[Federal Register Volume 64, Number 207 (Wednesday, October 27, 1999)]
[Proposed Rules]
[Pages 57790-57792]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-28078]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-NM-210-AD]
RIN 2120-AA64


Airworthiness Directives; McDonnell Douglas Model MD-90-30 Series 
Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the adoption of a new airworthiness 
directive (AD) that is applicable to certain McDonnell Douglas Model 
MD-90-30 series airplanes. This proposal would require repetitive 
fluorescent penetrant and magnetic particle inspections to detect 
fatigue cracking of the main landing gear (MLG) piston, and repair, if 
necessary. This proposal is prompted by reports of MLG failures during 
towing of in-service airplanes due to fatigue cracks. The actions 
specified by the proposed AD are intended to detect and correct fatigue 
cracking of MLG pistons, which could result in failure of the pistons, 
and

[[Page 57791]]

consequent damage to the airplane structure and injury to flight crew, 
passengers, or ground personnel.

DATES: Comments must be received by December 13, 1999.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 99-NM-210-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.
    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, 
Transport Airplane Directorate, Los Angeles Aircraft Certification 
Office, 3960 Paramount Boulevard, Lakewood, California.

FOR FURTHER INFORMATION CONTACT: Carl Fountain, Aerospace Engineer, 
Airframe Branch, ANM-120L, FAA, Transport Airplane Directorate, Los 
Angeles Aircraft Certification Office, 3960 Paramount Boulevard, 
Lakewood, California 90712-4137; telephone (562) 627-5222; fax (562) 
627-5210.

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.
    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 notice must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 99-NM-210-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. 99-NM-210-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-
4056.

Discussion

    The FAA has received reports of main landing gear (MLG) piston 
failures during towing of McDonnell Douglas Model DC-9-80 (MD-80) 
series airplanes. Investigation revealed that the fracture surface 
extended around the barrel section at the piston/axle transition. The 
fractures originated at a fatigue crack located where the inner/upper 
edge of a torque link lug blended into this transition. This condition, 
if not corrected, could result in failure of the pistons, and 
consequent damage to the airplane structure and injury to flight crew, 
passengers, or ground personnel.
    The subject MLG torque link lugs on Model MD-90-30 series airplanes 
are similar to those on the affected McDonnell Douglas Model DC-9-80 
series airplanes. Therefore, all of these airplanes may be subject to 
the same unsafe condition.

Other Relevant Rulemaking

    On September 5, 1996, the FAA issued AD 96-19-09, amendment 39-9756 
(61 FR 48617, September 16, 1996), applicable to certain McDonnell 
Douglas DC-9 and MD-88 series airplanes, to require a one-time 
inspection to detect cracking of the MLG pistons, and repair or 
replacement of the pistons with new or serviceable parts, if necessary. 
However, this proposed AD would not affect the current requirements of 
that previously issued AD.

Explanation of Relevant Service Information

    The FAA has reviewed and approved McDonnell Douglas Service 
Bulletin MD90-32-012, dated May 19, 1997, and Revision 01, dated June 
2, 1998, which describes procedures for repetitive fluorescent 
penetrant and magnetic particle inspections of the MLG torque link lugs 
to detect fatigue cracking, and repair, if necessary. Accomplishment of 
the actions specified in the service bulletin 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 require accomplishment of the actions specified in 
the service bulletin described previously, except as discussed below.

Differences Between Proposed Rule and Service Bulletin

    Operators should note that, although the service bulletin specifies 
that the manufacturer may be contacted for disposition of certain 
repair conditions, this proposal would require the repair of those 
conditions to be accomplished in accordance with a method approved by 
the FAA.
    Operators also should note that, although the service bulletin 
recommends accomplishing the fluorescent inspections only for MLG's 
that have accumulated more than a specified number of landings, the FAA 
has determined that all of the subject parts are subject to the same 
fatigue cracking. Therefore, the compliance times for the proposed 
inspections address all MLG's of the affected design. In developing an 
appropriate compliance time for this proposed AD, the FAA 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 inspection (two hours). In light of all of these factors, the FAA 
finds that intervals of 4,000 landings for inspection of MLG piston, 
part number (P/N) 5935347-509, and 5,000 landings for MLG piston, P/N's 
5935347-511 and -513, address the identified unsafe condition in a 
timely manner. Therefore, the FAA has determined these compliance times 
for initiating the required actions to be warranted, in that they 
represent an appropriate interval of time allowable for affected 
airplanes to continue to operate without compromising safety.

Interim Action

    This is considered to be interim action. The manufacturer has 
advised that it currently is developing a modification that will 
positively address the unsafe condition addressed by this AD. Once this 
modification is developed, approved, and available, the

[[Page 57792]]

FAA may consider additional rulemaking.

Cost Impact

    There are approximately 19 airplanes of the affected design in the 
worldwide fleet. The FAA estimates that 15 airplanes of U.S. registry 
would be affected by this proposed AD, that it would take approximately 
2 work hours per airplane to accomplish the proposed inspections, and 
that the average labor rate is $60 per work hour. Based on these 
figures, the cost impact of the proposed AD on U.S. operators is 
estimated to be $1,800, or $120 per airplane, per inspection cycle.
    The cost impact figure discussed above is 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.

Regulatory Impact

    The regulations proposed herein would 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 
proposal would not have sufficient federalism implications to warrant 
the preparation of a Federalism Assessment.
    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.


Sec. 39.13  [Amended]

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

McDonnell Douglas: Docket 99-NM-210-AD.

    Applicability: Model MD-90-30 airplanes, as listed in McDonnell 
Douglas Service Bulletin MD90-32-012, Revision 01, dated June 2, 
1998; 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 (d) 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 detect and correct 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 flight 
crew, passengers, or ground personnel, accomplish the following:

Inspection of MLG Piston Part Number 5935347-509

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

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

    (b) For MLG pistons P/N's 5935347-511 and -513: Within 5,000 
landings after the effective date of this AD, 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. Repeat the inspections thereafter at intervals 
not to exceed 5,000 landings.

Repair

    (c) If any crack is found during any inspection required by this 
AD: Repair in accordance with a method approved by the Manager, Los 
Angeles Aircraft Certification Office (ACO), FAA, Transport Airplane 
Directorate.

Alternative Methods of Compliance

    (d) 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 ACO. 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.

Special Flight Permits

    (e) Special flight permits may be issued in accordance with 
Secs. 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 October 21, 1999.
D.L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 99-28078 Filed 10-26-99; 8:45 am]
BILLING CODE 4910-13-U