[Federal Register Volume 63, Number 97 (Wednesday, May 20, 1998)]
[Proposed Rules]
[Pages 27692-27694]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-13402]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97-NM-258-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 
inspections to detect debris in the areas behind the aft lavatory 
toilet shroud, behind the aft lavatory modules, and below the cabin 
floor aft of the aft cargo compartment bulkhead; and removal of debris. 
This proposal also would require modification of the lavatory toilet 
shroud assemblies and modification of the lavatory entry door louvers, 
which would terminate the repetitive inspections. This proposal is 
prompted by reports of paper debris collecting on the hot pneumatic 
ducts below the cabin floor. The actions specified by the proposed AD 
are intended to prevent paper debris from collecting on the ducts, 
which could result in a potential fire hazard or possible loss of 
elevator control system redundancy.

DATES: Comments must be received by July 6, 1998.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 97-NM-258-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 The Boeing Company, Douglas Products 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: Albert H. Lam, Aerospace Engineer, 
Systems and Equipment Branch, ANM-130L, FAA, Transport Airplane 
Directorate, Los Angeles Aircraft Certification Office, 3960 Paramount 
Boulevard, Lakewood, California 90712-4137; telephone (562) 627-5346; 
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 97-NM-258-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

[[Page 27693]]

FAA, Transport Airplane Directorate, ANM-114, Attention: Rules Docket 
No. 97-NM-258-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

Discussion

    The FAA has received reports indicating that lavatory paper debris 
was found behind the toilet seat shroud in the aft lavatory, behind the 
aft lavatory modules, and below the cabin floor aft of the aft cargo 
compartment bulkhead of McDonnell Douglas Model MD-90-30 series 
airplanes. This condition has been attributed to a gap between the 
lavatory floor pan perimeter and the toilet shroud. Airflow through the 
lavatory module can force paper and lint from the floor through the gap 
in the toilet shroud and the floor; this debris can collect on the hot 
pneumatic ducts below the cabin floor aft of the aft cargo compartment 
bulkhead. This condition, if not corrected, could result in a potential 
fire hazard or possible loss of elevator control system redundancy.

Explanation of Relevant Service Information

    The FAA has reviewed and approved McDonnell Douglas Alert Service 
Bulletin MD90-25A017, Revision R01, dated October 16, 1997, which 
describes procedures for repetitive inspections to detect paper and 
lint debris in the areas behind the aft lavatory toilet shroud, behind 
the aft lavatory modules, and below the cabin floor aft of the aft 
cargo compartment bulkhead, and removal of debris.
    The FAA also has reviewed and approved McDonnell Douglas Service 
Bulletin MD90-25-022, Revision R01, dated October 15, 1997, which 
describes procedures for modification of the lavatory toilet shroud 
assemblies. The modification involves adding a rubber seal to the 
shroud assemblies to close the gap between the shroud assemblies and 
the lavatory floor pans. This service bulletin references Jamco Service 
Bulletin MD090-25-1140, Revision 3, dated May 30, 1997, as an 
additional source of service information for accomplishment of the 
modification.
    In addition, the FAA has reviewed and approved McDonnell Douglas 
Service Bulletin MD90-25-023, Revision R01, dated October 15, 1997, 
which describes procedures for modification of the lavatory entry door 
louvers. The modification entails installing a new frame panel and new 
louvers on the entry door assembly. This service bulletin references 
Jamco Service Bulletin MD090-25-1155, Revision 2, dated June 11, 1997, 
as an additional source of service information for accomplishment of 
this modification.
    Accomplishment of the modifications specified in McDonnell Douglas 
Service Bulletins MD90-25-022 and MD90-25-023 is intended to adequately 
address the identified unsafe condition. These modifications, when 
accomplished, would eliminate the need for the repetitive inspections 
described in the alert service bulletin described previously.

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 alert service bulletin and service bulletins described previously.

Cost Impact

    There are approximately 55 airplanes of the affected design in the 
worldwide fleet. The FAA estimates that 19 airplanes of U.S. registry 
would be affected by this proposed AD.
    It would take approximately 5 work hours per airplane to accomplish 
the proposed inspection, at an average labor rate of $60 per work hour. 
Based on these figures, the cost impact of the inspection proposed by 
this AD on U.S. operators is estimated to be $5,700, or $300 per 
airplane, per inspection cycle.
    It would take approximately 1 work hour per airplane to accomplish 
the proposed modification of the toilet shroud assemblies, at an 
average labor rate is $60 per work hour. Required parts would be 
supplied by the manufacturer at no cost to the operators. Based on 
these figures, the cost impact of this modification proposed by this AD 
on U.S. operators is estimated to be $1,140, or $60 per airplane.
    It would take approximately 1 work hour per airplane to accomplish 
the proposed modification of the lavatory entry door louvers, at an 
average labor rate is $60 per work hour. Required parts would be 
supplied by the manufacturer at no cost to the operators. Based on 
these figures, the cost impact of this modification proposed by this AD 
on U.S. operators is estimated to be $1,140, or $60 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.

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 97-NM-258-AD.

    Applicability: Model MD-90-30 series airplanes; as listed in 
paragraph 1.A.1. of McDonnell Douglas Alert Service Bulletin MD90-
25A017, Revision R01, dated October 16, 1997, McDonnell Douglas 
Service Bulletin MD90-25-022, Revision R01, dated October 15, 1997 , 
and McDonnell Douglas Service Bulletin MD90-25A023, Revision R01, 
dated October 15, 1997; certificated in any category.

    Note 1: This AD applies to each airplane identified in the 
preceding applicability provision, regardless of whether it has been

[[Page 27694]]

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 (e) 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 a potential fire hazard or the possible loss of 
elevator control system redundancy due to paper debris collecting on 
the hot pneumatic ducts below the cabin floor, accomplish the 
following:
    (a) Within 450 flight hours or 3 months after the effective date 
of this AD, whichever occurs later, perform an inspection to detect 
paper and lint debris in the areas behind the aft lavatory toilet 
shroud, behind the aft lavatory modules, and below the cabin floor 
aft of the aft cargo compartment bulkhead, in accordance with 
paragraph 3. (``Accomplishment Instructions'') of McDonnell Douglas 
Alert Service Bulletin MD90-25A017, Revision R01, dated October 15, 
1997. If any debris is found, prior to further flight, remove it in 
accordance with the alert service bulletin. Repeat the inspection 
thereafter at intervals not to exceed 450 flight hours.
    (b) Within 12 months after the effective date of this AD, modify 
the lavatory toilet shroud assemblies in accordance with paragraph 
3. (``Accomplishment Instructions'') of McDonnell Douglas Service 
Bulletin MD90-25-022, Revision R01, dated October 15, 1997.
    (c) Within 12 months after the effective date of this AD, modify 
the lavatory entry door louvers in accordance with paragraph 3. 
(``Accomplishment Instructions'') of McDonnell Douglas Service 
Bulletin MD90-25-023, Revision R01, dated October 15, 1997.
    (d) Modification of the toilet shroud assemblies and the 
lavatory entry door louvers in accordance with paragraphs (b) and 
(c) of this AD constitutes terminating action for the repetitive 
inspection requirements of paragraph (a) of this AD.
    (e) 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 2: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Los Angeles ACO.

    (f) 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 May 14, 1998.
John J. Hickey,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 98-13402 Filed 5-19-98; 8:45 am]
BILLING CODE 4910-13-U