A proposal to amend part 39 of the Federal Aviation Regulations to include an AD that would apply to certain de Havilland DHC-6 series airplanes was published in the Federal Register on October 27, 1993 (58 FR 57758). The action proposed to supersede AD 69-02-01 and AD 85-16-10 with a new AD that would (1) initially retain the repetitive inspection of the wing attachment fittings required by the current AD's; and (2) eventually require installing new steel adapter fittings as terminating action for those repetitive inspections. The inspections would be accomplished in accordance with de Havilland Service Bulletin (SB) No. 6/476, Revision B, dated January 22, 1988, and the installation would be accomplished in accordance with de Havilland SB No. 6/500, dated January 22, 1988.
Interested persons have been afforded an opportunity to participate in the making of this amendment. One comment was received supporting the proposed rule and no comments were received on the FAA's determination of the cost to the public.
After careful review of all available information, the FAA has determined that air safety and the public interest require the adoption of the rule as proposed except for minor editorial corrections. The FAA has determined that these minor corrections will not change the meaning of the AD nor add any additional burden upon the public than was already proposed.
The FAA estimates that 169 airplanes in the U.S. registry will be affected by this AD, that it will take approximately 96 workhours per airplane to accomplish the required action, and that the average labor rate is approximately $55 an hour. Parts cost approximately $6,750 per airplane. Based on these figures, the total cost impact of this AD on U.S. operators is estimated to be $2,033,072.
AD 69-02-01 and AD 85-16-10, both of which are superseded by this action, currently require inspecting the top inner faces of the wing attachment fittings for cracks atintervals of 500 hours time-in-service (TIS), but require removing both the left and right upper wing-fuselage fairings, dye penetrant inspecting them utilizing a 10-power glass, and reattaching the fairings. These inspections take approximately 3 workhours at an average cost of $55 per hour; approximately $165 per airplane or $297,440 for the entire fleet. The inspection procedures of this AD take approximately 3 workhours at an average cost of $55 per hour.
The cost figures do not account for the recurring costs of the repetitive inspections required by AD 69-02-01 and AD 85-16-10. This AD only requires these repetitive inspections until accomplishment of the mandatory modification. This elimination of the repetitive inspections reduces the cost of the required modification requirement.
The intent of the FAA's aging commuter airplane program is to ensure safe operation of commuter-class airplanes that are in commercial service without adversely impacting private operators. Of the approximately 169 airplanes in the U.S. registry that are affected by this AD, the FAA has determined that approximately 50 percent are operated in scheduled passenger service by 14 different operators. A significant number of the remaining 50 percent are operated in other forms of air transportation such as air cargo and air taxi.
This AD allows 2,000 hours time-in-service (TIS) before mandatory accomplishment of the design modification. The average utilization of the fleet for those airplanes in commercial commuter service is approximately 25 to 50 hours TIS per week. Based on these figures, operators of commuter-class airplanes involved in commercial operation would have to accomplish the required modification within 10 to 20 calendar months after this AD becomes effective. For private owners, who typically operate between 100 to 200 hours TIS per year, this will allow 120 to 240 calendar months (about 10 to 20 years) before the required modification is mandatory.In addition, replacing the fittings terminates the need for the repetitive inspections.
The incremental costs of this AD depend on the utilization of de Havilland DHC-6 series airplanes, and whether cracks were found during any of the repetitive inspections accomplished within 2,000 hours TIS after the effective date of this AD. The discussion that follows assumes that no cracked fittings are found and operators/owners do not replace the fittings until required at 2,000 hours TIS after the effective date of this AD.
This AD imposes additional costs on most operators/owners of de Havilland DHC-6 series airplanes. Although the action eliminates the repetitive inspections upon replacement of the fitting at 2,000 hours TIS after the effective date of the AD, the cost of the replacement fittings will most likely be more than the cost of the repetitive inspections. The following presents the greatest present value incremental costs for 10, 20, and 30-year remaining service lives(a chart that represents this is contained in the regulatory flexibility analysis and may be obtained by contacting the Docket at the location contained in the ADDRESSES section of the preamble of this AD):
o 10-year remaining service life - Approximately $9,000 for de Havilland DHC-6 series airplanes utilized an average of 725 hours TIS annually;
o 20-year remaining service life - Approximately $8,200 for de Havilland DHC-6 series airplanes utilized an average of 560 hours TIS annually; and
o 30-year remaining service life - Approximately $7,800 for de Havilland DHC-6 series airplanes utilized an average of 525 hours annually.
