[Federal Register Volume 64, Number 28 (Thursday, February 11, 1999)]
[Rules and Regulations]
[Pages 6791-6793]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-3188]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-NM-258-AD; Amendment 39-11035; AD 99-04-11]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 737-600, -700, and -800 
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 737-600, -700, and -800 series 
airplanes, that requires repetitive inspections to detect damage of the 
aft strut insulation blanket. This AD also requires eventual 
replacement of the insulation blankets with new, improved blankets, 
which constitutes terminating action for the requirements of this AD. 
This amendment is prompted by reports of damaged aft strut insulation 
blankets. The actions specified by this AD are intended to prevent such 
damage, which could result in exposure of the lower surface of the 
strut to extreme high temperatures, consequent creation of a source of 
fuel ignition, and increased risk of a fuel tank explosion and fire.

DATES: Effective March 18, 1999.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of March 18, 1999.

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: Bernie Gonzalez, Aerospace Engineer, 
Propulsion Branch, ANM-140S, FAA, Transport Airplane Directorate, 
Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, 
Washington 98055-4056; telephone (425) 227-2682; 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 737-600, -
700, and -800 series airplanes was published in the Federal Register on 
October 15, 1998 (63 FR 55343). That action proposed to require 
repetitive inspections to detect damage of the aft strut insulation 
blanket. That action also proposed to require eventual replacement of 
the insulation blankets with new, improved blankets, which would 
constitute terminating action for the requirements of the AD.

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.

[[Page 6792]]

    Two commenters express no objection to the proposed rule, and one 
commenter supports the proposed 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 as proposed.

Cost Impact

    There are approximately 33 Model 737-600, -700, and -800 series 
airplanes of the affected design in the worldwide fleet. The FAA 
estimates that 26 airplanes of U.S. registry will be affected by this 
AD.
    It will take approximately 1 work hour per airplane to accomplish 
the required inspection, at an average labor rate of $60 per work hour. 
Based on these figures, the cost impact of the inspection required by 
this AD on U.S. operators is estimated to be $1,560, or $60 per 
airplane, per inspection cycle.
    It will take approximately 1 work hour per airplane to accomplish 
the required replacement, at an average labor rate of $60 per work 
hour. Required parts will be provided by the manufacturer at no cost to 
the operators. Based on these figures, the cost impact of the 
replacement required by this AD on U.S. operators is estimated to be 
$1,560, or $60 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 substantial direct 
effects on the States, on the relationship between the national 
government and the States, or on the distribution of power and 
responsibilities among the various levels of government. Therefore, in 
accordance with Executive Order 12612, it is determined that this final 
rule does not have sufficient federalism implications to warrant the 
preparation of a Federalism Assessment.
    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:

99-04-11 Boeing: Amendment 39-11035. Docket 98-NM-258-AD.

    Applicability: Model 737-600, -700, and -800 series airplanes, 
line numbers 1 through 64 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 (d) 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 damage of the aft strut insulation blankets, which 
could result in exposure of the lower surface of the strut to 
extreme high temperatures, consequent creation of a source of fuel 
ignition, and increased risk of a fuel tank explosion and fire, 
accomplish the following:
    (a) Within 500 flight hours since date of manufacture of the 
airplane, or within 30 days after the effective date of this AD, 
whichever occurs later, perform a visual or borescope inspection to 
detect damage (cracks greater than 2.00 inches and/or separation of 
the face sheet) of the aft strut insulation blanket, part number (P/
N) S315A213-42, in accordance with Boeing Alert Service Bulletin 
737-54A1038, dated May 7, 1998, as revised by Notice of Status 
Change 737-54A1038 NSC 01, dated June 18, 1998. Thereafter, repeat 
the visual or borescope inspection at intervals not to exceed 250 
flight hours.
    (b) If damage (cracks greater than 2.00 inches and/or separation 
of the face sheet) of any aft strut insulation blanket is detected 
during any inspection required by paragraph (a) of this AD, prior to 
further flight, accomplish either paragraph (b)(1) or (b)(2) of this 
AD.
    (1) Replace any damaged insulation blanket having P/N S315A213-
42 with a new insulation blanket having P/N S315A213-42, in 
accordance with Boeing Alert Service Bulletin 737-54A1038, dated May 
7, 1998, as revised by Notice of Status Change 737-54A1038 NSC 01, 
dated June 18, 1998. Thereafter, repeat the visual or borescope 
inspection required by paragraph (a) of this AD at intervals not to 
exceed 250 flight hours. Or
    (2) Replace any damaged insulation blanket having P/N S315A213-
42 with a new, improved insulation blanket having P/N S315A213-47, 
in accordance with Boeing Alert Service Bulletin 737-54A1038, dated 
May 7, 1998, as revised by Notice of Status Change 737-54A1038 NSC 
01, dated June 18, 1998. Accomplishment of this replacement 
constitutes terminating action for the repetitive inspection 
requirements of this AD.
    (c) Within 18 months after the effective date of this AD, 
replace any aft strut insulation blanket having P/N S315A213-42 with 
a new, improved insulation blanket having P/N S315A213-47, in 
accordance with Boeing Alert Service Bulletin 737-54A1038, dated May 
7, 1998, as revised by Notice of Status Change 737-54A1038 NSC 01, 
dated June 18, 1998. Accomplishment of this replacement constitutes 
terminating action for the requirements of this AD.
    (d) 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 Aircraft Certification 
Office (ACO), FAA, Transport Airplane Directorate. 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 2: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Seattle ACO.
    (e) 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.
    (f) The actions shall be done in accordance with Boeing Alert 
Service Bulletin 737-54A1038, dated May 7, 1998, as revised by 
Notice of Status Change 737-54A1038 NSC 01, dated June 18, 1998. 
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

[[Page 6793]]

Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the 
Office of the Federal Register, 800 North Capitol Street, NW., suite 
700, Washington, DC.
    (g) This amendment becomes effective on March 18, 1999.

    Issued in Renton, Washington, on February 4, 1999.
John J. Hickey,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 99-3188 Filed 2-10-99; 8:45 am]
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