AD 2003-10-06

[Federal Register Volume 68, Number 101 (Tuesday, May 27, 2003)]
[Rules and Regulations]
[Pages 28692-28695]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 03-12840]



[[Page 28692]]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2000-NM-377-AD; Amendment 39-13151; AD 2003-10-06]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 747 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment adopts a new airworthiness directive (AD), 
applicable to certain Boeing Model 747 series airplanes, that requires 
repetitive inspections for cracking of the skin, bear strap, and sill 
chord of the lower lobe cargo door cutout, and repair, if necessary. 
For certain airplanes, the AD also provides an optional modification of 
the lower lobe cargo door cutout, which ends the pre-modification 
repetitive inspections, but necessitates new post-modification 
repetitive inspections after a certain time. The actions specified by 
this AD are intended to find and fix cracking of the skin, bear strap, 
and sill chord of the lower lobe cargo door cutout, which could lead to 
reduced structural integrity of the lower lobe cargo door cutout, and 
result in rapid depressurization of the airplane. This action is 
intended to address the identified unsafe condition.

DATES: Effective July 1, 2003.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of July 1, 2003.

ADDRESSES: 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 Federal 
Aviation Administration (FAA), Transport Airplane Directorate, Rules 
Docket, 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, Seattle Aircraft Certification Office, 
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 
917-6434; fax (425) 917-6590.

SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal 
Aviation Regulations (14 CFR part 39) to include an airworthiness 
directive (AD) that is applicable to certain Boeing Model 747 series 
airplanes was published as a supplemental notice of proposed rulemaking 
(NPRM) in the Federal Register on June 21, 2002 (67 FR 42207). That 
action proposed to require repetitive inspections for cracking of the 
skin, bear strap, and sill chord of the lower lobe cargo door cutout, 
and repair, if necessary. For certain airplanes, the action also 
proposed to provide an optional modification of the lower lobe cargo 
door cutout, which would end the pre-modification repetitive 
inspections, but would necessitate new post-modification repetitive 
inspections after a certain time. The action also proposed to expand 
the optional modification of the lower lobe cargo door cutout specified 
in the NPRM and reduce the compliance threshold for the existing post-
modification inspections.

Comments

    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due consideration has been given to 
the comments received.
    One commenter concurs with the proposed rule.

Request To Allow Modification/Repair Per Structural Repair Manual (SRM)

    Two commenters ask that accomplishment of the modification/repair 
required by the proposed AD per SRM Chapter 53-30-03, Figure 62, or 
Chapter 53-60-01, Figure 204, be allowed as terminating action for the 
repetitive inspections. The first commenter states that, according to 
information received from the manufacturer, repair per SRM Chapter 53-
30-03, Figure 62, terminates the repetitive inspections specified in 
Boeing Service Bulletin 747-53A2448, Revision 1, dated April 4, 2002 
(referenced in the proposed rule as the appropriate source of service 
information for accomplishment of the inspections). The commenter adds 
that post-modification inspections are done per the Repair Assessment 
Program required by section 121.370 (``Repair assessment for 
pressurized fuselages'') of the Federal Aviation Regulations (14 CFR 
121.370). The second commenter states that, according to information 
received from the manufacturer, the repair doubler installation is 
terminating action for the repetitive inspections, and post-repair 
inspections should be done per the inspection program defined in the 
SRM.
    The FAA partially agrees with the commenters. We agree that repairs 
done per Revision 1 of the referenced service bulletin, and the post-
repair inspections defined in the applicable SRMs and listed in the 
service bulletin, terminate the repetitive inspections required by 
paragraph (a) of the proposed AD for the repaired area only. We have 
changed paragraph (c) of the final rule (paragraph (b) of the proposed 
rule) to specify such terminating action. However, we have determined 
that compliance with section 121.370 of the Federal Aviation 
Regulations (14 CFR 121.370) does not meet the post-repair inspection 
requirements specified in this AD. This is because the repair 
assessment guidelines approved for Model 747 series airplanes are 
applicable only for normal skin surface structure, not for underlying 
stringers, frames, supporting structure and fuselage cutouts. 
Therefore, the Repair Assessment Program is not acceptable for doing 
the post-repair inspections required by this AD. No change to the final 
rule is necessary in this regard.

