AD 94-08-10

This amendment supersedes Airworthiness Directive (AD) 88-13-11, which currently requires repetitively inspecting both wing main spar lower cap angles for corrosion, and repairing or replacing any corroded part. This action retains these inspection and possible repair or replacement requirements, but eliminates the dual compliance time of both hours time-in-service (TIS) and calendar time. The Federal Aviation Administration (FAA) has determined that, since corrosion occurs regardless of whether the airplane is in service, the best compliance method for the proposed action is calendar time. The actions specified by this AD are intended to prevent failure of the wing structure because of corroded wing main spar lower cap angles.

Final rule.

94-08-10 DE HAVILLAND: Amendment 39-8882; Docket No. 91-CE-47-AD. Supersedes AD 88-13-11, Amendment 39-5960.

Applicability: Models DHC-6-1, DHC-6-100, DHC-6-200, and DHC-6-300 airplanes (all serial numbers), certificated in any category.

Compliance: Required initially in accordance with whichever of the following is applicable, unless already accomplished, and thereafter at intervals not to exceed 60 calendar months:

o Upon the accumulation of 120 calendar months from the date of manufacture or within the next 3 calendar months after the effective date of this AD, whichever occurs later;

o Upon the accumulation of 120 calendar months after incorporating Wing Box Replacement Modification No. 6/1630 in accordance with de Havilland Service Bulletin (SB) No. 6/362, Revision 1, dated January 18, 1985, or within the next 3 calendar months after the effective date of this AD, whichever occurs later; or

o Upon the accumulation of 120 calendar months of originalmanufacture of wings if used wings have been installed on the airplane or within the next 3 calendar months after the effective date of this AD, whichever occurs later.

To prevent failure of the wing structure because of corroded wing main spar lower cap angles, accomplish the following:

(a) Visually inspect the wing main spar and lower spar cap extensions for corrosion using a high intensity light in accordance with paragraph A in the ACCOMPLISHMENT INSTRUCTIONS section of de Havilland SB No. 6/492, Revision A, dated October 23, 1987.

(b) If corrosion is found during the inspection required by paragraph (a) of this AD that exceeds the criteria specified in the COMPLIANCE section of de Havilland SB No. 6/492, Revision A, dated October 23, 1987, prior to further flight, accomplish the following:

(1) Remove all surface corrosion and replace the cap angles in accordance with the ACCOMPLISHMENT INSTRUCTIONS section of de Havilland SB No. 6/492, Revision A, dated October 23, 1987.

(2) Dye penetrant inspect all parts where corrosion was removed to ensure that the part is corrosion-free. Replace any parts that have corrosion damage and reprotect reworked areas utilizing information specified in de Havilland Technical Advisory Bulletin No. 626/1, dated November 1970.

(c) If any parts are reworked per the inspection result requirements of this AD, prior to further flight, accomplish the following:

(1) Submit the details of all reworked areas to the manufacturer through the New York Aircraft Certification Office (ACO) at the address specified in paragraph (e) of this AD; and

(2) Incorporate any additional instructions provided by the New York ACO as a condition for returning the airplane to service.

(d) Special flight permits may be issued in accordance with 14 CFR 21.197 and 21.199 to operate the airplane to a location where the requirements of this AD can be accomplished.

(e) 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, New York ACO, FAA, 181 South Franklin Avenue, Room 202, Valley Stream, New York 11581. The request shall be forwarded through an appropriate FAA Maintenance Inspector, who may add comments and then send it to the Manager, New York ACO.

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

(f) The inspections and repair or replacement (as necessary) required by this AD shall be done in accordance with de Havilland Service Bulletin No. 6/492, Revision A, dated October 23, 1987. 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 de Havilland, Inc., 123 Garratt Boulevard, Downsview, Ontario, Canada, M3K 1Y5. 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.

(g) This amendment (39-8882) supersedes AD 88-13-11, Amendment 39-5960.

(h) This amendment becomes effective on June 13, 1994.

A proposal to amend part 39 of the Federal Aviation Regulations to include an AD that would apply to certain de Havilland DHC-6 series airplanes was published in the Federal Register on December 28, 1993 (58 FR 68575). The action proposed to supersede AD 88-13-11 with a new AD that would retain the requirement of repetitively inspecting both wing main spar lower cap angles for corrosion, but require these inspections with a compliance method based solely on calendar time. The proposed actions would be accomplished in accordance with the ACCOMPLISHMENT INSTRUCTIONS section of de Havilland Service Bulletin No. 6/492, Revision A, dated October 23, 1987.

Interested persons have been afforded an opportunity to participate in the making of this amendment. One comment was received in support of the proposed rule.

After careful review of all available information, 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 nor add any additional burden upon the public than was already proposed.

The FAA estimates that 169 airplanes in the U.S. registry will be affected by this AD, that it will take approximately 8 workhours per airplane to accomplish the required initial inspection, and that the average labor rate is approximately $55 an hour. Based on these figures, the total cost impact of the AD on U.S. operators is estimated to be $74,360. This figure does not account for repetitive inspections. The only difference between this AD and AD 88-13-11, which will be superseded by this required action, is limiting the compliance method to only calendar time instead of both calendar time and hours TIS. Therefore, the required action will not impose any additional cost impact upon the public than that which is already required by AD 88-13-11.

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 14 CFR part 39 of the Federal Aviation Regulations as follows:

PART 39 - AIRWORTHINESS DIRECTIVES
1. The authority citation for part 39 continues to read as follows:
Authority: 49 U.S.C. App. 1354(a), 1421 and 1423; 49 U.S.C. 106(g); and 14 CFR 11.89.

Section 39.13 - [AMENDED]
2. Section 39.13 is amended by removing AD 88-13-11, Amendment 39-5960 (53 FR 23755, June 24, 1988), and by adding a new airworthiness directive to read as follows: