[Federal Register Volume 65, Number 149 (Wednesday, August 2, 2000)]
[Rules and Regulations]
[Pages 47255-47258]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-19381]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-NM-285-AD; Amendment 39-11840; AD 2000-15-08]
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 supersedes an existing airworthiness directive 
(AD), applicable to certain Boeing Model 747 series airplanes, that 
currently requires repetitive inspections for damage or cracking of the 
aft pressure bulkhead, and cracking of the bulkhead web-to-Y-ring lap 
joint area and the upper segment of the bulkhead web. That AD also 
requires certain follow-on actions, if necessary. This amendment 
requires that a currently required one-time

[[Page 47256]]

inspection to detect cracking of the upper segment of the bulkhead web 
be accomplished repetitively, and adds additional repetitive 
inspections to detect cracking of the upper and lower segments of the 
aft bulkhead web. The actions specified by this AD are intended to 
detect and correct fatigue cracking of the bulkhead web, which could 
result in rapid depressurization of the airplane, and consequent 
reduced controllability of the airplane.

DATES: Effective September 6, 2000.
    The incorporation by reference of certain publications listed in 
the regulations was approved previously by the Director of the Federal 
Register as of October 7, 1998 (63 FR 50495, September 22, 1998).

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, 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: A proposal to amend part 39 of the Federal 
Aviation Regulations (14 CFR part 39) by superseding AD 98-20-20, 
amendment 39-10786 (63 FR 50495, September 22, 1998), which is 
applicable to certain Boeing 747 series airplanes, was published in the 
Federal Register on February 2, 2000 (65 FR 4906). The action proposed 
to continue to require certain actions required by the existing AD. The 
action proposed to add a requirement that a detailed visual inspection 
to detect fatigue cracking of the upper segment of the bulkhead web 
required by the existing AD be accomplished repetitively, along with 
corrective actions, if necessary. The action also proposed to require 
additional repetitive surface probe high frequency eddy current (HFEC) 
inspections to detect cracking of the upper and lower segments of the 
bulkhead web, and repair, if necessary.

Comments

    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due consideration has been given to 
the comment received.

Request To Exclude Portion of Inspection Area

    One commenter requests that the FAA revise paragraph (h) of the 
proposed AD to include the following statement: ``For the inspection of 
the lower segment of the bulkhead web, the area between the 149 degree 
radial zee stiffeners may be omitted. These stiffeners are immediately 
outboard of pressure pans which reinforce the electrical wires [sic] 
penetrations, part number 65B02633-xx.'' The commenter states that this 
area does not need surface probe HFEC inspections because splice straps 
and reinforcing doublers installed on the web during production improve 
the durability of the lap joint and significantly reduce the stress 
level of the web-to-Y-ring lap joint in this area.
    The FAA concurs with the commenter's request and its rationale. The 
FAA also infers that the commenter's request applies to paragraph (i) 
as well as paragraph (h), and has revised those paragraphs in this 
final rule accordingly.

Conclusion

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

Cost Impact

    There are approximately 671 Model 747 series airplanes of the 
affected design in the worldwide fleet. The FAA estimates that 149 
airplanes of U.S. registry will be affected by this AD.
    The actions that are currently required by AD 98-20-20 and retained 
in this AD take approximately 360 work hours per 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 $3,218,400, or $21,600 per airplane, 
per inspection cycle.
    The new repetitive detailed visual inspections that are required in 
this AD take approximately 4 work hours per airplane to accomplish, at 
an average labor rate of $60 per work hour. Based on these figures, the 
cost impact of this requirement on U.S. operators is estimated to be 
$35,760, or $240 per airplane, per inspection cycle.
    The new repetitive HFEC inspections that are required in this AD 
take approximately 48 work hours per airplane to accomplish, at an 
average labor rate of $60 per work hour. Based on these figures, the 
cost impact of this requirement on U.S. operators is estimated to be 
$429,120, or $2,880 per airplane, per inspection cycle.
    The cost impact figures discussed above are based on assumptions 
that no operator has yet accomplished any of the requirements of this 
AD, 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

    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:

[[Page 47257]]

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 39-10786 (63 FR 
50495, September 22, 1998), and by adding a new airworthiness directive 
(AD), amendment 39-11840, to read as follows:

2000-15-08 Boeing: Amendment 39-11840. Docket 98-NM-285-AD. 
Supersedes AD 98-20-20, Amendment 39-10786.

