[Federal Register Volume 67, Number 231 (Monday, December 2, 2002)]
[Proposed Rules]
[Pages 71497-71500]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 02-30349]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2002-NM-55-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 747-100, 747-100B, 747-
100B SUD, 747-200B, 747-200F, 747-200C, 747-300, 747-400, 747-400D, 
747-400F, and 747SR Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the supersedure of an existing 
airworthiness directive (AD), applicable to certain Boeing Model 747 
series airplanes, that currently requires inspections for cracking of 
the forward end clevis lugs of the flap track, and replacement of the 
flap track with a new flap track, if necessary. That AD also provides 
for an optional modification of the forward end clevis lugs, which 
terminates the required inspections. This action would expand the 
applicability of the existing AD, and would require new repetitive 
inspections for evidence of rotation or migration of the bushings or 
cracking of the lugs of the forward end clevis of the flap tracks that 
support the wing trailing edge flaps, and corrective actions if 
necessary. This action also would require an eventual terminating 
action. This action is necessary to prevent cracking and fracture of 
the forward end clevis of the flap track, which could result in reduced 
structural capability of the flap and reduced controllability of the 
airplane. This action is intended to address the identified unsafe 
condition.

DATES: Comments must be received by January 16, 2003.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 2002-NM-55-AD, 1601 Lind Avenue, SW., 
Renton, Washington 98055-4056. Comments may be inspected at this 
location between 9 a.m. and 3 p.m., Monday through Friday, except 
Federal holidays. Comments may be submitted via fax to (425) 227-1232. 
Comments may also be sent via the Internet using the following address: 
[email protected]. Comments sent via fax or the Internet must 
contain ``Docket No. 2002-NM-55-AD'' in the subject line and need not 
be submitted in triplicate. Comments sent via the Internet as attached 
electronic files must be formatted in Microsoft Word 97 for Windows or 
ASCII text.
    The service information referenced in the proposed rule may be 
obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, 
Washington 98124-2207. This information may be examined at the FAA, 
Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, 
Washington.

FOR FURTHER INFORMATION CONTACT: Tamara Anderson, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 
227-2771; fax (425) 227-1181.

SUPPLEMENTARY INFORMATION:

Comments Invited

    Interested persons are invited to participate in the making of the 
proposed rule by submitting such written data, views, or arguments as 
they may desire. Communications shall identify the Rules Docket number 
and be submitted in triplicate to the address specified above. All 
communications received on or before the closing date for comments, 
specified above, will be considered before taking action on the 
proposed rule. The proposals contained in this action may be changed in 
light of the comments received.
    Submit comments using the following format:
    [sbull] Organize comments issue-by-issue. For example, discuss a 
request to change the compliance time and a request to change the 
service bulletin reference as two separate issues.
    [sbull] For each issue, state what specific change to the proposed 
AD is being requested.
    [sbull] Include justification (e.g., reasons or data) for each 
request.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the proposed rule. All 
comments submitted will be available, both before and after the closing 
date for comments, in the Rules Docket for examination by interested 
persons. A report summarizing each FAA-public contact concerned with 
the substance of this proposal will be filed in the Rules Docket.
    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this action must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 2002-NM-55-AD.'' The postcard will be date-stamped and 
returned to the commenter.

Availability of NPRMs

    Any person may obtain a copy of this NPRM by submitting a request 
to the FAA, Transport Airplane Directorate, ANM-114, Attention: Rules 
Docket No. 2002-NM-55-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    The FAA has previously issued AD 90-24-09, amendment 39-6815 (55 FR 
48228, November 20, 1990), applicable to certain Boeing Model 747 
series airplanes. That AD requires inspections of the forward end 
clevis lugs of the flap track, and replacement of the flap track with a 
new flap track, if necessary. That AD also provides for an optional 
modification of the forward end clevis lugs, which terminates the 
required inspections. That action was prompted by reports of cracked or 
failed clevis lugs on two flap tracks. The requirements of that AD are 
intended to prevent separation of the wing trailing edge flap track 
from the airplane and reduction in the controllability of the airplane.

[[Page 71498]]

Actions Since Issuance of Previous Rule

    Since the issuance of that AD, the FAA has received many reports of 
rotated and migrated bushings of the forward end clevis of the flap 
tracks that support the wing trailing edge flaps. Rotation and 
migration of the bushings has been attributed to insufficient 
interference fit. These findings occurred on airplanes not included in 
the applicability of the existing AD. In some cases, the rotation or 
migration of bushings resulted in stress corrosion cracking and 
fracture of the forward end clevis. This condition, if not corrected, 
could result in reduced structural capability of the flap and reduced 
controllability of the airplane.

Explanation of Relevant Service Information

    The existing AD refers to Boeing Service Bulletin 747-57-2231, 
Revision 2, dated September 27, 1990, as the applicable source of 
service information for the actions required by that AD. Since the 
issuance of the existing AD, the FAA has reviewed and approved Boeing 
Service Bulletin 747-57-2307, Revision 1, dated January 17, 2002. That 
service bulletin replaces Boeing Service Bulletin 747-57-2231, and 
describes actions similar to those in Boeing Service Bulletin 747-57-
2231, Revision 2, as described below. Modification of the forward end 
clevis lugs as described in Boeing Service Bulletin 747-57-2231, 
Revision 2, eliminates the need to do the actions in Boeing Service 
Bulletin 747-57-2307, Revision 1.
    Boeing Service Bulletin 747-57-2307, Revision 1, describes 
procedures for repetitive detailed inspections for evidence of rotation 
or migration of the bushings or cracking of the lugs of the forward end 
clevis of the flap tracks that support the wing trailing edge flaps, 
and corrective actions if necessary. Evidence of migration or rotation 
of the bushings includes cracked or missing sealant around the bushing 
flange, or a gap between the bushing flange and the lug face. If 
migration or rotation of the bushings is found, but there is no 
cracking of the lugs, corrective actions include application of 
corrosion-inhibiting compound to the area around the flanged and shank 
ends of the migrated or rotated bushings, and repetitive inspections at 
a reduced interval. If any cracking is found, corrective actions 
involve replacement of the flap track with a new track. Replacement 
with a new track having certain part numbers eliminates the need for 
the repetitive inspections described previously for the replaced track.
    The service bulletin also describes procedures for a terminating 
modification'replacement of the bushings of the forward end clevis with 
new bushings with a higher interference fit (including machining, 
performing magnetic particle inspections, and applying cadmium plating 
to the clevis bore and bushing). If migration or rotation of the 
bushings is found, but there is no cracking of the lugs, it may be 
necessary to do this terminating modification before further flight or 
at a reduced compliance time, depending on what group the airplane is 
listed in. The service bulletin recommends eventually doing this 
terminating modification on any forward end clevis for which the flap 
track is not replaced with a new flap track with certain part numbers, 
or on which the modification described in Boeing Service Bulletin 747-
57-2231, Revision 2, has not been done. Doing the terminating 
modification eliminates the need for the repetitive inspections 
described previously.
    Doing the actions specified in Boeing Service Bulletin 747-57-2307, 
Revision 1, is intended to adequately address the identified unsafe 
condition.

Explanation of Change to Requirements of Existing AD

    Paragraph (a) of the existing AD requires visual inspections of the 
forward end clevis lugs of the flap tracks for cracking. Under the 
heading ``Restatement of Requirements of AD 90-24-09,'' we have revised 
paragraph (a) of this proposed AD to specify that the required 
inspection is considered to be a ``detailed'' inspection. Note 2 of 
this proposed AD defines such an inspection.

Explanation of Requirements of Proposed Rule

    Since an unsafe condition has been identified that is likely to 
exist or develop on other products of this same type design, the 
proposed AD would supersede AD 90-24-09 to continue to require 
inspections of the forward end clevis lugs of the flap track, and 
replacement of the flap track with a new flap track, if necessary. The 
proposed AD also would require the actions specified in Boeing Service 
Bulletin 747-57-2307, Revision 1, described previously, except as 
discussed below. Doing a modification according to Boeing Service 
Bulletin 747-57-2231, Revision 2; or Boeing Service Bulletin 747-57-
2307, Revision 1; would terminate the requirements of this proposed AD.