Request To Change Paragraph (b) or (d)

    One commenter states that it has frequently found cracking in the 
area specified in the proposed AD, and has installed many repairs that 
were approved by a Boeing Company Designated Engineering Representative 
(DER) who will presumably be granted alternative method of compliance 
(AMOC) approval authority by the Manager of the Seattle Aircraft 
Certification Office (ACO). Since so many repairs have been installed, 
the commenter asks that paragraph (b) or (d) of the proposed AD be 
changed, or that a new repair paragraph be added. This would allow a 
repair previously approved per data meeting the type certification 
basis of the airplane approved by a Boeing DER who has been authorized 
by the Manager, Seattle ACO, to make such findings, as an acceptable 
repair method that meets the requirements of the proposed AD. The 
commenter adds that making this change would prevent operators with 
previously issued forms for approved repairs from resubmitting the 
forms with the AD number included.
    We do not agree with the commenter. Repairs previously approved by 
a Boeing DER do require new approval as an AMOC. AMOC delegation to a 
DER requires findings of compliance that include all the design 
considerations, practices, and load cases used during the certification 
process, even if those defined in part 25 (``Airworthiness Standards: 
Transport Category Airplanes'') of the Federal Aviation Regulations (14 
CFR part 25) are exceeded. A non-AMOC repair approval may or may not 
include all of these

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considerations, and only complies with part 25 of the Federal Aviation 
Regulations (14 CFR part 25) as a minimum. For this reason, paragraph 
(e) of the final rule requires that repair approval must specifically 
refer to this AD. No change to the final rule is necessary in this 
regard.

Request for Credit for Modification Per Original Issue of Service 
Bulletin

    One commenter states that paragraph (c) of the proposed AD 
describes optional modification and post-modification inspections per 
Revision 1 of the referenced service bulletin; however, the commenter 
notes that operators may already have done the modification of the area 
specified per the original issue of that service bulletin. The 
commenter adds that information received from the manufacturer suggests 
that airplanes modified per the original issue should have additional 
inspections and modifications. The manufacturer recommends (and the 
commenter agrees) that these actions should be done within 3,000 flight 
cycles or 18 months after the initial modification.
    Although the commenter does not specifically ask for a change to 
the proposed AD, we infer that the commenter wants credit for airplanes 
previously modified per the original issue of the service bulletin, and 
confirmation that the additional actions recommended by the 
manufacturer are indeed required. We agree that any operator that has 
done the modifications per the original issue of the service bulletin 
is required to do additional inspections and modifications per Revision 
1 of the service bulletin. With regard to actions accomplished per the 
original issue of the service bulletin that correspond to actions in 
Revision 1 of the service bulletin, we already give credit for actions 
accomplished before the effective date of an AD by means of the phrase 
``Compliance: Required as indicated, unless accomplished previously,'' 
which appears in every AD. Therefore, no change to the final rule is 
necessary in this regard.

Request To Reference Existing AD and Relation to New AD

    One commenter states that the proposed AD affects an area that is 
the subject of AD 94-15-18, amendment 39-8989 (59 FR 41233, August 11, 
1994), and Boeing 747 Supplemental Structural Inspection Document 
(SSID) D6-35022, and can affect Structurally Significant Item (SSI) F-
39E. The commenter asks that any related requirements between the new 
AD and the existing AD be discussed. The commenter adds that the effect 
of repairs, modifications, and duplication of inspections done per the 
existing AD should be reviewed, and a determination made of whether one 
set of AD requirements meets the existing AD requirements.
    We have been informed by the manufacturer that the Boeing 747 SSID 
is being revised to remove the portions of SSI F-39 inspections that 
are required by this AD. This revision to the Boeing 747 SSID may be 
approved as an alternative method of compliance to AD 94-15-18, which 
would eliminate the potential for duplication of inspections. In 
addition, repairs and modifications done per the existing AD will not 
be affected by the requirements in this AD. Therefore, no change to the 
final rule is necessary in this regard.

