AD 2001-16-07

[Federal Register Volume 66, Number 161 (Monday, August 20, 2001)]
[Rules and Regulations]
[Pages 43465-43467]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 01-20698]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2000-NM-275-AD; Amendment 39-12375; AD 2001-16-07]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 747-400 and 767 Series 
Airplanes Equipped With General Electric CF6-80C2 Series Engines

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 747-400 and 767 series airplanes, 
that requires modification of the core cowl assemblies of the engines. 
This action is necessary to prevent failure of the core cowl latches 
during an engine fire, and consequent in-flight separation of an engine 
core cowl and its strut fire barrier from the airplane. This action is 
intended to address the identified unsafe condition.

DATES: Effective September 24, 2001.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of September 24, 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: Sulmo Mariano, Aerospace Engineer, 
Propulsion Branch, ANM-140S, FAA, Seattle Aircraft Certification 
Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone 
(425) 227-2686; 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 747-400 and 
767 series airplanes was published in the Federal Register on December 
5, 2000 (65 FR 75881). That action proposed to require modification of 
the core cowl assemblies of the engines.

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.
    One commenter states that it does not own or operate any of the 
subject airplanes and, thus, offers no additional comment on the 
proposed AD.

Requests To Extend Compliance Time

    Three commenters request that the FAA extend the compliance time 
for the proposed modification. One of the commenters requests that the 
FAA extend the compliance time from 24 months to 36 months after the 
effective date of this AD, due to its concerns about availability of 
necessary parts for the modification. The other two commenters request 
that the FAA extend the compliance time to 48 months after the 
effective date of this AD. One of these commenters is also concerned 
about parts availability, while the other commenter wants the extension 
so that it may accomplish the modification during its regularly 
scheduled ``C'' and ``D'' checks.
    The FAA concurs with the one commenter's request to extend the 
compliance time to 36 months after the effective date of this AD. We 
have determined that extending the compliance time to 36 months will 
allow a sufficient supply of parts to be made available for the 
required modification without adversely affecting safety. We have 
revised paragraph (a) of this final rule accordingly.

[[Page 43466]]

    We do not concur with the other commenters' requests to extend the 
compliance time for the modification to 48 months. With regard to parts 
availability, as stated above, we find that a 36-month compliance time 
will be adequate for a sufficient quantity of parts to be available. 
With regard to extending the compliance time to allow the modification 
to be accomplished at a ``C'' or ``D'' check, we have already 
considered factors such as operators' maintenance schedules in setting 
a compliance time for the required modification and determined that 36 
months is an appropriate compliance time in which the modification may 
be accomplished during scheduled airplane maintenance for the majority 
of affected operators. Since maintenance schedules vary from operator 
to operator, it would not be possible to guarantee that all affected 
airplanes could be modified during scheduled maintenance, even with a 
compliance time of 48 months. In any event, we find that 36 months 
represents the maximum time wherein the affected airplanes may continue 
to operate prior to modification without compromising safety. No 
further change to the final rule is necessary in this regard.

