AD 95-23-08 ACTIVE

This amendment adopts a new airworthiness directive (AD), applicable to certain Avro Model BAe 146 series airplanes. This action requires inspections to detect cracking and damage of the fastener holes in the butt strap at rib 2 at the lower surface of the right-hand wing; repair of discrepancies; and replacement of the fastener bolts. This amendment is prompted by a report that certain wings were manufactured with a reduction in the amount of edge margin between the fastener hole centers and the edge of the butt strap; this condition can result in a decrease in the long-term damage tolerance residual strength of the wing. The actions specified in this AD are intended to prevent cracking and other problems associated with a such decrease in the long-term damage tolerance residual strength of the wing.

Final rule; request for comments

95-23-08 AVRO INTERNATIONAL AEROSPACE (Formerly British Aerospace): Amendment 39-9428. Docket 95-NM-210-AD.
Applicability: Model BAe 146 series airplanes; having constructors' numbers E2188, E2192, E3190, and E3194; 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 use the authority provided in paragraph (d) of this AD to request approval from the FAA. This approval may address either no action, if the current configuration eliminates the unsafe condition; or different actions necessary to address the unsafe condition described in this AD. Such a request should include an assessment of the effect of the changed configuration on the unsafe condition addressed by this AD. In no case does the presence of any modification, alteration, or repair remove any airplane from the applicability of this AD.

Compliance: Required as indicated, unless accomplished previously.

To prevent cracking and other problems associated with a decrease in the long-term damage tolerance residual strength of the wing, accomplish the following:

(a) Prior to the accumulation of 36,000 total landings or within 3 months after the effective date of this AD, whichever occurs later, remove the 4 fasteners from the rib 2 butt strap on the lower wing surface of the right-hand wing and accomplish the requirements of paragraphs (a)(1) and (a)(2) of this AD, in accordance with Avro Service Bulletin 57-40, dated March 19, 1994:

(1) Perform an eddy current inspection of each of the fastener holes to detect cracking.

(2) Perform a visual inspection of each of the fastener holes to detect evidence of damage, such as scoring that has resulted from removal of the bolts; and to check the diameter of each hole to determine if it is within the allowable tolerance specified in the service bulletin.

(b) If the fastener hole is free of cracks and damage, and if the hole's diameter is within the allowable tolerance, prior to further flight, install a new bolt in accordance with the service bulletin. Thereafter, repeat the inspections specified in paragraph (a) of this AD at intervals not to exceed 9,000 landings.

(c) If the hole is cracked or shows evidence of damage, or if the hole's diameter is outside the allowable tolerance, prior to further flight, oversize the hole, clean out the damage, and install a new bolt, in accordance with the service bulletin. Thereafter, repeat the inspections specified in paragraph (a) of this AD at intervals not to exceed 9,000 landings.

(d) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safetymay be used if approved by the Manager, Standardization Branch, ANM-113, FAA, Transport Airplane Directorate. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Standardization Branch, ANM-113.

NOTE 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Standardization Branch, ANM-113.

(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 Avro Service Bulletin 57-40, dated March 19, 1994. 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 British Aerospace Holdings, Inc., Avro International Aerospace Division, P.O. Box 16039, Dulles International Airport, Washington, DC 20041-6039. Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

(g) This amendment becomes effective on December 1, 1995.

The Civil Aviation Authority (CAA), which is the airworthiness authority for the United Kingdom, recently notified the FAA that an unsafe condition may exist on certain Avro Model BAe 146 series airplanes. The CAA advises that four wing-sets, delivered from the vendor and installed on four airplanes, were manufactured with a marked reduction in the amount of edge margin between the fastener hole centers and edge of the rib 2 butt strap on the lower surface of the right-hand wing. (Edge margin is defined as the distance from the center of the fastener hole to the nearest edge of the part.) A reduction in edge margin could lead to a decrease in the long-term damage tolerance residual strength of the wing. This condition, if not corrected, could result in fatigue cracking and other damage occurring in the subject area at a time that is earlier than anticipated.

