AD Amdt-39-12317

[Federal Register Volume 66, Number 133 (Wednesday, July 11, 2001)]
[Rules and Regulations]
[Pages 36146-36149]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 01-17118]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2000-NM-205-AD; Amendment 39-12317; AD 2000-06-13 R1]
RIN 2120-AA64


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

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment revises an existing airworthiness directive 
(AD), applicable to certain Boeing Model 737-200, -200C, -300, and -400 
series airplanes, that currently requires repetitive visual and high 
frequency eddy current (HFEC) 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. That amendment also mandates 
accomplishment of a modification to the aft cargo door, which would 
terminate the repetitive inspection requirements. This amendment 
revises the compliance time for the terminating modification. The 
actions specified by this AD are intended to prevent fatigue cracking 
of the corners of the doorframe and the crossbeams of the aft cargo 
door, which could result in rapid depressurization of the airplane.

DATES: Effective August 15, 2001.
    The incorporation by reference of Boeing Alert Service Bulletin 
737-52A1079, Revision 6, dated November 18, 1999, as listed in the 
regulations, was approved previously by the Director of the Federal 
Register as of May 9, 2000 (65 FR 17583, April 4, 2000).

[[Page 36147]]

    The incorporation by reference of Boeing Service Bulletin 737-52-
1079, Revision 5, dated May 16, 1996, as listed in the regulations, was 
approved previously by the Director of the Federal Register as of 
December 24, 1998 (63 FR 67769, December 9, 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: James Blilie, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 
1601 Lind Avenue, SW., Renton, Washington 98055-2028; telephone (425) 
227-2131; fax (425) 227-1181.

SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal 
Aviation Regulations (14 CFR part 39) by revising AD 2000-06-13, 
amendment 39-11654 (65 FR 17583, April 4, 2000); which is applicable to 
certain Boeing Model 737-200, -200C, -300, and -400 series airplanes; 
was published in the Federal Register on October 5, 2000 (65 FR 59381). 
The action proposed to continue to require repetitive visual and high 
frequency eddy current (HFEC) 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. The action also proposed to 
continue to mandate accomplishment of a modification to the aft cargo 
door, which would terminate the repetitive inspection requirements. 
However, the action proposed to revise the compliance time of the 
terminating action.

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.

Support for the Proposal

    One commenter supports the proposed rule.

Request for Clarification of Note 4

    One commenter requests clarification of Note 4 of the proposed 
rule. That note states, ``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; is considered acceptable for 
compliance with paragraph (e) of this AD.'' The commenter states that 
certain repair angles installed per those service bulletins may have 
been installed with inadequate edge margin, and the commenter questions 
whether repair angles installed without cracks but with inadequate edge 
margin are acceptable for compliance with paragraph (e) of this AD. 
Furthermore, the commenter notes that Revision 6 of the service 
bulletin, dated November 18, 1999, requires that certain repair angles 
installed with a short edge margin be repetitively inspected, and 
questions whether these repetitive inspections would be required by the 
proposed AD.
    The FAA does not concur that any change to Note 4 of this AD is 
necessary. To be acceptable for compliance with paragraph (e) of this 
AD, the modification of the corners of the door frame must have been 
properly installed according to the referenced service bulletins. To 
properly install any repair or modification, all fastener edge margins 
must meet normal rework requirements which are explicitly stated in the 
Boeing Structural Repair Manual and other service information. If the 
edge margins for an installation of the terminating modification are 
not adequate, as specified in the service bulletin, then the repetitive 
inspections identified in the service bulletin would be necessary for 
the modification to be considered to have been accomplished ``in 
accordance with the service bulletin.'' No change to the final rule is 
necessary in this regard.

Explanation of Editorial Change

    In paragraph (d) of the proposed rule, an editing error resulted in 
that paragraph including a compliance time of ``Within 4,500 flight 
cycles or one year after the effective date of this AD.'' The paragraph 
should have referenced the effective date of AD 2000-06-13, which is 
May 9, 2000. Therefore, paragraph (d) of this final rule has been 
revised to correct this error and specify a compliance time of 4,500 
flight cycles or 1 year after May 9, 2000.

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 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 1,636 Model 737 series airplanes of the 
affected design in the worldwide fleet. The FAA estimates that 707 
airplanes of U.S. registry are affected by this AD. This AD adds no new 
requirements, but only extends a compliance time for an action already 
required by AD 2000-06-13. Thus, this AD adds no new additional 
economic burden on affected operators, other than the cost of 
additional repetitive inspection cycles if operators elect to 
accomplish the modification at a later compliance time as allowed by 
this AD. The current costs associated with this amendment are 
reiterated in their entirety (as follows) for the convenience of 
affected operators:
    The detailed visual inspections currently required by AD 2000-06-13 
take approximately 2 work hours per airplane to accomplish, at an 
average labor rate of $60 per work hour. Based on these figures, the 
cost impact of these currently required inspections on U.S. operators 
is estimated to be $84,840, or $120 per airplane, per inspection cycle.
    The HFEC inspections currently required by AD 2000-06-13 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 these inspections on U.S. operators is estimated to be 
$169,680, or $240 per airplane, per inspection cycle.
    The modification currently required by AD 2000-06-13 takes 
approximately 144 work hours per airplane to accomplish, at an average 
labor rate of $60 per work hour. Required parts cost approximately 
$4,530 per airplane. Based on these figures, the estimated cost impact 
of this modification on U.S. operators is estimated to be $9,311,190, 
or $13,170 per airplane.
    The cost impact figures discussed above are 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.