    Applicability: Model 747 series airplanes, line numbers 1 
through 671 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 (j)(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.

    Compliance: Required as indicated, unless accomplished 
previously.
    To detect and correct fatigue cracking of the bulkhead web, 
which could result in rapid depressurization of the airplane, and 
consequent reduced controllability of the airplane, accomplish the 
following:

Restatement of Actions Required by AD 98-20-20, Amendment 39-10786

Initial Detailed Visual Inspection

    (a) Within 750 landings after December 10, 1987 (the effective 
date for AD 87-23-10, amendment 39-5758), unless accomplished within 
the last 1,250 landings [for airplanes subject to a 2,000-landing 
repeat inspection interval in accordance with paragraph (b) of this 
AD], or unless accomplished within the last 250 landings [for 
airplanes subject to a 1,000-landing repeat inspection interval in 
accordance with paragraph (b) of this AD], perform a detailed visual 
inspection; in accordance with Boeing Service Bulletin 747-53-2275, 
dated March 26, 1987, Revision 1, dated August 13, 1987, Revision 2, 
dated March 31, 1988, Revision 3, dated March 29, 1990, Revision 4, 
dated March 26, 1992, or Revision 5, dated January 16, 1997, or 
Boeing Alert Service Bulletin 747-53A2275, Revision 6, dated August 
27, 1998; of the aft side of the entire Body Station (BS) 2360 aft 
pressure bulkhead for damage such as dents, tears, nicks, gouges, or 
scratches; and cracks at splices and doublers, and around the 
Auxiliary Power Unit pressure pan cutout; and, for Group 4 airplanes 
only, inspect from the forward side, the area adjacent to the window 
cutout for damage or cracks.

    Note 2: Notwithstanding provisions to the contrary in AD 87-23-
10, and in Boeing Service Bulletin 747-53-2275, dated March 26, 
1987, Revision 1, dated August 13, 1987, Revision 2, dated March 31, 
1988, Revision 3, dated March 29, 1990, Revision 4, dated March 26, 
1992, and Revision 5, dated January 16, 1997: For Model 747SR 
airplanes operating at a cabin pressure differential lower than 8.6 
pounds-per-square-inch (psi), an adjustment factor of 1.2 shall NOT 
be used after October 7, 1998 (the effective date for AD 98-20-20), 
as a multiplier for inspection thresholds and intervals specified in 
this AD.


    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.''

Repetitive Detailed Visual Inspections

    (b) After initial compliance with paragraph (a) of this AD, 
continue to inspect as follows:
    (1) For Group 1 airplanes, repeat the inspections required by 
paragraph (a) of this AD, at intervals not to exceed 2,000 landings.
    (2) For Groups 2 and 3 airplanes, repeat the inspections 
required by paragraph (a) of this AD, at intervals not to exceed 
1,000 landings; or optionally, at the applicable time specified in 
paragraph (b)(2)(i) or (b)(2)(ii) of this AD.
    (i) For Group 2 airplanes that operate the entire interval with 
aft lavatory complexes or galleys adjacent to bulkheads, repeat the 
inspections required by paragraph (a) of this AD at intervals not to 
exceed 2,000 landings.
    (ii) For Groups 2 and 3 airplanes that operate the entire 
interval with an intact protective shield on the lower half of the 
forward side of the bulkhead, repeat the inspections required by 
paragraph (a) of this AD at intervals not to exceed 2,000 landings; 
and perform a detailed visual inspection of the protective shield 
for damage in accordance with Boeing Service Bulletin 747-53-2275, 
dated March 26, 1987, Revision 1, dated August 13, 1987, Revision 2, 
dated March 31, 1988, Revision 3, dated March 29, 1990, Revision 4, 
dated March 26, 1992, or Revision 5, dated January 16, 1997, or 
Boeing Alert Service Bulletin 747-53A2275, Revision 6, dated August 
27, 1998, at intervals not to exceed 1,000 landings. If damage is 
found to the protective shield that exceeds the limits indicated in 
the service bulletin, prior to further flight, repeat the inspection 
required by paragraph (a) of this AD.
    (3) For Group 4 airplanes, repeat the inspections required by 
paragraph (a) of this AD at intervals not to exceed 1,000 landings.

