AD 94-09-12

A proposal to amend part 39 of the Federal Aviation Regulations to include an airworthiness directive (AD) that is applicable to certain McDonnell Douglas Model DC-8, DC-9, and DC-9-80 series airplanes; Model MD-88 airplanes; and C-9 (military) airplanes was published as a supplemental notice of proposed rulemaking (NPRM) in the Federal Register on February 15, 1994 (59 FR 7233). That action proposed to require inspection of the center and side windshields, and replacement of discrepant windshields.

Interested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the comments received.

Three commenters support the proposed rule.

One commenter requests that inspections performed prior to the effective date of the AD be considered acceptable for compliance with the inspection requirement in the proposal. The FAA concurs. As allowed by the phrase, "unless accomplished previously," in the "Compliance" section of this AD, if the inspection has been accomplished prior to the effective date of the AD, this AD does not require that it be repeated. Therefore, no change to the final rule is necessary.

One commenter requests that the final rule be revised to include the option of reviewing purchasing records in lieu of the proposed inspection requirement. The commenter asserts that a review of purchasing records would be more cost effective, and safety would not be compromised since the end result would be the same: a determination of the manufacturing source of the windshields. The FAA does not concur. Since tracking systems for shipping and purchasing records vary from operator to operator, the possibility exists for windshields to be tracked by part number alone. These common part numbers may be assigned to several manufacturers. Therefore, purchasing records would not be reliable in determining the manufacturing source of windshields.

One commenter requests that the proposed compliance time of 30 days to inspect the windshields be extended to 90 days or at the next regularly scheduled "B" check. The commenter states that a compliance time of 30 days would impose an unnecessary hardship on operators of large fleets. Two commenters also express concern that replacement parts would not be available in sufficient quantities; therefore, the extension in compliance time would give the manufacturer sufficient time to produce an adequate quantity of replacement windshields. The FAA does not concur. In developing an appropriate compliance time for this action, the FAA considered not only the degree of urgency associated with addressing the subject unsafe condition, but the availability of required parts and the practical aspect of inspecting and installing the necessary parts within a maximum interval of time allowable for all affected airplanes to continue to operate without compromising safety. The FAA has verified that, of the original 730 discrepant windshields known to have been produced and in service, 599 (82%) have already been removed from service and returned to the vendor; that leaves only 131 windshields remaining in service. Further, the FAA also has verified that an adequate supply of replacement windshields will be available for affected operators to accomplish the requirements of this AD within the 30-day compliance time. In light of all of these factors, the FAA has determined that the 30-day compliance time is warranted and appropriate. However, under the provisions of paragraph (d) of the final rule, operators may apply for the approval of an alternative method of compliance or adjustment of the compliance time by submitting justification for such an alternative or adjustment to the FAA.

One commenter requests that proposed paragraphs (a)(2)(ii), (b)(2)(ii), and (c) be changed to limit applicability only to those airplanes on which the windshield has been replaced after February1992. The FAA does not consider that this suggested change is necessary. Since the applicability statement of the AD states that the AD applies to "airplanes on which the. . .windshield has been replaced after February 1992," that statement applies to paragraphs (a), (b), and (c) of the AD. Therefore, no change to the final rule is warranted.

This same commenter requests that the final rule be revised to include a requirement to inspect for discrepant windshields that are identifiable by part numbers and serial numbers beginning with the letters "SWU." The FAA does not concur. Windshields that have a part number or serial number beginning with "SWU" are made of acrylic and, as such, are not subject to the unsafe condition addressed by this AD. The unsafe condition addressed by this AD is the result of incorrect tempering of the core ply of certain glass windshields during the manufacturing process. NOTE 2 has been added to the final rule to make clear that the requirementsof this AD apply only to windshields made of glass.

After careful review of the available data, including the comment noted above, the FAA has determined that air safety and the public interest require the adoption of the rule as proposed.

There are approximately 235 Model DC-8 series airplanes of the affected design in the worldwide fleet. The FAA estimates that 140 airplanes of U.S. registry will be affected by this AD, that it will take approximately 0.5 work hour per airplane to accomplish the required inspection, and that the average labor rate is $55 per work hour. Based on these figures, the total cost impact of the AD on U.S. operators of Model DC-8 series airplanes is estimated to be $3,850, or $27.50 per airplane.

There are approximately 1,978 Model DC-9 and DC-9-80 series airplanes, Model MD-88 airplanes, and C-9 (military) airplanes of the affected design in the worldwide fleet. The FAA estimates that 1,079 airplanes of U.S. registry will be affected by this AD, that it will take approximately 0.5 work hour per airplane to accomplish the required inspection, and that the average labor rate is $55 per work hour. Based on these figures, the total cost impact of the AD on U.S. operators of Model DC-9 and DC-9-80 series airplanes, Model MD-88 airplanes, and C-9 (military) airplanes is estimated to be $29,673, or $27.50 per airplane.

Based on the figures discussed above, the total cost impact of the AD actions on U.S. operators is estimated to be $33,523.

Should an inspection reveal that a discrepant windshield was installed, the replacement of that windshield will require approximately 10 additional work hours to accomplish, at an average labor rate of $55 per work hour. Required replacement parts will be provided at no cost to operators. Based on these figures, the total cost impact for the replacement of discrepant windshields for U.S. operators will be $550 per airplane.

The total cost impact figures discussed above are based on assumptions that no operator has yet accomplished any of the requirements of this AD action, and that no operator would accomplish those actions in the future if this AD were not adopted. However, the FAA has been advised that 599 out of 730 discrepant windshields already have been identified and returned by affected operators; therefore, the future total cost impact of this AD is expected to be much less that the figures indicated above.

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 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. § 39.13 - (Amended)

2. Section 39.13 is amended by adding the following new airworthiness directive: