[Federal Register Volume 64, Number 224 (Monday, November 22, 1999)]
[Proposed Rules]
[Pages 63757-63759]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-30370]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 99-NM-85-AD]
RIN 2120-AA64
Airworthiness Directives; Boeing Model 737-200 and -300 Series
Airplanes Equipped With Cargo Doors Installed in Accordance With
Supplemental Type Certificate (STC) SA2969SO
AGENCY: Federal Aviation Administration, DOT.
ACTION: Notice of proposed rulemaking (NPRM).
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SUMMARY: This document proposes the supersedure of an existing
airworthiness directive (AD), applicable to certain Boeing Model 737-
200 and -300 series airplanes, that currently requires repetitive
inspections to detect cracking in the radii on the support angles on
the lower jamb (latch lug fittings) of the main deck cargo door, and
replacement of cracked parts. This action would add a requirement for
installation of redesigned lower jamb latch support angles in the main
cargo door surround structure, which would terminate the repetitive
inspections. This proposal is prompted by the development of a
modification that will provide better protection of the subject area
against effects of structural fatigue. The actions specified by the
proposed AD are intended to prevent in-flight separation of the main
deck cargo door from the airplane due to fatigue cracking on the
support angles on the lower door jamb.
DATES: Comments must be received by January 6, 2000.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-114,
Attention: Rules Docket No. 99-NM-85-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 Pemco Aeroplex, Inc., P.O. Box 2287, Birmingham, Alabama
35201-2287. This information may be examined at the FAA, Transport
Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at
the FAA, Small Airplane Directorate, Atlanta Aircraft Certification
Office, One Crown
[[Page 63758]]
Center, 1895 Phoenix Boulevard, suite 450, Atlanta, Georgia.
FOR FURTHER INFORMATION CONTACT: Paul Sconyers, Manager, Airframe and
Propulsion Branch, ACE-117A; FAA, Small Airplane Directorate, Atlanta
Aircraft Certification Office, One Crown Center, 1895 Phoenix
Boulevard, suite 450, Atlanta, Georgia 30337-2748; telephone (770) 703-
6076; fax (770) 703-6097.
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 99-NM-85-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. 99-NM-85-AD, 1601 Lind Avenue, SW., Renton, Washington
98055-4056.
Discussion
On December 29, 1994, the FAA issued AD 95-01-06, amendment 39-9117
(60 FR 2323, January 9, 1995), as revised by AD 95-01-06 R1, amendment
39-9449 (60 FR 62192, December 5, 1995), applicable to certain Boeing
Model 737-200 and -300 series airplanes [those equipped with main deck
cargo doors installed in accordance with supplemental type certificate
(STC) SA2969SO]. That AD requires repetitive visual inspections to
detect cracking in the radii on the support angles on the lower jamb
(latch lug fittings) of the main deck cargo door, and replacement of
cracked parts with new parts. That action was prompted by reports of
premature fatigue cracking on the support angles on the lower jamb of
the main deck cargo door. The requirements of that AD are intended to
prevent in-flight separation of the main deck cargo door from the
airplane due to fatigue cracking on the support angles on the lower
door jamb.
Actions Since Issuance of Previous Rule
When the FAA originally issued AD 95-01-06R1, it was noted in the
preamble that the AD was considered interim action until final action
was identified, at which time the FAA might consider further
rulemaking. Since the issuance of that AD, the STC holder for the cargo
door airplane modification has generated a design change for the lower
latch lug fitting support angles for the main cargo door surround
structure. This design change, consisting of the installation of new
lower jamb latch support angles in the main cargo door surround
structure, would eliminate the need for the repetitive inspections (as
required by AD 95-01-06R1). Upon consideration, the FAA has determined
that installation of the design change is necessary to correct the
unsafe condition addressed by AD 95-01-06R1.
The FAA has determined that long-term continued operational safety
will be better assured by modifications or design changes to remove the
source of the problem, rather than by repetitive inspections. Long term
inspections may not be providing 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 design change requirement is in consonance with these
considerations.
The actions specified by the proposed AD are intended to prevent
in-flight separation of the main deck cargo door from the airplane due
to fatigue cracking on the support angles on the lower door jamb.
Explanation of Relevant Service Information
The FAA has reviewed and approved Pemco Service Bulletin 737-53-
0003, Revision 4, dated February 22, 1995, and Revision 5, dated March
25, 1999, which describe, among other things, procedures for
installation of new, improved lower jamb latch support angles in the
main cargo door surround structure. Accomplishment of the actions
specified in the service bulletin is intended to adequately address the
identified unsafe condition.
Explanation of Requirements of Proposed Rule
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 supersede AD 95-01-06 R1 to continue to require the
repetitive visual inspections to detect cracking in the radii on the
support angles on the lower jamb (latch lug fittings) of the main deck
cargo door, and replacement of cracked parts with new parts. The
proposed AD would also add a requirement for accomplishment of the
design change specified in the service bulletins described previously,
which would terminate the repetitive visual inspections. The actions
would be required to be accomplished in accordance with the service
information described previously, except as discussed below.
The FAA has clarified the inspection requirement contained in AD
95-01-06 R1. Whereas that AD specified a visual inspection, the FAA has
revised this proposed AD to clarify that its intent is to require a
detailed visual inspection. Additionally, a note has been added to the
proposed rule to define that inspection.
Differences Between Proposed Rule and Service Information
Operators should note that, unlike the procedures described in
Pemco Alert Service Letter 737-53-0003, Revision 3, dated December 22,
1994, this proposed AD would not permit further flight if cracks are
detected in the affected area of the cargo door installation. The FAA
has determined that, because of the safety implications and
consequences associated with such cracking, any affected area of the
cargo door installation that is found to be cracked must be repaired or
modified prior to further flight.
Cost Impact
There are approximately 32 airplanes of the affected design in the
worldwide fleet. The FAA estimates that 2 airplanes of U.S. registry
would be affected by this proposed AD.
The inspection that is currently required by AD 95-01-06 R1 and
retained in this proposed AD takes approximately 8 work hours per
[[Page 63759]]
airplane to accomplish, at an average labor rate of $60 per work hour.
Based on these figures, the cost impact of the currently required
actions on U.S. operators is estimated to be $480 per airplane, per
inspection cycle.
The new installation that is proposed in this AD action would take
approximately 500 work hours per airplane to accomplish, at an average
labor rate of $60 per work hour. Required parts would cost
approximately $9,700 per airplane. Based on these figures, the cost
impact of the proposed requirements of this AD on U.S. operators is
estimated to be $79,400, or $39,700 per airplane.
The cost impact figures discussed above are based on assumptions
that no operator has yet accomplished any of the current or proposed
requirements of this AD action, and that no operator would accomplish
those actions in the future if this AD were not adopted.
Regulatory Impact
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. 106(g), 40113, 44701.
Sec. 39.13 [Amended]
2. Section 39.13 is amended by removing amendment 39-9449 (60 FR
62192, December 5, 1995), and by adding a new airworthiness directive
(AD), to read as follows:
Boeing: Docket 99-NM-85-AD. Supersedes AD 95-01-06 R1, Amendment 39-
9449.
Applicability: Model 737-200 and -300 series airplanes equipped
with main deck cargo doors installed in accordance with supplemental
type certificate (STC) SA2969SO, 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 use the authority
provided in paragraph (c)(1) of this AD to request approval from the
FAA. This approval may address either no action, if the current
configuration eliminates the unsafe condition; or different actions
necessary to address the unsafe condition described in this AD. Such
a request should include an assessment of the effect of the changed
configuration on the unsafe condition addressed by this AD. In no
case does the presence of any modification, alteration, or repair
remove any airplane from the applicability of this AD.
Compliance: Required as indicated, unless accomplished
previously.
To prevent in-flight separation of the main deck cargo door from
the airplane, accomplish the following:
Note 2: This AD references Pemco Alert Service Letter 737-53-
0003, Revision 3, dated December 22, 1994; Pemco Service Bulletin
737-53-0003, Revision 4, dated February 22, 1995; and Pemco Service
Bulletin 737-53-0003, Revision 5, dated March 25, 1999; for
information concerning inspection and replacement procedures. In
addition, this AD specifies replacement requirements different from
those included in the service letter or service bulletin. Where
there are differences between the AD and the service letter or
service bulletin, the AD prevails.
Restatement of Requirements of AD 95-01-06R1, Amendment 39-9449
Repetitive Inspections
(a) Within 50 flight cycles after January 24, 1995 (the
effective date of AD 95-01-06, amendment 39-9117), or within 50
flight cycles after installation of STC SA2969SO, whichever occurs
later, perform a detailed visual inspection to detect cracking in
the radii on the support angles on the lower jamb of the main deck
cargo door, in accordance with Pemco Alert Service Letter 737-53-
0003, Revision 3, dated December 22, 1994.
(1) If no cracking is detected, repeat the detailed visual
inspection thereafter at intervals not to exceed 450 flight cycles.
(2) If any cracking is detected, prior to further flight,
replace the cracked part with a new part in accordance with the
alert service letter. Repeat the detailed visual inspection
thereafter at intervals not to exceed 450 flight cycles.
Note 3: For the purposes of this AD, a detailed visual
inspection is defined as: ``An intensive visual examination of a
specific structural area, system, installation, or assembly to
detect damage, failure, or irregularity. Available lighting is
normally supplemented with a direct source of good lighting at
intensity deemed appropriate by the inspector. Inspection aids such
as mirror, magnifying lenses, etc., may be used. Surface cleaning
and elaborate access procedures may be required.''
New Requirements of This AD
Terminating Action
(b) Within 1,500 flight cycles after the effective date of this
AD, install redesigned lower jamb latch lug support angles in the
main cargo door surround structure in accordance with Pemco Service
Bulletin 737-53-0003, Revision 4, dated February 22, 1995, or
Revision 5, dated March 25, 1999. This action constitutes
terminating action for the requirements of this AD.
Alternative Methods of Compliance
(c)(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, FAA, Small Airplane Directorate,
Atlanta Aircraft Certification Office (ACO). Operators shall submit
their requests through an appropriate FAA Principal Maintenance
Inspector, who may add comments and then send it to the Manager,
Atlanta ACO.
(c)(2) Alternative methods of compliance, approved previously in
accordance with AD 95-01-06 R1, amendment 39-9449, are approved as
alternative methods of compliance with paragraphs (a) and (b) of
this AD.
Note 4: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may be
obtained from the Atlanta ACO.
Special Flight Permits
(d) 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 16, 1999.
D.L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 99-30370 Filed 11-19-99; 8:45 am]
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