Repetitive Eddy Current, Ultrasonic, and X-Ray Inspections

    (c) Within 750 landings after December 10, 1987, or prior to the 
accumulation of 20,000 total landings, whichever occurs later, 
unless accomplished within the last 3,250 landings; and at intervals 
thereafter not to exceed 4,000 landings; perform eddy current, 
ultrasonic, and X-ray inspections of the aft side of the BS 2360 aft 
pressure bulkhead for cracks; in accordance with Boeing Service 
Bulletin 747-53-2275, dated March 26, 1987, Revision 1, dated August 
13, 1987, Revision 2, dated March 31, 1988, Revision 3, dated March 
29, 1990, Revision 4, dated March 26, 1992, or Revision 5, dated 
January 16, 1997, or Boeing Alert Service Bulletin 747-53A2275, 
Revision 6, dated August 27, 1998.

Repetitive Detailed Visual Inspections

    (d) Within 750 landings after December 10, 1987, or prior to the 
accumulation of 20,000 total landings, whichever occurs later, 
unless accomplished within the last 6,250 landings; and thereafter 
at intervals not to exceed 7,000 landings until the inspection 
required by paragraph (g) of this AD is accomplished: Perform a 
detailed visual inspection to detect cracking of the BS 2360 aft 
pressure bulkhead web-to-Y-ring lap joint area between radial 
stiffeners from the forward side of the bulkhead, in accordance with 
Boeing Service Bulletin 747-53-2275, dated March 26, 1987, Revision 
1, dated August 13, 1987, Revision 2, dated March 31, 1988, Revision 
3, dated March 29, 1990, Revision 4, dated March 26, 1992, or 
Revision 5, dated January 16, 1997, or Boeing Alert Service Bulletin 
747-53A2275, Revision 6, dated August 27, 1998.

Repair

    (e) If any cracking or damage is found during any inspection 
required by paragraph (a), (b), (c), or (d) of this AD, repair prior 
to further flight in accordance with Boeing Service Bulletin 747-53-
2275, dated March 26, 1987, Revision 1, dated August 13, 1987, 
Revision 2, dated March 31, 1988, Revision 3, dated March 29, 1990, 
Revision 4, dated March 26, 1992, or Revision 5, dated January 16, 
1997, or Boeing Alert Service Bulletin 747-53A2275, Revision 6, 
dated August 27, 1998.

Cabin Pressure Differential

    (f) For the purpose of complying with this AD, the number of 
landings may be determined to equal the number of pressurization 
cycles where the cabin pressure differential was greater than 2.0 
psi.

Initial Detailed Visual Inspection

    (g) Perform a detailed visual inspection from the forward side 
of the bulkhead of the upper segment of the bulkhead web at BS 2360 
to detect cracking, in accordance with Boeing Alert Service Bulletin 
747-53A2275, Revision 6, dated August 27, 1998, at the earlier of 
the times specified in paragraphs (g)(1) and (g)(2) of this AD. 
Accomplishment of this inspection terminates the repetitive 
inspection requirement of paragraph (d) of this AD.
    (1) Within 7,000 landings after the most recent detailed visual 
inspection accomplished in accordance with paragraph (d) of this AD.
    (2) At the latest of the times specified in paragraphs 
(g)(2)(i), (g)(2)(ii), and (g)(2)(iii) of this AD.

[[Page 47258]]

    (i) Prior to the accumulation of 20,000 total landings.
    (ii) Within 1,500 landings after the most recent detailed visual 
inspection accomplished in accordance with paragraph (d) of this AD.
    (iii) Within 90 days after October 7, 1998 (the effective date 
of AD 98-20-20).

Follow-On Action: High Frequency Eddy Current Inspection

    (h) If any cracking is detected during the detailed visual 
inspections required by paragraph (g) of this AD, prior to further 
flight, accomplish a surface probe high frequency eddy current 
(HFEC) inspection from the forward side of the bulkhead to detect 
cracking of the upper and lower segments of the bulkhead web around 
the fasteners that attach the web to the outer chord of the Y-ring, 
in accordance with Boeing Alert Service Bulletin 747-53A2275, 
Revision 6, dated August 27, 1998. For the inspection of the lower 
segment of the bulkhead web, the area between the 149 degree radial 
zee stiffeners may be omitted. Repair any cracking, prior to further 
flight, 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.

New Requirements of This AD

Repetitive Detailed Visual and HFEC Inspections

    (i) If no cracking is detected during the detailed visual 
inspection required by paragraph (g) of this AD, within 1,500 flight 
cycles after accomplishment of that inspection or within 250 flight 
cycles after the effective date of this AD, whichever occurs later: 
Repeat the detailed visual inspection, as specified in paragraph 
(g); and perform a surface probe HFEC inspection from the forward 
side of the bulkhead to detect cracking of the upper and lower 
segments of the bulkhead web, in accordance with Figure 15 of Boeing 
Alert Service Bulletin 747-53A2275, Revision 6, dated August 27, 
1998. For the inspection of the lower segment of the bulkhead web, 
the area between the 149 degree radial zee stiffeners may be 
omitted.
    (1) If no cracking is detected, repeat the detailed visual 
inspection thereafter at intervals not to exceed 1,500 flight 
cycles; and repeat the surface probe HFEC inspection thereafter at 
intervals not to exceed 3,000 flight cycles.

Repair

    (2) If any cracking is detected, prior to further flight, repair 
in accordance with a method approved by the Manager, Seattle 
Aircraft Certification Office (ACO), FAA, Transport Airplane 
Directorate, or a Boeing Company Designated Engineering 
Representative who has been authorized by the FAA to make such 
findings. For a repair method to be approved by the Manager, Seattle 
ACO, as required by this paragraph, the Manager's approval letter 
must specifically reference this AD.

Alternative Methods of Compliance

    (j)(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.
    (2) Alternative methods of compliance, approved previously in 
accordance with AD 98-20-20, amendment 39-10786, are approved as 
alternative methods of compliance with this AD.

    Note 4: 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

    (k) 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

    (l) Except as provided by paragraphs (h) and (i)(2) of this AD, 
the actions shall be done in accordance with Boeing Service Bulletin 
747-53-2275, dated March 26, 1987; Boeing Service Bulletin 747-53-
2275, Revision 1, dated August 13, 1987; Boeing Service Bulletin 
747-53-2275, Revision 2, dated March 31, 1988; Boeing Service 
Bulletin 747-53-2275, Revision 3, dated March 29, 1990; Boeing 
Service Bulletin 747-53-2275, Revision 4, dated March 26, 1992; 
Boeing Service Bulletin 747-53-2275, Revision 5, dated January 16, 
1997; or Boeing Alert Service Bulletin 747-53A2275, Revision 6, 
dated August 27, 1998; as applicable. This incorporation by 
reference was approved previously by the Director of the Federal 
Register as of October 7, 1998 (63 FR 50495, September 22, 1998). 
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

    (m) This amendment becomes effective on September 6, 2000.

    Issued in Renton, Washington, on July 26, 2000.
Donald L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 00-19381 Filed 8-1-00; 8:45 am]
BILLING CODE 4910-13-U