[Federal Register Volume 59, Number 229 (Wednesday, November 30, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-29438]
[[Page Unknown]]
[Federal Register: November 30, 1994]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 94-NM-153-AD]
Airworthiness Directives; Boeing Model 747-300 and -400 Series
Airplanes Equipped With BFGoodrich Stretched Upper Deck Evacuation
Slides, Part Number 7A1323-( )
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 Boeing Model 747-300 and -400
series airplanes equipped with certain stretched upper deck evacuation
slides manufactured by BFGoodrich. This proposal would require
modification of the slide's main restraint strap, regulator assembly,
and turbo fan flapper retaining roll pins. This proposal is prompted by
reports of loss of air pressure and non-inflation of the inflatable
tubes of the slide due to problems associated with the restraint strap,
regulator assembly, and turbo fan flapper retaining roll pins. The
actions specified by the proposed AD are intended to prevent loss of
air pressure or non-inflation of the inflatable tubes of the slide,
which could impede the successful evacuation of passengers from the
airplane during an emergency.
DATES: Comments must be received by January 26, 1995.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-103,
Attention: Rules Docket No. 94-NM-153-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 BFGoodrich Company, Aircraft Evacuation Systems, Dept.
7916, Phoenix , Arizona 85040. 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,
Transport Airplane Directorate, 3229 East Spring Street, Long Beach,
California.
FOR FURTHER INFORMATION CONTACT: Andrew Gfrerer, Aerospace Engineer,
Systems & Equipment Branch, ANM-130L, Los Angeles Aircraft
Certification Office, 3229 East Spring Street, Long Beach, California
90806-2425; telephone (310) 988-5338; fax (310) 988-5210.
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 94-NM-153-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. 94-NM-153-AD, 1601 Lind Avenue, SW., Renton, Washington
98055-4056.
Discussion
The FAA has received reports of various problems involving
BFGoodrich stretched upper deck evacuation slides, part number (P/N)
7A1323-( ), installed on Boeing Model 747-300 and -400 series
airplanes:
There have been several incidents in which the main restraint strap
of the slide was ingested into one of the turbo fans. This resulted in
damage to the turbo fan and loss of air pressure in one tube of the
slide.
There have been two occurrences of the inflation system regulator
shutting down due to internal pressure differentials. These incidents
resulted in non-inflation of one inflatable tube of the slide.
There has been a report that, during deployment of the slide, the
turbo fan flapper retaining roll pin broke, allowing the flapper to
fall out. This resulted in the loss of air pressure in the inflation
tube. The cause of the broken pin was determined to be the particular
heat treatment used during manufacture of a certain lot of roll pins.
Loss of air pressure or non-inflation of the inflation tubes of an
evacuation slide, if not corrected, could impede the successful
evacuation of passengers from the airplane during an emergency.
The FAA has reviewed and approved BFGoodrich Service Bulletin
7A1323-25-266, Revision 1, dated September 30, 1994, which describes
procedures for the following modifications:
1. Relocating the slide's elastic cord ``bungee strap'' attachment
point and shortening the elastic cord. This will prevent the main
restraint strap of the slide from being ingested into the turbo fan.
2. Modifying and making other changes to the regulator assembly,
such as modifying the regulator cartridge engagement sleeve by the
addition of drilled holes to prevent the potential for pressure
differentials that could cause the regulator to shut down; installing a
revised burst disk to prevent galling when tightening the cartridge
assembly; changing the type of lubricant to reduce friction forces; and
installing a new regulator release pin with a baked-on lubricant to
provide a consistent release force.
3. Replacing the turbo fan flapper retaining roll pins. This will
prevent breakage of the pins, thereby preventing the possibility of the
flapper falling out.
4. Replacing the original bottle relief valve assembly (P/N 5A2644-
4) with a safety plug assembly (P/N 3A3259-3); and adding a charge
fitting on the reservoir safety plug assembly to allow for bottle
charging after the modifications described above have been
accomplished.
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 modifying the stretched upper deck evacuation
slide by relocating the elastic cord ``bungee strap'' attachment point
and shortening the elastic cord; modifying the regulator assembly; and
replacing the turbo fan flapper retaining roll pins. The actions would
be required to be accomplished in accordance with the service bulletin
described previously.
Operators should note that this proposed AD is applicable to the
manufacturer of the airplane model on which the evacuation slides are
installed, rather than to the manufacturer of the slide. The FAA's
general policy is that, when an unsafe condition results from the
installation of an appliance or other item that is installed in only
one particular make and model of aircraft, the AD is issued so that it
is applicable to the aircraft, rather than the item. The reason for
this is simple: Making the AD applicable to the airplane model on which
the item is installed ensures that operators of those airplanes will be
notified directly of the unsafe condition and the action required to
correct it. While it is assumed that an operator will know the models
of airplanes that it operates, there is a potential that the operator
will not know or be aware of specific items that are installed on its
airplanes. Therefore, calling out the airplane model as the subject of
the AD prevents ``unknowing non-compliance'' on the part of the
operator.
(The FAA recognizes that there are situations when an unsafe condition
exists in an item that is installed in many different aircraft. In
those cases, the FAA considers it impractical to issue AD's against
each aircraft; in fact, many times, the exact models and numbers of
aircraft on which the item is installed may not be known. Therefore, in
those situations, the AD is issued so that it is applicable to the
item; furthermore, those AD's usually indicate that the item is known
to be installed on, but not limited to, various aircraft models.)
There are approximately 900 BFGoodrich stretched upper deck
evacuation slides of the affected design installed on Boeing Model 747
series airplanes worldwide. The FAA estimates that 100 of these slides
are installed on airplanes of U.S. registry that would be affected by
this proposed AD. It would take approximately 4.5 work hours per slide
to accomplish the proposed actions, and that the average labor rate is
$60 per work hour. Required parts would cost approximately $1,402 per
slide assembly. Based on these figures, the total cost impact of the
proposed AD on U.S. operators is estimated to be $167,200, or $1,672
per slide.
The total 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.
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. App. 1354(a), 1421 and 1423; 49 U.S.C.
106(g); and 14 CFR 11.89.
Sec. 39.13 [Amended]
2. Section 39.13 is amended by adding the following new
airworthiness directive:
Boeing: Docket 94-NM-153-AD.
Applicability: Model 747-300 and -400 series airplanes equipped
with BFGoodrich stretched upper deck evacuation slides, part number
(P/N) 7A1323-1, -2, -3, -4, -105, -106, -107, -108, -109, or -110;
certificated in any category.
Compliance: Required as indicated, unless accomplished
previously.
To prevent loss of air pressure or non-inflation of the
inflation tubes of an evacuation slide, which could impede the
evacuation of passengers from the airplane during an emergency,
accomplish the following:
(a) Within 36 months after the effective date of this AD, modify
the BFGoodrich stretched upper deck evacuation slide, P/N 7A1323-(
), in accordance with the Accomplishment Instructions of BFGoodrich
Service Bulletin 7A1323-25-266, Revision 1, dated September 30,
1994.
Note 1: Installation of the ``product improvements,'' specified
in paragraph 2.J. of the Accomplishment Instructions of the service
bulletin, is not required by this AD.
(b) 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.
(c) 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 November 23, 1994.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 94-29438 Filed 11-29-94; 8:45 am]
BILLING CODE 4910-13-U
