AD 97-15-02

This amendment adopts a new airworthiness directive (AD), applicable to all Aerospatiale Model ATR42 and ATR72 series airplanes, that requires replacement of the attachment clips on the wing-to-fuselage fairings and on the upper cowlings of the engine nacelle with new improved attachment clips, and adding cup washers on the wing-to-fuselage fairing panels on certain airplanes. This amendment also requires a one-time inspection of certain fairings and the upper cowlings of the engine nacelle to detect discrepancies of the attachment hardware and the fairing panel; and replacement of the panel with a serviceable panel, if necessary. This amendment is prompted by a report of deformed attachment clips found on the wing-to-fuselage fairings and on the upper cowlings of the engine nacelle, and by a report of severe inflight vibration due to a loose wing/body fairing panel. The actions specified by this AD are intended to prevent deformation of the attachment clips due to insufficient strength of the attachment clip material. Such deformation of the attachment clips could result in the fairings and cowlings detaching from the airplane during flight and subsequently causing damage to the empennage or posing a hazard to persons or property on the ground.

Final rule; request for comments.

97-15-02 AEROSPATIALE: Amendment 39-10075. Docket 95-NM-84-AD.

Applicability: All Model ATR42 series airplanes and Model ATR72 series airplanes, certificated in any category.

NOTE 1: This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been 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 (e) 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 deformation of the attachment clips on the wing-to-fuselage fairings and on the upper cowlings of the engine nacelle, which could result in the fairing and cowlings detaching from the airplane during flight and subsequently causing damage to the empennage or posing a hazard to persons or property on the ground, accomplish the following:

(a) Within 30 days after the effective date of this AD, perform a one-time detailed visual inspection of the wing-to-fuselage fairings and the upper cowlings of the engine nacelle to ensure that all attachment screws, clips, and other attachment hardware is secure, and that the fairing panel contains no visible cracks, tears, delamination, or other damage.

(b) If no discrepancy is found during the inspection required by paragraph (a) of this AD, within 9 months after the effective date of this AD, accomplish the requirements of paragraph (b)(1), (b)(2), (b)(3), or (b)(4) of this AD, as applicable.

(1) For Model ATR42 seriesairplanes on which Modification 2601 (Aerospatiale Service Bulletin ATR42-53-0063) has been installed: Replace the existing attachment clips at the wing-to-fuselage fairings and the engine nacelle upper cowlings with new attachment clips, in accordance with Aerospatiale Service Bulletin ATR42-53-0081, Revision 1, dated December 9, 1994.

(2) For Model ATR42 series airplanes on which Modification 2601 (Aerospatiale Service Bulletin ATR42-53-0063) has not been installed: Install cup washers (NAS1169C10) on the wing-to-fuselage fairing panels, and replace the existing attachment clips at the wing-to-fuselage fairings and the engine nacelle upper cowlings with new attachment clips, in accordance with Aerospatiale Service Bulletin ATR42-53-0082, dated June 6, 1994.

(3) For Model ATR72 series airplanes on which Modification 2601 (Aerospatiale Service Bulletin ATR72-53-1008) has been installed: Replace the existing attachment clips at the wing-to-fuselage fairings and the engine nacelle upper cowlings with new attachment clips, in accordance with Aerospatiale Service Bulletin ATR72-53-1043, Revision 1, dated December 9, 1994.

(4) For Model ATR72 series airplanes on which Modification 2601 (Aerospatiale Service Bulletin ATR72-53-1008) has not been installed: Install cup washers (NAS1169C10) on the wing-to-fuselage fairing panels, and replace the existing attachment clips at the wing-to-fuselage fairings and the engine nacelle upper cowlings with new attachment clips, in accordance with Aerospatiale Service Bulletin ATR72-53-1044, dated June 6, 1994.

(c) If any discrepancy is found during the inspection required by paragraph (a) of this AD, prior to further flight, remove the fairing panel, and perform a detailed visual inspection to detect cracks, tears, delamination, or other visible signs of damage of the fairing panel.

(1) If no discrepancy is found during the detailed visual inspection required by paragraph (c) of this AD, prior to further flight, reinstall the panel and accomplish the requirements of paragraph (b)(1), (b)(2), (b)(3), or (b)(4) of this AD, as applicable. No further action is required by this AD.

(2) If any discrepancy is found during the detailed visual inspection required by paragraph (c) of this AD, prior to further flight, replace the fairing panel with a serviceable panel, and install the panel on the airplane in accordance with the requirements of paragraph (b)(1), (b)(2), (b)(3), or (b)(4) of this AD, as applicable. No further action is required by this AD.

(d) As of the effective date of this AD, no person shall install an attachment clip, part number S5391010000000 or part number S5391009400000, on any airplane.

(e) 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, 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.

(f) 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.

(g) The actions shall be done in accordance with the following Aerospatiale service bulletins, which contains the specified effective pages:

Service Bulletin
Referenced and Date
Page
Number
Revision Level
Shown on Page
Date
Shown on Page
ATR42-53-0081,
Revision 1,
December 9, 1994
1-3

4-15
1

Original
December 9, 1994

June 6, 1994
ATR42-53-0082,
June 6, 1994
1-31
OriginalJune 6, 1994
ATR72-53-1043,
Revision 1,
December 9, 1994
1, 2

3-15
1

Original
December 9, 1994

June 6, 1994
ATR72-53-1044,
June 6, 1994
1-38
Original
June 6, 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 Aerospatiale, 316 Route de Bayonne, 31060 Toulouse, Cedex 03, France. 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.

