AD 97-1437

[Federal Register Volume 62, Number 18 (Tuesday, January 28, 1997)] [Rules and Regulations] [Pages 3985-3988] From the Federal Register Online via the Government Publishing Office [www.gpo.gov] [FR Doc No: 97-1437]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 96-NM-99-AD; Amendment 39-9893; AD 97-02-08] RIN 2120-AA64

Airworthiness Directives; McDonnell Douglas Model DC-9, DC-9-80 and C-9 (Military) Series Airplanes, and Model MD-88 Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment adopts a new airworthiness directive (AD) that is applicable to certain McDonnell Douglas Model DC-9, DC-9-80 and C-9 (military) series airplanes, and Model MD-88 airplanes It requires either the installation of external protective

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doublers between the outboard flight spoiler actuators and the aft spar webs of the wings, or replacement of the pistons of the outboard flight spoiler actuators with improved pistons. This amendment is prompted by reports of failure of the piston of the outboard flight spoiler actuator due to fatigue at the clevis end of the upper lug mounting hole of the piston. The actions specified by this AD are intended to prevent such failure of the piston and the consequent puncturing of the aft spar web, which could result in fuel leakage and reduced structural integrity of the wings.

DATES: Effective March 4, 1997. The incorporation by reference of certain publications listed in the regulations is approved by the Director of the Federal Register as of March 4, 1997.

ADDRESSES: The service information referenced in this AD may be obtained from McDonnell Douglas Corporation, 3855 Lakewood Boulevard, Long Beach, California 90846, Attention: Technical Publications Business Administration, Department C1-L51 (2-60). This information may be examined at the Federal Aviation Administration (FAA), Transport Airplane Directorate, Rules Docket, 1601 Lind Avenue, SW., Renton, Washington; or at the FAA, Transport Airplane Directorate, Los Angeles Aircraft Certification Office, 3960 Paramount Boulevard, Lakewood, California; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

FOR FURTHER INFORMATION CONTACT: Brent Bandley, Aerospace Engineer, Airframe Branch, ANM-120L, FAA, Los Angeles Aircraft Certification Office, 3960 Paramount Boulevard, Lakewood, California 90712; telephone (310) 627-5237; fax (310) 627-5210.

SUPPLEMENTARY INFORMATION: 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 McDonnell Douglas Model DC-9, DC-9-80 and C-9 (military) series airplanes, and Model MD-88 airplanes was published in the Federal Register on September 17, 1996 (61 FR 48864). That action proposed to require either installation of external protective doublers between the aft spar webs and the pistons of the outboard flight spoiler actuators on the wings, or replacement of the pistons of the outboard flight spoiler actuators with improved pistons. Interested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the comments received.

Support for the Proposal

Several commenters support the proposed rule.

Request to Permit Use of Previously Issued Service Documents

One commenter requests that the proposed rule be revised to give credit to those operators who previously have accomplished either of the proposed actions in accordance with earlier versions of McDonnell Douglas Service Bulletin 27-300. This commenter, a U.S. operator, points out that the proposal cites only Revision 2 of that service bulletin as the appropriate source of service information. However, the commenter has already accomplished the actions on its fleet in accordance with the initial release of that service bulletin, which was issued on April 14, 1992. The commenter wants assurance that it will not have to repeat the actions in accordance with Revision 2 of the service bulletin. The FAA concurs that credit should be given as requested by this commenter. The final rule has been revised to indicate that the use of previous versions of the referenced service bulletin is acceptable for compliance with this AD.

Request to Extend Compliance Time for Replacement of Pistons

One commenter requests that the compliance time for replacement of the pistons of the outboard flight spoiler actuators, as specified in proposed paragraph (a)(2), be extended from the proposed 5,000 landings (after the effective date of the final rule) to 10,500 landings. The commenter requests this extension so that the replacement can be accomplished during a regularly scheduled heavy maintenance visit, where trained personnel and ample parts would be available. The FAA does not concur with the commenter's request. 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 necessary parts and the practical aspect of accomplishing the replacement within an interval of time that parallels normal scheduled maintenance for the majority of affected operators. The FAA also took into account the manufacturers' recommendation (specified in McDonnell Douglas Service Bulletin DC9-27- 300) that the replacement be conducted ``at the earliest practical maintenance period.'' The FAA finds that, for the majority of affected operators, some scheduled maintenance will occur within the 5,000- landing compliance period; thus, special scheduling for the accomplishment of the replacement can be avoided. No technical data has been presented to the FAA to justify extending the compliance time any further. In consideration of these factors, the FAA has determined that the 5,000-landing compliance time for accomplishing the replacement of pistons (or the installation of doublers) is both appropriate and warranted.

Request to Allow Repetitive Inspections in Lieu of Replacement of Pistons

One commenter requests that, in lieu of the proposed installation or replacement actions, the proposed rule be revised to allow operators to conduct repetitive non-destructive test (NDT) inspections of the pistons and actuator assembly at intervals of 3,000 flight hours or 3,000 flight cycles. The commenter states that most of the subject actuators already are being ``driven off'' these airplanes by the requirements of AD 90-18-03 [amendment 39-6701, (50 FR 34704, August 24, 1990)], which mandated the inspections and modifications specified in ``DC-9/MD-80 Aging Aircraft Service Action Requirements Document,'' McDonnell Douglas Report No. MDC-K1572. Therefore, in the interim before replacement, the commenter suggests that operators should be allowed to perform repetitive NDT inspections. Further, by performing these inspections at the suggested interval, operators could accomplish them at the same time that they conduct the inspections of the spoiler links and fittings that currently are required by AD 85-01-03 [amendment 39-4977, (50 FR 2040, January 15, 1985). The FAA does not concur. The commenter provided neither technical data to justify the appropriateness of such inspections, nor suitable inspection and repair procedures. Further, the FAA does not consider that NDT inspections of the old pistons will necessarily enhance the safety of these parts. The FAA maintains that long term continued operational safety will be better assured by design changes to remove the source of a problem altogether, rather than by repetitive inspections. An understanding of the effectiveness of long term repetitive inspections and the human factors associated with conducting them, has led the FAA generally to consider placing less emphasis on inspections and more emphasis on design improvements. The replacement and installation requirements of this AD are

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in consonance with these considerations.

Request To Allow Modification in Lieu of Replacement of Pistons

Two commenters request that the proposed rule be revised to provide an option of modifying the actuator pistons instead of replacing them. These commenters point out that McDonnell Douglas Service Bulletin 27- 183 was issued previously to address fatigue cracking in the inboard and outboard spoiler actuator pistons. Among other things, that service bulletin describes procedures for reworking the pistons by stress coining the holes of the piston attach lug and installing fatigue bushings in the holes. One of the commenters states that tests conducted on actuator pistons that had been modified in accordance with these procedures demonstrated an increase in the fatigue strength of the piston over the original design by a factor of 10. The FAA does not concur with the commenters' request. The FAA acknowledges that testing did indicate that the stress coining procedure described in Service Bulletin 27-183 appeared to stop the cracking in the subject location. However, after this modification was implemented on actuator pistons in service, other parts failed in new locations; additional actions (such as dimensional changes) then had to be taken to address those failures. In light of this, the FAA does not find that the procedures described in Service Bulletin 27-183 are a viable option in and of themselves.

Request To Revise Cost Impact Information

One commenter requests that the FAA revise the information it provided concerning the estimated costs of replacing the pistons of the outboard flight spoiler actuators with improved pistons. This commenter contends that the FAA has underestimated the cost impact by a factor of four for some operators. This commenter points out that many operators will have to accomplish additional modifications of the actuator before the new improved pistons can be installed. This commenter refers to the modifications described in McDonnell Service Bulletin 27-240 (which would entail approximately $780 in parts and labor) and Service Bulletin 27-274 (which would entail approximately $110 in parts and labor). The commenter requests that the costs associated with performing the work specified in those service bulletins be included in the cost estimates for the proposed AD. The FAA does not consider that any revision to the cost estimate is necessary. The FAA acknowledges that the actions specified in the two service bulletins cited by the commenter must be accomplished prior to (or in conjunction with) the installation of the improved pistons. However, this AD requires only that the replacement action specified in McDonnell Douglas Service Bulletin DC9-27-300 be accomplished. Naturally, operators who have not already accomplished the other modifications will encounter additional costs, but the FAA is not mandating the other two service bulletins cited by the commenter. Further, operators are not obligated to install the improved pistons; that action is but one of two different actions provided by this AD. Instead of that installation, operators can elect to install the external protective doublers, as specified in paragraph (a)(1) of this final rule, and may find that action to be more cost effective for their operations.

