Airworthiness Directives; Airbus Model A330, A340-200, and A340-300 Series Airplanes

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

This document proposes the adoption of a new airworthiness directive (AD) that is applicable to all Airbus Model A330, A340-200, and A340-300 series airplanes. This proposal would require repetitive detailed inspections for discrepancies of the grease and gear teeth of the radial variable differential transducer of the nose wheel steering gearbox; or repetitive detailed inspections for damage of the chrome on the bearing surface of the nose landing gear (NLG) main fitting barrel; as applicable. For airplanes on which any discrepancy or damage is found, this proposal would require either an additional inspection or corrective actions, as applicable. This action is necessary to prevent incorrect operation or jamming of the nose wheel steering, which could cause reduced controllability of the airplane on the ground. This action is intended to address the identified unsafe condition.

DATES:

Comments must be received by July 16, 2004.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2001-NM-381-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Comments may be inspected at this location between 9 a.m. and 3 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: 9-anm-nprmcomment@faa.gov. Comments sent via fax or the Internet must contain “Docket No. 2001-NM-381-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 or 2000 or ASCII text.

The service information referenced in the proposed rule may be obtained from Airbus, 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.

FOR FURTHER INFORMATION CONTACT:

Tim Backman, Aerospace Engineer, International Branch, ANM-116, FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 227-2797; fax (425) 227-1149.

SUPPLEMENTARY INFORMATION:

Comments Invited

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 2001-NM-381-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. 2001-NM-381-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

Discussion

The Direction Générale de l'Aviation Civile (DGAC), which is the airworthiness authority for France, notified the FAA that an unsafe condition may exist on all Airbus Model A330, A340-200, and A340-300 series airplanes. The DGAC advises that an operator of a Model A340 airplane reported the failure of the nose wheel steering (NWS) system. An investigation found abnormal wear of the gear teeth of the radial variable differential transducer (RVDT) gearbox, which led to incorrect driving of the command channel and monitoring-channel feedback sensors. Subsequent analyses of grease samples taken from the RVDT gearbox showed the presence of significant quantities of water in the grease, which, when frozen, could have jammed the gearboxes. The investigation also found chrome flaking and extensive corrosion of the nose landing gear (NLG) main fitting barrel under the NWS rotating sleeve.

The investigators concluded that abrasion from metallic particles in the grease caused the wear of the gear teeth. These metallic particles came from the corroded areas of the NLG main fitting barrel, and had been carried into the system by grease that was used during the normal lubrication of the rotating sleeve. The investigators also concluded that water entered the gearbox through the seal between the steering collar and the NLG main fitting; improvement of this seal is the subject of Airbus Modification 51318 (Airbus Service Bulletins A330-32-3164 and A340-32-4204).

Wear of the gear teeth of the RVDT caused by the metallic particles from corrosion in the grease, and jamming of the gearbox caused by water freezing in the grease, could result in incorrect operation or jamming of the NWS, which could cause reduced controllability of the airplane on the ground.

The subject area on certain Model A330 series airplanes is almost identical to that on the affected Model A340-200, and A340-300 series airplanes. Therefore, those Model A330 series airplanes may be subject to the unsafe condition revealed on the Model A340-200, and A340-300 series airplanes.

Explanation of Relevant Service Information

Airbus has issued the following service bulletins:

• For Model A330 series airplanes: Airbus Service Bulletin A330-32-3134, Revision 02, excluding Appendix 01, dated August 8, 2003; and
• For Model A340-200 and A340-300 series airplanes: Airbus Service Bulletin A340-32-4172, Revision 02, excluding Appendix 01, dated August 8, 2003.

For certain airplanes, these service bulletins specify that operators may choose between two different inspections. Depending on the inspection choice, the service bulletins recommend different repetitive intervals. The service bulletins also state that operators may alternate between the inspection choices as long as the interval until the next inspection is the interval described for the last inspection performed.

The first inspection choice for airplanes without the Airbus Modification is repetitive inspections of the grease and gear teeth of the RVDT driving ring and the gears in the RVDT gearboxes to find discrepancies such as metallic particles in the grease, abnormal wear of the gear teeth, or missing rubber sealant at the mating face between the main fitting and the RVDT gearbox. If there are discrepancies, the service bulletins describe procedures for inspecting the chrome on the bearing surface of the NLG main fitting barrel under the NWS rotating sleeve for damage such as flaking, corrosion, or blistering.

The second inspection choice for airplanes without the Airbus Modification is repetitive inspections of the chrome on the bearing surface of the NLG main fitting barrel under the NWS rotating sleeve for damages such as flaking, corrosion, or blistering.

For certain other airplanes, the service bulletins recommend only the inspection of the chrome on the bearing surface of the NLG main fitting barrel, which is described in the paragraph above.

For all airplanes on which discrepancies and/or damage are found, the service bulletins specify that operators should take corrective actions. The corrective actions are included in the two Messier-Dowty service bulletins listed below. These corrective actions include degreasing bare base metal and protecting the metal with cadmium Cd10 or a complete paint scheme, restoring the rubber sealant, and/or contacting Messier-Dowty for disposition.

• For certain airplanes: Messier-Dowty Special Inspection Service Bulletin D23285-32-037, dated November 8, 2001.
• For certain other airplanes airplanes: Messier-Dowty Special Inspection Service Bulletin D23285-32-044, dated January 12, 2004.

Both Airbus service bulletins refer to the Messier-Dowty service bulletins as additional sources of service information for accomplishment of the inspections and any applicable corrective actions.

The DGAC classified the Airbus service bulletins as mandatory and issued French airworthiness directives 2001-503(B) R3, dated October 1, 2003; and 2001-504(B) R4, dated October 1, 2003; to ensure the continued airworthiness of these airplanes in France.

FAA's Conclusions

These airplane models are manufactured in France and are type certificated for operation in the United States under the provisions of § 21.29 of the Federal Aviation Regulations (14 CFR 21.29) and the applicable bilateral airworthiness agreement. Pursuant to this bilateral airworthiness 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 require accomplishment of the actions specified in the service bulletins described previously, except as discussed below.

Differences Among the Proposed Rule, Service Bulletins, and the French Airworthiness Directive

Operators should note that, although the Messier-Dowty service bulletins specify that the manufacturer may be contacted for disposition of certain repair conditions, this proposal would require the repair of those conditions to be accomplished per a method approved by either the FAA, or the DGAC (or its delegated agent). In light of the type of repair that would be required to address the identified unsafe condition, and in consonance with existing bilateral airworthiness agreements, the FAA has determined that, for this proposed AD, a repair approved by either the FAA or the DGAC would be acceptable for compliance with this proposed AD.

Operators should also note that, although the Messier-Dowty service bulletins specify to submit reporting forms to the manufacturer, this proposed AD does not include such a requirement.

The French airworthiness directives do not give a compliance time for inspecting the chrome on the bearing surface of the NLG main fitting barrel for airplanes without Airbus Modification 51318 that have discrepancies of the grease and gear teeth of the RVDT driving ring and the gears in the RVDT gearboxes. This proposed AD would require that operators inspect the chrome within 3 months after the RVDT inspection.

The French airworthiness directives and the service bulletins do not define the type of inspections to be performed. This proposed AD calls the inspections “detailed inspections.” Note 1 of this proposed AD defines this inspection.

Cost Impact

We estimate that 16 airplanes of U.S. registry would be affected by this proposed AD.

For operators of airplanes without Airbus Modification 51318, who choose to do the inspection of the grease and gear teeth of the RVDT gearbox, we estimate that it would take approximately 2 work hours per airplane to accomplish the proposed inspection and that the average labor rate is $65 per work hour. Based on these figures, the cost impact of this action on U.S. operators is estimated to be $130 per airplane, per inspection cycle.

For operators of airplanes with Airbus Modification 51381, or for operators of airplanes without Airbus Modification 51381 who choose to do the proposed inspection of the chrome on the bearing surface of the NLG main fitting barrel, we estimate that it would take approximately 8 work hours per airplane to accomplish the inspection, and that the average labor rate is $65 per work hour. Based on these figures, the cost impact of the proposed AD on U.S. operators is estimated to be $520 per airplane, per inspection cycle.

The cost impact figure discussed above is based on assumptions that no operator has yet accomplished any of the 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.

Regulatory Impact

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.

List of Subjects in 14 CFR Part 39

• Air transportation
• Aircraft
• Aviation safety
• Safety

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:

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.