Avro International Aerospace has issued Service Bulletin 57-40, dated March 19, 1994. This service bulletin describes procedures for removing four specific fasteners from the rib 2 butt strap on the lower surface of the right-hand wing, and conducting an eddy current inspection to detect cracking of the vacant fastener holes. The service bulletin also describes procedures for conducting a visual inspection of the fastener holes to detect other damage, such as scoring that has resulted from removal of the bolts; and to check the diameter of each hole to determine if it is within the allowable tolerance. The service bulletin also contains procedures for repairing cracked, damaged, or incorrectly sized holes by oversizing them, and for installing new fastener bolts. The CAA classified this service bulletin as mandatory in order to assure the continued airworthiness of these airplanes in the United Kingdom.

This airplane model is manufactured in the United Kingdom and is type certificated for operation in the United States under the provisions of section 21.29 of the Federal Aviation Regulations (14 CFR 21.19) and the applicable bilateral airworthiness agreement. Pursuant to this bilateral airworthiness agreement, the CAA has kept the FAA informed of the situation described above. The FAA has examined the findings of the CAA, reviewed all available information, and determined that AD action is necessary for products of this type design that are certificated for operation in the United States.

Since an unsafe condition has been identified that is likely to exist or develop on other airplanes of the same type design registered in the United States, this AD is being issued to prevent cracking and other problems associated with a decrease in the long-term damage tolerance residual strength of the wing. This AD requires repetitive eddy current inspections to detect cracking of the 4 fastener holes at the rib 2 butt strap on the lower surface of the right-hand wing. It also requires repetitive visual inspections of the fastener holes to detect other damage, such as scoring that has resulted from removal of the bolts; and to check the diameter of each fastener hole to determine if it is within the allowable tolerance. If no cracking or damage is detected in a fastener hole, and if the hole's diameter is within tolerance limits, a new bolt must be installed. If any cracking or damage is detected, or if the hole's diameter is outside of tolerance limits, the hole must be oversized and cleaned, and a new bolt must be installed. The actions are required to be accomplished in accordance with the service bulletin described previously.

None of the Model BAe 146 series airplanes affected by this action are on the U.S. Register. All airplanes included in the applicability of this rule currently are operated by non-U.S. operators under foreign registry; therefore, they are not directly affected by this AD action. However, the FAA considers that this rule is necessary to ensure that the unsafe condition is addressed in the eventthat any of these subject airplanes are imported and placed on the U.S. Register in the future.

Should an affected airplane be imported and placed on the U.S. Register in the future, it would require approximately 8 work hours to accomplish the required actions, at an average labor charge of $60 per work hour. Based on these figures, the total cost impact of this AD would be $480 per airplane.

Since this AD action does not affect any airplane that is currently on the U.S. register, it has no adverse economic impact and imposes no additional burden on any person. Therefore, notice and public procedures hereon are unnecessary and the amendment may be made effective in less than 30 days after publication in the Federal Register.

Comments Invited
Although this action is in the form of a final rule and was not preceded by notice and opportunity for public comment, comments are invited on this rule. Interested persons are invited to comment on this rule by submitting such written data, views, or arguments as they may desire. Communications shall identify the Rules Docket number and be submitted in triplicate to the address specified under the caption "ADDRESSES." All communications received on or before the closing date for comments will be considered, and this rule may be amended in light of the comments received. Factual information that supports the commenter's ideas and suggestions is extremely helpful in evaluating the effectiveness of the AD action and determining whether additional rulemaking action would be needed.

Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the rule that might suggest a need to modify the rule. All comments submitted will be available, both before and after the closing date for comments, in the Rules Docket for examination by interested persons. A report that summarizes each FAA-public contact concerned with the substance of this AD will be filed in the Rules Docket.

Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this rule must submit a self-addressed, stamped postcard on which the following statement is made: "Comments to Docket Number 95-NM-210-AD." The postcard will be date stamped and returned to the commenter.

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 USC 106(g), 40101, 40113, 44701.

39.13 - [Amended]
2. Section 39.13 is amended by adding the following new airworthiness directive:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-103, Attention: Rules Docket No. 95-NM-210-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

The service information referenced in this AD may be obtained from British Aerospace Holdings, Inc., Avro International Aerospace Division, P.O. Box 16039, Dulles International Airport, Washington, DC 20041-6039. This information may be examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

Tim Backman, Aerospace Engineer, Standardization Branch, ANM-113, FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (206) 227-2797; fax (206) 227-1149.