AD 2000-26-04

[Federal Register Volume 65, Number 251 (Friday, December 29, 2000)]
[Rules and Regulations]
[Pages 82901-82903]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 00-33017]


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

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2000-NM-217-AD; Amendment 39-12054; AD 2000-26-04]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 747, 757, 767 and 777 
Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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

SUMMARY: This amendment adopts a new airworthiness directive (AD), 
applicable to certain Boeing Model 747, 757, 767 and 777 series 
airplanes, that requires modification of certain drip shields located 
on the flight deck, and follow-on actions. This action is necessary to 
prevent potential ignition of the moisture barrier cover of the drip 
shield, which could propagate a small fire that results from an 
otherwise harmless electrical arc, leading to a larger fire. This 
action is intended to address the identified unsafe condition.

DATES: Effective February 2, 2001.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of February 2, 2001.

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 Cashdollar, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 
227-2785; 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, 757, 767 
and 777 series airplanes was published in the Federal Register on 
August 10, 2000 (65 FR 48950). That action proposed to require 
modification of certain drip shields located on the flight deck, and 
follow-on actions.

Comments Received

    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.

Requests to Revise Compliance Time

    Several commenters request an extension of the proposed compliance 
time. Generally, the commenters claim that the proposed five-year 
compliance time will result in a need to accomplish the proposed 
requirements on some airplanes before the next scheduled heavy 
maintenance visit, which would cause significant airplane down time, 
and would impose a substantial cost penalty. Individual comments are 
presented below.
    One of the commenters suggests a compliance time of six years for 
Model 747, 757, and 767 series airplanes, and seven years for Model 777 
series airplanes. The commenter states that such an extension will not 
compromise safety. Another commenter requests that the compliance time 
be stated as follows: ``* * * within five years after the effective 
date of the AD, or at the next scheduled heavy maintenance visit, 
whichever occurs later, not to exceed eight years after the effective 
date.'' This commenter performs segmented ``C'' checks approximately 
every two years, and it takes four such checks to reach all areas of 
the airplane. Therefore, under that commenter's maintenance program, 
access to the specific areas affected may not occur for eight years.
    The Air Transport Association (ATA) of America, on behalf of its 
members, states that the compliance time should be stated as follows: 
``* * * within five years after the effective date of this AD, or at 
the next scheduled heavy maintenance visit, whichever occurs later, not 
to exceed six years after the effective date.'' The ATA contends that 
its suggested compliance time ``would preclude the press associated 
with significant, unscheduled maintenance visits''; in practical terms, 
this would affect the installation time of less than 20 percent of the 
applicable airplanes. The ATA believes that its suggested compliance 
time would achieve a level of safety equivalent to that intended by the 
proposed AD.
    Another commenter states that it participated in a Boeing-hosted 
meeting on the subject drip shield flammability concerns and asked 
Boeing to recommend to the FAA that the actions be required during a 
heavy maintenance visit. The commenter notes that Boeing did indeed 
make this recommendation to the FAA in the referenced FAA-approved 
service bulletins. The commenter says that six years would facilitate 
making use of the first heavy maintenance visit under current 
maintenance programs. The commenter adds that compliance periods that 
intend to make use of scheduled down time per an approved maintenance 
program should reflect an interval taking into account such approved 
maintenance programs.
    The FAA concurs that the compliance time can be extended somewhat. 
The FAA has closely reviewed the rationale presented by the commenters. 
In addition, the FAA has examined related comments to two AD's that 
require replacement of metallized Mylar insulation blankets with new 
blankets made of more flame-resistant material on certain McDonnell 
Douglas airplanes [AD 2000-11-01, amendment 39-11749 (65 FR 34321, May 
26, 2000), and AD 2000-11-02, amendment 39-11750 (65 FR 34341, May 26, 
2000)]. In those AD's, the compliance time was extended from four to 
five years in the final rules.
    The FAA acknowledges that a compliance time of six years will more 
closely align with heavy maintenance visits. Paragraph (a) of the final 
rule has been revised accordingly. For any operator that performs 
segmented ``C'' checks every two years, the revised compliance time 
should allow enough time to schedule the drip shield rework during one 
of the next three such checks. The extension of the compliance time 
also will minimize the amount of unscheduled work and associated down 
time. The FAA considers that this extension of the compliance time will 
not adversely affect safety.

[[Page 82902]]

Request for Sampling Program

    One commenter requests that a sampling program be incorporated for 
all fleet types affected to establish the requirements to replace the 
drip shields. (The proposed rule allows sampling of Model 747 and 767 
fleets to establish if individual airplanes have unsafe adhesives.) The 
commenter states that neither Boeing nor the FAA has provided concrete 
evidence that BAC 5010, Type 97 adhesive was used in the assembly of 
all the drip shields. The commenter adds that the applicable service 
bulletins and proposed rule are based purely on conjecture. The 
commenter suggests that a sampling program would offer terminating 
action for the proposed rule.
    The FAA does not concur. The FAA finds that there is a significant 
amount of evidence pointing to widespread use of unsafe adhesives (that 
is, material and adhesive combinations that are easily ignited and 
consequently able to propagate a small fire) on Model 747, 757, 767, 
and 777 series airplanes. This evidence is supported by the fact that 
unsafe adhesives were stocked in the manufacturing facilities where the 
drip shields were constructed. The FAA concludes that there is a high 
probability that unsafe adhesives were used in the construction of all 
drip shields on Model 757 and 777 series airplanes, as well as in the 
construction of the drip shields on certain Model 747 and 767 series 
airplanes. These conclusions are based on information provided by 
Boeing, interviews conducted with manufacturing personnel, and the 
materials (i.e., adhesives) that were and were not available in the 
manufacturing facilities.
    The FAA did not propose sampling for Model 757 and 777 series 
airplanes because all Model 757 and 777 series airplanes are subject to 
the unsafe condition. In contrast, not all Model 747 and 767 series 
airplanes are subject to the unsafe condition because the unsafe 
adhesives were not always available in the manufacturing facilities 
that constructed the drip shields used on those airplanes.
    No change to the final rule is necessary in this regard. However, 
an operator may request approval of an alternative method of compliance 
in accordance with the provisions of paragraph (d) of this final rule, 
provided that evidence is submitted to show that no unsafe adhesive was 
used in the construction of the drip shields on the airplanes in its 
fleet.

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 3,137 airplanes of the affected design in 
the worldwide fleet. The FAA estimates that 999 airplanes of U.S. 
registry will be affected by this AD. The following table shows the 
estimated cost impact for airplanes affected by this AD. The average 
labor rate is $60 per work hour. The estimated maximum cost impact of 
the AD on U.S. operators of all airplanes affected by this AD is 
$3,695,460. Table 1 is as follows:

                                              Table 1.--Cost Impact
----------------------------------------------------------------------------------------------------------------
                                       U.S.-                                                       Maximum fleet
              Model                 Registered      Work hours      Labor cost      Parts cost         cost
                                     airplanes      (estimated)     (estimated)     (estimated)     (estimated)
----------------------------------------------------------------------------------------------------------------
747.............................             194              39          $2,340             \1\      $1,132,960
757.............................             491              26           1,560          $1,700       1,600,660
767.............................             258              17           1,020           2,300         856,560
777.............................              56               3             180           1,700        105,280
----------------------------------------------------------------------------------------------------------------
\1\ $2,300 to $3,500.

    For Model 747 and 767 series airplanes listed in Group 1 in the 
applicable service bulletin, in lieu of accomplishment of the 
modification of the drip shields, this AD provides an option to take 
samples of the drip shields to determine if the modification is 
necessary. Therefore, the cost impact of this AD as presented above may 
be reduced if some airplanes do not need the modification. For 
airplanes that accomplish the sampling, it will take approximately 18 
work hours, at an average labor rate of $60 per work hour. Based on 
these figures, the cost impact of the sampling on affected U.S. 
operators is estimated to be $1,080 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. 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.
    The manufacturer has advised the FAA that warranty remedies may be 
available for parts and labor costs associated with accomplishing the 
actions that are required by this AD. Therefore, the future economic 
cost impact of this AD on U.S. operators may be less than the cost 
impact figures indicated above.