The Regulatory Flexibility Act of 1980 (RFA) was enacted by Congress to ensure that small entities are not unnecessarily or disproportionally burdened by government regulations. The RFA requires government agencies to determine whether rules would have a "significant economic impact on a substantial number of small entities," and, in cases where they would, conduct a Regulatory Flexibility Analysis in which alternatives to the rule are considered. FAA Order 2100.14A, Regulatory Flexibility Criteria and Guidance, outlines FAA procedures and criteria for complying with the RFA. Small entities are defined as small businesses and small not-for-profit organizations that are independently owned and operated or airports operated by small governmental jurisdictions. A "substantial number" is defined as a number that is not less than 11 and that is more than one-third of the small entities subject to the required rule, or any number of small entities subject to the rule which is substantial in the judgment of the rulemaking official. A "significant economic impact" is defined as an annualized net compliance cost, adjusted for inflation, which is greater than a threshold cost level for defined entity types. FAA Order 2100.14A sets the size threshold for small entities operating aircraft for hire at 9 aircraft owned and annualizedcost threshold at $65,300 for scheduled operators and $4,600 for unscheduled operators (expressed in second quarter 1993 dollars).
The 169 U.S.-registered airplanes affected by this AD are owned according to the following breakdown: 13 by individuals, 8 by U.S. government agencies, and 148 by businesses or not-for-profit enterprises. Of the 148 entities, one owns 26 airplanes, one owns 11 airplanes, nineteen own between 2 and 9 airplanes, and fifty own 1 airplane each.
The FAA cannot determine the sizes of all the 148 owner entities nor the relative significance of the costs or cost savings estimated above. However, more than one-third of these entities operate their de Havilland DHC-6 series airplanes in scheduled service. According to statistics obtained by the FAA, these airplane operators in scheduled service utilize their airplanes an average of 1,383 hours TIS annually, and general aviation operators utilize their airplanes an average of 706 hours TIS annually. These figures may have a standard of error of 14.4 percent and the general aviation average may include some airplanes in commuter service. The FAA cannot reasonably estimate the distribution of these hours among the de Havilland DHC-6 fleet.
Because of these uncertainties, no cost thresholds for significant economic impact can be reasonably determined. The FAA solicited comments concerning the impact of the notice of proposed rulemaking (NPRM) on owners of affected airplanes, and received no comments on this matter. Based on the possibility that this AD could have a significant impact on a substantial number of small entities, the FAA conducted a regulatory flexibility analysis. A copy of this analysis may be obtained by contacting the Rules Docket at the location provided under the caption "ADDRESSES".
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 significant under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979) because of substantial public interest; and, (3) if promulgated, may have a significant economic impact on a substantial number of small entities. The FAA has conducted an Initial Regulatory Flexibility Determination and Analysis and has considered alternatives to this action that could minimize the impact on small entities. A copy of this analysis may be obtained by contacting the Rules Docket at the location provided under the caption "ADDRESSES". After careful consideration, the FAA hasdetermined that the required action is the best course to achieve the safety objective of returning the airplane to its original certification level of safety.
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 14 CFR part 39 of the Federal Aviation Regulations as follows:
PART 39 - AIRWORTHINESS DIRECTIVES
1. The authority citation for part 39 continues to read as follows:
Authority: 49 U.S.C. App. 1354(a), 1421 and 1423; 49 U.S.C. 106(g); and 14 CFR 11.89.
Section 39.13 - [AMENDED]
2. Section 39.13 is amended by removing AD 69-02-01, Amendment 39-2347, and AD 85-16-10, Amendment 39-5216, and adding the following new AD to read as follows: