AD 96-20-03

This amendment supersedes an existing airworthiness directive (AD), applicable to all de Havilland DHC-8-100 and -300 series airplanes, that currently requires repetitive inspections to detect loose bolts at the retract actuator support fitting of the main landing gear, and various follow-on actions, if necessary. That AD was prompted by a report of loose actuator supporting bolts and cracks in the relief radius of the boss at the forward surface of the fittings. This amendment adds a requirement to install a new modification, which, when accomplished, terminates the repetitive inspections. The actions specified by this AD are intended to prevent loss of hydraulic systems and reduced controllability of the airplane due to loose actuator support bolts or cracks in the relief radius of the boss at the forward surface of the fittings.

Final rule

96-20-03 DE HAVILLAND, INC.: Amendment 39-9769. Docket 95-NM-72-AD. Supersedes AD 91-20-12, Amendment 39-8046, which superseded AD 91-15-51 amendment 39-8016.
Applicability: Model DHC-8-100 and -300 series airplanes, serial numbers 3 through 400 inclusive, except serial number 391; 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 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 loss of hydraulic systems and reduced controllability of the airplane due to loose actuator support bolts or cracks in the relief radius of the boss at the forward surface of the fittings, accomplish the following:

(a) For Model DHC-8-100 series airplanes: Within 24 hours after September 9, 1991 (the effective date of AD 91-15-51, amendment 39-8016), inspect the three actuator attachment fitting bolts on the right- and left-hand main landing gears (MLG) to detect loose bolts by applying a torque of not less than 10 foot-pounds to each bolt.

(1) If no loose bolt is found as a result of the inspection required by paragraph (a) of this AD, repeat this inspection thereafter at intervals not to exceed 500 landings.

(2) If any loose bolt is found as a result of the inspection required by paragraph (a) of this AD, accomplish paragraphs (a)(2)(i), (a)(2)(ii), and (a)(2)(iii) of this AD.

(i) Prior to further flight, replace the loose bolt with a new bolt of the same part number.

(ii) Within 250 landings after October 7, 1991 (the effective date of 91-20-12, amendment 39-8046) accomplish paragraphs (a)(2)(ii)(A) and (a)(2)(ii)(B) of this AD.

(A) Remove the associated support fitting having part number (P/N) 85410084.

(B) Perform a magnetic particle inspection to detect cracks throughout the fitting, paying particular attention to the relief radius at the forward surface boss. If any crack is detected as a result of this inspection, prior to further flight, replace the fitting with a serviceable part.

(iii) Repeat the inspection required by paragraph (a) of this AD thereafter at intervals not to exceed 500 landings.

(b) For Model DHC-8-300 series airplanes: Within 250 landings after October 7, 1991 (the effective date of AD 91-20-12, amendment 39-8046), inspect the three actuator attachment fitting bolts on the right- and left-hand MLG's to detect loose bolts by applying a torque of not less than 10-foot-pounds to each bolt.

(1) If no loose bolt is found as a result of the inspection required by paragraph (b) of this AD, repeat this inspection thereafter at intervals not to exceed 500 landings.

(2) If any loose bolt is found as a result of the inspection required by paragraph (a) of this AD, accomplish paragraphs (b)(2)(i), (b)(2)(ii), and (b)(2)(iii) of this AD.

(i) Prior to further flight, replace the loose bolt with a new bolt of the same part number.

(ii) Within 250 landings after October 7, 1991 (the effective date of AD 91-20-12, amendment 39-8046), accomplish (b)(2)(ii)(A) and (b)(2)(ii)(B) of this AD.

(A) Remove the associated support fitting (P/N 85410084 for Model DHC-8-301 airplanes, and P/N 85411701 for Model DHC-8-311 airplanes).

(B) Perform a magnetic particle inspection to detect cracks throughout the fitting, pay particular attention to the relief radius at the forward surface boss. If any crack is detected as a result of this inspection, prior to further flight, replace the fitting with a serviceable part.

(iii) Repeat the inspection required by paragraph (b) of this AD thereafter at intervals not to exceed 500 landings.

(c) Within 90 days after the effective date of this AD, accomplish paragraphs (c)(1) and (c)(2), as applicable, of this AD. Accomplishment of this paragraph constitutes terminating action for the inspections required by paragraphs (a) and (b) of this AD.

(1) For Model DHC-8-100 and -300 series airplanes, having serial numbers 3 through 400 inclusive, except serial number 391: Modify the frame and the retraction actuator fitting of the MLG, in accordance with de Havilland Service Bulletin S.B. 8-54-34, Revision `A', dated July 21, 1995.

(2) For Model DHC-8-100 and -300 series airplanes, having serial number 3 through 332 inclusive: Modify the retraction actuator fitting of the MLG, in accordance with de Havilland Service Bulletin S.B. 8-54-27, Revision `B', dated August 22, 1994.

(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 modifications shall be done in accordance with de Havilland Service Bulletin S.B. 8-54-34, Revision `A', dated July 21, 1995; and de Havilland Service Bulletin S.B. 8-54-27, Revision `B', dated August 22, 1994, as applicable. 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 Bombardier, Inc., Bombardier Regional Aircraft Division, Garratt Boulevard, Downsview, Ontario, Canada M3K 1Y5. 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 November 4, 1996.

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) by superseding AD 91-20-12, amendment 39-8046 (56 FR 47901, September 23, 1991), which is applicable to all deHavilland DHC-8-100 and -300 series airplanes, was published in the Federal Register on July 16, 1996 (61 FR 37019). The action proposed to supersede AD 91-20-12 to continue to require repetitive inspections to detect loose bolts at the retract actuator support fitting of the main landing gear (MLG); and, if necessary, to require a magnetic particle inspection, replacement of loose bolts, and replacement of cracked fittings. In addition, the action proposed to require modification of the frame and the retraction actuator fitting of the MLG, which would constitute terminating action for the repetitive inspection requirements. The action also proposed to revise to 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
There are approximately 125 de Havilland Model DHC-8-100 and -300 series airplanes of U.S. registry that will be affected by this proposed AD.

The actions that are currently required by AD 91-20-12, and retained in this AD, take approximately 1 work hour per airplane to accomplish, at an average labor rate of $60 per work hour. Based on these figures, the cost impact on U.S. operators of the actions currently required is estimated to be $7,500, or $60 per airplane.

The installation of modified brackets with new fasteners that is required by this AD will take approximately 10 work hours per airplane to accomplish, at an average labor rate of $60 per work hour. Required parts will costapproximately $3,500 per airplane. Based on these figures, the cost impact of the installation required on U.S. operators is estimated to be $512,500, or $4,100 per airplane.

The removal of the enamel application (Modification 8/1830) that is required by this AD will take approximately 5 work hours per airplane to accomplish, at an average labor rate of $60 per work hour. Based on these figures, the cost impact on U.S. operators of the enamel removed required of this AD is estimated to be $37,500, or $300 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 39-8046 (56 FR 47901, September 23, 1991), and by adding a new airworthiness directive (AD), amendment 39-9769, to read as follows: