03-25868. Airworthiness Directives; McDonnell Douglas Model MD-90-30 Airplanes

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

This document proposes the supersedure of an existing airworthiness directive (AD), applicable to certain McDonnell Douglas Model MD-90-30 airplanes, that currently requires repetitive fluorescent penetrant and magnetic particle inspections to detect fatigue cracking of the main landing gear (MLG) piston, and repair if necessary. This action would expand the applicability of the existing AD to require the currently required inspections, and corrective actions if necessary, on additional airplanes and MLG piston part numbers, and would require repetitive inspections for evidence of cracking in the paint topcoat of the MLG pistons. This action also would require replacement of certain MLG shock strut piston assemblies with new or serviceable improved assemblies, which would terminate the requirements of this AD. These actions are necessary to prevent fatigue cracking of MLG pistons, which could result in failure of the pistons, and consequent damage to the airplane structure and injury to flightcrew, passengers, or ground personnel. These actions are intended to address the identified unsafe condition.

DATES:

Comments must be received by November 28, 2003.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2001-NM-275-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Comments may be inspected at this location between 9 a.m. and 3 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. 2001-NM-275-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 or 2000 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: Data and Service Management, Dept. C1-L5A (D800-0024). 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:

Carl Fountain, 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 action 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 2001-NM-275-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. 2001-NM-275-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

Discussion

On February 8, 2000, the FAA issued AD 2000-03-08, amendment 39-11567 (65 FR 7719, February 16, 2000), applicable to certain McDonnell Douglas Model MD-90-30 airplanes, to require repetitive fluorescent penetrant and magnetic particle inspections to detect fatigue cracking of the main landing gear (MLG) piston, and repair if necessary. That action was prompted by reports that, during towing of in-service airplanes, MLG failures occurred due to fatigue cracks. The requirements of that AD are intended to detect and correct fatigue cracking of MLG pistons, which could result in failure of the pistons, and consequent damage to the airplane structure and injury to flightcrew, passengers, or ground personnel.

In the preamble to AD 2000-03-08, we specified that the actions required by that AD were considered “interim action” and that the manufacturer was developing a modification to address the unsafe condition. We indicated that we might consider further rulemaking action once the modification was developed, approved, and available. The manufacturer now has developed such a modification, and we have determined that further rulemaking action is indeed necessary. This proposed AD follows from that determination.

Actions Since Issuance of Previous Rule

Since the issuance of AD 2000-03-08, we have issued AD 2002-10-03, amendment 39-12749 (67 FR 34823), which applies to certain McDonnell Douglas Model DC-9-81 (MD-81), DC-9-82 (MD-82), DC-9-83 (MD-83), DC-9-87 (MD-87), MD-88, and MD-90-30 airplanes. For Model MD-90-30 airplanes, that AD requires replacement of certain MLG shock strut piston assemblies with new or serviceable improved assemblies, according to Boeing Service Bulletin MD90-32-031, Revision 01, dated April 25, 2001. Accomplishment of that replacement will terminate the requirements of this AD, as noted in paragraph (b) of AD 2002-10-03. Therefore, we have included in paragraph (j) of this proposed AD the requirements of paragraph (a) of AD 2002-10-03 that apply to the Model MD-90-30 airplanes subject to this proposed AD. The compliance time for the replacement specified in this proposed AD (“Before the accumulation of 30,000 total landings on the MLG shock strut piston assemblies, or within 5,000 landings after June 20, 2002 (the effective date of AD 2002-10-03, amendment 39-12749), whichever occurs later”) is the same as the compliance time in paragraph (a) of AD 2002-10-03. Once this proposed AD becomes effective, we may consider further rulemaking to revise or rescind AD 2002-10-03 to remove the duplicate requirement.

Explanation of Relevant Service Information

We have reviewed and approved Boeing Service Bulletin MD90-32-012, Revision 03, dated June 29, 2001. (AD 2000-03-08 refers to Boeing Service Bulletin MD90-32-012, Revision 01, dated June 2, 1998, as the acceptable source of service information for the actions required by that AD. Also, the applicability statement of AD 2000-03-08 states that the AD applies to Model MD-90-30 airplanes as listed in Boeing Service Bulletin MD90-32-012, Revision 01). Revision 03 of the service bulletin is also effective for additional airplanes and MLG piston part numbers that were not included in Revision 01 of the service bulletin. Revision 03 describes procedures for initial fluorescent penetrant and magnetic particle inspections to detect cracking of the MLG torque link lugs; follow-on repetitive visual, fluorescent penetrant, and magnetic particle inspections for cracking of the MLG torque link lugs; and repetitive visual inspections for evidence of cracking in the paint topcoat, and, if any evidence of cracking in the paint topcoat is found, a follow-on NDT inspection of the MLG piston to determine if any cracking is present. Revision 03 of the service bulletin specifies to contact Boeing for repair instructions if any crack is found.

As explained previously in the preamble of the notice of proposed rulemaking (NPRM) for AD 2002-10-03, the FAA has reviewed and approved Boeing Service Bulletin MD90-32-031, Revision 01. That service bulletin describes procedures for replacement of the MLG shock strut piston assemblies, left and right-hand side, with new or serviceable, improved assemblies, which would eliminate the need for the repetitive inspections described above.

Accomplishment of the actions specified in the service bulletins is intended to adequately address the identified unsafe condition.

Explanation of Requirements of Proposed Rule

Since an unsafe condition has been identified that is likely to exist or develop on other products of this same type design, the proposed AD would supersede AD 2000-03-08 to continue to require repetitive fluorescent penetrant and magnetic particle inspections to detect fatigue cracking of the MLG piston, and repair if necessary. The proposed AD would expand the applicability of the existing AD to include additional airplanes and MLG piston part numbers. These actions would be required to be accomplished per Boeing Service Bulletin MD90-32-012, Revision 03, which was described previously, except as discussed below under the heading “Differences Between Proposed AD and Service Bulletin.” The proposed AD also would require replacement of certain MLG shock strut piston assemblies with new or serviceable improved assemblies, which would terminate the existing requirements of this proposed AD. This action would be required to be accomplished per Boeing Service Bulletin MD90-32-031, Revision 01.

Operators may note that, consistent with the provisions of Boeing Service Bulletin MD90-32-012, Revision 03, if any evidence of cracking in the paint topcoat of the MLG piston is found, the proposed AD would allow deferral, for the earlier of 7 days or 50 landings, of the follow-on NDT inspection to detect any cracking of the MLG piston. We have determined that, for this proposed AD, such a deferral would not adversely affect the continued operating safety of an affected airplane. Accomplishment of the NDT inspection for cracking of the MLG piston, and any necessary repair, within 7 days or 50 landings after evidence of cracking in the topcoat paint is found, would adequately ensure that any cracking of the MLG piston would be detected before it represents a hazard to the airplane.

Differences Between Proposed AD and Service Bulletin

Although Boeing Service Bulletin MD90-32-012, Revision 03, describes procedures for fluorescent penetrant and magnetic particle inspections, that service bulletin does not emphasize the sequence of these inspections. We find that, in each inspection cycle, it is necessary for the fluorescent penetrant inspection to precede the magnetic particle inspection. This sequencing is important because we are aware of cases in which accomplishment of a magnetic particle inspection before a fluorescent penetrant inspection interfered with the results of the fluorescent penetrant inspection. Therefore, paragraph (e) has been included in this proposed AD to clarify that, for inspections performed after the effective date of this AD, accomplishment of the fluorescent penetrant inspection must precede accomplishment of the magnetic particle inspection.

Operators should note that, although Boeing Service Bulletin MD90-32-012, Revision 03, specifies that the manufacturer may be contacted for disposition of repair conditions, this proposed AD would require repairs to be accomplished per a method approved by the FAA.

Cost Impact

There are approximately 114 Model MD-90-30 airplanes of the affected design in the worldwide fleet.

In AD 2000-03-08, we estimated that the actions in that AD applied to 15 airplanes of U.S. registry. The actions that are currently required by AD 2000-03-08 take approximately 2 work hours per airplane to accomplish, at an average labor rate of $65 per work hour. Based on these figures, the cost impact of the currently required actions on U.S. operators is estimated to be $1,950, or $130 per airplane, per inspection cycle.

The FAA estimates that 21 airplanes of U.S. registry would be affected by this new proposed AD.

The new inspections that are proposed in this AD action would take approximately 2 work hours per airplane to accomplish, at an average labor rate of $65 per work hour. Based on these figures, the cost impact of the proposed requirements of this AD on U.S. operators is estimated to be $2,730, or $130 per airplane.