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

[[Page 36148]]

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 removing amendment 39-11654 (65 FR 
17583, April 4, 2000), and by adding a new airworthiness directive 
(AD), amendment 39-12317, to read as follows:

2000-06-13 R1  Boeing: Amendment 39-12317. Docket 2000-NM-205-AD. 
Revises AD 2000-06-13, Amendment 39-11654.

    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; excluding:
    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 (f)(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 prevent fatigue cracking of the corners of the doorframe and 
the cross beams of the aft cargo door, which could result in rapid 
depressurization of the airplane, accomplish the following:

Restatement of the Requirements of AD 2000-06-13

Inspections and Corrective Actions

    (a) Within 90 days or 700 flight cycles after December 24, 1998 
(the effective date of AD 98-25-06, amendment 39-10931), whichever 
occurs later, perform an internal detailed visual inspection to 
detect cracking 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 Boeing Alert Service 
Bulletin 737-52A1079, Revision 6, dated November 18, 1999.
    (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 
doorframe and the crossbeams of the aft cargo door in accordance 
with the service bulletin. Accomplishment of such modification 
constitutes terminating action for the repetitive inspection 
requirements of paragraph (a)(1)(i) 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 Part I of the Accomplishment Instructions of the 
service bulletin. Accomplishment of such modification constitutes 
terminating action for the repetitive inspection requirements of 
paragraph (a)(1)(i) 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 
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 paragraph (a)(1)(i) of this AD for the 
upper doorframe.

    Note 2: Cracks of the forward or aft upper door frame, 
regardless of length, must be repaired prior to further flight in 
accordance with 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 Part I of the Accomplishment Instructions 
of the service bulletin. Accomplishment of such modification 
constitutes terminating action for the repetitive inspection 
requirements of paragraph (a)(1)(i) of this AD for the lower 
doorframe.
    (b) Where Boeing Service Bulletin 737-52-1079, Revision 5, dated 
May 16, 1996; or Boeing Alert Service Bulletin, 737-52A1079, 
Revision 6, dated November 18, 1999; 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.

Inspections and Corrective Actions

    (c) If any cracking of the outer chord of the upper or lower 
cross beams of the aft cargo door is detected as a result of any 
inspection required by paragraph (a) of this AD, prior to further 
flight, repair in accordance with a method approved by the Manager, 
Seattle ACO; Boeing Alert Service Bulletin 737-52A1079, Revision 6, 
dated November 18, 1999; 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 
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.
    (d) Within 4,500 flight cycles or 1 year after May 9, 2000 (the 
effective date of AD 2000-06-13, amendment 39-11654), whichever 
occurs later: Perform a high frequency eddy current inspection 
(HFEC) to detect cracking of the four corners of the door frame of 
the aft cargo door, in accordance with the procedures specified in 
Boeing 737 Nondestructive Test Manual, Part 6, Chapter 51-00-00 
(Figure 4 or Figure 23); or Boeing Alert Service Bulletin 737-
52A1079, Revision 6, dated November 18, 1999.
    (1) If no cracking of the corners of the doorframe of the aft 
cargo door is detected, repeat the HFEC inspections thereafter at 
intervals not to exceed 4,500 flight cycles until accomplishment of 
the modification specified in paragraph (e) of this AD.
    (2) If any cracking of the corners of the door frame of the aft 
cargo door is detected, prior to further flight, replace the damaged 
frame with a new frame, and modify the four corners of the door 
frame, in accordance with Parts II and III of the Accomplishment 
Instructions of Boeing Service Bulletin 737-52-1079, Revision 5, 
dated May 16, 1996; or Boeing Alert Service Bulletin 737-52A1079, 
Revision 6, dated November 18, 1999. Accomplishment of such 
modification constitutes terminating action for the repetitive 
inspection requirements of paragraph (d)(1) of this AD for that 
doorframe.

[[Page 36149]]

Requirement Revised by This AD

Terminating Action

    (e) Within 4 years or 12,000 flight cycles after the effective 
date of this AD, whichever occurs later: Modify the four corners of 
the door frame and the cross beams of the aft cargo door, in 
accordance with Part II of the Accomplishment Instructions of Boeing 
Service Bulletin 737-52-1079, Revision 5, dated May 16, 1996; or 
Boeing Alert Service Bulletin 737-52A1079, Revision 6, dated 
November 18, 1999. Accomplishment of that modification constitutes 
terminating action for the repetitive inspection requirements of 
this AD.

    Note 3: Accomplishment of the modification required by paragraph 
(a) of AD 90-06-02, amendment 39-6489, is considered acceptable for 
compliance with paragraph (e) of this AD.


    Note 4: 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; is considered 
acceptable for compliance with paragraph (e) of this AD.

Alternative Methods of Compliance

    (f)(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 98-25-06, amendment 39-10931, are approved as 
alternative methods of compliance with this AD.

    Note 5: 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 
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.

Incorporation by Reference

    (h) Except as provided in paragraphs (b), (c), and (d) of this 
AD, the actions shall be done in accordance with Boeing Service 
Bulletin 737-52-1079, Revision 5, dated May 16, 1996; or Boeing 
Alert Service Bulletin 737-52A1079, Revision 6, dated November 18, 
1999.
    (1) The incorporation by reference of Boeing Alert Service 
Bulletin 737-52A1079, Revision 6, dated November 18, 1999, was 
approved previously by the Director of the Federal Register as of 
May 9, 2000 (65 FR 17583, April 4, 2000).
    (2) The incorporation by reference of Boeing Service Bulletin 
737-52-1079, Revision 5, dated May 16, 1996, was approved previously 
by the Director of the Federal Register as of December 24, 1998 (63 
FR 67769, December 9, 1998).
    (3) 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 August 15, 2001.

    Issued in Renton, Washington, on July 2, 2001.
Vi L. Lipski,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 01-17118 Filed 7-10-01; 8:45 am]
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