[Federal Register Volume 68, Number 182 (Friday, September 19, 2003)]
[Proposed Rules]
[Pages 54869-54872]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 03-23936]



[[Page 54869]]

-----------------------------------------------------------------------

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2001-NM-88-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 737-300, -400, and -500 
Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Supplemental notice of proposed rulemaking; reopening of 
comment period.

-----------------------------------------------------------------------

SUMMARY: This document revises an earlier proposed airworthiness 
directive (AD), applicable to certain Boeing Model 737-300, -400, and -
500 series airplanes, that would have required replacement of the hinge 
assemblies on certain escape slide compartments of the forward doors 
with new, stronger hinge assemblies. This new action revises the 
proposed rule by adding an inspection for incorrectly crimped hinge 
assemblies, and corrective action if necessary, for certain airplanes. 
The actions specified by this new proposed AD are intended to prevent 
forward door escape slides from falling out of their compartments into 
the airplane interior and inflating, which could impede an evacuation 
in the event of an emergency. This action is intended to address the 
identified unsafe condition.

DATES: Comments must be received by October 14, 2003.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 2001-NM-88-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 (425) 227-1232. 
Comments may also be sent via the Internet using the following address: 
[email protected]. Comments sent via fax or the Internet must 
contain ``Docket No. 2001-NM-88-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 Airplane Group, P.O. Box 3707, Seattle, 
Washington 98124-2207. This information may be examined at the FAA, 
Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, 
Washington.

FOR FURTHER INFORMATION CONTACT: Keith Ladderud, Aerospace Engineer, 
Cabin Safety and Environmental Systems Branch, ANM-150S, FAA, Seattle 
Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, 
Washington 98055-4056; telephone (425) 917-6435; fax (425) 917-6590.

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:
    [sbull] 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.
    [sbull] For each issue, state what specific change to the proposed 
AD is being requested.
    [sbull] 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-88-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-88-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    A proposal to amend part 39 of the Federal Aviation Regulations (14 
CFR part 39) to add an airworthiness directive (AD), applicable to 
certain Boeing Model 737-300, -400, and -500 series airplanes, was 
published as a notice of proposed rulemaking (NPRM) in the Federal 
Register on July 9, 2002 (67 FR 45412). That NPRM (the ``original 
NPRM'') would have required replacement of the hinge assemblies on 
certain escape slide compartments of the forward doors with new, 
stronger hinge assemblies. The original NPRM was prompted by an 
investigation that revealed that the soft aluminum hinge assemblies on 
the escape slide compartments on affected airplanes are susceptible to 
deformation. That condition, if not corrected, could result in forward 
door escape slides falling out of their compartments into the airplane 
interior and inflating, which could impede an evacuation in the event 
of an emergency.

Comments

    Due consideration has been given to the comments received in 
response to the original NPRM.

Support for the Original NPRM

    Several commenters support the original NPRM. One commenter adds 
that accomplishment of the proposed actions will help eliminate 
unintended slide deployments on affected airplanes.

Request To Cite Revised Service Bulletin

    The manufacturer states that Boeing Service Bulletin 737-25-1430, 
dated February 22, 2001, misidentifies certain part numbers in the 
Existing Parts Accountability table. (That service bulletin was cited 
as the appropriate source of service information for the actions 
specified in the original NPRM.) The manufacturer advises of the 
revision of that service bulletin to correct the part number 
discrepancy, and requests that the original NPRM be revised to cite the 
revised service bulletin.
    The FAA agrees with the request. Revision 1 of the service 
bulletin, dated April 10, 2003, was issued to correct the part numbers 
and to add an inspection for incorrectly crimped hinge assemblies for 
airplanes already modified by the original issue of the service 
bulletin, which may have not ensured that all hinge assemblies are 
crimped at one or both ends. An incorrectly crimped hinge assembly may 
not hold the hinge pin correctly. In this supplemental NPRM:

[[Page 54870]]

    [sbull] Paragraph (a) has been revised to limit its applicability 
to airplanes on which the original issue of the service bulletin has 
not been done.
    [sbull] Paragraph (a) has been revised to cite Revision 1 of the 
service bulletin.
    [sbull] New paragraph (b) has been added to require inspection of 
airplanes on which the original service bulletin was done.
    [sbull] Subsequent paragraphs have been reidentified accordingly.

Request To Withdraw the Proposed AD

    One commenter requests withdrawal of the proposed AD as 
unnecessary. The commenter suggests that the proposed AD was prompted 
by an isolated incident during which multiple unfavorable conditions 
existed. The commenter, an operator, reports that, since the early 
1990s, its affected airplanes have flown over seven million miles 
without an escape slide inflating inside the cabin.
    The FAA does not agree with the request to withdraw the original 
NPRM. While few slides have actually inflated inside an airplane, there 
have been multiple incidents of escape slides dropping out of the 
closed door-mounted stowage compartment into the passenger compartment. 
An escape slide that drops out of its compartment could automatically 
inflate inside the passenger compartment and impede an emergency 
evacuation. This supplemental NPRM would mandate a design change that 
will prevent the slide from dropping out of its closed compartment.

Request for Additional Information

    One commenter, an operator, suggests that the manufacturer 
investigate the prevalence of the incident that prompted this AD (i.e., 
an escape slide dropping out of its closed door-mounted stowage 
compartment and inflating inside the passenger compartment). The 
operator asserts its intent to ascertain the background of the unsafe 
condition by requesting from Boeing all previous correspondence on this 
issue between the manufacturer and operators.
    The FAA acknowledges the comment, although the commenter requests 
no specific change to the original NPRM. In light of the previous 
comment and response, the FAA finds it necessary to proceed with this 
AD action to address the identified unsafe condition.

Request To Extend the Compliance Time

    Several commenters request that the proposed compliance time to 
replace the hinge assemblies be extended from 24 months to 36 months to 
enable operators to do the work during the normal overhaul schedule for 
the escape slides.
    The FAA agrees with this request. In revising this compliance time, 
the FAA considered the safety implications, parts availability, and 
typical maintenance schedules of affected operators. Extending the 
compliance time to the suggested 36 months will not adversely affect 
safety but will accommodate the time necessary for the operators to 
obtain replacement parts and schedule the work. Paragraph (a) of the 
original NPRM has been revised accordingly in this supplemental NPRM.

Request To Revise Compliance Time

    Several commenters request revision of paragraph (b) of the 
original NPRM (paragraph (c) in this supplemental NPRM), which 
specifies that certain hinge assemblies may no longer be installed 
after the effective date of the AD. The commenters request that this 
compliance time be extended to coincide with the compliance time to 
replace all hinge assemblies. The commenters state that this extension 
would give operators more time to update airplane manuals and prevent 
unforeseen delays if parts are not readily available.
    The FAA does not agree. Once an unsafe condition has been 
identified, the FAA generally prohibits that condition from being 
introduced (or re-introduced) into the fleet. When it is determined 
that replacement (safe) parts are immediately available to operators, 
the FAA typically prohibits installation of the unsafe parts as of the 
effective date of the AD. While this AD action was being developed, the 
FAA carefully considered all relevant information including parts 
availability and determined that sufficient parts would be available to 
meet operator demand.
    Further, the FAA considers the period of time between publication 
of the final rule in the Federal Register and the effective date of the 
AD (35 days) sufficient for operators to determine their immediate need 
for parts and to obtain them. In individual cases where this is not 
possible, this supplemental NPRM contains a provision (in paragraph 
(d)) that would allow operators to request an extension of the 
compliance time, based upon a specific showing of need. The FAA 
considers that this provision ensures an adequate level of safety 
without imposing any undue burden on operators.
    No change to this supplemental NPRM is necessary regarding this 
issue.

Request for Coinciding Compliance Times

    One commenter questions the timing of this AD in connection with 
the issuance of AD 2001-15-01, amendment 39-12335 (66 FR 38361, July 
24, 2001). AD 2001-15-01 requires modification of the escape slides by 
modifying the latch assembly and installing a cover assembly on the 
trigger housing of the inflation cylinder. The commenter advises that 
the two ADs will require closely associated work at different times. 
The FAA infers that the commenter requests harmonization of the ADs' 
compliance times.
    The FAA does not agree. The compliance time for AD 2001-15-01 is 18 
months for some actions and 36 months for the remaining actions, 
effective from August 28, 2001. Therefore, a coordinated work schedule 
for the two ADs would necessitate a shorter compliance time for the 
proposed requirements in this supplemental NPRM. As stated previously, 
the FAA finds the proposed compliance time'extended to 36 months as 
requested'to be adequate. No further change to this supplemental NPRM 
is necessary regarding the compliance time.

Request To Provide Alternative Actions

    One commenter requests that the original NPRM be revised to provide 
for the option of repetitively inspecting and testing the hinge 
assemblies, instead of replacing them within the specified compliance 
time. The commenter states that the alternative repetitive inspections 
would prevent the unnecessary replacement of functional parts.
    The FAA does not agree, based on the determination that the subject 
hinge assemblies are weak and must be replaced within the proposed 
compliance time. The FAA has determined that long-term continued 
operational safety will be better ensured by modifications or design 
changes to remove the source of the problem, rather than by repetitive 
inspections. Long-term inspections may not provide the degree of safety 
assurance necessary for the transport airplane fleet. This, coupled 
with a better understanding of the human factors associated with 
numerous repetitive inspections, has led the FAA to consider placing 
less emphasis on special procedures and more emphasis on design 
improvements. The proposed modification requirement is consistent with 
these considerations. No further

[[Page 54871]]

change to this supplemental NPRM is necessary regarding this issue.

Request To Allow Alternative Finishes

    One commenter prefers that the service bulletin avoid specifying 
the finish (for the primer or topcoat) to be used to conceal the flush 
rivets. Because some operators may have already painted the container 
assemblies with an unspecified finish, the operator suggests that the 
original NPRM be revised to specifically allow use of an ``equivalent'' 
finish.
    The FAA does not agree. An ``operator's equivalent procedure'' may 
be used only if approved as an alternative method of compliance (AMOC) 
in accordance with paragraph (d) of this supplemental NPRM. No change 
to this supplemental NPRM is necessary regarding this issue.

Request To Revise Reference to Service Bulletin Figure

    One operator suggests that Boeing Service Bulletin 737-25-1430 
depicts the latch assembly in use before AD 2001-15-01 was issued. This 
latch assembly, part number 65C19901-20, is depicted in Figure 2, Sheet 
2 of 6, of that service bulletin. The commenter suggests this was an 
oversight, but expresses concern about the potential confusion it may 
raise for other operators. The FAA infers that the commenter requests 
that reference to this figure be revised or removed from the proposed 
AD.
    The FAA agrees. As stated earlier, this supplemental NPRM has been 
revised to cite Revision 1 of the service bulletin, which includes the 
commenter's suggested change.

Request To Revise Part Reidentification Method

    One commenter requests a revision of the method of reidentification 
(reidentifying the part number) specified in the original NPRM. The 
commenter doubts that the existing part number would be present on all 
affected escape slide covers, which may have been subject to prior 
maintenance, repair, or repainting. The commenter suggests 
reidentifying the reworked escape slide compartment by adding ``SB 737-
25-1430 Compliant'' adjacent to any existing part numbers.
    The FAA does not agree with the request. Reidentification with the 
new part number, as proposed in this supplemental NPRM, would ensure 
that the correct part number is installed. However, the FAA may 
consider requests for AMOCs if submitted with detailed procedures that 
would ensure an acceptable level of safety, under the provisions of 
paragraph (d) of this supplemental NPRM.

Request To Revise Description of Unsafe Condition

    The manufacturer states that an escape slide released from its 
compartment into the airplane interior would not always automatically 
inflate. The commenter requests that the original NPRM be revised to 
imply only the potential for the slide to inflate--the slide ``could,'' 
rather than ``would,'' automatically inflate. The original NPRM refers 
to one incident of the escape slide inflating inside the airplane; in 
that instance, the commenter suggests that the severe swerving motion 
of the airplane likely caused the escape slide to move across the floor 
and inflate. The FAA infers that the commenter requests that the 
discussion of the unsafe condition identified in the original NPRM be 
reworded accordingly.
    The FAA agrees that the commenter's suggested wording is clearer 
than the wording in the Discussion section of the original NPRM. 
Although this supplemental NPRM does not repeat that section, the 
events associated with the identified unsafe condition are clarified in 
the discussion under ``Request to Withdraw the Proposed AD.''

