01-3700. Airworthiness Directives; McDonnell Douglas Model DC-9, DC-9-80, and C-9 (Military) Series Airplanes; Model MD-88 Airplanes; and Model MD-90 Airplanes

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Supplemental notice of proposed rulemaking; reopening of comment period.

SUMMARY:

This document revises an earlier proposed airworthiness directive (AD), applicable to certain McDonnell Douglas Model DC-9, DC-9-80, and C-9 (military) series airplanes; Model MD-88 airplanes; and Model MD-90 airplanes that would have required, among other actions, a visual check to determine the part and serial numbers of the upper lock link assembly of the nose landing gear (NLG); repetitive inspections of certain upper lock link assemblies to detect fatigue cracking; and replacement of the upper lock link assembly with an assembly made from aluminum forging material, if necessary. Such replacement would constitute terminating action for the requirements of this AD. That proposal was prompted by a report indicating that an NLG upper lock link fractured prior to landing and jammed against the NLG shock strut, restricting the NLG from fully extending. This new action revises, among other actions, a list of suspect parts; delays accomplishment of a certain replacement; and revises the initial compliance time. The actions specified by this new proposed AD are intended to address the identified unsafe condition.

DATES:

Comments must be received by March 12, 2001.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 97-NM-298-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Comments may be inspected at this location between 9:00 a.m. and 3:00 p.m., Monday through Friday, except Federal holidays. Comments may be submitted via fax to [phone]. Comments may also be sent via the Internet using the following address: [e-mail]. Comments sent via fax or the Internet must contain “Docket No. 97-NM-298-AD” in the subject line and need not be submitted in triplicate. Comments sent via the Internet as attached electronic files must be formatted in Microsoft Word 97 for Windows or ASCII text.

The service information referenced in the proposed rule may be obtained from Boeing Commercial Aircraft Group, Long Beach Division, 3855 Lakewood Boulevard, Long Beach, California 90846, Attention: Technical Publications Business Administration, Dept. C1-L51 (2-60). This information may be examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the FAA, Los Angeles Aircraft Certification Office, 3960 Paramount Boulevard, Lakewood, California.

FOR FURTHER INFORMATION CONTACT:

Brent Bandley, Aerospace Engineer, Airframe Branch, ANM-120L, FAA, Los Angeles Aircraft Certification Office, 3960 Paramount Boulevard, Lakewood, California 90712-4137; telephone [phone]; fax [phone].

SUPPLEMENTARY INFORMATION:

Comments Invited

Interested persons are invited to participate in the making of the proposed rule by submitting such written data, views, or arguments as they may desire. Communications shall identify the Rules Docket number and be submitted in triplicate to the address specified above. All communications received on or before the closing date for comments, specified above, will be considered before taking action on the proposed rule.

The proposals contained in this notice may be changed in light of the comments received.

Submit comments using the following format:

• Organize comments issue-by-issue. For example, discuss a request to change the compliance time and a request to change the service bulletin reference as two separate issues.
• For each issue, state what specific change to the proposed AD is being requested.
• Include justification (e.g., reasons or data) for each request.

Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the proposed rule. All comments submitted will be available, both before and after the closing date for comments, in the Rules Docket for examination by interested persons. A report summarizing each FAA-public contact concerned with the substance of this proposal will be filed in the Rules Docket.

Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this action must submit a self-addressed, stamped postcard on which the following statement is made: “Comments to Docket Number 97-NM-98-AD.” The postcard will be date stamped and returned to the commenter.

