[Federal Register Volume 63, Number 207 (Tuesday, October 27, 1998)]
[Rules and Regulations]
[Pages 57240-57243]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-28540]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 98-NM-245-AD; Amendment 39-10858; AD 98-22-10]
RIN 2120-AA64
Airworthiness Directives; Boeing Model 737 Series Airplanes
AGENCY: Federal Aviation Administration, DOT.
ACTION: Final rule; request for comments.
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SUMMARY: This amendment supersedes an existing airworthiness directive
(AD),
[[Page 57241]]
applicable to certain Boeing Model 737 series airplanes, that currently
requires repetitive inspections for cracking of the aft frame and frame
support structure of the forward service doorway, and repair, if
necessary. This amendment reduces the compliance time for performing
the initial inspection, and reduces the repetitive inspection
intervals. This amendment also adds repetitive inspections for cracking
of the aft frame web of the forward service doorway, and follow-on
corrective actions, if necessary. This amendment also provides for an
optional terminating action for the repetitive inspection requirements
of this AD. This amendment is prompted by reports indicating that the
repetitive inspections required by the existing AD may not detect
cracking of the aft frame and frame support structure of the forward
service doorway in a timely manner. The actions specified in this AD
are intended to prevent fatigue cracking of the aft frame and frame
support structure of the forward service doorway, which could result in
loss of the door, and consequent rapid decompression of the fuselage.
DATES: Effective November 12, 1998.
The incorporation by reference of certain publications listed in
the regulations is approved by the Director of the Federal Register as
of November 12, 1998.
Comments for inclusion in the Rules Docket must be received on or
before December 28, 1998.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-114,
Attention: Rules Docket No. 98-NM-245-AD, 1601 Lind Avenue, SW.,
Renton, Washington 98055-4056.
The service information referenced in this AD 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; or at
the Office of the Federal Register, 800 North Capitol Street, NW.,
suite 700, Washington, DC.
FOR FURTHER INFORMATION CONTACT: Rick Kawaguchi, Aerospace Engineer,
Airframe Branch, ANM-120S, FAA, Transport Airplane Directorate, Seattle
Aircraft Certification Office, 1601 Lind Avenue, SW., Renton,
Washington 98055-4056; telephone (425) 227-1153; fax (425) 227-1181.
SUPPLEMENTARY INFORMATION: On January 11, 1988, the FAA issued AD 88-
03-03, amendment 39-5832 (53 FR 1609, January 21, 1988), applicable to
certain Boeing Model 737 series airplanes, to require repetitive
inspections for cracking of the aft frame and frame support structure
of the forward service doorway, and repair, if necessary. That action
was prompted by several reports of cracks of the doorstop support
structure for the doorstops on the aft frame. The actions required by
that AD are intended to prevent such cracking, which could result in
loss of pressurization.
Actions Since Issuance of Previous Rule
Since the issuance of that AD, the FAA has received reports
indicating that cracked door frames and severed intercostals of the
frame support structure have been found on several Boeing Model 737
series airplanes.
One operator reported two airplanes with two severed intercostals
on each airplane. The severed intercostals were detected during a
repetitive inspection of both airplanes that was performed in
accordance with AD 88-03-03 at approximately 24,000 total landings. The
same operator also reported another airplane with one severed
intercostal and two additional airplanes with cracked frames. The
severed intercostals were attributed to severe fatigue cracking. The
initial inspection on each affected airplane was performed at
approximately 18,000 total landings, and no cracking was detected
during the initial inspections.
These findings indicate that fatigue cracking could develop on the
affected airplanes at a lower number of landings than the initial
inspection threshold of 25,000 total landings that is mandated by the
existing AD, and that such fatigue cracking could grow from
undetectable to severe in fewer landings than the repetitive inspection
interval of 9,000 landings that is mandated by the existing AD.
Fatigue cracking of the aft frame and frame support structure of
the forward service doorway, if not detected and corrected in a timely
manner, could result in loss of the door, and consequent rapid
decompression of the fuselage.
Explanation of Relevant Service Information
The FAA has reviewed and approved Boeing Service Bulletin 737-
53A1108, Revision 5, dated October 26, 1989. That service bulletin
describes procedures for a close visual inspection to detect cracking
of the aft frame web of the forward service doorway around the doorstop
fittings, an internal visual inspection to detect cracking of the
intercostals and stringers of the frame support structure, and repair
of any cracking that is detected. That service bulletin also describes
a preventive modification that can be accomplished on any uncracked
intercostals.
