[Federal Register Volume 63, Number 236 (Wednesday, December 9, 1998)]
[Rules and Regulations]
[Pages 67769-67771]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-32361]
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Rules and Regulations
Federal Register
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Federal Register / Vol. 63, No. 236 / Wednesday, December 9, 1998 /
Rules and Regulations
[[Page 67769]]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 98-NM-291-AD; Amendment 39-10931; AD 98-25-06]
RIN 2120-AA64
Airworthiness Directives; Boeing Model 737-200, -200C, -300, and
-400 Series Airplanes
AGENCY: Federal Aviation Administration, DOT.
ACTION: Final rule; request for comments.
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SUMMARY: This amendment adopts a new airworthiness directive (AD) that
is applicable to certain Boeing Model 737-200, -200C, -300, and -400
series airplanes. This action requires repetitive inspections to detect
cracking of the corners of the door frame and the cross beams of the
aft cargo door, and corrective actions, if necessary. This action also
provides an optional terminating action for the repetitive inspection
requirement of this AD. This amendment is prompted by reports
indicating that fatigue cracks have been detected in the corners of the
door frame and the cross beams of the aft cargo door on several in-
service airplanes, and by another report indicating that rapid
depressurization occurred during flight on one of those airplanes. The
actions specified in this AD are intended to prevent fatigue cracking
of the corners of the door frame and the cross beams of the aft cargo
door, which could result in rapid depressurization of the airplane.
DATES: Effective December 24, 1998.
The incorporation by reference of certain publications listed in
the regulations is approved by the Director of the Federal Register as
of December 24, 1998.
Comments for inclusion in the Rules Docket must be received on or
before February 8, 1999.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-114,
Attention: Rules Docket No. 98-NM-291-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: The FAA has received reports indicating that
fatigue cracks have been detected in the corners of the door frame and
the cross beams of the aft cargo door on several in-service Boeing
Model 737-200, -200C, -300, and -400 series airplanes. Such fatigue
cracking results from cabin pressurization cycles. The FAA also has
received a report indicating that an incident of rapid depressurization
occurred during flight on one of the affected Boeing Model 737-200
series airplanes. Investigation of that incident revealed fatigue
cracks in the corners of the frame of the aft cargo door of the
airplane. These conditions, if not corrected, could result in rapid
depressurization of the airplane.
Explanation of Relevant Service Information
The FAA has reviewed and approved Boeing Service Bulletin 737-52-
1079, Revision 5, dated May 16, 1996. That service bulletin describes
procedures for repetitive internal detailed visual inspections to
detect cracking of the corners of the door frame and the upper and
lower cross beams of the aft cargo door, and corrective actions, if
necessary. Those corrective actions include repair, replacement of the
damaged frame, and modification of the aft cargo door. The modification
entails installation of a steel reinforcement angle at each corner of
the door and installation of reinforcements on the upper and lower
cross beams of the door. Accomplishment of such modification eliminates
the need for the repetitive internal detailed visual inspections.
Explanation of the Requirements of the Rule
Since an unsafe condition has been identified that is likely to
exist or develop on other airplanes of the same type design, this AD is
being issued to prevent fatigue cracking of the corners of the door
frame and the cross beams of the aft cargo door, which could result in
rapid depressurization of the airplane. This AD requires accomplishment
of the actions specified in the service bulletin described previously,
except as discussed below.
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. AD 90-06-02 requires accomplishment of certain structural
modifications, which constitutes terminating action for the repetitive
inspection requirements of this AD.
Differences Between Service Bulletin and This AD
Operators should note that, unlike the procedures described in the
service bulletin, this AD does not permit further flight with stop-
drilled cracks in the frame of the aft cargo door. The FAA has
determined that, because of the safety implications and consequences
associated with such cracking, any subject aft cargo door frame that is
found to be cracked must be permanently repaired and modified prior to
further flight.
Operators also should note that, although the service bulletin
specifies that the manufacturer may be contacted for disposition of
certain repair conditions, this AD requires the repair of those
conditions to be accomplished in accordance with a method approved by
the FAA.
Explanation of Applicability
Operators should note that the effectivity listing of the service
bulletin includes Boeing Model 737-200 and
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-200C series airplanes having line numbers 6 through 873 inclusive. The
applicability of this AD includes not only those airplanes listed in
the effectivity listing of the service bulletin, but also Boeing Model
737-200, -200C, -300, and -400 series airplanes; having line numbers
874 through 1642 inclusive; that have certain replacement doors
installed and that have not been modified in accordance with Boeing
Service Bulletin 737-52-1079.
Explanation of Compliance Threshold
Although the service bulletin recommends that the initial
inspection be performed prior to the accumulation of 12,000 total
flight cycles, this AD requires that the initial inspection be
performed within 90 days or 700 flight cycles after the effective date
of this AD, whichever occurs later. The FAA has determined that the
number of total flight cycles for an airplane may not be a good
indicator of the total cycle count for the subject aft cargo door,
because a door may have been removed from an airplane with many total
flight cycles and reinstalled on an airplane with relatively fewer
total flight cycles. Also, the FAA finds that, in view of the reports
indicating that rapid depressurization occurred on an airplane on which
fatigue cracks were found in the frame of the aft cargo door, and
because of the safety implications and consequences associated with
such cracking, the initial compliance time specified in this AD is
appropriate.
