[Federal Register Volume 67, Number 71 (Friday, April 12, 2002)]
[Rules and Regulations]
[Pages 17929-17931]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 02-8456]


-----------------------------------------------------------------------

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2000-NM-73-AD; Amendment 39-12704; AD 2002-07-10]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 737-200, -200C, -300, -
400, and -500 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

-----------------------------------------------------------------------

SUMMARY: This amendment adopts a new airworthiness directive (AD), 
applicable to certain Boeing Model 737-200, -200C, -300, -400, and -500 
series airplanes, that requires replacement of certain repairs in 
certain fuselage lap joints with improved repairs. This amendment also 
requires a high frequency eddy current inspection to find cracking of 
the repairs of the lower skin at the lower row of fasteners in the lap 
joints of the fuselage, and repair of any cracking found. This action 
is necessary to find and fix premature cracking of certain lap joint 
repairs, which could result in rapid decompression of the airplane. 
This action is intended to address the identified unsafe condition.

DATES: Effective May 17, 2002.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of May 17, 2002.

ADDRESSES: The service information referenced in this AD may be 
obtained from Boeing Commercial Airplane Group, PO 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: Scott Fung, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 
1601 Lind Avenue, SW., Renton, Washington; telephone (425) 227-1221; 
fax (425) 227-1181.

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 737-200, -
200C, -300, -400, and -500 series airplanes was published in the 
Federal Register on July 12, 2001 (66 FR 36513). That action proposed 
to require replacement of certain repairs in certain fuselage lap 
joints with improved repairs. That action also proposed to require a 
high frequency eddy current inspection to find cracking of the repairs 
of the lower skin at the lower row of fasteners in the lap joints of 
the fuselage, and repair of any cracking found.

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.

Clarify Wording in Paragraphs (b) and (f)

    One commenter states that paragraph (b) of the proposed rule should 
include repairs that are configured like Figures 39 and 227 of the 
Structural Repair Manual (SRM), where the repair parts are common to 
the overlapping skin of the fuselage lap joint, but where the damage is 
outside the lap joint lower row. The commenter notes that fatigue 
testing of the SRM repairs that are the subject of this proposed AD 
showed that premature cracking occurred on repairs configured like the 
SRM Figure 39, where the repair was common to the overlapping skin of 
the fuselage lap joint. The commenter adds that paragraph (f) of the 
proposed rule also should be changed. Paragraph (f) states, ``* * * 
installed in any area between BS 259.5 and BS 1016, other than those 
specified in paragraph (d) of this AD * * *.'' The commenter notes that 
the correct reference for establishing the area of the fuselage subject 
to this portion of the AD is paragraph (e).
    The FAA agrees with the commenter. For clarification, we have 
changed paragraphs (b) and (e) of the final rule to add ``* * * or that 
have a lap joint repair configured like 737-200 SRM, Figure 39 or the 
737-300 SRM, Figure 227 (paragraph b), and 737-400 SRM, Figure 229 or 
737-500 SRM, Figure 227 (paragraph e), where the repair parts are 
common to the overlapping skin of the fuselage lap joint, but where the 
damage is outside the lap joint lower row.'' Paragraph (e) is similar 
to paragraph (b) but is applicable to Model 737-400 and -500 series 
airplanes. We have also changed paragraph (f) of the final rule to 
specify, ``* * * installed in any area between BS 259.5 and BS 1016, 
other than those specified in paragraph (e) of this AD * * *.'' We 
inadvertently cross referenced paragraph (d) within paragraph (f) of 
the proposed rule.

Structural Repair Manual Information

    One commenter asks that a point of contact be specified in the 
final rule so it can get SRM repair figures. The commenter states that 
it does not have access to the SRM repair figures specified in the 
proposed rule, and it will be difficult to determine if a repair was 
installed per one of those figures.
    We agree and have added Note 2 to this final rule (and reordered 
subsequent notes accordingly) to specify a point of contact for 
obtaining the SRM repair figures.
    A second commenter states that paragraph (a) of the proposed rule 
would mandate inspections of lap joints for specific repairs that were 
previously included in the applicable SRM. The commenter notes that if 
these repairs are found they are to be replaced with improved repairs, 
and adds that since those ``bad'' repairs were later determined to have 
poor fatigue characteristics, they were removed from the SRMs and are 
no longer illustrated in current revisions of the SRM. To facilitate 
inspection of these repairs, the commenter asks that the final rule 
include an attachment that depicts the repairs specified in the 
proposed rule.
    The FAA does not agree, including attachments depicting all the 
repairs specified is not feasible due to the variety and number of 
repairs done. As stated above, we have added Note 2 to the final rule 
which includes a point of contact for obtaining the SRM repair figures 
specified. The commenter may also obtain the above requested 
information from the point of contact specified in Note 2.
    A third commenter states that paragraph (b) of the proposed rule 
specifies that for repairs installed using the procedures specified in 
the SRM, the new replacement repairs must be installed before the 
accumulation of 15,000 flight cycles since repair installation, or 
within 5,000 flight cycles

[[Page 17930]]

after the effective date of the AD, whichever occurs later. The 
commenter notes that it does not keep track of repair dates or cycles, 
especially if they are out of the SRM. The commenter asks that the date 
of the SRM incorporation be referenced in the final rule to provide a 
solid date that can be used to meet the flight cycle requirements 
specified in paragraph (b).
    The FAA does not agree. Repair method incorporation dates differ 
from operator to operator, and the 5,000 flight cycle grace period 
specified in paragraph (b) of the final rule covers those operators 
that do not meet the compliance requirement of installation before the 
accumulation of 15,000 flight cycles since repair installation. 
However, the commenter may obtain the above requested information from 
the point of contact specified in Note 2 of the final rule.