(h) This amendment becomes effective on July 30, 1997.

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 all Aerospatiale Model ATR42 and ATR72 series airplanes was published in the Federal Register on January 11, 1996 (61 FR 1015). That action proposed to require replacement of the existing attachment clips on the wing-to-fuselage fairings and on the engine nacelle upper cowlings with new and improved attachment clips for certain airplanes. That action also proposed to require adding cup washers under the fastener countersunk holes, as well as replacement of the existing attachment clips on the wing-to-fuselage fairings and on the engine nacelle upper cowlings with new and improved attachment clips for certain other airplanes.

Interested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the comments received.

Support for the Proposal
One commenter supports the proposed rule.

Request to Revise Work Hour Estimate
One commenter requests that the number of work hours required to accomplish the proposed replacement of the attachment clips and addition of cup washers be increased from 20 to 80. The commenter states that there is an economic loss associated with the longer down time required to accomplish the proposed actions; however, the commenter does not provide specifics nor offer a proposed solution.

The FAA agrees that 80 work hours represents a more accurate representation of the number of work hours necessary to accomplish the required actions. The FAA has revised the cost impact information, below, to reflect this revised work hour estimate.

Actions Since Issuance of the Proposal
Since the issuance of the proposal, the FAA has received a report indicating that severe inflight vibration occurred in the rudder and aileron controls on a Model ATR42 series airplane. This vibration was caused by a loose wing/body fairing panel. During this incident, the flightcrew experienced difficulty controlling the airplane. During descent, the flightcrew could not maintain altitude, and the airplane descended at 1,500 feet per minute until the flaps were lowered and control of the airplane was regained. The flightcrew diverted the airplane and landed it safely. Investigation revealed that three other recent instances of loose fairing panels had occurred previously on the same airplane. In each case, resultant vibration occurred during descent of the airplane; the vibration occurred at relatively high airspeed.

During subsequent replacement of the affected fairing panel, close inspection revealed cracking at the upper edge (towards the center) of the upper forward wing access panel 291BL. The crack extended from the upper leading edge rearward for approximately eight inches. The operator of the affected airplane stated that the crack was not visible with the fairing panel installedon the airplane because the panel is composite, and normal flexing of the panel with the airplane on the ground made the crack invisible. The operator suspected that the panel may have been damaged during a heavy maintenance check, or that the panel may have failed due to its age. The FAA believes that flight operations with improper attachment screws and clips also may have contributed to the development of the crack.

Explanation of Additional Requirements of this AD
The FAA considers that the incident described above indicates the unsafe condition addressed in the proposal is more severe than understood previously. Consequently, due to the seriousness of the incident, the FAA finds it prudent to require actions beyond those specified in the proposal to ensure an acceptable level of safety during the time period prior to accomplishment of the actions required by the original proposed AD.

Therefore, this AD adds a requirement for a one-time detailed visual inspection of the wing-to-fuselage fairings and the upper cowlings of the engine nacelle to ensure that all attachment screws, clips, and other attachment hardware is secure, and that the fairing panel contains no visible cracks, tears, delamination, or other damage. If any screw, clip, or other attachment hardware is loose, bent or otherwise not secure, this AD requires that the panel be removed and a detailed visual inspection be performed to detect cracks, tears, delamination, or other visible signs of damage. If any discrepancy is found, this AD requires replacement of the panel with a serviceable panel.

In making this change to the original proposal, the FAA finds that, with respect to requiring this inspection, since a situation exists that requires immediate adoption of this requirement, notice and public procedure hereon are impracticable, and good cause exists for making this amendment effective in less than 30 days.

Conclusion
After careful review of the available data, including the comments noted above, the FAA has determined that air safety and the public interest require the adoption of the rule with the changes previously described.

Cost Impact
The FAA estimates that 175 airplanes of U.S. registry will be affected by this AD.

It will take approximately 2 work hours per airplane to accomplish the required detailed inspection, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of the required detailed inspection on U.S. operators is estimated to be $21,000, or $120 per airplane.

Should an operator be required to accomplish the required replacement of attachment clips and addition of cup washers, it will take approximately 80 work hours per airplane to accomplish, at an average labor rate of $60 per work hour. The manufacturer will provide required parts at no cost to operators. Based on these figures, the cost impact of these required actions on U.S. operators (approximately 81 airplanes) is estimated to be $388,800, or $4,800 per airplane.

Should an operator be required to accomplish the required replacement of attachment clips, it will take approximately 20 work hours per airplane to accomplish, at an average labor rate of $60 per work hour. The manufacturer will provide required parts at no cost to operators. Based on these figures, the cost impact of this required action on U.S. operators (approximately 94 airplanes) is estimated to be $112,800, or $1,200 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.

Comments Invited
Although this action is in the form of a final rule that involves requirements affecting flight safety and, the inspection and repair requirements of this AD were not preceded by notice and an opportunity for public comment, comments are invited on this portionof the 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 summarizeseach 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-84-AD." The postcard will be date stamped and returned to the commenter.

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 adding the following new airworthiness directive: