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 Airbus Model A319, A320, and A321 series airplanes was published in the Federal Register on March 20, 1998 (63 FR 13570). That action proposed to require replacing certain Monogram toilet rinse valves with modified rinse valves.
Interested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the comments received.
One commenter supports the proposed rule.
Two commenters express their concerns that additional sources of fluid contamination of avionics computers exist. One commenter specifies that other possible fluid sources include water supply and drain lines, coffee makers, water boilers, water filters, hot-cups, beverage containers, trash cans, rain, snow, waste tanks, waste tank rinse systems, hydraulic lines, fuel lines, and de-icing fluid systems. The other commenter states that, since the avionics computers probably have cooling air holes in their cases and are not intrinsically tolerant of moisture ingress, it may be desirable to provide additional protection of the avionics computers such as installing drip shields. The commenter further suggests that the need for such additional protection could be verified by a safety analysis conducted to consider the probability of failure of the rinse valve, the probability of overflow fluids entering the computers, and the probability of hazardous malfunction of the computers due to moisture ingress.
The FAA acknowledges the commenters concern that other potential sources of fluid contamination may exist. However, an existing unsafe condition (water contamination of the avionics computers due to malfunction of the toilet rinse valve) has been identified and a corrective action required in this rule. The FAA finds that to delay issuance of this final rule would be inappropriate, since issuance of an AD is the means by which the identified unsafe condition will be addressed. Therefore, no change to this final rule is necessary.
However, the FAA has been advised that additional safety analyses have been conducted to address other probabilities of contamination of the avionics computers. Additionally, the FAA is reviewing additional information received from the Direction G n rale de l'Aviation Civile (DGAC), the airworthiness authority for France, concerning contamination of the avionics computers. After review of the findings of this information, the FAA may consider further rulemaking.
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 as proposed.
Cost Impact
The FAA estimates that 16 airplanes of U.S. registry will be affected by this AD, that it will take approximately 6work hours per airplane to accomplish the required actions, and that the average labor rate is $60 per work hour. Required parts will be provided by the manufacturer at no cost to the operators. Based on these figures, the cost impact of the AD on U.S. operators is estimated to be $5,760, or $360 per airplane.
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.
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: