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 Dornier Model 328-100 series airplanes was published in the Federal Register on March 30, 1998 (63 FR 15105). That action proposed to require replacement of the de-icing system timer with a new, improved timer.
Explanation of Changes Made to This Final Rule
Since the issuance of that Notice of Proposed Rulemaking (NPRM), the FAA has determined that the descriptions of what prompted the AD, and of the unsafe condition, in the proposed rule require clarification. Those descriptions are revised to read "possible overheating and debonding of the propeller blade due to a failure of the de-icing system timer and a dormant short circuit in the propeller de-icer system. Such overheating and debonding of the propeller blade could result in reduced controllability of the airplane."
The FAA also has determined that a more accurate description of the unsafe condition of the propeller blade addressed by this AD is to use the descriptor "debonding, " rather than "disbonding" (as used in the proposed rule) and has revised the final rule accordingly.
Interested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the single comment received.
One commenter, the airframe manufacturer, states that all airplanes in the fleet have incorporated the A-5639-3 propeller timer/monitor, and includes copies of records to verify the installations. Therefore, the manufacturer considers that there is no necessity for the issuance of an AD.
The FAA does not concur with the manufacturer s position that there is no necessity to issue an AD to address the identified unsafe condition. The FAA does acknowledge that the fleet may currently be in compliance with the requirements of this AD (installation of the A-5639-3 propeller timer). However, the propeller vendor, Hartzell, has advised the FAA that the locations of approximately 40 of the A-5639-2 timers cannot be accounted for. Therefore, this AD must be issued to ensure that the addressed unsafe condition addressed by this final rule is not reintroduced by an inadvertent reinstallation of an A-5639-2 timer/monitor.
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. The FAA has determined that these changes will neither increase the economic burden on any operator nor increase the scope of the AD.
Cost Impact
The FAA estimates that 25 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 replacement, and that the average labor rate is $60 per work hour. Required parts will befurnished by the manufacturer at no cost to the operators. Based on these figures, the cost impact of this AD on U.S. operators is estimated to be $1,500, or $60 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: