[Federal Register Volume 68, Number 3 (Monday, January 6, 2003)]
[Rules and Regulations]
[Pages 476-479]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 03-26]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2002-NM-85-AD; Amendment 39-13003; AD 2002-26-15]
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 to detect evidence of wear damage in the area at 
the interface between the vertical stabilizer and fuselage skin, and 
corrective actions, if necessary. This amendment also provides for an 
optional terminating action for the repetitive inspections. The actions 
specified by this AD are intended to detect and correct wear damage of 
the fuselage skin, which could result in thinning and cracking of the 
fuselage skin, and consequent in-flight depressurization of the 
airplane. This action is intended to address the identified unsafe 
condition.

DATES: Effective February 10, 2003.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of February 10, 2003.

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, 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) to include an airworthiness 
directive (AD) that is applicable to certain Boeing Model 747 series 
airplanes was published in the Federal Register on May 30, 2002 (67 FR 
37734). That action proposed to require repetitive inspections to 
detect evidence of wear damage in the area at the interface between the 
vertical stabilizer and fuselage skin, and corrective actions, if 
necessary. That action also proposed to provide for an optional 
terminating action for the repetitive inspections.

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 477]]

Request To Change Cost Impact

    One commenter states that the work hours cited in the cost impact 
section of the proposed AD are significantly understated. The commenter 
notes that the hours for access and restoration have been omitted from 
the cost figures, so the true cost impact is not specified. The 
commenter states that access and restoration tasks do not routinely 
occur during scheduled maintenance visits in this instance. The 
commenter adds that 18 hours are necessary to gain access, perform the 
inspection and terminating action, and restore the airplane. The 
commenter asks that the cost impact section be changed to 18 hours for 
these actions.
    The FAA agrees that access to the area under the vertical seal is 
not a task normally accomplished during routine maintenance, and the 
work hours required for access and closeup should be added. We have 
changed the work hours for the inspection specified in the cost impact 
section to 12 work hours; the optional terminating action will remain 
at 6 work hours, as it can be done immediately following the 
inspection, before closeup.

Request To Change Limits for Allowable Wear Damage

    One commenter states that the definition for the limits for 
allowable skin damage as specified in the structural repair manual 
(SRM) was recently revised, and the damage limits have been reduced. 
The commenter adds that Section 3 of the referenced service bulletin 
specifies these new allowable damage limits in the Accomplishment 
Instructions. The commenter asks that the proposed AD be changed to 
refer to the service bulletin or list the revision date of the 
appropriate SRM to assure operators use the new limits for allowable 
damage.
    We do not agree with the commenter. Operators should use the new 
allowable damage limits cited in the service bulletin or they may not 
be evaluating existing blendouts against the proper limits. However, we 
have determined that evaluation of existing blendouts against the old 
damage limits will not compromise an acceptable level of safety. 
Regarding new repairs, paragraph (a)(2) of the proposed AD requires 
that operators repair and refinish the skin per the service bulletin. 
In order to comply with this requirement, operators must use the 
allowable limits specified in the service bulletin. No change to the 
final rule is necessary in this regard.

Request Credit for Previous Inspections and Terminating Action

    One commenter asks that credit be given for the inspections and 
terminating action required by the proposed AD, if done before the 
effective date of the proposed AD per Boeing Service Bulletin 747-53-
2192, dated July 21, 1981. The commenter states that the service 
bulletin referenced in the proposed AD includes a provision that 
specifies such credit.
    We agree that credit can be given under certain explicit 
conditions. Service Bulletin 747-53-2192 specifies that, for airplanes 
having line numbers 0001 through 0414 inclusive, there is an option of 
using enamel coating or BMS 10-86 Teflon-filled coating. If operators 
can confirm that BMS 10-86 Teflon-filled coating was used, and the new 
allowable damage limits specified in Boeing Alert Service Bulletin 747-
53A2478 (referenced in the proposed AD as the appropriate source of 
service information for accomplishment of the actions specified) are 
met, then no more work is necessary. A new paragraph (c) has been added 
to this final rule to provide credit if the conditions are met.

Request Credit for Inspections Done per Certain Maintenance Procedures

    One commenter states that the Boeing Model 747 Maintenance Planning 
Document (MPD) recommends inspections of the affected areas of the 
fuselage skin at no greater than ``D'' check intervals. The commenter 
adds that the Corrosion Prevention and Control Program (CPCP) 
recommends inspections of the exterior surface of the fuselage skin for 
corrosion and other discrepancies at 5-year intervals. Based on these 
requirements, the commenter does the inspections required by the 
proposed AD earlier than the 6,000-flight-cycle compliance time 
specified for the repetitive inspections. The commenter also adds that, 
since the existing inspection programs already require inspections more 
frequently, there is no additional safety to be gained from 
promulgation of the proposed AD. The commenter asks that credit be 
given for the repetitive inspections required by paragraph (a)(1) of 
the proposed AD if done as part of these maintenance programs.
    Based on operator reports of wear damage of the fuselage skin at 
the interface area of the vertical stabilizer seal and fuselage skin, 
we do not agree with the commenter that existing maintenance programs 
are providing acceptable levels of safety. Additionally, this area is 
not accessed by all operators during scheduled maintenance visits, as 
specified previously under ``Request to Change Cost Impact,'' so no 
change to the final rule is necessary in this regard. However, under 
the provisions of paragraph (d) of the final rule, we may approve 
requests for alternate inspections if data are submitted to 
substantiate that the inspections are equivalent and that repairs and 
any existing wear meet the allowable damage limits specified in the 
referenced service bulletin.

Request To Change Paragraphs (a)(2) and (b)

    One commenter states that paragraph (b) of the proposed AD allows 
refinishing of the fuselage skin with BMS 10-86 Teflon-filled coating 
as terminating action for the proposed inspections. The commenter notes 
that there are other Teflon-filled coatings that are equivalent or 
better than BMS 10-86, and operators may already be using these 
``equivalent'' coatings in their paint specifications. The commenter 
asks that, if the proposed AD is deemed necessary, paragraphs (a)(2) 
and (b) be changed to allow the use of other Teflon-filled coatings 
with equivalent abrasion resistant properties.
    We do not agree with the commenter's request, as no supporting data 
were provided to us to substantiate the request. However, under the 
provisions of paragraph (d) of the final rule, we may approve requests 
for the use of other Teflon-filled coatings if data are submitted to 
substantiate that such coatings would provide an acceptable level of 
safety.

Request To Reconsider Terminating Action

    One commenter states that paragraphs (a)(2) and (b) of the proposed 
AD allow the one-time application of Teflon-filled paint coating as 
terminating action for the repetitive inspections required by paragraph 
(a)(1) of the proposed AD. The commenter states that the proposed AD 
seems to indicate that the external paint will never again be removed 
and replaced, but is reapplied on an irregular basis. The commenter 
adds that, if this problem is as serious as alleged, a one-time 
application of a Teflon-filled paint coating to the exterior of the 
airplane would not provide a realistic terminating action. The paint 
will have to be reapplied whenever the external paint is stripped and 
refinished.
    We do not agree with the commenter. If the external paint is 
stripped, refinishing the skin with BMS 10-86 Teflon-filled coating is 
required to remain in compliance with paragraph (a)(2) of this AD. 
Therefore, no change

[[Page 478]]

to the final rule is necessary 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 1,104 Boeing Model 747 series airplanes of 
the affected design in the worldwide fleet. The FAA estimates that 253 
airplanes of U.S. registry will be affected by this AD, that it will 
take approximately 12 work hours per airplane (including time required 
to gain access and to close up) to accomplish the required inspection, 
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 
$182,160, or $720 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. 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.
    Should an operator elect to accomplish the proposed optional 
terminating action per paragraph (b) of this AD, it would take 
approximately 6 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 optional termination action would be $360 per airplane.

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:

2002-26-15 Boeing: Amendment 39-13003. Docket 2002-NM-85-AD.

    Applicability: Model 747 series airplanes, as listed in Boeing 
Alert Service Bulletin 747-53A2478, dated February 7, 2002; 
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 detect and correct wear damage of the fuselage skin in the 
area at the interface between the vertical stabilizer and fuselage 
skin, which could result in thinning and cracking of the fuselage 
skin, and consequent in-flight depressurization of the airplane, 
accomplish the following:

Inspections for Damage/Corrective Actions

    (a) Prior to the accumulation of 15,000 total flight cycles, or 
within 1,200 flight cycles after the effective date of this AD, 
whichever occurs later: Perform a detailed inspection to detect 
evidence of wear damage of the fuselage skin at the interface area 
of the vertical stabilizer seal and fuselage skin, per Boeing Alert 
Service Bulletin 747-53A2478, dated February 7, 2002.
    (1) If no wear damage of the fuselage skin is detected or any 
existing blendout is within the structural repair manual (SRM) 
allowable damage limits: Repeat the detailed inspection at intervals 
not to exceed 6,000 flight cycles.
    (2) If any wear damage of the fuselage skin is detected or any 
existing blendout exceeds the allowable damage limits specified in 
the SRM: Before further flight, repair the vertical stabilizer seal 
interface and refinish the skin with BMS 10-86 Teflon-filled 
coating, per the alert service bulletin. Accomplishment of the 
repair and refinishing is terminating action for the repetitive 
inspections required by paragraph (a)(1) of this AD.

    Note 2: For the purposes of this AD, a detailed 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.''

Optional Terminating Action

    (b) Refinishing the fuselage skin with BMS 10-86 Teflon-filled 
coating, per Boeing Alert Service Bulletin 747-53A2478, dated 
February 7, 2002, terminates the repetitive inspections required by 
paragraph (a)(1) of this AD.

Previously Accomplished Inspections and Terminating Action

    (c) Inspections and terminating action done before the effective 
date of this AD per Boeing Service Bulletin 747-53-2192, dated July 
21, 1981, are acceptable for compliance with the corresponding 
actions required by this AD, provided BMS 10-86 Teflon-filled 
coating was used, and the new allowable damage limits specified in 
Boeing Alert Service Bulletin 747-53A2478, dated February 7, 2002, 
are met.

Alternative Methods of Compliance

    (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. 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.


[[Page 479]]



Special Flight Permits

    (e) Special flight permits may be issued in accordance with 
Sec. Sec.  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

    (f) Unless otherwise specified in this AD, the actions shall be 
done in accordance with Boeing Alert Service Bulletin 747-53A2478, 
dated February 7, 2002. 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

    (g) This amendment becomes effective on February 10, 2003.

    Issued in Renton, Washington, on December 24, 2002.
Charles D. Huber,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 03-26 Filed 1-3-03; 8:45 am]
BILLING CODE 4910-13-U