Interim Action
This is considered to be interim action until final action is
identified, at which time the FAA may consider further rulemaking.
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-291-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 adding the following new
airworthiness directive:
98-25-06 Boeing: Amendment 39-10931. Docket 98-NM-291-AD.
Applicability: The following airplane models, certificated in
any category:
Model 737-200 and -200C series airplanes, line numbers
6 through 873 inclusive;
Model 737-200, -200C, -300, and -400 series airplanes;
line numbers 874 through 1642 inclusive; equipped with an aft cargo
door having Boeing part number (P/N) 65-47952-1 or P/N 65-47952-524;
except:
1. Those airplanes on which that door has been modified in
accordance with Boeing Service Bulletin 737-52-1079; or,
2. Those airplanes on which the door assembly having P/N 65-
47952-524 includes four straps (P/N's 65-47952-139, 65-47952-140,
65-47952-141, and 65-47952-142) and a thicker lower cross beam web
(P/N 65-47952-157).
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 (d) 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 fatigue cracking of the corners of the door frame and
the cross beams of the aft cargo door, which could result in rapid
depressurization of the airplane, accomplish the following:
(a) Within 90 days or 700 flight cycles after the effective date
of this AD, whichever occurs later, perform an internal detailed
visual inspection to detect cracking of the
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corners of the door frame and the cross beams of the aft cargo door,
in accordance with Boeing Service Bulletin 737-52-1079, Revision 5,
dated May 16, 1996.
(1) If no cracking is detected, accomplish the requirements of
either paragraph (a)(1)(i) or (a)(1)(ii) of this AD.
(i) Repeat the internal visual inspection thereafter at
intervals not to exceed 4,500 flight cycles. Or,
(ii) Prior to further flight, modify the corners of the door
frame and the cross beams of the aft cargo door in accordance with
the service bulletin. Accomplishment of such modification
constitutes terminating action for the repetitive inspection
requirements of this AD.
(2) If any cracking is detected in the upper or lower cross
beams, prior to further flight, modify the cracked beam in
accordance with paragraph III.C. of Part I of the Accomplishment
Instructions of the service bulletin. Accomplishment of such
modification constitutes terminating action for the repetitive
inspection requirements of this AD for the repaired beam.
(3) If any cracking is detected in the forward or aft upper door
frame, prior to further flight, repair the frame and modify the
corners of the door frame of the aft cargo door, in accordance with
paragraph III.E. of Part I of the Accomplishment Instructions of the
service bulletin, except as provided by paragraph (b) of this AD.
Accomplishment of such modification constitutes terminating action
for the repetitive inspection requirements of this AD for the upper
door frame.
Note 2: Cracks of the forward or aft upper door frame,
regardless of length, must be repaired prior to further flight in
accordance with paragraph III.E. of Part I of the Accomplishment
Instructions of the service bulletin.
(4) If any cracking is detected in the forward or aft lower door
frame, prior to further flight, replace the damaged frame with a new
frame, and modify the corners of the door frame of the aft cargo
door, in accordance with paragraph III.F. of Part I of the
Accomplishment Instructions of the service bulletin. Accomplishment
of such modification constitutes terminating action for the
repetitive inspection requirements of this AD for the lower door
frame.
(b) Where Boeing Service Bulletin 737-52-1079, Revision 5, dated
May 16, 1996, specifies that certain repairs are to be accomplished
in accordance with instructions received from Boeing, this AD
requires that, prior to further flight, such repairs be accomplished
in accordance with a method approved by the Manager, Seattle
Aircraft Certification Office (ACO), FAA, Transport Airplane
Directorate.
(c) Modification of the corners of the door frame and the cross
beams of the aft cargo door in accordance with Boeing Service
Bulletin 737-52-1079, Revision 5, dated May 16, 1996, or in
accordance with the requirements of AD 90-06-02, amendment 39-6489,
constitutes terminating action for the repetitive inspection
requirements of this AD.
Note 3: Modification of the corners of the door frame and the
cross beams of the aft cargo door accomplished prior to the
effective date of this AD in accordance with Boeing Service Bulletin
737-52-1079, dated December 16, 1983; Revision 1, dated December 15,
1988; Revision 2, dated July 20, 1989; Revision 3, dated May 17,
1990; or Revision 4, dated February 21, 1991; are considered
acceptable for compliance with paragraph (c) of this AD.
(d) 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.
Note 4: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may be
obtained from the Seattle ACO.
(e) 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.
(f) Except as provided by paragraph (b) of this AD, the
inspections, repair, replacement, and modification (if
accomplished), shall be done in accordance with Boeing Service
Bulletin 737-52-1079, Revision 5, dated May 16, 1996. 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.
(g) This amendment becomes effective on December 24, 1998.
Issued in Renton, Washington, on November 30, 1998.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 98-32361 Filed 12-8-98; 8:45 am]
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