Request To Revise Cost Estimate

    Several commenters report that the price of the replacement parts 
has increased since the original NPRM was issued. The manufacturer has 
confirmed that the current parts cost is $1,569. The Cost Impact 
section has been revised accordingly in this supplemental NPRM.

Additional Changes to the Original NPRM

    In the original NPRM, the heading for paragraph (b) is ``Spare 
Parts.'' In this supplemental NPRM, the heading for that paragraph 
(reidentified as paragraph (c)) has been renamed ``Part Installation'' 
to more accurately define the proposed requirement.

Conclusion

    Since certain changes expand the scope of the original NPRM, the 
FAA has determined that it is necessary to reopen the comment period to 
provide additional opportunity for public comment.

Cost Impact

    There are approximately 1,974 airplanes of the affected design in 
the worldwide fleet. The FAA estimates that 793 airplanes of U.S. 
registry would be affected by this supplemental NPRM.
    Replacement of the hinge assemblies, if necessary, would take 
approximately 5 work hours per airplane, at an average labor rate of 
$65 per work hour. Required parts would cost approximately $1,569 per 
airplane. Based on these figures, the cost impact of the proposed hinge 
replacement is estimated to be $1,894 per airplane.
    The inspection, if necessary, would take approximately 1 to 3 work 
hours per airplane, at an average labor rate of $65 per work hour. 
Based on these figures, the cost impact of the proposed inspection is 
estimated to be $65 to $195 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 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.

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.

[[Page 54872]]

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:

Boeing: Docket 2001-NM-88-AD.

    Applicability: Model 737-300, -400, and -500 series airplanes; 
certificated in any category; as listed in Boeing Special Attention 
Service Bulletin 737-25-1430, Revision 1, dated April 10, 2003.
    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent forward door escape slides from falling out of their 
compartments into the airplane interior and inflating, which could 
impede an evacuation in the event of emergency, accomplish the 
following:

Hinge Assembly Replacement

    (a) For airplanes on which the hinge assemblies have not been 
replaced as of the effective date of this AD in accordance with 
Boeing Special Attention Service Bulletin 737-25-1430, dated 
February 22, 2001: Within 36 months after the effective date of this 
AD, replace the hinge assemblies on the escape slide stowage 
compartments of the forward doors with new, stronger hinge 
assemblies, in accordance with Part 1 of the Accomplishment 
Instructions of Boeing Special Attention Service Bulletin 737-25-
1430, Revision 1, dated April 10, 2003.

Hinge Assembly Inspection

    (b) For airplanes on which the hinge assemblies were replaced 
before the effective date of this AD in accordance with Boeing 
Special Attention Service Bulletin 737-25-1430, dated February 22, 
2001: Within 36 months after the effective date of this AD, perform 
a general visual inspection for incorrectly crimped hinge 
assemblies, in accordance with Part 2 of the Accomplishment 
Instructions of Boeing Special Attention Service Bulletin 737-25-
1430, Revision 1, dated April 10, 2003. If any hinge assembly is not 
correctly crimped, perform corrective action before further flight 
in accordance with Revision 1 of the service bulletin.

    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.''

Part Installation

    (c) As of the effective date of this AD, no person may install a 
hinge assembly P/N 65C30431-6 or 65C30431-7 on any airplane.

Alternative Methods of Compliance

    (d) In accordance with 14 CFR 39.19, the Manager, Seattle 
Aircraft Certification Office, FAA, is authorized to approve 
alternative methods of compliance for this AD.

    Issued in Renton, Washington, on September 15, 2003.
Ali Bahrami,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 03-23936 Filed 9-18-03; 8:45 am]
BILLING CODE 4910-13-U