Explanation of Requirements of Rule
Since an unsafe condition has been identified that is likely to
exist or develop on other airplanes of this same type design, this AD
supersedes AD 88-03-03 to continue to require repetitive internal
visual inspections for cracking of the frame support structure of the
forward service doorway, and repair, if necessary. This AD also
requires repetitive close visual inspections for cracking of the aft
frame web of the forward service doorway, and follow-on corrective
actions, if necessary. This AD also provides for an optional
terminating action for the repetitive inspection requirements of this
AD. The actions are required to be accomplished in accordance with the
service bulletin described previously, except as discussed below.
Differences Between Service Bulletin and This AD
Operators should note that, although the service bulletin describes
procedures for a close visual inspection of the aft frame web of the
forward service doorway around the doorstop fittings, this AD does not
permit that inspection to be accomplished in lieu of the internal
visual inspection. The FAA has determined that, because cracking in the
frame may be masked by the doorstop fittings, the close visual
inspection is not an adequate indicator of the condition of the
intercostals and stringers of the frame support structure. Therefore,
if any cracking is found, this AD requires removal of the doorstop
fittings and a detailed visual inspection to detect further cracking of
the frame, prior to the repair of any cracking.
Operators also should note that, although the service bulletin
recommends accomplishing the initial inspection prior to the
accumulation of 25,000 total flight cycles (landings) or within the
next 4,500 flight cycles (after receipt of the service bulletin),
whichever occurs later, the FAA has determined that such a threshold
does not address the identified unsafe condition in a timely manner. In
addition, the FAA has determined that the repetitive inspection
interval of 9,000 landings, as specified in the service bulletin, does
not address the identified unsafe condition in a timely manner. The
FAA's determination is based upon the case of two airplanes, described
previously, on which no cracking was detected during internal visual
inspections of the intercostals at
[[Page 57242]]
18,000 total landings; but, during repetitive inspections conducted at
approximately 24,000 total landings, two severed intercostals were
found. This evidence reveals that cracking may appear earlier than
25,000 total landings and grow from being undetectable to severe in
fewer than 6,000 flight cycles. In light of these factors, the FAA
finds a compliance time of 18,000 total landings (or within 700
landings or 90 days after the effective date of this AD, whichever
occurs later) for initiating the required inspections, and a repetitive
interval of 4,500 landings, is warranted, in that those times represent
an appropriate interval of time allowable for affected airplanes to
continue to operate without compromising safety.
Operators also should note that, although the service bulletin
specifies Boeing 737 Structural Repair Manual Items (SRM) 51-40-2 and
51-40-3 as optional sources of service information for repairing
cracked intercostals, this AD requires that all future repairs of
cracked intercostals be accomplished in accordance with Figure 3 of the
service bulletin. The FAA has determined that SRM's 51-40-2 and 51-40-3
may not provide an acceptable source of service information for repair
of the intercostals.
Additionally, although the service bulletin specifies that SRM 53-
10-4 is an appropriate source of service information for repairing
cracked frames, and that SRM 53-10-3 is an appropriate source of
service information for repairing cracked stringers, this AD requires
that all future repairs of cracked frames or stringers be accomplished
in accordance with a method approved by the FAA. The FAA has determined
that SRM's 53-10-4 and 53-10-3 may not provide structurally acceptable
methods of repair for frames and stringers.
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.
Explanation of Revision to Applicability
AD 88-03-03 applies to certain Boeing Model 737 series airplanes,
as listed in Boeing Service Bulletin 737-53A1108, Revision 2, dated
August 13, 1987. This AD is applicable to certain Boeing Model 737
series airplanes, as listed in Boeing Service Bulletin 737-53A1108,
Revision 5, dated October 26, 1989. Revision 5 of the service bulletin
updates the effectivity listing of the service bulletin only to reflect
current airplane ownership but adds no new airplanes.
Other Relevant Rulemaking
The FAA previously has issued AD 90-06-02, amendment 39-6489 (55 FR
8372, March 7, 1990), applicable to certain Boeing Model 737 series
airplanes. That AD requires accomplishment of certain structural
modifications, which constitutes terminating action for the repetitive
inspection requirements of this AD.
Determination of Rule's Effective Date
Since a situation exists that requires the immediate adoption of
this regulation, it is found that notice and opportunity for prior
public comment hereon are impracticable, and that good cause exists for
making this amendment effective in less than 30 days.