Difference Between Proposed AD and Service Bulletin

    Certain compliance times in the proposed AD would differ from those 
specified in Boeing Service Bulletin 747-57-2307, Revision 1, as 
explained below.
    For certain airplanes not inspected previously, the service 
bulletin specifies an inspection threshold of 8 years after airplane 
delivery or 30,000 [total] flight hours, whichever occurs sooner. 
However, for these same airplanes, paragraph (e)(2)(i) of this proposed 
AD specifies an inspection threshold of 8 years after the earlier of 
the date of issuance of the ORIGINAL Airworthiness Certificate or the 
date of issuance of the Export Certificate of Airworthiness. This 
decision is based on our determination that ``date of delivery'' may be 
interpreted differently by different operators. We find that our 
proposed terminology is generally understood within the industry and 
records will always exist that establish these dates with certainty.
    For airplanes not inspected previously that are near or over the 
threshold specified above, the service bulletin specifies a compliance 
time of 300 or 1,200 flight cycles after the issue date of the service 
bulletin, depending on the airplane's configuration. However, for all 
airplanes not inspected previously, paragraph (e)(2)(ii) of the 
proposed AD specifies a compliance time of the earlier of 300 flight 
cycles or 120 days after the effective date of the AD. This decision is 
based on new data received by the FAA that indicate that inspecting 
within 1,200 flight cycles may not provide an adequate level of safety. 
In light of these new data, we find a compliance time of 300 flight 
cycles or 120 days after the effective date of the AD, whichever occurs 
first, for completing the required actions to be warranted, in that it 
represents an appropriate interval of time allowable for affected 
airplanes to continue to operate without compromising safety.

Cost Impact

    There are approximately 1,002 airplanes of the affected design in 
the worldwide fleet. The FAA estimates that 219 airplanes of U.S. 
registry would be affected by this proposed AD.
    The actions that are currently required by AD 90-24-09 take 
approximately 2 work hours per airplane, at an average labor rate of 
$60 per work hour. Based on these figures, the cost impact of the 
currently required actions is estimated to be $120 per airplane, per 
inspection cycle.
    The new inspections that are proposed in this AD action would take

[[Page 71499]]

approximately 2 work hours per airplane, at an average labor rate of 
$60 per work hour. Based on these figures, the cost impact of the newly 
proposed inspections on U.S. operators is estimated to be $26,280, or 
$120 per airplane, per inspection cycle.
    The cost impact figures discussed above are based on assumptions 
that no operator has yet accomplished any of the proposed requirements 
of this AD action, and that no operator would accomplish those actions 
in the future if this proposed 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 proposed herein would 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 proposal would not have federalism implications 
under Executive Order 13132.
    For the reasons discussed above, I certify that this proposed 
regulation (1) is not a ``significant regulatory action'' under 
Executive Order 12866; (2) is not a ``significant rule'' under the DOT 
Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); 
and (3) if promulgated, 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 copy of the draft 
regulatory evaluation prepared for this action is contained in the 
Rules Docket. A copy of it may be obtained by contacting the Rules 
Docket at the location provided under the caption ADDRESSES.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Safety.

The Proposed Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration proposes to amend 
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 removing amendment 39-6815 (55 FR 
48228, November 20, 1990), and by adding a new airworthiness directive 
(AD), to read as follows:

Boeing: Docket 2002-NM-55-AD. Supersedes AD 90-24-09, Amendment 39-
6815.

    Applicability: Model 747-100, 747-100B, 747-100B SUD, 747-200B, 
747-200F, 747-200C, 747-300, 747-400, 747-400D, 747-400F, and 747SR 
series airplanes; as listed in Boeing Service Bulletin 747-57-2307, 
Revision 1, dated January 17, 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 (k)(1) 
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 cracking and fracture of the forward end clevis of 
the flap track, which could result in reduced structural capability 
of the flap and reduced controllability of the airplane, accomplish 
the following:

