AD 97-24-13

This amendment adopts a new airworthiness directive (AD), applicable to certain British Aerospace BAe Model ATP airplanes, that requires a detailed visual inspection of the flap drive torque tubes in the wing root area to detect inadequate clearance between the torque tubes and surrounding structure or scoring damage to the tubes; and follow-on repetitive inspections or corrective action, if necessary. Accomplishment of certain replacements and modifications would constitute terminating action for the repetitive inspections. This amendment is prompted by reports of inadequate clearance between flap drive torque tubes and surrounding structures, and possible scoring damage to the tubes. The actions specified by this AD are intended to prevent failure of the torque tubes, which could result in an asymmetric flap condition and reduced controllability of the airplane.

Final rule

97-24-13 British Aerospace Regional Aircraft [Formerly Jetstream Aircraft Limited, British Aerospace (Commercial Aircraft) Limited]: Amendment 39-10220. Docket 96-NM-189-AD.
Applicability: BAe Model ATP airplanes, constructor numbers 2002 through 2063 inclusive; 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 (c) 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 shouldinclude specific proposed actions to address it.

Compliance: Required as indicated, unless accomplished previously.

To prevent failure of the torque tubes, which could result in an asymmetric flap condition and reduced controllability of the airplane, accomplish the following:

(a) Within 90 days after the effective date of this AD, conduct a detailed visual inspection of the flap drive torque tubes in the left and right wing root areas to detect inadequate clearance between the torque tubes and surrounding structure or scoring damage to the tubes, in accordance with Jetstream Service Bulletin ATP-27-80, dated April 23, 1996.

(1) If adequate clearance exists between all flap drive torque tubes and surrounding structure at the sites specified in the service bulletin, with no scoring damage to any of the tubes, no further action is required by this AD.

(2) If inadequate clearance exists between any flap drive torque tube and surrounding structure at the sites specified in the service bulletin, with no scoring damage to the tubes: Accomplish the requirements of paragraphs (a)(2)(i) and (a)(2)(ii) of this AD.

(i) At intervals not to exceed 250 hours time-in-service, repeat the detailed visual inspections required by paragraph (a) of this AD.

(ii) Within 2,000 hours time-in-service after the initial inspection required by paragraph (a) of this AD, modify the structure to gain the required minimum clearance in accordance with the service bulletin. Accomplishment of the modification constitutes terminating action for the repetitive inspection requirement of paragraph (a)(2)(ii) of this AD.

(3) If any scoring damage to the torque tubes is detected, accomplish the requirements specified in paragraph (a)(3)(i), (a)(3)(ii), or (a)(3)(iii) of this AD, as applicable, in accordance with the service bulletin, and at the time specified in the applicable paragraph.

(i) If only one torque tube on one side or both sidesof the airplane is damaged, and the scoring is within the maximum allowable damage limits in the service bulletin: Within 250 hours time-in-service after any inspection required by this AD in which the damage was initially detected, modify the surrounding structure to gain the required minimum clearance and install a new torque tube.

(ii) If both torque tubes on the same side of the airplane are damaged, and the scoring is within the maximum allowable damage limits in the service bulletin: Prior to further flight after any inspection required by this AD in which damage was initially detected, modify the surrounding structure to gain the required minimum clearance and replace at least one of the damaged torque tubes with a new torque tube. Within 250 hours time-in-service after any inspection in which damage was initially detected, replace the remaining damaged torque tube with a new torque tube.

(iii) If any torque tube is damaged, and the scoring is more than theallowable damage limits described in the service bulletin: Prior to further flight, modify the surrounding structure to gain the required minimum clearance and replace the damaged tube(s) with a new torque tube(s).

(b) Accomplishment of the modification to gain the required minimum clearance between the torque tubes and surrounding structure and the replacement of damaged torque tube(s) with a new torque tube(s) constitutes terminating action for the requirements of this AD.

(c) 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, International Branch, ANM-116, 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, International Branch, ANM-116.

NOTE 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the International Branch, ANM-116.

(d) 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.

(e) The actions shall be done in accordance with Jetstream Service Bulletin ATP-27-80, dated April 23, 1996. 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 AI(R) American Support, Inc., 13850 McLearen Road, Herndon, Virginia 20171. 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.

NOTE 3: The subject of this AD is addressed in British airworthiness directive 003-04-96.(f) This amendment becomes effective on January 2, 1998.

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an airworthiness directive (AD) that is applicable to certain British Aerospace BAe Model ATP airplanes was published in the Federal Register on August 25, 1997 (62 FR 44917). That action proposed to require a detailed visual inspection of the flap drive torque tubes in the wing root area to detect inadequate clearance between the torque tubes and surrounding structure or scoring damage to the tubes; and follow-on repetitive inspections or corrective action, if necessary.

Comments
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 10 British Aerospace BAe Model ATP airplanes of U.S. registry will be affected by this AD, that it will take approximately 1 work hour per airplane to accomplish the required actions, and that the average labor rate is $60 per work hour. Based on these figures, the cost impact of the AD on U.S. operators is estimated to be $600, or $60 per airplane.

The cost impact figure discussed above is 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 part39) 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 adding the following new airworthiness directive: