Federal Aviation Administration, DOT.
Notice of proposed rulemaking (NPRM).
This document proposes the supersedure of an existing airworthiness directive (AD), applicable to all Model A320 series airplanes, that currently requires repetitive measurements of the deflection of the elevator trailing edge; inspections of the elevator servo controls and their attachments; and replacement of worn or damaged parts, if necessary. This action would require periodic inspection of the elevators for excessive freeplay; repair or replacement of worn parts, if excessive freeplay is detected; replacement of the elevator servo controls with modified elevator servo controls; and modification of the elevator neutral setting. It would also revise the applicability to include additional models of airplanes. This proposal is prompted by additional reports of severe vibration in the aft cabin of Model A320 series airplanes and studies which indicate that the primary cause is excessive freeplay in the elevator attachments. The actions specified by the proposed AD are intended to prevent excessive vibration of the elevators, which could result in reduced structural integrity, leading to reduced controllability of the airplane.
Comments must be received by April 2, 2001.
Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2000-NM-342-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Comments may be inspected at this location between 9:00 a.m. and 3:00 p.m., Monday through Friday, except Federal holidays. Comments may be submitted via fax to (425) 227-1232. Comments may also be sent via the Internet using the following address: firstname.lastname@example.org. Comments sent via fax or the Internet must contain “Docket No. 2000-NM-342-AD” in the subject line and need not be submitted in triplicate. Comments sent via the Internet as attached electronic files must be formatted in Microsoft Word 97 for Windows or ASCII text.
The service information referenced in the proposed rule may be obtained from Airbus Industrie, 1 Rond Point Maurice Bellonte, 31707 Blagnac Cedex, France. This information may be examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington.Start Further Info
FOR FURTHER INFORMATION CONTACT:
Tim Dulin, Aerospace Engineer, ANM-116, FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 227-2141; fax (425) 227-1149.End Further Info End Preamble Start Supplemental Information
Interested persons are invited to participate in the making of the proposed 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 above. All communications received on or before the closing date for comments, specified above, will be considered before taking action on the proposed rule. The proposals contained in this action may be changed in light of the comments received.
Submit comments using the following format:
- Organize comments issue-by-issue. For example, discuss a request to change the compliance time and a request to change the service bulletin reference as two separate issues.
- For each issue, state what specific change to the proposed AD is being requested.
- Include justification (e.g., reasons or data) for each request.
Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the proposed 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 summarizing each FAA-public contact concerned with the substance of this proposal will be filed in the Rules Docket.
Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this action must submit a self-addressed, stamped postcard on which the following statement is made: “Comments to Docket Number 2000-NM-342-AD.” The postcard will be date stamped and returned to the commenter.
Availability of NPRMs
Any person may obtain a copy of this NPRM by submitting a request to the FAA, Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2000-NM-342-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.
On January 29, 1992, the FAA issued AD 92-04-06, amendment 39-8177, (57 FR 6068, February 20, 1992), applicable to all Airbus Model A320 series airplanes. [A correction to that final rule was published in the Federal Register on April 1, 1992 (57 FR 11137).] That AD requires repetitive measurements of the deflection of the elevator trailing edge; inspections of the elevator servo controls and their attachments; and replacement of worn or damaged parts, if necessary. The AD was prompted by reports of in-flight airframe vibrations resulting from worn bolts and bushings on the elevator servo attachments. The requirements of that AD are intended to prevent excessive freeplay (backlash) at the elevator trailing edge, resulting in in-flight airframe vibrations, which could lead to reduced controllability of the airplane.
Actions Since Issuance of Previous Rule
Since issuance of AD 92-04-06, there have been more reports of airframe vibration. To investigate this problem, Airbus conducted extensive flight tests with varying degrees of elevator servo control backlash (freeplay) and elevator hinge moments to determine the source of the elevator vibration. Airbus found that a combination of elevator freeplay and low hinge moment caused the Start Printed Page 12914vibration. Airbus describes this vibration as limit cycle oscillation (i.e., sustained vibration at a fixed frequency and limited amplitude).
Explanation of Relevant Service Information
To address this problem, Airbus issued two service bulletins and made a change to the Aircraft Maintenance Manual for the affected airplanes.
Airbus has issued Service Bulletin A320-27-1111, dated August 16, 1996, and Revision 01, dated November 14, 2000, which provides procedures to replace the existing elevator servo controls with modified elevator servo controls having improved spherical bearings. The service bulletin addresses the problem of elevator freeplay (backlash) at the servo control eye-end, which had been found to be due to wear of the spherical bearings.
Airbus has also issued Service Bulletin A320-27-1114, Revision 04, dated December 7, 1999, which provides procedures to modify the elevator neutral setting to ensure that the elevators are sufficiently loaded in most flight conditions. The Direction Generale de l'Aviation Civile (DGAC), which is the airworthiness authority for France, has approved these service bulletins, but has not classified them as mandatory.
Finally, Airbus has changed the Aircraft Maintenance Manual (AMM) to reduce the allowable elevator freeplay from 10 millimeters to 7 millimeters.
Airbus describes the vibration as a limit cycle oscillation (resulting from a nonlinear behavior of the structure) that is acceptable from a static strength, fatigue, and controllability standpoint. Nevertheless, the FAA considers the vibration to be an aeroelastic stability problem, which could potentially result in reduced structural integrity, leading to reduced controllability of the airplane. In order to ensure that this condition does not occur in-service, the FAA proposes to mandate repetitive inspections for freeplay per the new aircraft maintenance manual limits, modification of the actuator bearings, and incorporation of the new neutral setting of the elevator control surface.
