dated June 30, 1995, is 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 Bombardier, Inc., Bombardier Regional Aircraft Division, Garratt Boulevard, Downsview, Ontario M3K 1Y5, Canada. Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the FAA, New York Aircraft Certification Office, Engine and Propeller Directorate, 10 Fifth Street, Third Floor, Valley Stream, New York; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.(g) This amendment becomes effective on December 27, 1996.

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) by superseding AD 93-08-03, amendment 39-8550 (58 FR 25549, April 27, 1993), which is applicable to certain de Havilland Model DHC-8-100 and -300 series airplanes, was published as a supplemental notice of proposed rulemaking (NPRM) in the Federal Register on September 9, 1996 (61 FR 47459). The action proposed to supersede AD 93-08-03 to continue to require repetitive inspections to detect cracks of the upper drag strut trunnion fittings of the nose landing gear (NLG) and to verify tightness of the fitting attachment bolts, and replacement of the fittings or fasteners, if necessary. That action also proposed to require the installation of a modification to terminate the repetitive inspections. Additionally, the action also proposed revise the applicability of the existing AD.

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 that 146 de Havilland Model DHC-8-100 and -300 series airplanes of U.S. registry will be affected by this AD.

Accomplishment of the currently required inspections takes approximately 1 work hour per airplane, at an average labor rate of $60 per hour. Based on these figures, the cost impact of the currently required inspection actions on U.S. operators is estimated to be $8,760, or $60 per airplane, per inspection.

The modification will take approximately 18 work hours per airplane to accomplish, at an average labor rate of $60 per work hour. Required parts will cost approximately $3,325 per airplane. Based on these figures, the cost impact of the AD on U.S. operators is estimated to be $638,725, or $4,405per 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 39-8550 (58 FR 25549, April 27, 1993), and by adding a new airworthiness directive (AD), amendment 39-9814, to read as follows: