[Federal Register Volume 61, Number 35 (Wednesday, February 21, 1996)]
[Proposed Rules]
[Pages 6581-6583]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-3834]
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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39
[Docket No. 95-NM-191-AD]
Airworthiness Directives; McDonnell Douglas Model MD-11 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-11 series airplanes. This proposal would require inspections to
detect damage of the sidewall vent box diaphragms, and repair, if
necessary. This proposal also would require eventual installation of
stops on the vent box diaphragm, which would terminate the inspection
requirements of the proposed AD. This proposal is prompted by reports
of damage to sidewall vent box diaphragms, which can result in non-
functional diaphragms during a rapid decompression. The actions
specified by the proposed AD are intended to prevent buckling of the
floor beams due to insufficient air flow of the cabin sidewall vent box
diaphragms during rapid decompression, and subsequent reduction in the
controllability of the airplane.
DATES: Comments must be received by April 1, 1996.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-103,
Attention: Rules Docket No. 95-NM-191-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 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
[[Page 6582]]
FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton,
Washington.
FOR FURTHER INFORMATION CONTACT: Andrew Gfrerer, Aerospace Engineer,
Systems and Equipment Branch, ANM-130L, FAA, Los Angeles Aircraft
Certification Office, 3960 Paramount Boulevard, Lakewood, California
90712; telephone (310) 627-5338; fax (310) 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 95-NM-191-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-103, Attention: Rules
Docket No. 95-NM-191-AD, 1601 Lind Avenue, SW., Renton, Washington
98055-4056.
Discussion
The FAA has received several reports indicating that the cabin
sidewall vent box diaphragms on McDonnell Douglas Model MD-11 series
airplanes have been found to be damaged. In one case, during an
interior cabin modification, an operator found many of these diaphragms
on one airplane bent into an undesirable shape; these units failed to
pass a decompression test. Other operators have reported similar
damage. Investigation revealed that such damage may be caused by
passengers or maintenance personnel inadvertently hitting or applying
pressure to the vent box face plate. This causes excessive loads to the
sidewall vent box diaphragm and stop pads. Such damage to the diaphragm
can prevent sufficient air flow during rapid decompression on an
airplane. This condition, if not corrected, could result in buckled
floor beams, and subsequent reduction in the controllability of the
airplane.
The FAA has reviewed and approved McDonnell Douglas Alert Service
Bulletin MD11-25A181, dated September 28, 1995, which describes
procedures for repetitive inspections to detect damage of the sidewall
vent box diaphragm, and repair, if necessary. The service bulletin also
describes procedures for installation of stops in all vent box
diaphragms, which, when accomplished, terminates the need for the
repetitive inspections. Installation of the stops enables the diaphragm
to withstand excessive loads and minimizes damage to the vent box
diaphragm.
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 repetitive inspections to detect damage of
the sidewall vent box assemblies. Initially, the proposed AD would
permit continued flight if only a certain number of assemblies are
found to be damaged. However, once that number is exceeded, the damaged
assemblies would be required to be modified, prior to further flight,
until the remaining number of damaged assemblies does not exceed a
certain number. The proposed AD also would require the eventual
installation of stop pads for all vent box diaphragms and
reidentification of the assemblies, which, when accomplished,
terminates the requirement for the repetitive inspections. The actions
would be required to be accomplished in accordance with the alert
service bulletin described previously.
There are approximately 123 Model MD-11 series airplanes of the
affected design in the worldwide fleet. The FAA estimates that 39
airplanes of U.S. registry would be affected by this proposed AD.
To accomplish the proposed inspections would take approximately 2
work hours per airplane per inspection, at an average labor rate of $60
per work hour. Based on these figures, the cost impact of the proposed
inspections on U.S. operators is estimated to be $4,680, or $120 per
airplane, per inspection cycle.
To accomplish the proposed installation and reidentification would
take a total of approximately 270 work hours per airplane. This figure
represents 3 work hours per vent box, and up to a maximum of 90 vent
boxes on an airplane. The average labor rate is $60 per work hour. The
cost of required parts would be negligible; the parts may be fabricated
locally. Based on these figures, the cost impact of the proposed
installation on U.S. operators is estimated to be $631,800, or $16,200
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 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:
[[Page 6583]]
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 95-NM-191-AD.
Applicability: Model MD-11 series airplanes, as listed in
McDonnell Douglas Alert Service Bulletin MD11-25A181, dated
September 28, 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 (c) 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 buckling of the floor beams due to insufficient air
flow of the cabin sidewall vent box diaphragms during rapid
decompression, and subsequent loss of airplane control capabilities;
accomplish the following:
(a) Within 90 days after the effective date of this AD, perform
an inspection to detect damage of the sidewall vent box diaphragms,
in accordance with McDonnell Douglas Alert Service Bulletin MD11-
25A181, dated September 28, 1995. Based on the findings of the
initial inspection, or any repetitive inspection, accomplish the
requirements of paragraph (a)(1), (a)(2), or (a)(3) of this AD, as
applicable:
(1) Condition 1. If no damage is detected: Repeat the inspection
at intervals not to exceed 90 days.
(2) Condition 2. If damage is detected, but the number of
damaged sidewall vent box assemblies does not exceed the applicable
allowable number specified in Table 1 of the alert service bulletin:
Repeat the inspection at intervals not to exceed 90 days.
(3) Condition 3. If damage is detected, and the number of
damaged vent box assemblies exceeds the applicable number specified
in Table 1 of the alert service bulletin: Prior to further flight,
install stops on and re-identify as many damaged sidewall vent box
assemblies as necessary so that the total number of damaged vent box
assemblies does not exceed the applicable allowable number specified
in Table 1 of the alert service bulletin. Accomplish the
installation of the stops and reidentification of the assemblies in
accordance with the alert service bulletin. The installation of
stops on and reidentification of an assembly constitutes terminating
action for the repetitive inspections of that assembly only. All
other assemblies must continue to be inspected thereafter at
intervals not to exceed 90 days.
(b) Within 30 months after the effective date of this AD,
install stops on and reidentify all sidewall vent box assemblies
that do not already have stops installed and have not been
reidentified in accordance with McDonnell Douglas Alert Service
Bulletin MD11-25A181, dated September 28, 1995. Accomplishment of
this action constitutes terminating action for the inspection
requirements of this AD.
(c) 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.
(d) 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 14, 1996.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 96-3834 Filed 2-20-96; 8:45 am]
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