Request To Withdraw Proposed Rule

    One commenter requests that the FAA withdraw the proposed rule. In 
the proposed rule, we explained that, in the event of an engine fire, 
the core cowl latches may fail, and opening of the core cowls breaches 
the engine fire containment design and could allow the fire to spread 
to the strut and wing of the airplane. The commenter states that, 
following extensive review of the engine cowling configuration, it 
cannot see that the core cowls would open during an engine fire even if 
the frame is weakened, because the trailing edge of the thrust reverser 
covers up the leading edge of the core cowl. Therefore, the commenter 
does not agree that there is risk of a fire spreading to the strut. The 
commenter further requests that we withdraw the proposed rule because 
the total cost of the modification that would be required by this AD 
for its fleet would be very expensive.
    We do not concur with the commenter's request to withdraw the 
proposed rule. With regard to the commenter's doubts about whether 
failure of the core cowl latches is an unsafe condition, we acknowledge 
that the commenter is correct when it states that the trailing edge of 
the thrust reverser covers the leading edge of the core cowl. However, 
in the event of an engine fire when the aluminum structure supporting 
the steel latches holding the core cowls closed is significantly 
weakened, the structural continuity between the hinges at the top of 
the core cowl and the latches at the bottom no longer exists. 
Therefore, the structural integrity of the attachment of the core cowl 
to the airplane is compromised, and aerodynamic loads will force the 
core cowls to open and subsequently detach from the airplane. As 
explained in the NPRM, this condition could allow the engine fire to 
spread to the strut and wing. We have determined that this risk of a 
fire propagating to the strut and wing is significant and constitutes 
an unsafe condition that must be addressed.
    With regard to the commenter's concern about the cost of the AD, we 
acknowledge that there are relatively high costs associated with the 
required modification. For operators with many affected airplanes, the 
cost could run into millions of dollars. However, in considering 
whether to issue this AD, we conducted a cost analysis and determined 
that the costs of the modification required by this AD are commensurate 
with the level of risk involved, and it is necessary to issue this AD 
to ensure the continued safety of the affected airplanes.
    No change 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 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 563 Model 747-400 and 767 series airplanes 
of the affected design in the worldwide fleet.
    The FAA estimates that 14 Model 747-400 series airplanes of U.S. 
registry will be affected by this AD, that it will take approximately 
168 work hours (42 per engine) per airplane to accomplish the required 
modification, and that the average labor rate is $60 per work hour. 
Required parts will cost approximately $84,732 ($21,183 per engine) per 
airplane. Based on these figures, the cost impact of the modification 
required by this AD on U.S. operators of Model 747-400 series airplanes 
is estimated to be $1,327,368, or $94,812 per airplane.
    The FAA estimates that 64 Model 767 series airplanes of U.S. 
registry will be affected by this AD, that it will take approximately 
84 work hours (42 per engine) per airplane to accomplish the required 
modification, and that the average labor rate is $60 per work hour. 
Required parts will cost approximately $42,366 ($21,183 per engine) per 
airplane. Based on these figures, the cost impact of the modification 
required by this AD on U.S. operators of Model 767 series airplanes is 
estimated to be $3,033,984 or $47,406 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.

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:

[[Page 43467]]

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:

2001-16-07  Boeing: Amendment 39-12375. Docket 2000-NM-275-AD.

    Applicability: Model 747-400 and 767 series airplanes, 
certificated in any category, equipped with General Electric CF6-
80C2 series engines; as listed in Boeing Service Bulletin 747-71-
2285 or 767-71-0088, both dated October 8, 1998.

    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 (c) 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 failure of the core cowl latches during an engine 
fire, and consequent in-flight separation of an engine core cowl and 
its strut fire barrier from the airplane, accomplish the following:

Modification

    (a) Within 36 months after the effective date of this AD: Modify 
the left- and right-hand core cowl assemblies of the engines per the 
Accomplishment Instructions of Boeing Service Bulletin 747-71-2285 
(for Model 747-400 series airplanes) or 767-71-0088 (for Model 767 
series airplanes), both dated October 8, 1998.

    Note 2: The Boeing service bulletins reference ROHR Service 
Bulletin TBC/80C2-NAC-71-028, dated August 1, 1998, as an additional 
source of service information for accomplishment of the 
modification.

Spares

    (b) As of 6 months after the effective date of this AD, no one 
may install an aluminum core cowl assembly, part number 224-2301-513 
(left-hand) or 224-2302-539 (right-hand), on any airplane.

Alternative Methods of Compliance

    (c) 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 Operations Inspector or Principal 
Maintenance Inspector, as applicable, who may add comments and then 
send the request and any comments 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.

Special Flight Permits

    (d) 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.

Incorporation by Reference

    (e) The actions shall be done in accordance with Boeing Service 
Bulletin 747-71-2285, dated October 8, 1998; or Boeing Service 
Bulletin 767-71-0088, dated October 8, 1998; 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

    (f) This amendment becomes effective on September 24, 2001.

    Issued in Renton, Washington, on August 10, 2001.
Vi L. Lipski,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 01-20698 Filed 8-17-01; 8:45 am]
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