[Federal Register Volume 64, Number 26 (Tuesday, February 9, 1999)]
[Rules and Regulations]
[Pages 6189-6191]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-2723]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-NM-144-AD; Amendment 39-11025; AD 99-04-01]
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 of the outboard nacelle struts to detect fatigue 
cracking of the strut skin and spring beam support fittings, and to 
detect cracked or loose fasteners of the support fittings; and 
corrective actions, if necessary. This amendment also provides for 
optional terminating action for the repetitive inspection requirements. 
This amendment is prompted by reports indicating that several cracked 
or broken spring beam support fittings were found on the outboard 
nacelle struts. The actions specified by this AD are intended to detect 
and correct such fatigue cracking and loose fasteners, which could 
result in failure of the outboard nacelle struts and consequent 
separation of the engine.

DATES: Effective March 16, 1999.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of March 16, 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: Tamara L. Anderson, Aerospace 
Engineer, Airframe Branch, ANM-120S, FAA, 1601 Lind Avenue, SW., 
Renton, Washington 98055-4056; telephone (425) 227-2771; 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 747 series 
airplanes was published in the Federal Register on November 24, 1998 
(63 FR 64913). That action proposed to require repetitive inspections 
of the outboard nacelle struts to detect fatigue cracking of the strut 
skin and spring beam support fittings, and to detect cracked or loose 
fasteners of the support fittings; and corrective actions, if 
necessary. That action also proposed to provide for optional 
terminating action for the repetitive inspection requirements.
    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due consideration has been given to 
the single comment received.
    The commenter supports the proposed AD.

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 as proposed.

Cost Impact

    There are approximately 145 Model 747 series airplanes of the 
affected design in the worldwide fleet. The FAA estimates that 9 
airplanes of U.S. registry will be affected by this AD, that it will 
take approximately 16 work hours per airplane to accomplish the 
required inspection, and that the average labor rate is $60 per work 
hour. Based on these figures, the cost impact

[[Page 6190]]

of the AD on U.S. operators is estimated to be $8,640, or $960 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.
    Should an operator elect to accomplish the fastener hole inspection 
and modification, it would take approximately 20 work hours (excluding 
removal of the strut and spring beam) to accomplish it, at an average 
labor rate of $60 per hour. Based on these figures, the cost impact of 
this optional terminating action is estimated to be $1,200 per strut.
    Should an operator elect to accomplish the replacement of the 
spring beam support fittings with new support fittings, it would take 
approximately 108 work hours (excluding removal of the strut and spring 
beam) to accomplish it, at an average labor rate of $60 per hour. Based 
on these figures, the cost impact of this optional terminating action 
is estimated to be $6,480 per support fitting.

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:

99-04-01  Boeing: Amendment 39-11025. Docket 98-NM-144-AD.

    Applicability: Model 747 series airplanes, line numbers 202 
through 886 inclusive, equipped with General Electric Model CF6-45/
50 and Pratt & Whitney Model JT9D-70 series engines; on which the 
strut/wing modification has not been accomplished in accordance with 
AD 95-13-07, amendment 39-9287; certificated in any category.