U.S. Type Certification of the Airplanes
These airplane models are manufactured in France and are type certificated for operation in the United States under the provisions of section 21.29 of the Federal Aviation Regulations (14 CFR 21.29) and the applicable bilateral airworthiness agreement. Pursuant to this bilateral agreement, the DGAC has kept the FAA informed of the situation described above. The FAA has examined the findings of the DGAC, 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.
Explanation of Requirements of Proposed Rule
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, the proposed AD would supersede AD 92-04-06 to require periodic inspection of the elevators for excessive freeplay; repair or replacement of worn parts, if excessive freeplay is detected; replacement of the elevator servo controls with modified elevator servo controls; and modification of the elevator neutral setting. These actions would be required to be accomplished in accordance with the service bulletins and AMM described above. The proposed AD would also revise the applicability to add Model A319 and A321 series airplanes, which are similar in design to Model A320 series airplanes, but were not on the U.S. registry at the time of issuance of AD 92-04-06.
There are approximately 291 airplanes of U.S. registry that would be affected by this proposed AD.
Inspection for freeplay in the elevators would take approximately 2 work hours at an average labor rate of $60 per work hour. There would be no charge for required parts. Based on these figures, the cost impact of the initial inspection proposed by this AD on U.S. operators is estimated to be $34,920, or $120 per airplane.
Replacement of the elevator servo controls would take approximately 7 work hours at an average labor rate of $60 per work hour. There would be no charge for required parts. Based on these figures, the cost impact of the replacement of the elevator servo controls proposed by this AD on U.S. operators is estimated to be $122,220, or $420 per airplane.
Change of the elevator neutral setting would take approximately 12 work hours at an average labor rate of $60 per work hour. There would be no charge for required parts. Based on these figures, the cost impact of the replacement of the change of the elevator neutral setting proposed by this AD on U.S. operators is estimated to be $209,520, or $720 per airplane.
The cost impact figures discussed above are based on assumptions that no operator has yet accomplished any of the current or proposed requirements of this AD action, and that no operator would accomplish those actions in the future if this AD were not adopted. The cost impact figures discussed in AD rulemaking actions represent only the time necessary to perform the specific actions actually required by the AD. These figures typically do not include incidental costs, such as the time required to gain access and close up, planning time, or time necessitated by other administrative actions.
The regulations proposed herein would not have a substantial direct effect 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, it is determined that this proposal would not have federalism implications under Executive Order 13132.
For the reasons discussed above, I certify that this proposed regulation (1) is not a “significant regulatory action” under Executive Order 12866; (2) is not a “significant rule” under the DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (3) if promulgated, 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 draft regulatory 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.Start List of Subjects
List of Subjects in 14 CFR Part 39End List of Subjects
The Proposed Amendment
Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration proposes to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) as follows:Start Part
PART 39—AIRWORTHINESS DIRECTIVES
1. The authority citation for part 39 continues to read as follows:
2. Section 39.13 is amended by removing amendment 39-8177 (57 FR Start Printed Page 129156068, February 20, 1992), and by adding a new airworthiness directive (AD), to read as follows:
Airbus Industrie: Docket 2000-NM-342-AD. Supersedes AD 92-04-06, Amendment 39-8177.
Applicability: All Model A319, A320, and A321 series airplanes; certificated in any category.
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 excessive vibration of the elevators, which could result in reduced structural integrity, leading to reduced controllability of the airplane, accomplish the following:
(a) Within 18 months from the last inspection for excessive freeplay or within 3 months after the effective date of this AD, whichever occurs later: Inspect the elevators for excessive freeplay, using a load application tool and a spring scale assembly, in accordance with Airbus A319/A320 Aircraft Maintenance Manual (AMM) Task 27-34-00-200-001, including all changes through August 1, 2000. Thereafter, repeat the inspection at intervals not to exceed 18 months.
(b) If any inspection required by paragraph (a) of this AD indicates that the freeplay in the elevator exceeds 7 millimeters: Prior to further flight, repair the elevator or servo controls, in accordance with Airbus A319/A320 AMM Task 27-34-51-200-001 and/or 27-34-41-200-001, as applicable, including all changes through August 1, 2000.
(c) For the airplanes listed in Airbus Service Bulletin A320-27-1111, Revision 01, dated November 14, 2000: Within 18 months after the effective date of this AD, replace the elevator servo controls with modified elevator servo controls, in accordance with Airbus Service Bulletin A320-27-1111, dated August 16, 1996; or Revision 01, dated November 14, 2000.
(d) For the airplanes listed in Airbus Service Bulletin A320-27-1114, Revision 04, dated December 7, 1999: Within 18 months after the effective date of this AD, shift the elevator neutral setting to minus 0.5 degrees, nose-up, in accordance with Airbus Service Bulletin A320-27-1114, Revision 04, dated December 7, 1999.
Alternative Methods of Compliance
(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, International Branch, ANM-116, Transport Airplane Directorate, FAA. 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.
Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the International Branch, ANM-116.
Special Flight Permits
(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.
Issued in Renton, Washington, on February 22, 2001.
Donald L. Riggin,
Acting Manager,, Transport Airplane Directorate, Aircraft Certification Service.
[FR Doc. 01-4934 Filed 2-28-01; 8:45 am]
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