AD 2000-09-08

[Federal Register Volume 65, Number 93 (Friday, May 12, 2000)]
[Rules and Regulations]
[Pages 30532-30534]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 00-11545]



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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-NM-242-AD; Amendment 39-11717; AD 2000-09-08]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 747-100, -200, 747SP, and 
747SR Series Airplanes Equipped With Pratt & Whitney JT9D-7, -7A, -7F, 
and -7J 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 747-100, -200, 747SP, and 747SR 
series airplanes, that requires one-time detailed visual and eddy 
current inspections to detect cracking of the nose cowl mounting 
flange; rework of the nose cowl mounting flange; eddy current 
inspection to detect cracking of the reworked nose cowl mounting 
flange; and corrective action, if necessary. This amendment is prompted 
by reports of the nose cowl separating from the engine and departing 
the airplane following severe engine vibration. The actions specified 
by this AD are intended to prevent separation of the nose cowl from the 
engine, which could cause collateral damage to the airplane, and, 
possibly, reduced controllability of the airplane.

DATES: Effective June 16, 2000.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of June 16, 2000.

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: Dionne Krebs, Aerospace Engineer, 
Propulsion Branch, ANM-140S, FAA, Transport Airplane Directorate, 
Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, 
Washington 98055-4056; telephone (425) 227-2250; 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 747-100, -
200, 747SP, and 747SR series airplanes was published in the Federal 
Register on October 6, 1999 (64 FR 54240). That action proposed to 
require one-time detailed visual and eddy current inspections to detect 
cracking of the nose cowl mounting flange; rework of the nose cowl 
mounting flange; eddy current inspection to detect cracking of the 
reworked nose cowl mounting flange; and corrective action, if 
necessary.

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.

Support for the Proposed Rule

    One commenter supports the proposed rule.

Request to Remove Paragraph (c)

    Two commenters (who otherwise support the proposal) request that 
paragraph (c) of the proposed rule be eliminated. That paragraph reads, 
``As of the effective date of this AD, no person shall install a nose 
cowl on any airplane, unless it has been inspected and modified in 
accordance with paragraph (a) of this AD.'' One commenter states that 
this paragraph would effectively require modification of nose cowls 
well before the 24-month compliance time, which could result in an 
airplane being out of service for an extended period if an unexpected 
engine change is necessary. The other commenter states that, if 
paragraph (c) is included in the final rule, the commenter would have 
to purchase at least one additional spare nose cowl, because 
approximately 50 percent of its engine changes occur at locations that 
do not have a spare nose cowl. The commenter states that if an engine 
change occurs at a location that does not have a spare modified nose 
cowl, the time necessary to return the airplane to service will 
increase by at least six hours, which would result in lengthy flight 
delays or cancellations that would be costly and would cause 
disruptions for the traveling public. The commenter states that 
purchasing a new spare nose cowl would be expensive and would require a 
lead time of 300 days.
    The FAA concurs with the commenters' request to eliminate paragraph 
(c) of the proposed rule. The FAA's intent is to allow operators to 
accomplish the necessary inspections and rework during a regularly 
scheduled maintenance interval. Therefore, paragraph (c) of the 
proposed rule has not been included in this final rule. The FAA finds 
that eliminating paragraph (c) of the proposed rule will not adversely 
impact the safety of the affected airplane fleet and will allow more 
flexibility for operators in complying with the requirements within the 
specified compliance time.

Request to Extend Compliance Time

    One commenter requests that paragraph (a) of the proposed rule be 
revised to extend the compliance time from 24 months, as proposed, to 
36 months. The commenter states that the ``very aggressive 
incorporation rate requirements'' are not justified, given that there 
have been few incidents of nose cowl separations. The commenter states 
that extending the compliance time would allow the required actions to 
be accomplished during scheduled maintenance opportunities.
    The FAA does not concur with the commenter's request. In developing 
an appropriate compliance time for this action, the FAA considered the 
safety implications, parts availability, and normal maintenance 
schedules for timely accomplishment of the requirements of this AD. In 
consideration of these items, as well as the reports of six in-service 
nose cowl separations, the FAA has determined that 24 months represents 
an appropriate interval of time allowable wherein the modifications can 
be accomplished during scheduled maintenance intervals for the majority 
of affected operators and an acceptable level of safety can be 
maintained. No change to the final rule is necessary in this regard.

Challenge to Justification for Proposed Requirements

    One commenter, an operator, states that, while it has no technical 
objection to the rework of the nose cowl mounting flange described in 
the proposed rule, it cannot recall any incident on its fleet of 
affected airplanes, in which ingestion of a foreign object into the 
engine resulted in separation of the nose cowl. The commenter questions 
the conditions that existed and the events that occurred during the 
incidents of nose cowl separation referenced in the proposed rule. The 
commenter challenges the justification for the proposed requirements if 
the FAA determines that unique conditions or circumstances led to the 
incidents in question. The commenter makes no specific request for a 
change to the proposed rule.

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    The FAA infers that the commenter is requesting that the FAA 
consider withdrawing the proposed rule. The FAA does not concur. The 
information that the FAA has received regarding incidents of nose cowl 
separation does not suggest that there were any conditions common to 
all incidents besides the configuration of the nose cowl mounting 
flange. The information has led the FAA to determine that the 37-bolt 
mounting flange configuration is not adequate to retain the nose cowl 
on Pratt & Whitney JT9D series engines, and that the modification of 
the nose cowl mounting flange described in the proposed rule is 
necessary. No change to the final rule is necessary in this regard.

Request to Remove References to ``Reduced Controllability of the 
Airplane''

    One commenter states that, ``To date, no evidence of reduced 
airplane controllability during or after separation [of the nose cowl] 
has been reported.'' The commenter makes no specific request and 
provides no further information related to its comment.
    The FAA infers that the commenter is requesting that references to 
``reduced controllability of the airplane'' be removed from the 
proposed rule. The FAA concurs with the commenter's statement that 
there have been no reported instances of reduced airplane 
controllability during or after the separation of a nose cowl. However, 
the potential exists for reduced controllability during or after the 
separation of a nose cowl, if the separated nose cowl comes into 
contact with the airplane. This possibility is the basis for 
determining that the separation of a nose cowl is an unsafe condition. 
Therefore, the FAA finds that no change to the final rule is necessary 
in this regard.

Request to Revise ``Explanation of Relevant Service Information'' 
Section

    One commenter, the manufacturer, states that the service bulletin 
referenced in the proposed rule was issued not as an inspection 
bulletin to detect cracking in the mounting flange, but, instead, to 
provide instructions for strengthening the attachment capability of the 
nose cowl by increasing the number of attachment fasteners. The 
commenter also states that it has not received reports of cracking in 
the nose cowl flange, nor has cracking been identified as the cause of 
the nose cowl separation. The commenter further states that the eddy 
current and detailed visual inspections described in the service 
bulletin are a common maintenance/rework practice after machining 
operations such as drilling holes, to ensure that no damage was done 
during the operation.
    The commenter makes no specific request for a change to the 
proposed rule. However, the FAA infers that the commenter is requesting 
that the ``Explanation of Relevant Service Information'' section of the 
proposed rule be revised to eliminate references to cracking and to 
clarify the purpose of the eddy current and detailed visual 
inspections. The FAA concurs with the commenter's description of the 
intent of the service bulletin; however, because the referenced section 
is not restated in the final rule, no change to this section is 
necessary. In response to this comment, the FAA has also reviewed the 
explanation of the unsafe condition in the ``Discussion'' section of 
the proposed rule, and finds that the section accurately describes the 
intent and background of the proposed rule. No change to the final rule 
is necessary in this regard.

Request to Revise Cost Impact Estimate

    One commenter requests an increase in the cost estimate of the 
proposed rule. The commenter points out that the proposed rule 
estimates that it will take approximately 19 work hours per airplane to 
accomplish the proposed actions, while the service bulletin estimates 
approximately 34 work hours per airplane for the actions described in 
the service bulletin. Also, the commenter points out that the cost 
figures in the proposed rule do not account for the cost of 
accomplishing the proposed actions on spare nose cowls, which the 
commenter estimates will take approximately 5.5 work hours per nose 
cowl.
    The FAA infers that the commenter is requesting that the cost 
impact information in the final rule be revised to reflect the service 
bulletin estimates and to incorporate the estimated cost for inspecting 
and reworking spares. The FAA does not concur with the commenter's 
request. The cost impact information in AD rulemaking actions describes 
only the ``direct'' costs of the specific actions required by this AD. 
The number of work hours necessary to accomplish the required actions 
(specified as 19 in the cost impact information in the proposed rule 
and restated below) was provided to the FAA by the manufacturer based 
on the best data available to date. This number represents the time 
necessary to perform only the actions actually required by this AD. The 
FAA recognizes that, in accomplishing the requirements of any AD, 
operators may incur ``incidental'' costs in addition to the ``direct'' 
costs. The cost analysis in AD rulemaking actions, however, typically 
does not include incidental costs, such as the time required to gain 
access and close up, planning time, or time necessitated by other 
administrative actions. Because incidental costs may vary significantly 
from operator to operator, they are almost impossible to calculate. In 
addition, the estimated cost to modify ``spare'' parts is not typically 
included in AD rulemaking actions. 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 257 airplanes of the affected design in the 
worldwide fleet. The FAA estimates that 106 airplanes of U.S. registry 
will be affected by this AD, that it will take approximately 19 work 
hours per airplane to accomplish the required actions, and that the 
average labor rate is $60 per work hour. Required parts will cost 
approximately $500 per airplane. Based on these figures, the cost 
impact of the AD on U.S. operators is estimated to be $173,840, or 
$1,640 per airplane.
    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.

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)

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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:

2000-09-08  Boeing: Amendment 39-11717. Docket 99-NM-242-AD.

    Applicability: Model 747-100, -200, 747SP, and 747SR series 
airplanes; certificated in any category; equipped with Pratt & 
Whitney JT9D-7, -7A, -7F, and -7J series engines.

    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 separation of the nose cowl from the engine, which 
could cause collateral damage to the airplane, and, possibly, 
reduced controllability of the airplane, accomplish the following:

One-Time Inspections and Rework

    (a) Within 24 months after the effective date of this AD, 
perform one-time detailed visual and eddy current inspections to 
detect cracking of the existing nose cowl mounting flange, rework 
the nose cowl mounting flange to increase the number of attachment 
fastener holes from 37 to 67, and perform a one-time eddy current 
inspection to detect cracking of the new fastener holes in the 
reworked nose cowl mounting flange, in accordance with the 
Accomplishment Instructions of Boeing Service Bulletin 747-71-2290, 
dated March 18, 1999.

    Note 2: For the purposes of this AD, a detailed visual 
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 aides such 
as mirror, magnifying lenses, etc., may be used. Surface cleaning 
and elaborate access procedures may be required.''

Corrective Action

    (b) If any crack is found during any inspection required by 
paragraph (a) of 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.

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 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 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) Except as provided by paragraph (b) of this AD, the actions 
shall be done in accordance with Boeing Service Bulletin 747-71-
2290, dated March 18, 1999. 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 June 16, 2000.

    Issued in Renton, Washington, on May 3, 2000.
Vi L. Lipski,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 00-11545 Filed 5-11-00; 8:45 am]
BILLING CODE 4910-13-U