Availability of NPRMs

Any person may obtain a copy of this NPRM by submitting a request to the FAA, Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 97-NM-298-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

Discussion

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to add an airworthiness directive (AD), applicable to certain McDonnell Douglas Model DC-9, DC-9-80, and C-9 (military) series airplanes, Model MD-88 airplanes, and Model MD-90 airplanes, was published as a notice of proposed rulemaking (NPRM) in the Federal Register on October 14, 1999 (64 FR 55644). That NPRM would have required, among other actions, a visual check to determine the part and serial numbers of the upper lock link assembly of the nose landing gear (NLG); repetitive inspections of certain upper lock link assemblies to detect fatigue cracking; and replacement of the upper lock link assembly with an assembly made from aluminum forging material, if necessary. Such replacement would have constituted terminating action for the requirements of this AD. That NPRM was prompted by a report indicating that, due to fatigue cracking, a NLG upper lock link fractured prior to landing and jammed against the NLG shock strut, restricting the NLG from fully extending. That condition, if not corrected, could result in injury to passengers and flight crew, and damage to the airplane.

Actions Since Issuance of Previous Proposal

Due consideration has been given to the comments received in response to the NPRM.

Support for Proposed AD

One commenter supports the proposed AD.

Requests To Revise Compliance Time

Two commenters request that the compliance time of paragraph (a) of the proposed AD be revised to eliminate the words “5,000 landings since the last inspection in accordance with paragraph (a) of AD 97-02-10, [amendment 39-9895 (62 FR 3781, January 27, 1997)] whichever occurs first.” The commenters state that paragraph (a) of AD 97-02-10 requires classification of the subject links as exempt or non-exempt. According to AD 97-02-10, no further action is required if an airplane has an exempt link. One commenter also states that the proposed AD would require re-inspection of all NLG links regardless of classification findings in AD 97-02-10. As the compliance time is currently written in the proposed AD, the commenters state that their airplanes could exceed the 5,000-landing requirement for previously classified “exempt” links. The commenters also state that the proposed compliance time could severely limit the timeframe to inspect non-exempt links approaching the 5,000-landing repetitive inspection interval required by paragraph (c)(1) of AD 97-02-10.

Based on the commenters' statements and after reviewing the wording of the compliance time of paragraph (a) of the proposed AD, the FAA finds that clarification is necessary. As indicated in the preamble of the proposed AD, unlike in Boeing Alert Service Bulletins MD90-32A019 and DC9-32A298, there are no lock link assemblies specified as “exempt” or “non-exempt” in this proposed AD. Instead, a one-time inspection is required to determine whether the upper lock link assembly is from an “affected lot,” as specified in Boeing Service Bulletin MD90-32-033 or DC9-32-315.

In addition, we find that operators that are currently accomplishing the 5,000-landing repetitive inspection required by paragraph (c)(1) of AD 97-02-10 may have already exceeded or be near the threshold specified in paragraph (a) of the proposed AD [i.e., 5,000 landings since the last inspection accomplished in accordance with paragraph (c)(1) of AD 97-02-10]. Therefore, we have determined that a 90-day grace period is necessary to preclude those airplanes from being grounded unnecessarily. In developing an appropriate compliance time for this action for the subject airplanes, we considered not only the manufacturer's recommendation, but the degree of urgency associated with addressing the subject unsafe condition, the average utilization of the affected fleet, and the time necessary to perform the inspections (one hour). In light of all of these factors, we find a 90-day grace period for initiating the proposed actions to be warranted, in that it represents an appropriate interval of time allowable for affected airplanes to continue to operate without compromising safety.

Therefore, for airplanes on which the inspection required by paragraph (c)(1) of AD 97-02-10 has been accomplished, the proposed actions required by paragraph (a) of this AD must be accomplished prior to accumulation of 5,000 landings since the last inspection accomplished in accordance with paragraph (c)(1) of AD 97-02-10, or within 90 days after the effective date of this AD, whichever occurs later. For airplanes on which the inspection required by paragraph (c)(1) of AD 97-02-10 has NOT been accomplished, the proposed actions required by paragraph (a) of the AD must be accomplished within 2,500 landings on the NLG after the effective date of this AD. We have revised paragraph (a) of the supplemental NPRM accordingly.

Request to Clarify the Requirements of Paragraph (c)(2)(iii) of the Proposed AD

One commenter questions whether the FAA's intent in paragraph (c)(2)(iii) of the proposed AD was to require both a high frequency eddy current (HFEC) inspection “and” Type 1 fluorescent penetrant inspection or to require either one of those inspections. The commenter notes that the service bulletins referenced in the proposed AD recommend performing either an HFEC “or” a Type 1 fluorescent inspection, and that AD 97-02-10 requires accomplishment of either inspection.

The FAA's intent was that paragraph (c)(2)(iii) of the proposed AD require either a HFEC inspection OR a Type 1 fluorescent penetrant inspection. We have revised paragraph (c)(2)(iii) of the supplemental NPRM accordingly.

Request to Delay Accomplishment of the Replacement

One commenter, the airplane manufacturer, requests that the FAA revise paragraph (c)(2)(iii)(A) of the proposed AD to require a second inspection and, within 2,500 landings following accomplishment of the second inspection, replacement of the lock link specified in that paragraph. The commenter states that this second inspection and eventual replacement were identified in the referenced service bulletins. The commenter also states that the 5,000-landing delay of the replacement is necessary because there may be a parts-availability problem.

The FAA agrees. Our intent was to follow the procedures recommended in the referenced service bulletins for these actions. We have revised paragraph (d) of the supplemental NPRM [paragraph (c)(2)(iii)(A) of the original NPRM] accordingly.

Explanation of New Service Information

Since issuance of the NPRM, the FAA has reviewed and approved Revision 01 of Boeing (McDonnell Douglas) Service Bulletins DC9-32-315 and MD90-32-033, both dated October 24, 2000. The effectivity listing of Revision 01 of the services bulletins has been revised to remove certain manufacturer's fuselage numbers from the effectivity listing and to add certain others. Revision 01 of these service bulletins also has been revised to:

1. Update the list of affected serial numbers of the NLG upper lock link that are identifed as hand forging material;

2. Redefine the type of etching method to be used when marking certain parts; and

3. Clarify that, under a certain condition, the upper lock link must be reidentified with a “black” paint stripe.

In addition, the revised service bulletins clarify the wording “aluminum forging” as die forged aluminum to differentiate from hand forged aluminum and provide a method to identify materials made from a specific process. We have revised the supplemental NPRM accordingly to reference Revision 01 of the subject service bulletins as an appropriate source of service information.

Operators should note that Revision 01 of Boeing Service Bulletin DC9-32-315 misidentifies the date of the original issue as June 21, 1999. The correct date is March 11, 1999. Boeing is planning to correct this error in the next revision of the service bulletin.

Explanation of Change to the Applicability

Because the effectivity listing in these revised service bulletins described above reflects the most current composition of operators and airplanes affected by this AD, the FAA has revised the applicability statement of the supplemental NPRM to reference these revised service bulletins.

Explanation of Change of Type of Inspection

The FAA finds that it is not necessary to perform a “detailed visual” inspection to to determine a certain serial number of the lock link in paragraph (b) of the proposed AD.

We have deleted the reference to “detailed visual” throughout the supplemental NPRM and deleted NOTE 2 (definition of a detailed visual inspection).

Conclusion

Since these changes expand the scope of the originally proposed rule, the FAA has determined that it is necessary to reopen the comment period to provide additional opportunity for public comment.

Cost Impact

There are approximately 2,100 Model DC-9, DC-9-80, and C-9 (military) series airplanes; Model MD-88 airplanes; and Model MD-90 airplanes of the affected design in the worldwide fleet. The FAA estimates that 1,400 airplanes of U.S. registry would be affected by this proposed AD.

It would take approximately 1 work hour per airplane to accomplish the proposed inspections of the NLG upper lock link, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of this inspection proposed by this AD on U.S. operators is estimated to be $84,000, or $60 per airplane.

It would take approximately 4 work hours per airplane to accomplish each proposed replacement of the NLG upper lock link, at an average labor rate of $60 per work hour. Required parts would cost approximately $5,803 per airplane. Based on these figures, the cost impact of each replacement proposed by this AD on U.S. operators is estimated to be $8,460,200, or $6,043 per airplane.

The cost impact figures discussed above are 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. The cost impact figures discussed in AD rulemaking actions represent only the time necessary to perform the specific actions actually required by the AD. These figures typically do not include incidental costs, such as the time required to gain access and close up, planning time, or time necessitated by other administrative actions.

Regulatory Impact

The regulations proposed herein would not have a substantial direct effect 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, it is determined that this proposal would not have federalism implications under Executive Order 13132.

For the reasons discussed above, I certify that this proposed regulation (1) is not a “significant regulatory action” under Executive Order 12866; (2) is not a “significant rule” under the DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (3) if promulgated, 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 copy of the draft regulatory evaluation prepared for this action is contained in the Rules Docket. A copy of it may be obtained by contacting the Rules Docket at the location provided under the caption ADDRESSES.

List of Subjects in 14 CFR Part 39

• Air transportation
• Aircraft
• Aviation safety
• Safety

The Proposed Amendment

Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration proposes to amend 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 removing amendment 39-9895 (62 FR 3781, January 27, 1997), and by adding a new airworthiness directive (AD), to read as follows:

McDonnell Douglas: Docket 97-NM-298-AD. Supersedes AD 97-02-10, Amendment 39-9895.

Applicability: Model DC-9, DC-9-80, and C-9 (military) series airplanes; Model MD-88 airplanes; and Model MD-90 airplanes; as listed in Boeing Service Bulletins DC9-32-315, and MD90-32-033, both Revision 01, dated October 24, 2000; certificated in any category.

Note 1:

This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been 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 (f)(1) 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 the upper lock link assembly of the nose landing gear (NLG) from fracturing due to fatigue cracking, and the NLG consequently failing to extend fully, which could result in injury to passengers and flight crew, and damage to the airplane, accomplish the following:

Removing and Retaining Upper Lock Link

(a) Remove and retain the upper lock link, part number (P/N) 3914464, and attaching parts; and do the inspections required by paragraphs (b) and (c) of this AD, per the applicable Boeing (McDonnell Douglas) service bulletin listed in Table 1 of this AD. The actions required by this paragraph shall be done at the applicable time specified in paragraph (a)(1) or (a)(2) of this AD. Table 1 is as follows:

Table 1.

Service bulletin	Revision level	Date	Model
DC9-32-315	Original or Revision 01	March 11, 1999 October 24, 2000	DC-9, DC-9-80, and C-9 (military) series airplanes; and MD-88 airplanes.
MD90-32-033	Original or Revision 01	March 11, 1999 October 24, 2000	MD-90 airplanes.

(1) For airplanes on which the inspection required by paragraph (c)(1) of AD 97-02-10 has been done: Do the actions before 5,000 landings since the last inspection done per paragraph (c)(1) of AD 97-02-10, or within 90 days after the effective date of this AD, whichever occurs later.

(2) For airplanes on which the inspection required by paragraph (c)(1) of AD 97-02-10 has NOT been done: Do the actions within 2,500 landings on the NLG after the effective date of this AD.

Inspection

(b) Do a one-time inspection of the NLG upper lock link assembly per Revision 01 of the applicable service bulletin listed in Table 1 of this AD to determine whether the serial number of the lock link is identified in the affected lot specified in Condition 1 of the Accomplishment Instructions of Revision 01 of the applicable Boeing (McDonnell Douglas) service bulletin listed in Table 1 of this AD.

Condition 1 (Hand Forging Serial Number)

(1) If the serial number of the upper lock link is not from the affected lot specified in Revision 01 of the applicable service bulletin (Condition 1), before further flight, do the etch inspection required by paragraph (c) of this AD.

(2) If the serial number of the upper lock link is from the affected lot specified in the Revision 01 of the applicable service bulletin (Condition 1), before further flight, replace the lock link with a new upper lock link, P/N 3914464-507; a reidentified upper lock link by adding an “F” to the part number, using an electro chemical deep etch method; or a new upper lock link assembly, P/N 5965065-507; all made from die forged aluminum material; per the applicable service bulletin. Accomplishment of the replacement constitutes terminating action for the requirements of this AD.