Comments Invited
Although this action is in the form of a final rule that involves
requirements affecting flight safety and, thus, was not preceded by
notice and an opportunity for public comment, comments are invited on
this rule. Interested persons are invited to comment on this 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 under the caption ADDRESSES. All
communications received on or before the closing date for comments will
be considered, and this rule may be amended in light of the comments
received. Factual information that supports the commenter's ideas and
suggestions is extremely helpful in evaluating the effectiveness of the
AD action and determining whether additional rulemaking action would be
needed.
Comments are specifically invited on the overall regulatory,
economic, environmental, and energy aspects of the rule that might
suggest a need to modify the 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 that
summarizes each FAA-public contact concerned with the substance of this
AD will be filed in the Rules Docket.
Commenters wishing the FAA to acknowledge receipt of their comments
submitted in response to this rule must submit a self-addressed,
stamped postcard on which the following statement is made: ``Comments
to Docket Number 98-NM-245-AD.'' The postcard will be date stamped and
returned to the commenter.
Regulatory Impact
The regulations adopted herein will 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 final
rule does not have sufficient federalism implications to warrant the
preparation of a Federalism Assessment.
The FAA has determined that this regulation is an emergency
regulation that must be issued immediately to correct an unsafe
condition in aircraft, and that it is not a ``significant regulatory
action'' under Executive Order 12866. It has been determined further
that this action involves an emergency regulation under DOT Regulatory
Policies and Procedures (44 FR 11034, February 26, 1979). If it is
determined that this emergency regulation otherwise would be
significant under DOT Regulatory Policies and Procedures, a final
regulatory evaluation will be prepared and placed in the Rules Docket.
A copy of it, if filed, may be obtained from the Rules Docket at the
location provided under the caption ADDRESSES.
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Incorporation by
reference, Safety.
Adoption of the Amendment
Accordingly, pursuant to the authority delegated to me by the
Administrator, the Federal Aviation Administration amends 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 removing amendment 39-5832 (53 FR
1609, January 21, 1988), and by adding a new airworthiness directive
(AD), amendment 39-10858, to read as follows:
98-22-10 BOEING: Amendment 39-10858. Docket 98-NM-245-AD.
Supersedes AD 88-03-03, amendment 39-5832.
Applicability: Model 737 series airplanes, as listed in Boeing
Service Bulletin 737-
[[Page 57243]]
53A1108, Revision 5, dated October 26, 1989; 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 (f)(1)
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. 3
Compliance: Required as indicated, unless accomplished
previously.
To prevent fatigue cracking of the aft frame and frame support
structure of the forward service doorway, which could result in loss
of the door, and consequent rapid decompression of the fuselage,
accomplish the following:
Restatement of the Requirements of AD 88-03-03
(a) Prior to the accumulation of 25,000 total landings or within
4,500 landings after February 28, 1988 (the effective date of AD 88-
03-03, amendment 39-5832), whichever occurs later, perform an
internal visual inspection for cracking in the intercostals and
stringers, which support the doorstop fittings of the aft frame of
the service doorway, in accordance with Boeing Service Bulletin 737-
53A1108, Revision 1, dated March 12, 1987; Revision 2, dated August
13, 1987; Revision 3, dated March 3, 1988; Revision 4, dated
November 17, 1988; or Revision 5, dated October 26, 1989.
(1) If no cracking is found during any inspection performed in
accordance with paragraph (a) of this AD, repeat the inspection
thereafter at intervals not to exceed 9,000 landings, until the
inspection required by paragraph (b) of this AD is accomplished.
(2) If any cracking is found during any inspection performed in
accordance with paragraph (a) of this AD, prior to further flight,
repair in accordance with the service bulletin. Thereafter, repeat
the inspection at intervals not to exceed 9,000 landings, until the
inspection required by paragraph (b) of this AD is accomplished.
New Requirements of This AD
(b) Perform a close visual inspection for cracking of the aft
frame web and an internal visual inspection for cracking of the
intercostals and stringers of the frame support structure of the
forward service doorway, in accordance with Boeing Service Bulletin
737-53A1108, Revision 1, dated March 12, 1987; Revision 2, dated
August 13, 1987; Revision 3, dated March 3, 1988; Revision 4, dated
November 17, 1988; or Revision 5, dated October 26, 1989; at the
latest of the times specified in paragraphs (b)(1), (b)(2), (b)(3),
and (b)(4) of this AD. Accomplishment of these inspections
constitutes terminating action for the repetitive inspection
requirements of paragraphs (a)(1) and (a)(2) of this AD.
(1) Prior to the accumulation of 18,000 total landings.
(2) If an internal visual inspection was performed in accordance
with paragraph (b) of AD 88-03-03: Within 4,500 landings after the
last inspection performed in accordance with paragraph (b) of AD 88-
03-03.
(3) Within 700 landings after the effective date of this AD.
(4) Within 90 days after the effective date of this AD.
(c) If no cracking of the aft frame web, intercostals, or
stringers is detected during any inspection required by paragraph
(b) of this AD, repeat the inspection thereafter at intervals not to
exceed 4,500 landings, until the actions specified by paragraph (e)
of this AD are accomplished.
(d) If any cracking of the aft frame web, intercostals, or
stringers is detected during any inspection required by paragraph
(b) of this AD, prior to further flight, remove the six doorstop
fittings, and perform a detailed visual inspection to detect further
cracking of the frame web. Prior to further flight, repair any
cracked intercostal in accordance with Figure 3 of Boeing Service
Bulletin 737-53A1108, Revision 1, dated March 12, 1987; Revision 2,
dated August 13, 1987; Revision 3, dated March 3, 1988; Revision 4,
dated November 17, 1988; or Revision 5, dated October 26, 1989.
Prior to further flight, repair any cracked frame web or stringer in
accordance with a method approved by the Manager, Seattle Aircraft
Certification Office (ACO), FAA, Transport Airplane Directorate; or
in accordance with data meeting the type certification basis of the
airplane approved by a Boeing Company Designated Engineering
Representative who has been authorized by the Manager, Seattle ACO,
to make such findings. Thereafter, repeat the inspection specified
in paragraph (b) of this AD at intervals not to exceed 4,500
landings, until the actions specified by paragraph (e) of this AD
are accomplished.
(e) Repair of all intercostals in accordance with Figure 3 of
Boeing Service Bulletin 737-53A1108, Revision 1, dated March 12,
1987; Revision 2, dated August 13, 1987; Revision 3, dated March 3,
1988; Revision 4, dated November 17, 1988; or Revision 5, dated
October 26, 1989; or modification of all intercostals accomplished
in accordance with the requirements of AD 90-06-02, amendment 39-
6489; constitutes terminating action for the repetitive inspection
requirements of this AD.
(f)(1) 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, Seattle ACO. Operators shall submit
their requests through an appropriate FAA Principal Maintenance
Inspector, who may add comments and then send it to the Manager,
Seattle ACO.
(f)(2) Alternative methods of compliance pertaining to
inspection methods, approved previously in accordance with AD 88-03-
03, amendment 39-5832, are not considered to be approved as
alternative methods of compliance with this AD.
(f)(3) Alternative methods of compliance pertaining to repairs
or modifications, approved previously in accordance with AD 88-03-
03, amendment 39-5832, are considered to be approved as alternative
methods of compliance with this AD.
Note 2: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may be
obtained from the Seattle ACO.
(g) 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.
(h) The internal visual inspection for cracking in the
intercostals and stringers, close visual inspection for cracking of
the aft frame web, and repair of intercostals, if necessary, shall
be done in accordance with Boeing Service Bulletin 737-53A1108,
Revision 1, dated March 12, 1987; Boeing Service Bulletin 737-
53A1108, Revision 2, dated August 13, 1987; Boeing Service Bulletin
737-53A1108, Revision 3, dated March 3, 1988; Boeing Service
Bulletin 737-53A1108, Revision 4, dated November 17, 1988; or Boeing
Service Bulletin 737-53A1108, Revision 5, dated October 26, 1989.
Boeing Service Bulletin 737-53A1108, Revision 3, dated March 3,
1988, contains the following list of effective pages:
------------------------------------------------------------------------
Revision
level
Page number shown on page shown on Date shown on page
page
------------------------------------------------------------------------
1-14, 22.......................... 3 March 3, 1988.
15-21, 23-27...................... 2 August 13, 1987.
------------------------------------------------------------------------
This incorporation by reference was approved by the Director of
the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR
part 51. Copies may be obtained from Boeing Commercial Airplane
Group, P.O. Box 3707, Seattle, Washington 98124-2207. Copies may be
inspected at the FAA, Transport Airplane Directorate, 1601 Lind
Avenue, SW., Renton, Washington; or at the Office of the Federal
Register, 800 North Capitol Street, NW., suite 700, Washington, DC.
(i) This amendment becomes effective on November 12, 1998.
Issued in Renton, Washington, on October 19, 1998.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 98-28540 Filed 10-26-98; 8:45 am]
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