Restatement of Requirements of AD 90-24-09

Initial Inspection

    (a) For airplanes listed in Boeing Service Bulletin 747-57-2231, 
Revision 2, dated September 27, 1990: Perform a detailed inspection 
of the forward end clevis lugs of the flap tracks for evidence of 
cracking, according to Boeing Service Bulletin 747-57-2231, Revision 
2, dated September 27, 1990, and according to the following 
schedule:
    (1) For airplanes listed in Group 1 in the service bulletin: 
Perform the inspection at flap track positions 1 through 8 within 
the next 30 days after December 5, 1990 (the effective date of AD 
90-24-09, amendment 39-6815).
    (2) For airplanes listed in Group 2 in the service bulletin: 
Perform the inspection at flap track positions 1, 2, 7, and 8 prior 
to the later of the following:
    (i) Prior to the accumulation of 30,000 flight hours or 8 years 
after airplane delivery, whichever occurs first; or
    (ii) Within 120 days after December 5, 1990.
    (3) For airplanes listed in Group 3 in the service bulletin: 
Perform the inspection at flap track positions 1 through 8 prior to 
the later of the following:
    (i) Prior to the accumulation of 30,000 flight hours or 8 years 
after airplane delivery, whichever occurs first; or
    (ii) Within 120 days after December 5, 1990.

Flap Track Replacement

    (b) If cracking is found during any inspection required by 
paragraph (a) of this AD, replace the flap track prior to further 
flight, according to Boeing Service Bulletin 747-57-2231, Revision 
2, dated September 27, 1990.

Repetitive Inspections

    (c) If no cracking is found during any inspection required by 
paragraph (a) of this AD, repeat the inspection required by 
paragraph (a) of this AD at intervals not to exceed 300 flight 
cycles for Group 1 airplanes, and 1,200 flight cycles for Group 2 
and Group 3 airplanes, until paragraph (d), (e), or (i) of this AD 
has been done.

Optional Terminating Action

    (d) For airplanes listed in Boeing Service Bulletin 747-57-2231, 
Revision 2, dated September 27, 1990: Accomplishment of the 
modification of the forward end clevis lugs of the flap tracks as 
specified in Boeing Service Bulletin 747-57-2231, Revision 2, dated 
September 27, 1990, constitutes terminating action for the 
requirements of paragraphs (a), (c), (e), and (i) of this AD.

New Requirements 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.''

Detailed Inspections

    (e) At the applicable compliance time specified in paragraph 
(e)(1) or (e)(2) of this AD, perform detailed inspections for 
evidence of rotation or migration of the bushings (including cracked 
or missing sealant around the bushing flange, or a gap between the 
bushing flange and the lug face) or cracking of the lugs of the 
forward end clevis of the flap tracks that support the wing trailing 
edge flaps, according to Part 1 of the Work Instructions in Boeing 
Service Bulletin 747-57-2307, Revision 1, dated January 17, 2002.
    (1) For airplanes inspected before the effective date of this AD 
according to paragraph (a) of this AD: Do the inspection in 
paragraph (e) of this AD at the time specified in paragraph 
(e)(1)(i) or (e)(1)(ii) of this AD, as applicable. Doing this 
inspection terminates the requirements of paragraph (c) of this AD.
    (i) For airplanes listed in Group 1 of Boeing Service Bulletin 
747-57-2231, Revision 2:

[[Page 71500]]

Inspect within 300 flight cycles after the most recent inspection 
per paragraph (a) or (c) of this AD.
    (ii) For airplanes listed in Group 2 or 3 of Boeing Service 
Bulletin 747-57-2231, Revision 2: Inspect within 1,200 flight cycles 
after the most recent inspection per paragraph (a) or (c) of this 
AD.
    (2) For airplanes NOT inspected before the effective date of 
this AD according to paragraph (a) of this AD: Do the inspection in 
paragraph (e) of this AD at the time specified in paragraph 
(e)(2)(i) or (e)(2)(ii) of this AD, whichever occurs later. This 
terminates the requirement to do paragraph (a) of this AD.
    (i) Within 8 years after the EARLIER of the date of issuance of 
the ORIGINAL Airworthiness Certificate or the date of issuance of 
the Export Certificate of Airworthiness, or before the accumulation 
of 30,000 total flight hours, whichever occurs first.
    (ii) Within 300 flight cycles or 120 days after the effective 
date of this AD, whichever occurs first.

Repetitive Inspections

    (f) If no evidence of migration or rotation of the bushings or 
cracking of the lugs is found during the inspection required by 
paragraph (e) of this AD: Repeat the inspections at the applicable 
repetitive interval specified in Figure 1 of Boeing Service Bulletin 
747-57-2307, Revision 1, dated January 17, 2002, until paragraph (d) 
or (i) of this AD has been done.

Corrective Actions and Repetitive Inspections

    (g) If evidence of migration or rotation of the bushings is 
found during any inspection required by paragraph (e) or (f) of this 
AD, but NO cracking is found: Do paragraph (g)(1) or (g)(2) of this 
AD, as applicable, according to Boeing Service Bulletin 747-57-2307, 
Revision 1, dated January 17, 2002.
    (1) For airplanes listed in Group 1 in the service bulletin and 
flap track numbers 3 and 6 on airplanes listed in Group 2 of the 
service bulletin: Before further flight, do the terminating 
modification in paragraph (i) of this AD, as specified in paragraph 
(i)(2) of this AD.
    (2) For airplanes other than those identified in paragraph 
(g)(1) of this AD: Before further flight, apply corrosion-inhibiting 
compound according to the service bulletin, and do paragraphs 
(g)(2)(i) and (g)(2)(ii) of this AD at the intervals specified in 
those paragraphs, until paragraph (d) or (i) of this AD is done. Do 
paragraph (i) of this AD at the applicable time specified in 
paragraph (i)(2) of this AD.
    (i) Repeat the inspections in paragraph (e) of this AD at the 
intervals specified in Figure 1 of the service bulletin.
    (ii) Apply corrosion-inhibiting compound according to the 
service bulletin at intervals not to exceed 200 flight cycles.

Replacement of Flap Track

    (h) If any cracking is found during any inspection required by 
paragraph (e), (f), or (g)(2)(i) of this AD: Before further flight, 
replace the cracked flap track with a new flap track, according to 
Boeing Service Bulletin 747-57-2307, Revision 1, dated January 17, 
2002. Replacement with a new flap track having a part number listed 
in the ``New Part Number'' column of the table under paragraph 2.E. 
of the service bulletin constitutes terminating action for the 
requirements of this AD for the replaced track.

Terminating Modification

    (i) At the applicable time specified in paragraph (i)(1) or 
(i)(2) of this AD: Do all actions (including but not limited to 
machining, performing magnetic particle inspections, and applying 
cadmium plating to the clevis bore and bushing) associated with 
replacing the bushings of the forward end clevis with new bushings 
with a higher interference fit on flap tracks 1, 2, 3, 4, 5, 6, 7, 
and 8; as applicable; according to Boeing Service Bulletin 747-57-
2307, Revision 1, dated January 17, 2002. This replacement 
terminates the requirements of this AD.
    (1) If no evidence of migration or rotation of the bushings or 
cracking of the lugs is found during any inspection required by 
paragraph (e) or (f) of this AD: Do the replacement within 8 years 
after the effective date of this AD.
    (2) If any evidence of bushing migration or rotation is found 
during any inspection required by paragraph (e) or (f) of this AD: 
Do the replacement at the applicable time specified in Figure 1 of 
the service bulletin.

Credit for Actions According to Previous Revision of Service 
Bulletin

    (j) Inspections, corrective actions, and terminating action done 
before the effective date of this AD according to Boeing Service 
Bulletin 747-57-2307, dated July 29, 1999, are considered acceptable 
for compliance with the corresponding action specified in this AD.

Alternative Methods of Compliance

    (k)(1) 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.
    (2) Alternative methods of compliance, approved previously 
according to AD 90-24-09, amendment 39-6815, are approved as 
alternative methods of compliance with paragraphs (a), (b), (c), and 
(d) of this AD.

    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

    (l) 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.


    Issued in Renton, Washington, on November 21, 2002.
Ali Bahrami,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 02-30349 Filed 11-29-02; 8:45 am]
BILLING CODE 4910-13-P