AD 2000-21-06

[Federal Register Volume 65, Number 204 (Friday, October 20, 2000)]
[Rules and Regulations]
[Pages 63006-63008]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 00-26878]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2000-NM-98-AD; Amendment 39-11938; AD 2000-21-06]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 747 Series Airplanes 
Equipped with Pratt & Whitney (PW) JT9D-7Q and JT9D-7Q3 Turbofan 
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 series airplanes, that requires 
a detailed visual inspection to detect evidence of wear or contact 
between the precooler support fitting and link assembly; and rework and 
reidentification of the fitting. This amendment is prompted by a report 
of rupturing of a diffuser case on a PW JT9D-7Q engine due to cracking 
in the outer pressure wall in the rear skirt area. The actions 
specified by this AD are intended to prevent contact between the 
precooler support link and the precooler support fitting, which could 
contribute to an uncontained failure of the diffuser case and damage to 
the airplane.

DATES: Effective November 24, 2000.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of November 24, 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, 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 series 
airplanes was published in the Federal Register on

[[Page 63007]]

May 3, 2000 (65 FR 25696). That action proposed to require a detailed 
visual inspection to detect evidence of wear or contact between the 
precooler support fitting and link assembly; and rework and 
reidentification of the fitting.

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.

Request for Correction of Part Number

    One commenter states that the reidentification part number (P/N) 
65B09024-601, as specified in paragraphs (a)(1), (a)(2), and (b) of the 
proposal, is incorrect, and should be revised to P/N 65B90924-601. The 
FAA concurs with the commenter's statement; there was an error in the 
part number specified in the proposed rule and it has been corrected in 
the applicable paragraphs of the final rule.

Action Taken to Address Root Cause

    One commenter repeats a sentence in the Discussion section of the 
proposal which states, ``The diffuser case fracture was due to a crack 
that most likely developed in a toolmark that was left by a blending 
operation adjacent to the dog-bone-shaped embossment at the 11 o'clock 
circumferential location of the outer pressure wall of the case in the 
area of the rear skirt.'' The commenter requests information on the 
action that has been taken to address the toolmark and blending issue 
that is the apparent root cause of the unsafe condition.
    The FAA previously issued AD 99-04-05, amendment 39-11029 (64 FR 
6784, February 11, 1999), which addresses the toolmark and blending 
issue. That AD requires a fluorescent penetrant inspection (FPI) of the 
rear skirt of the diffuser case for cracks, and, if necessary, blending 
down to a minimum wall thickness to remove cracks and subsequent FPI to 
determine if cracks have been removed, polishing, and shotpeening. If 
the cracks are shown by subsequent FPI not to have been removed, that 
AD requires removing the diffuser case from service and replacing it 
with a serviceable part. No change to this final rule is necessary in 
this regard.

Request to Reference New Service Information

    One commenter requests the proposal be revised to reference Boeing 
Service Bulletin 747-36-2135 for accomplishment of the bracket 
modification. The commenter states that Boeing Service Letter 747-SL-
36-089, dated August 10, 1998 (the service information referenced in 
the proposal for accomplishment of the bracket modification), will be 
revised to refer to the new service bulletin for the modification 
instructions. The commenter disagrees with the wording in the proposal 
stating that the service letter will be revised to reidentify the P/N 
on the bracket, and plans to revise the service letter to reference the 
new service bulletin, which will contain modification instructions for 
the bracket.
    The FAA does not concur with the commenter's request. The 
referenced service bulletin has not been submitted for review and 
approval by the FAA; therefore, the final rule cannot be revised to 
cite as-yet unapproved service information. However, under the 
provisions of paragraph (c) of the final rule, the FAA may approve 
requests for an alternative method of compliance in accordance with 
Boeing Service Bulletin 747-36-2135 after it has been approved by the 
FAA and submitted to substantiate that such an adjustment would provide 
an acceptable level of safety that addresses the identified unsafe 
condition. Additionally, the proposal does not state that the service 
letter will be revised to reidentify the P/N on the bracket. No change 
to the final rule is necessary in this regard.

Request to Extend Compliance Time

    One commenter requests the proposed compliance time for 
accomplishment of the detailed visual inspection be extended to 
``Within 8,000 flight hours after the effective date of this AD,'' with 
no calendar grace period. The commenter states that, since removal of 
the precooler is necessary to accomplish the rework, the task is best 
accomplished during a scheduled `L,' `H,' or `M' maintenance check of 
the airplane. The commenter also states that an extension of the 
compliance time will ensure that it can accomplish the inspection on 
all of its affected airplanes during one of the scheduled checks 
described above.
    The FAA does not concur with the commenter's request. In developing 
an appropriate compliance time for this action, the FAA considered not 
only the degree of urgency associated with addressing the subject 
unsafe condition, but the manufacturer's recommendation as to an 
appropriate compliance time, and the practical aspect of accomplishing 
the required inspection and rework within an interval of time that 
parallels the normal scheduled maintenance for the majority of affected 
operators. The FAA has determined that 6,000 hours, time-in-service or 
18 months represents an appropriate compliance time allowable for the 
inspection and rework to be accomplished during scheduled maintenance 
intervals. However, under the provisions of paragraph (c) of the final 
rule, the FAA may approve requests for adjustments to the compliance 
time if data are submitted to substantiate that such an adjustment 
would provide an acceptable level of safety.

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 79 airplanes of the affected design in the 
worldwide fleet. The FAA estimates that 27 airplanes of U.S. registry 
will be affected by this AD.
    It will take approximately 2 work hours per airplane to accomplish 
the required inspection, at an average labor rate of $60 per work hour. 
Based on these figures, the cost impact of the required inspection on 
U.S. operators is estimated to be $3,240, or $120 per airplane.
    It will take approximately 16 work hours per airplane to accomplish 
the required rework, at an average labor rate of $60 per work hour. No 
parts are required to accomplish the rework. Based on these figures, 
the cost impact of the required rework on U.S. operators is estimated 
to be $25,920, or $960 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

[[Page 63008]]

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:

2000-21-06  Boeing: Amendment 39-11938. Docket 2000-NM-98-AD.

    Applicability: Model 747 series airplanes, certificated in any 
category; equipped with Pratt & Whitney JT9D-7Q and JT9D-7Q3 
turbofan 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 contact between the precooler support link and the 
precooler support fitting, which could contribute to an uncontained 
failure of the diffuser case and damage to the airplane, accomplish 
the following:

Detailed Visual Inspection

    (a) For any precooler support fitting having P/N 65B90924-1 or 
P/N 65B90924-600 that has not been reworked to the dimensions 
specified in Boeing Service Letter 747-SL-36-089, dated August 10, 
1998: Within 6,000 hours time-in-service after the effective date of 
this AD, or within 18 months after the effective date of this AD, 
whichever occurs first, perform a detailed visual inspection to 
detect evidence of contact wear or contact between the precooler 
support fitting and link assembly, P/N 69B93162-1 or 69B93162-3, in 
accordance with the service letter.

Rework and Reidentification

    (1) If no evidence of contact wear or contact between the 
precooler support fitting and link assembly is found: At the next 
engine removal, rework the precooler support fitting to the 
dimensions specified in the service letter, in accordance with the 
service letter; and permanently and legibly reidentify the support 
fitting as P/N 65B90924-601.
    (2) If any evidence of contact wear or contact between the 
precooler support fitting and link assembly is found: Prior to 
further flight, rework the precooler support fitting to the 
dimensions specified in the service letter, in accordance with the 
service letter; and permanently and legibly reidentify the support 
fitting as P/N 65B90924-601.

    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 aids such 
as mirror, magnifying lenses, etc., may be used. Surface cleaning 
and elaborate access procedures may be required.''

Reidentification

    (b) For any precooler support fitting having P/N 65B90924-1 or 
P/N 65B90924-600 that has been reworked to the dimensions specified 
in Boeing Service Letter 747-SL-36-089, dated August 10, 1998, but 
has not been permanently and legibly reidentified: Within 6,000 
hours time-in-service or 18 months after the effective date of this 
AD, whichever occurs first, permanently and legibly reidentify the 
reworked fitting as P/N 65B90924-601.

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 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 
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

    (e) Except as provided by paragraphs (a)(1), (a)(2), and (b) of 
this AD, the actions shall be done in accordance with Boeing Service 
Letter 747-SL-36-089, including attachment, dated August 10, 1998. 
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 November 24, 2000.

    Issued in Renton, Washington, on October 13, 2000.
Donald L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 00-26878 Filed 10-19-00; 8:45 am]
BILLING CODE 4910-13-P