Request To Withdraw Proposed AD

    One commenter disagrees that the cracking found in the upper 
corners of the aft lower cargo door cutout constitutes an unsafe 
condition that warrants regulatory action. The commenter states that 
the cracks reported by Boeing in the referenced service bulletin were 
small and did not pose an imminent threat of rapid depressurization. 
The commenter notes that the robust structure of the lower lobe cargo 
door cutout mitigates threats from minor skin cracks. The commenter 
adds that cracks found on the commenter's airplanes were found as a 
result of routine maintenance inspection, proving that existing 
inspection and maintenance programs will detect cracking in the subject 
areas before an unsafe condition exists. The commenter states that a 
minor revision to the maintenance program would ensure adequate crack 
detection, without the need for additional regulatory action.
    We do not agree with the commenter. Cracks over one inch in length 
have been found in both the fuselage skin and the adjacent bear strap. 
If cracks propagate into the sill chord, rapid decompression could 
occur. The door hinge fairing also covers up the area of cracking, 
making it unlikely that all cracks will be detected by routine 
maintenance inspections. No change to the final rule is necessary in 
this regard.

Request To Change Cost Impact Analysis

    One commenter states that the FAA estimate of approximately 3 work 
hours to accomplish the proposed inspection does not include the time 
required to gain access and close-up. In the case of this AD, some of 
the associated access and close-up time, including removing and re-
installing fasteners and fittings, is not incidental, and is only 
required for this particular inspection procedure. The commenter notes 
that those costs should be included in the cost impact analysis. The 
commenter adds that the other costs, such as access and closeup of 
seats, carpet, cargo handling equipment, floor panels, and insulation 
blankets, may be incidental during some scheduled heavy maintenance 
inspections, but would not be incidental if done during a special 
maintenance visit.
    We do not agree to change the number of estimated work hours for 
the inspections. The number of work hours necessary to accomplish the 
inspections, specified as 3 in the cost impact information, is 
consistent with the service bulletin. This number represents the time 
necessary to perform only the inspections actually required by this AD. 
We recognize that, in accomplishing the requirements of any AD, 
operators may incur additional costs due to special circumstances when 
scheduling maintenance visits. However, because maintenance schedules 
vary significantly from operator to operator, the hours necessary for 
access and closeup time, including removing and re-installing 
fasteners, are almost impossible to calculate. Therefore, no change is 
made to the final rule in this regard.

Requests To Change Compliance Time

    One commenter asks that the compliance time specified in paragraph 
(a)(2) of the proposed AD be changed from ``For airplanes with 13,000 
or more total flight cycles as of the effective date of this AD: Do the 
inspection within 1,000 flight cycles or 1 year after the effective 
date of this AD, whichever is first,'' to ``For airplanes with 13,000 
or more flight cycles as of the effective date of this AD: Do the 
inspection within 1,000 flight cycles after the effective date of this 
AD.'' If a calendar-driven timetable is used, to prevent unnecessary 
special maintenance visits, the commenter asks that paragraph (a)(2) be 
changed to, ``For airplanes with 13,000 or more flight cycles as of the 
effective date of this AD: Do the inspection within 1,000 flight cycles 
or 18 months after the effective date of this AD, whichever occurs 
first.'' The commenter states that the subject cracking is caused by 
fatigue, and such cracking is attributed to cyclic loading, not 
calendar time, so requiring a fatigue-related inspection based on 
calendar time is not justified. The commenter adds that most 747 
operators currently use C-check inspection intervals of 18 months. Due 
to this fact, the commenter

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notes that the one-year initial inspection interval specified in 
paragraph (a)(2) would impose special inspection visits on one-third of 
the fleet.
    A second commenter also asks that the compliance time specified in 
paragraph (a)(2) of the proposed AD be changed to ``For airplanes with 
13,000 or more flight cycles as of the effective date of this AD: Do 
the inspection within 1,300 flight cycles or 18 months after the 
effective date of this AD, whichever occurs first.'' The commenter adds 
that this compliance time supports maintenance flow.
    The same commenter asks that the compliance time in paragraph 
(a)(1) of the proposed AD be changed to ``For airplanes with less than 
13,000 flight cycles as of the effective date of this AD: Do the 
inspection prior to the accumulation of 13,000 flight cycles or within 
1,300 flight cycles after the effective date of this AD, whichever 
occurs later.'' The commenter adds that this compliance time results in 
inspections and rework during scheduled A-checks.
    We do not agree with the commenters. We have determined that a 
1,000 flight cycle grace period for airplanes having more than 13,000 
total flight cycles may not provide for an adequate level of safety for 
airplanes with low cycle usage. While there is some technical merit 
that a calendar-based compliance time should not apply to a fatigue 
issue, we have determined that the 1-year compliance time will ensure 
that the required inspections are completed in a timely manner, in 
particular, on airplanes that are well above the 13,000 total flight 
cycle threshold.
    In developing an appropriate compliance time for the actions 
required by this AD, we considered not only those safety issues, but 
the manufacturer's recommendations and the practical aspect of 
accomplishing the inspection within an interval paralleling normal 
scheduled maintenance for the majority of affected operators. In light 
of the factors described previously, we consider ``within 1,000 flight 
cycles or 1 year after the effective date of this AD, whichever occurs 
first,'' to be an appropriate compliance time wherein safety will not 
be adversely affected. No change to the final rule is necessary in this 
regard.

Additional Change to Final Rule

    Because the language in Note 3 of the proposed AD is regulatory in 
nature, that note has been redesignated as paragraph (b) of this final 
rule.

Conclusion

    After careful review of the available data, including the comments 
noted above, the FAA has determined that air safety and the public 
interest require the adoption of the rule with the changes previously 
described. The FAA has determined that these changes will neither 
increase the economic burden on any operator nor increase the scope of 
the AD.

Cost Impact

    There are approximately 1,129 airplanes of the affected design in 
the worldwide fleet. The FAA estimates that 275 airplanes of U.S. 
registry will be affected by this AD, that it will take approximately 3 
work hours per airplane to accomplish the inspection, and that the 
average labor rate is $60 per work hour. Based on these figures, the 
cost impact of this required inspection on U.S. operators is estimated 
to be $49,500, or $180 per airplane, per inspection cycle.
    The cost impact figure discussed above is based on assumptions that 
no operator has yet accomplished any of the 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 adopted herein will 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 final rule does not have federalism 
implications under Executive Order 13132.
    For the reasons discussed above, I certify that this action (1) is 
not a ``significant regulatory action'' under Executive Order 12866; 
(2) is not a ``significant rule'' under DOT Regulatory Policies and 
Procedures (44 FR 11034, February 26, 1979); and (3) 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 final evaluation has been prepared for this action 
and it is contained in the Rules Docket. A copy of it 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

0
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

0
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]

0
2. Section 39.13 is amended by adding the following new airworthiness 
directive:

2003-10-06 Boeing: Amendment 39-13151. Docket 2000-NM-377-AD.

    Applicability: Model 747 series airplanes, line numbers 1 
through 1255 inclusive, 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) 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 find and fix cracking of the skin, bear strap, and sill chord 
of the lower lobe cargo door cutout, which could lead to reduced 
structural integrity of the lower lobe cargo door cutout, and result 
in rapid depressurization of the airplane, accomplish the following:

Repetitive Inspections

    (a) Perform detailed and high frequency eddy current (HFEC) 
inspections to find cracking of the skin, bear strap, and sill chord 
at the upper aft and forward corners of the lower lobe cargo door 
cutout, per Boeing Service Bulletin 747-53A2448, Revision 1, dated 
April 4, 2002. Do the initial inspections at the time shown in 
paragraph (a)(1) or (a)(2) of this AD, as applicable, and repeat the 
inspections at least every 3,000 flight cycles until paragraph (d) 
of this AD is accomplished.


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    Note 2: For the purposes of this AD, a detailed 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.''

    (1) For airplanes with fewer than 13,000 total flight cycles as 
of the effective date of this AD: Do the inspection prior to the 
accumulation of 13,000 total flight cycles or within 1,000 flight 
cycles after the effective date of this AD, whichever is later.
    (2) For airplanes with 13,000 or more total flight cycles as of 
the effective date of this AD: Do the inspection within 1,000 flight 
cycles or 1 year after the effective date of this AD, whichever is 
first.

Credit for Inspections Accomplished Per Original Issue of Service 
Bulletin

    (b) Inspections accomplished prior to the effective date of this 
AD per Boeing Alert Service Bulletin 747-53A2448, including Appendix 
A, dated September 28, 2000, are considered acceptable for 
compliance with the applicable inspection(s) specified in paragraph 
(a) of this AD.

Repair

    (c) If any crack is found during any inspection required by 
paragraph (a) of this AD: Before the next flight, repair per Boeing 
Service Bulletin 747-53A2448, Revision 1, dated April 4, 2002, 
except as provided by paragraph (e) of this AD. Repairs and post-
repair inspections done per Part 4 of the service bulletin end the 
repetitive inspections required by paragraph (a) of this AD for the 
repaired area only.

Optional Modification and Post-Modification Inspections

    (d) If no crack is found during any inspection required by 
paragraph (a) of this AD, operators may accomplish paragraphs (d)(1) 
and (d)(2) of this AD.
    (1) Do an optional modification of the lower lobe cargo door 
cutout (including removing the hinge fairing and its fasteners, 
oversizing fastener holes, and replacing existing fasteners with new 
fasteners and the grounding strap with a new strap) per Figure 4 or 
7, as applicable, of Boeing Service Bulletin 747-53A2448, Revision 
1, dated April 4, 2002, except as provided by paragraph (e) of this 
AD. Such modification ends the repetitive inspections required by 
paragraph (a) of this AD.
    (2) At the applicable compliance time and repetitive inspection 
interval specified in Figure 1 of Boeing Service Bulletin 747-
53A2448, Revision 1, dated April 4, 2002, perform detailed and HFEC 
inspections to find cracking of the skin at the upper aft and 
forward corners of the lower lobe cargo door cutout, per Figure 5 of 
the service bulletin. If any crack is found, before the next flight, 
repair per the service bulletin, except as provided by paragraph (e) 
of this AD.

Repair and Modification: Exception

    (e) Where Boeing Service Bulletin 747-53A2448, Revision 1, dated 
April 4, 2002, specifies to contact Boeing for repair or 
modification information: Repair per a method approved by the 
Manager, Seattle Aircraft Certification Office (ACO), FAA; or per 
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. 
For a repair method to be approved as required by this paragraph, 
the approval must specifically refer to this AD.

Alternative Methods of Compliance

    (f) 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 3: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Seattle ACO.

Special Flight Permits

    (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.

Incorporation by Reference

    (h) Except as provided by paragraphs (b) and (e) of this AD, the 
actions shall be done in accordance with Boeing Service Bulletin 
747-53A2448, Revision 1, dated April 4, 2002. 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.

Effective Date

    (i) This amendment becomes effective on July 1, 2003.

    Issued in Renton, Washington, on May 16, 2003.
Vi L. Lipski,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 03-12840 Filed 5-23-03; 8:45 am]
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