As explained previously, the replacement of MLG pistons that is included in this proposed AD is already required by AD 2002-10-03. Therefore, this proposed AD would add no new costs associated with that action. We restate the cost impact estimate in its entirety in this proposed AD for the convenience of affected operators:

The replacement that is included in this AD action and currently required by AD 2002-10-03 takes approximately 28 work hours per airplane to accomplish, at an average labor rate of $65 per work hour. Required parts cost approximately $263,438 per airplane. Based on these figures, the cost impact of this requirement on U.S. operators of airplanes subject to this proposed AD is estimated to be $5,570,418, or $265,258 per airplane.

The cost impact figures discussed above are based on assumptions that no operator has yet accomplished any of the current or 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. The manufacturer may cover the cost of replacement parts associated with this proposed AD, subject to warranty conditions. As a result, the costs attributable to the proposed AD may be less than stated above.

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 39-11567 (65 FR 7719, February 16, 2000), and by adding a new airworthiness directive (AD), to read as follows:

McDonnell Douglas: Docket 2001-NM-275-AD. Supersedes AD 2000-03-08, Amendment 39-11567.

Applicability: Model MD-90-30 airplanes listed in Boeing Service Bulletin MD90-32-012, Revision 03, dated June 29, 2001; certificated in any category.

Compliance: Required as indicated, unless accomplished previously.

To prevent fatigue cracking of main landing gear (MLG) pistons, which could result in failure of the pistons, and consequent damage to the airplane structure and injury to flightcrew, passengers, or ground personnel, accomplish the following:

Restatement of Requirements of AD 2000-03-08

Inspection of MLG Piston Part Number 5935347-509

(a) For airplanes listed in McDonnell Douglas Service Bulletin MD90-32-012, Revision 01, dated June 2, 1998: For MLG pistons, part number (P/N) 5935347-509, perform fluorescent penetrant and magnetic particle inspections to detect fatigue cracking of the MLG pistons, in accordance with McDonnell Douglas Service Bulletin MD90-32-012, dated May 19, 1997, or Revision 01, dated June 2, 1998; or Boeing Service Bulletin MD90-32-012, Revision 03, dated June 29, 2001; at the later of the times specified in paragraphs (a)(1) and (a)(2) of this AD. Repeat the inspections thereafter at intervals not to exceed 2,500 landings.

(1) Prior to the accumulation of 4,000 total landings; or

(2) Within 2,500 landings or 12 months after March 22, 2000 (the effective date of AD 2000-03-08, amendment 39-11567), whichever is first.

Inspection of MLG Piston Part Numbers 5935347-511 and -513

(b) For airplanes listed in McDonnell Douglas Service Bulletin MD90-32-012, Revision 01, dated June 2, 1998: For MLG pistons, P/Ns 5935347-511 and -513, within 5,000 landings after March 22, 2000, perform fluorescent penetrant and magnetic particle inspections to detect fatigue cracking of the MLG pistons, in accordance with McDonnell Douglas Service Bulletin MD90-32-012, dated May 19, 1997, or Revision 01, dated June 2, 1998; or Boeing Service Bulletin MD90-32-012, Revision 03, dated June 29, 2001. Repeat the inspections thereafter at intervals not to exceed 5,000 landings.

Repair

(c) If any crack is found during any inspection required by paragraphs (a), (b), or (f) of this AD: Repair in accordance with a method approved by the Manager, Los Angeles Aircraft Certification Office (ACO), FAA. For a repair method to be approved by the Manager, Los Angeles ACO, as required by this paragraph, the Manager's approval letter must specifically refer to this AD.

New Requirements of This AD

No Requirement To Submit Information

(d) Although Boeing Service Bulletin MD90-32-012, Revision 03, dated June 29, 2001, specifies to submit information to the manufacturer, this AD does not include such a requirement.

Clarification of Inspection Sequence

(e) For inspections accomplished after the effective date of this AD: Where this AD requires fluorescent penetrant and magnetic particle inspections, accomplishment of the fluorescent penetrant inspection must precede accomplishment of the magnetic particle inspection.

Inspection of MLG Piston P/Ns 5935347-1 through -509, -511, and -513; and SR09320081-3 through -13

(f) For any MLG piston having P/N 5935347-1 through -509, -511, or -513; or P/Ns SR09320081-3 through -13: Perform fluorescent penetrant and magnetic particle inspections to detect fatigue cracking of the MLG pistons, in accordance with Boeing Service Bulletin MD90-32-012, Revision 03, dated June 29, 2001. Do the initial inspections at the later of the times specified in paragraphs (f)(1) and (f)(2) of this AD, except as provided by paragraph (g) of this AD. Repeat the inspections thereafter at intervals not to exceed 5,000 landings.

(1) Prior to the accumulation of 4,000 total landings; or

(2) Within 2,500 landings or 12 months after the effective date of this AD, whichever is first.

MLG Pistons Inspected Per Paragraph (a) or (b) of This AD

(g) MLG pistons having P/N 5935347-509, -511, or -513 that have been inspected as required by paragraph (a) or (b) of this AD, as applicable, are not required to be reinspected per paragraph (f) of this AD.

Repetitive Inspections for Evidence of Cracking and Follow-on Actions

(h) During the first brake change after the effective date of this AD, perform a general visual inspection to find evidence of cracking in the paint topcoat of the MLG piston, per the Accomplishment Instructions of Boeing Service Bulletin MD90-32-012, Revision 03, dated June 29, 2001. Repeat this inspection during every brake change.

(1) If any evidence of cracking in the paint topcoat, as described in the service bulletin, is found: Within 7 days or 50 landings after the evidence is found, whichever is first, perform a non-destructive test (NDT) inspection of the MLG piston to determine if there is any cracking.

(2) If any crack is found during the NDT inspection required by paragraph (h)(1) of this AD, before further flight, repair per a method approved by the Manager, Los Angeles ACO. For a repair method to be approved by the Manager, Los Angeles ACO, as required by this paragraph, the Manager's approval letter must specifically refer to this AD.

Note 1:

For the purposes of this AD, a general visual inspection is defined as: “A visual examination of an interior or exterior area, installation, or assembly to detect obvious damage, failure, or irregularity. This level of inspection is made from within touching distance unless otherwise specified. A mirror may be necessary to enhance visual access to all exposed surfaces in the inspection area. This level of inspection is made under normally available lighting conditions such as daylight, hangar lighting, flashlight, or droplight and may require removal or opening of access panels or doors. Stands, ladders, or platforms may be required to gain proximity to the area being checked.”

Inspections Accomplished Per Previous Issue of Service Bulletin

(i) Inspections accomplished before the effective date of this AD per McDonnell Douglas Service Bulletin MD90-32-012, Revision 02, dated June 29, 1999, are considered acceptable for compliance with the corresponding action specified in this AD.

Replacement of MLG Shock Strut Piston Assemblies

(j) Before the accumulation of 30,000 total landings on the MLG shock strut piston assemblies, or within 5,000 landings after June 20, 2002 (the effective date of AD 2002-10-03, amendment 39-12749), whichever occurs later: Replace the MLG shock strut piston assemblies, left- and right-hand sides, with new or serviceable improved assemblies, per the Accomplishment Instructions of Boeing Service Bulletin MD90-32-031, Revision 01, dated April 25, 2001. If the MLG shock strut piston is not serialized or the number of landings on the piston cannot be conclusively determined, consider the total number of landings on the piston assembly to be equal to the total number of landings accumulated by the airplane with the highest total number of landings in the operator's fleet.

Note 2:

Paragraph (a) of AD 2002-10-03, amendment 39-12749, requires the same actions as paragraph (j) of this AD.

Compliance With Requirements of Other ADs

(k) Accomplishment of the replacement required by paragraph (j) of this AD constitutes terminating action for the requirements of this AD and AD 2002-10-03, amendment 39-12749, for the Model MD-90-30 airplanes listed in Boeing Service Bulletin MD90-32-012, Revision 03, dated June 29, 2001.

Alternative Methods of Compliance

(l)(1) In accordance with 14 CFR 39.19, the Manager, Los Angeles ACO, is authorized to approve alternative methods of compliance for this AD.

(2) Alternative methods of compliance, approved previously per AD 2000-03-08, amendment 39-11567, are approved as alternative methods of compliance with paragraphs (a), (b), and (c) of this AD.

Issued in Renton, Washington, on October 7, 2003.

Kalene C. Yanamura,

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.