    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 (h) 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 strut skin and 
spring beam support fittings on the outboard nacelle struts, and 
cracked or loose fasteners of the support fittings, which could 
result in failure of the outboard nacelle struts and consequent 
separation of the engine, accomplish the following:
    (a) Prior to the accumulation of 13,000 total flight cycles, or 
within 6 months after the effective date of this AD, whichever 
occurs later, perform a detailed visual inspection of the outboard 
nacelle struts, as specified by paragraphs (a)(1), (a)(2), (a)(3), 
and (a)(4) of this AD, in accordance with Boeing Alert Service 
Bulletin 747-54A2172, dated February 23, 1995, or Boeing Service 
Bulletin 747-54A2172, Revision 1, dated January 4, 1996.
    (1) Inspect the spring beam support fittings to detect cracks of 
the support fittings.
    (2) Inspect the spring beam support fittings at the fasteners, 
using a borescope to detect cracks of the support fittings.
    (3) Inspect the fasteners of the outer spring beam support 
fittings to detect cracked or loose fasteners.
    (4) Inspect the strut skin to detect cracks.
    (b) If no discrepancy is found during any inspection required by 
paragraph (a) of this AD, perform detailed visual inspections of the 
outboard nacelle struts to detect any discrepancies specified in 
paragraphs (b)(1), (b)(2), (b)(3), and (b)(4) of this AD, in 
accordance with Boeing Alert Service Bulletin 747-54A2172, dated 
February 23, 1995; or Boeing Service Bulletin 747-54A2172, Revision 
1, dated January 4, 1996. Perform the inspection at the times 
specified in paragraph (c) or (d) of this AD, as applicable.
    (1) Perform a detailed visual inspection, using a borescope, of 
only the outer spring beam support fittings at the fasteners through 
the horizontal flange to detect cracks of the support fittings.
    (2) Perform a detailed visual inspection, using a borescope, of 
the fasteners through the vertical flange of only the outer spring 
beam support fittings to detect loose collars.
    (3) Perform an external detailed visual inspection of only the 
outer spring beam support fittings to detect cracked or loose 
fastener heads.
    (4) Perform a detailed visual inspection of the strut skin to 
detect cracks.
    (c) For Model 747-SR series airplanes equipped with General 
Electric Model CF6-45 series engines, on which no discrepancy is 
found during any inspection required by paragraph (a) of this AD: 
Perform the inspection required by paragraph (b) of this AD within 
1,600 flight cycles following the accomplishment of the inspection 
required by paragraph (a) of this AD; and thereafter at intervals 
not to exceed 1,600 flight cycles until accomplishment of the 
optional terminating action specified in paragraph (g) of this AD.
    (d) For Model 747 series airplanes other than those identified 
in paragraph (c) of this AD, on which no discrepancy is found during 
any inspection required by paragraph (a) of this AD: Perform the 
inspection required by paragraph (b) of this AD within 1,000 flight 
cycles following the accomplishment of the inspection required by 
paragraph (a) of this AD; and thereafter at intervals not to exceed 
1,000 flight cycles until accomplishment of the optional terminating 
action specified in paragraph (g) of this AD.
    (e) If any cracking is found in the spring beam support fittings 
during any inspection required by this AD, prior to further flight, 
replace the support fitting with a new support fitting, in 
accordance with the Accomplishment Instructions in Part IV. of 
Boeing Service Bulletin 747-54A2172, Revision 1, dated January 4, 
1996. Accomplishment of this replacement constitutes terminating 
action for the repetitive inspection requirements of this AD for 
only the new support fitting. Continue the repetitive inspections 
required by paragraph (b) of this AD for the other support fitting 
locations until accomplishment of the terminating action specified 
by paragraph (g)(1) or (g)(2) of this AD, as applicable.
    (f) If any crack is found on the strut skin, or if any cracked 
or loose fastener or collar

[[Page 6191]]

is found during any inspection required by this AD, prior to further 
flight, repair 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.
    (g) Accomplishment of an open-hole high frequency eddy current 
(HFEC) inspection, in accordance with Boeing Alert Service Bulletin 
747-54A2172, dated February 23, 1995, or Boeing Service Bulletin 
747-54A2172, Revision 1, dated January 4, 1996; and either paragraph 
(g)(1) or (g)(2) of this AD, as applicable; constitutes terminating 
action for the requirements of this AD.
    (1) If no discrepancy is found during the HFEC inspection, prior 
to further flight, rework the fastener holes and install new 
fasteners, in accordance with Figures 6 and 7 of Boeing Alert 
Service Bulletin 747-54A2172, dated February 23, 1995, or Boeing 
Service Bulletin 747-54A2172, Revision 1, dated January 4, 1996.
    (2) If any cracking is found during the HFEC inspection, prior 
to further flight, replace any cracked spring beam support fitting 
with a new support fitting, in accordance with Part IV. of the 
Accomplishment Instructions specified by Boeing Service Bulletin 
747-54A2172, Revision 1, dated January 4, 1996.
    (h) 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.

    (i) 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.
    (j) Except as provided by paragraph (f), (g), (g)(1), and (g)(2) 
of this AD, the actions shall be done in accordance with Boeing 
Alert Service Bulletin 747-54A2172, dated February 23, 1995, and 
Boeing Service Bulletin 747-54A2172, Revision 1, dated January 4, 
1996, as applicable. 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.
    (k) This amendment becomes effective on March 16, 1999.
    Issued in Renton, Washington, on February 1, 1999.
Dorenda D. Baker,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 99-2723 Filed 2-8-99; 8:45 am]
BILLING CODE 4910-13-P