Low Frequency Eddy Current (LFEC) Inspection

    Two commenters ask that an option be added to the final rule for 
doing an LFEC inspection in order to monitor the repair until it can be 
replaced at a scheduled maintenance visit. Both commenters propose a 
repetitive inspection interval of 1,200 flight cycles, with repair 
replacement to occur not later than 10,000 flight cycles after the 
effective date of the AD. The first commenter states that the test that 
identified the deficient repair, as identified in the proposed rule, 
was specifically designed to simulate pressurization cycles on crown 
skin laps. The commenter adds that, as these tests were not done on an 
in-service airplane, and the proposed rule does not reference any in-
service crack findings, the simulated cracks may not occur on an 
airplane or it may occur at a later flight cycle limit than that 
specified in the proposed rule. The second commenter states that, due 
to the potential difficulties in determining the age of a given repair, 
it would like the LFEC option added for the timing of the repair 
replacement.
    The FAA does not agree with the commenters. Although repetitive 
LFEC inspections could be done to reduce the exposure of premature 
cracking and consequent uncontrolled decompression of the airplane, the 
commenters did not provide sufficient technical justification for 
adding repetitive inspections and extending the replacement threshold. 
However, we would consider this option under the provisions for 
requesting approval of an alternative method of compliance, as provided 
by paragraph (g) of the final rule. No change is made to the final rule 
in this regard.

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 2,359 Model 737 series airplanes of the 
affected design in the worldwide fleet. The FAA estimates that 958 
airplanes of U.S. registry will be affected by this AD, that it will 
take approximately 14 work hours per airplane to accomplish the 
required actions, and that the average labor rate is $60 per work hour. 
Based on these figures, the cost impact of the AD on U.S. operators is 
estimated to be $804,720, or $840 per airplane.
    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

    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:

2002-07-10  Boeing: Amendment 39-12704. Docket 2000-NM-73-AD.

    Applicability: Model 737-200, -200C, -300, -400, and -500 series 
airplanes having line numbers 292 through 2565 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 (g) 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 premature cracking of certain fuselage lap joint 
repairs, which could result in rapid decompression of the airplane, 
accomplish the following:

Replacement of Structural Repair Manual (SRM) Lap Joint Repairs

    (a) For Model 737-200, -200C, and -300 series airplanes: Within 
5,000 flight cycles after the effective date of this AD, inspect all 
lap joints between body station (BS) 259.5 and BS 1016 to identify 
all repairs accomplished in accordance with Boeing 737-200 SRM, 
Subject 53-30-03, Figure 39 (for 737-200, 200C series airplanes); or 
Boeing 737-300 SRM, Subject 53-00-01, Figure 227 (for 737-300 series 
airplanes).
    (b) For Model 737-200, -200C, and -300 series airplanes that 
have a lap joint repair

[[Page 17931]]

installed at stringers S-4L and S-4R, located between BS 259.5 and 
BS 1016; and installed at S-10L and S-10R, or at S-14L and S-14R, 
located between BS 259.5 and BS 540, and between BS 727 and BS 1016; 
that was previously done per the procedures specified in Boeing 737-
200 SRM, Subject 53-30-03, Figure 39 repair (for 737-200, -200C 
series airplanes); or Boeing 737-300 SRM, Subject 53-00-01, Figure 
227 repair (for 737-300 series airplanes); or that have a lap joint 
repair configured like the 737-200 SRM, Figure 39 or the 737-300 SRM 
Figure 227: Where the repair parts are common to the overlapping 
skin of the fuselage lap joint, but where the damage is outside the 
lap joint lower row; before the accumulation of 15,000 flight cycles 
since repair installation, or within 5,000 flight cycles after the 
effective date of this AD, whichever is later, do the requirements 
of paragraph (b)(1) or (b)(2) of this AD, as applicable, per Boeing 
Service Bulletin 737-53A1177, Revision 6, dated May 31, 2001. If the 
area of damage that required the existing repair is outside the lap 
joint lower row, before further flight, 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 
(DER) who has been authorized by the Manager, Seattle ACO, to make 
such findings. For a repair method to be approved by the Manager, 
Seattle ACO, as required by this paragraph, the approval letter must 
specifically reference this AD.
    (1) If the lap joints are being cut out when replacing the SRM 
repair: Replace the Figure 39 repair of the lower skin at the lower 
row of fasteners in the lap joints of the fuselage per Figures 16, 
17, and 18 of the Accomplishment Instructions of the service 
bulletin.
    (2) If the lap joints are not being cut out when replacing the 
SRM repair: Do a high frequency eddy current (HFEC) open-hole 
rotating probe inspection to find cracking of the SRM repair of the 
lower skin at the lower row of fasteners in the lap joints of the 
fuselage, per the Figure 20 inspection procedures of the 
Accomplishment Instructions of the service bulletin. Before further 
flight after doing the inspection, replace a Boeing 737-200 SRM, 
Subject 53-30-03, Figure 39 repair with a Boeing 737-200 SRM, 
Subject 53-30-03, Figure 42 repair (for 737-200, 200C series 
airplanes); or replace a Boeing 737-300 SRM, Subject 53-00-01, 
Figure 227 repair with a Boeing 737-300 SRM, Subject 53-00-01, 
Figure 228 repair (for 737-300 series airplanes); as applicable; per 
Part II.D. (``Crack Repair'') of the Accomplishment Instructions of 
the service bulletin.
    (c) For Model 737-200, -200C, and -300 series airplanes that 
have a lap joint repair installed in any area between BS 259.5 and 
BS 1016, other than those specified in paragraph (b) of this AD, 
that was previously done per the procedures specified in Boeing 737-
200 SRM, Subject 53-30-03, Figure 39 repair (for 737-200, 200C 
series airplanes); or Boeing 737-300 SRM Subject 53-00-01, Figure 
227 repair (for 737-300 series airplanes): Before the accumulation 
of 20,000 flight cycles since repair installation, or within 5,000 
flight cycles after the effective date of this AD, whichever is 
later, do the requirements of paragraph (b)(1) or (b)(2) of this AD, 
as applicable, per Boeing Service Bulletin 737-53A1177, Revision 6, 
dated May 31, 2001.
    (d) For Model 737-400 and -500 series airplanes: Within 5,000 
flight cycles after the effective date of this AD, inspect all lap 
joints between BS 259.5 and BS 1016 to identify all repairs 
accomplished in accordance with; or that have a lap joint repair 
configured like Boeing 737-400 SRM, Subject 53-00-01, Figure 229 
(for 737-400 series airplanes); or Boeing 737-500 SRM, Subject 53-
00-01, Figure 227 (for 737-500 series airplanes).
    (e) For Model 737-400 and -500 series airplanes that have a lap 
joint repair installed at S-4L and S-4R, located between BS 259.5 
and BS 1016; and installed at S-10L and S-10R, or S-14L and S-14R, 
located between BS 259.5 and BS 540, and between BS 727 and BS 1016; 
that was previously done per the procedures specified in Boeing 737-
400 SRM, Subject 53-00-01, Figure 229 repair (for 737-400 series 
airplanes); or Boeing 737-500 SRM, Figure 227 repair (for 737-500 
series airplanes); or that have a lap joint repair configured like 
737-500 SRM, Figure 227 or 737-400 SRM, Figure 229: Where the repair 
parts are common to the overlapping skin of the fuselage lap joint, 
but where the damage is outside the lap joint lower row, before the 
accumulation of 15,000 flight cycles since repair installation, or 
within 5,000 flight cycles after the effective date of this AD, 
whichever is later, cut out and replace the repair per a method 
approved by the Manager, Seattle ACO; or per data meeting the type 
certification basis of the airplane approved by a Boeing Company DER 
who has been authorized by the Manager, Seattle ACO, to make such 
findings. For a repair method to be approved by the Manager, Seattle 
ACO, as required by this paragraph, the approval letter must 
specifically reference this AD.
    (f) For Model 737-400, and -500 series airplanes that have a lap 
joint repair installed in any area between BS 259.5 and BS 1016, 
other than those specified in paragraph (e) of this AD, that was 
previously done per the procedures specified in Boeing 737-400 SRM, 
Subject 53-00-01, Figure 229 repair (for 737-400 series airplanes); 
or Boeing 737-500 SRM, Figure 227 repair (for 737-500 series 
airplanes): Before the accumulation of 20,000 flight cycles since 
repair installation, or within 5,000 flight cycles after the 
effective date of this AD, whichever is later, cut out and replace 
the repair per a method approved by the Manager, Seattle ACO; or per 
data meeting the type certification basis of the airplane approved 
by a Boeing Company DER who has been authorized by the Manager, 
Seattle ACO, to make such findings. For a repair method to be 
approved by the Manager, Seattle ACO, as required by this paragraph, 
the approval letter must specifically reference this AD.

    Note 2: Copies of the SRM repair figures specified in paragraphs 
(b), (c), (e), and (f) of this AD may be obtained from Boeing 
Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 98124-
2207.

Alternative Methods of Compliance

    (g) 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

    (h) 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

    (i) The replacement and high frequency eddy current inspection, 
as specified in paragraphs (b)(1) and (b)(2) of this AD, shall be 
done in accordance with Boeing Service Bulletin 737-53A1177, 
Revision 6, dated May 31, 2001. 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

    (j) This amendment becomes effective on May 17, 2002.

    Issued in Renton, Washington, on April 2, 2002.
Ali Bahrami,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 02-8456 Filed 4-11-02; 8:45 am]
BILLING CODE 4910-13-P