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.

[[Page 82903]]

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:

2000-26-04  Boeing: Amendment 39-12054. Docket 2000-NM-217-AD.

    Applicability: Model 747, 757, 767, and 777 series airplanes 
having the line numbers listed below; certificated in any category.

----------------------------------------------------------------------------------------------------------------
                                   Affected line numbers (L/
              Model                            N)                                 Except L/N
----------------------------------------------------------------------------------------------------------------
747..............................  1 through 1234 inclusive.  1174, 1216
757..............................  2 through 895 inclusive..  870, 886, 894
767..............................  1 through 768 inclusive..  758
777..............................  2 through 254 inclusive..  120, 219, 230, 235, 242, 245, 249
----------------------------------------------------------------------------------------------------------------


    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 potential ignition of the moisture barrier cover of 
the drip shield, which could propagate a small fire that results 
from an otherwise harmless electrical arc, leading to a larger fire, 
accomplish the following:

Modification

    (a) Within 6 years after the effective date of this AD, 
accomplish paragraphs (a)(1), (a)(2), and (a)(3) of this AD; in 
accordance with Boeing Service Bulletin 747-25-3253, 767-25-0290, or 
777-25-0164; all including Appendices A, B, and C; all dated June 
29, 2000; or 757-25-0226 or 757-25-0228; both including Appendices 
A, B, and C; both dated July 3, 2000; as applicable; except as 
provided by paragraph (b) of this AD.
    (1) Modify drip shields located on the flight deck by installing 
fire blocks.
    (2) Prior to further flight following accomplishment of 
paragraph (a)(1) of this AD, perform a functional test of any system 
disturbed by the modification, in accordance with the applicable 
service bulletin or the Airplane Maintenance Manual (AMM), as 
applicable. If any functional test fails, prior to further flight, 
isolate the fault, correct the discrepancy in accordance with the 
applicable AMM, and repeat the failed test until it is successfully 
accomplished.
    (3) Prior to further flight following the accomplishment of 
paragraphs (a)(1) and (a)(2) of this AD, install placards on all 
modified drip shields.
    (b) If any wires or equipment are installed on the outboard 
surface of the drip shield (that is, between the drip shield and the 
airplane structure), modify that area in accordance with a method 
approved by the Manager, Seattle Aircraft Certification Office 
(ACO), FAA.

Optional Sampling (Certain Model 747 and 767 Series Airplanes)

    (c) For Model 747 and 767 series airplanes listed in Group 1 in 
Boeing Service Bulletins 747-25-3253 and 767-25-0290: In lieu of 
accomplishment of paragraph (a) of this AD, within 6 years after the 
effective date of this AD, collect samples of the insulation and 
adhesive of the drip shields, and submit the samples to the 
manufacturer for testing, in accordance with Boeing Service Bulletin 
747-25-3253 or 767-25-0290; both including Appendices A, B, and C; 
both dated June 29, 2000; as applicable.
    (1) If the test on all samples is positive, no further action is 
required by this AD.
    (2) If the test on any sample is negative, accomplish paragraph 
(a) of this AD before the compliance time specified in that 
paragraph.

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 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 2: 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

    (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.

Incorporation by Reference

    (f) Except as provided by paragraph (b) of this AD, the actions 
shall be done in accordance with Boeing Service Bulletin 747-25-
3253, including Appendices A, B, and C, dated June 29, 2000; Boeing 
Service Bulletin 767-25-0290, including Appendices A, B, and C, 
dated June 29, 2000; Boeing Service Bulletin 777-25-0164, including 
Appendices A, B, and C, dated June 29, 2000; Boeing Service Bulletin 
757-25-0226, including Appendices A, B, and C, dated July 3, 2000; 
or Boeing Service Bulletin 757-25-0228, including Appendices A, B, 
and C, dated July 3, 2000; 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.

Effective Date

    (g) This amendment becomes effective on February 2, 2001.

    Issued in Renton, Washington, on December 20, 2000.
John J. Hickey,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 00-33017 Filed 12-28-00; 8:45 am]
BILLING CODE 4910-13-P