AD 94-14-22 ACTIVE

This amendment adopts a new airworthiness directive (AD) that applies to de Havilland DHC-6 series airplanes. This action requires repetitively inspecting the horizontal stabilizer center hinge bracket for cracks, and replacing any cracked center hinge bracket. Several reports of cracks in the horizontal stabilizer center hinge bracket flange on the affected airplanes prompted this action. The actions specified by this AD are intended to prevent separation of the elevator control support from the airplane as a result of a cracked horizontal stabilizer center hinge bracket, which could result in reduced controllability of the airplane.

Final rule.

94-14-22 DE HAVILLAND: Amendment 39-8971; Docket No. 93-CE-52-AD.

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 within the next 250 hours time-in-service (TIS), unless already accomplished, and thereafter at intervals not to exceed 1,200 hours TIS.

To prevent separation of the elevator control support from the airplane as a result of a cracked horizontal stabilizer center hinge bracket, which could result in reduced controllability of the airplane, accomplish the following:

(a) Inspect the horizontal stabilizer center hinge bracket for cracks in accordance with the ACCOMPLISHMENT INSTRUCTIONS section of de Havilland Service Bulletin 6/512, dated October 25, 1991, except that where dye penetrant inspections are specified, accomplish visual inspections with a strong light source and 10X magnifying glass. If any cracks are found, prior to further flight, replace the center hinge bracket in accordance with the referenced service bulletin.

NOTE 1: The repetitive inspection requirement of this AD still applies if the center hinge bracket is replaced.

(b) 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.

(c) 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 Aircraft Certification Office (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 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the New York ACO.

(d) The inspections required by this AD shall be done in accordance with de Havilland Service Bulletin 6/512, dated October 25, 1991. 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 M3K 1Y5 Canada. 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.

(e) This amendment becomes effective on August 31, 1994.

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an AD that would apply to certain de Havilland DHC-6 series airplanes was published in the Federal Register on February 17, 1994 (59 FR 7913). The action proposed to require repetitively inspecting the horizontal stabilizer center hinge bracket for cracks, and replacing any cracked center hinge bracket. The proposed action would be accomplished in accordance with the ACCOMPLISHMENT INSTRUCTIONS section of de Havilland Service Bulletin 6/512, dated October 25, 1991.

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

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 1 workhour per airplane to accomplish the required action, 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 $9,295. This figure only includes the cost for the initial inspection and does not include replacement costs if a center hinge bracket is found cracked nor does it include repetitive inspection costs. The FAA has no way to determine how many center hinge brackets may be cracked or how many repetitive inspections each owner/operator may incur.

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 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 adding a new airworthiness directive to read as follows:

Service information that applies to this AD may be obtained from de Havilland, Inc., 123 Garratt Boulevard, Downsview, Ontario, Canada, M3K 1Y5. This information may also be examined at the Federal Aviation Administration (FAA), Central Region, Office of the Assistant Chief Counsel, Room 1558, 601 E. 12th Street, Kansas City, Missouri 64106; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

Jon Hjelm, Aerospace Engineer, FAA, New York Aircraft Certification Office, 181 South Franklin Avenue, Room 202, Valley Stream, New York 11581; telephone (516) 791-6220; facsimile (516) 791-9024.