Etch Inspection

(c) Perform a one-time etch inspection of the NLG upper lock link to determine whether the lock link is made from die forged aluminum material (Condition 2), or from plate or bar material (Condition 3); per the applicable Boeing (McDonnell Douglas) service bulletin listed in Table 1 of this AD.

Condition 2 (Die Forged Aluminum Material)

(1) If the upper lock link is made from die forged aluminum material, before further flight, restore the finish and reidentify the lock link by adding an “F” to the part number, using an electro chemical deep etch method, per the applicable service bulletin. Identification of the lock link as being made from die forged aluminum material constitutes terminating action for the requirements of this AD.

Condition 3 (Plate or Bar Material)

(2) If the NLG upper lock link is made from plate or bar material, before further flight, do either Condition 3, Option 1, as specified by paragraph (c)(2)(i) of this AD, or Condition 3, Option 2, as specified by paragraphs (c)(2)(ii) and (c)(2)(iii) of this AD.

Condition 3, Option 1

(i) Permanently remove any discrepant upper lock link and replace with a new upper lock link, P/N 3914464-507; a reidentified upper lock link by adding an “F” to the part number, using an electro chemical deep etch method; or a new upper lock link assembly, P/N 5965065-507; all made from die forged aluminum material; per the applicable service bulletin. Accomplishment of the replacement constitutes terminating action for the requirements of this AD.

Condition 3, Option 2

(ii) Restore the link finish and reidentify the upper lock link by adding a black paint stripe adjacent to the part number, indicating that the part is not made from die forged aluminum material, per the applicable service bulletin.

(iii) Do a high frequency eddy current (HFEC) or Type I fluorescent penetrant inspection of the upper lock link assembly, P/N 3914464—(any configuration), to detect cracking of the assembly; per McDonnell Douglas Alert Service Bulletin DC9-32A298, Revision 02 [for Model DC-9, DC-9-80, and C-9 (military) series airplanes; and Model MD-88 airplanes], or Alert Service Bulletin MD90-32A019, Revision 02 (for Model MD-90 airplanes), both dated October 29, 1997; as applicable.

Actions Following the Inspection Required by Paragraph (c)(2)(iii)

(d) If no crack is detected during the HFEC or Type I fluorescent penetrant inspection required by paragraph (c)(2)(iii) of this AD, within 2,500 landings on the NLG since accomplishment of the inspection performed per paragraph (c)(2)(iii) of this AD, as applicable, do that inspection a second time. If no crack is detected during this second inspection, within 2,500 landings after accomplishment of the second inspection, replace the upper lock link with a new upper lock link, P/N 3914464-507; a reidentified upper lock link by adding an “F” to the part number, using an electro chemical deep etch method; or a new upper lock link assembly, P/N 5965065-507; all made from die forged aluminum material; per the applicable Boeing (McDonnell Douglas) service bulletin listed in Table 1 of this AD. Accomplishment of the replacement action constitutes terminating action for the requirements of this AD.

(e) If any crack is detected during the HFEC or Type I fluorescent penetrant inspection required by paragraph (c)(2)(iii) or (d) of this AD, before further flight, replace the discrepant NLG upper lock link with a new upper lock link, P/N 3914464-507; a reidentified upper lock link by adding an “F” to the part number, using an electro chemical deep etch method; or a new upper lock link assembly, P/N 5965065-507; all made from die forged aluminum material; per the applicable Boeing (McDonnell Douglas) service bulletin listed in Table 1 of this AD. Accomplishment of the replacement constitutes terminating action for the requirements of this AD.

Alternative Methods of Compliance

(f)(1) 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. 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 2:

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

(2) Alternative methods of compliance, approved previously in accordance with AD 97-02-10, amendment 39-9895, are approved as alternative methods of compliance with paragraph (f)(1) of this AD.

Special Flight Permits

(g) 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.

Issued in Renton, Washington, on February 8, 2001.

Donald L. Riggin,

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.