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

There are approximately 1,571 Model DC-9, DC-9-80, and C-9 (military) series airplanes, and Model MD-88 airplanes of the affected design in the worldwide fleet. The FAA estimates that 1,047 airplanes of U.S. registry will be affected by this AD. The required installation of external doublers will take approximately 14 work hours per airplane to accomplish, at an average labor rate of $60 per work hour. Required parts will cost approximately $1,500 per airplane. Based on these figures, the cost impact of the installation of external doublers required by this AD on U.S. operators is estimated to be $2,340 per airplane. If all U.S. operators were to elect to accomplish this installation, the cost impact of this AD would be $2,449,980. The required replacement of the pistons of the outboard flight spoiler actuators will take approximately 12 work hours per airplane to accomplish, at an average labor rate of $60 per work hour. Required parts will cost approximately $5,180 per airplane. Based on these figures, the cost impact of the replaced of the pistons required by this AD on U.S. operators is estimated to be $5,900 per airplane. If all U.S. operators were to elect to accomplish this replacement, the cost impact of this AD would be $6,177,300. The 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, at least one affected U.S. operator has advised the FAA that it has already accomplished the actions required by this AD on the airplanes in its fleet. Therefore, the future cost impact of this AD is expected to be less than the figures indicated above.

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:

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Authority: 49 U.S.C. 106(g), 40113, 44701.

Sec. 39.13 [Amended]

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

97-02-08 McDonnell Douglas: Amendment 39-9893. Docket 96-NM-99-AD.

Applicability: Model DC-9, Model DC-9-80 and C-9 (military) series airplanes, and Model MD-88 airplanes; as listed in McDonnell Douglas Service Bulletin DC9-27-300, Revision 02, dated June 29, 1995; certificated in any category.

Note 1: This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been otherwise modified, altered, or repaired in the area subject to the requirements of this AD. For airplanes that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (b) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it. Compliance: Required as indicated, unless accomplished previously. To prevent fuel leakage and reduced structural integrity of the wings due to puncturing of the wings by a failed piston of the outboard flight spoiler actuator, accomplish the following: (a) Prior to the accumulation of 5,000 landings after the effective date of this AD, accomplish the actions specified in either paragraph (a)(1) or (a)(2) of this AD, in accordance with McDonnell Douglas Service Bulletin DC9-27-300, Revision 02, dated June 29, 1995.

Note 2. Accomplishment of the actions specified in this paragraph prior to the effective date of this AD in accordance with the original issue or Revision 1 of McDonnell Douglas Service Bulletin 27-300 is considered acceptable for compliance with this paragraph. Note 3: Installation of McDonnell Douglas flight spoiler actuator assembly, part number (P/N) 5915900-5525, on the right and left wings prior to the effective date of this AD is considered acceptable for compliance with the requirements of this paragraph.

(1) Install external protective doublers between the outboard flight spoiler actuators and the aft spar webs of the left and right wings; or (2) Replace the pistons of the outboard flight spoiler actuators on the left and right wings with improved pistons. (b) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, Los Angeles Aircraft Certification Office (ACO), FAA, Transport Airplane Directorate. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Los Angeles ACO.

Note 4: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Los Angeles ACO.

(c) Special flight permits may be issued in accordance with sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the airplane to a location where the requirements of this AD can be accomplished. (d) Except as specified in NOTE 2 of this AD, the actions shall be done in accordance with McDonnell Douglas Service Bulletin DC9- 27-300, Revision 02, dated June 29, 1995. This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from McDonnell Douglas Corporation, 3855 Lakewood Boulevard, Long Beach, California 90846, Attention: Technical Publications Business Administration, Department C1-L51 (2-60). Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the FAA, Transport Airplane Directorate, Los Angeles Aircraft Certification Office, 3960 Paramount Boulevard, Lakewood, California; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC. (e) This amendment becomes effective on March 4, 1997.

Issued in Renton, Washington, on January 14, 1997. S.R. Miller, Acting Manager, Transport Airplane Directorate, Aircraft Certification Service. [FR Doc. 97-1437 Filed 1-27-97; 8:45 am] BILLING CODE 4910-13-U