[Federal Register Volume 67, Number 3 (Friday, January 4, 2002)]
[Proposed Rules]
[Pages 544-547]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 02-207]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2001-NM-117-AD]
RIN 2120-AA64


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

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the adoption of a new airworthiness 
directive (AD) that is applicable to certain Boeing Model 747-100, -
100B, -100B SUD, -200B, -200C, -200F, -300, -400, -400D, and -400F 
series airplanes; and Model 747SR series airplanes. For certain 
airplanes, this proposal would require repetitive inspections of the 
clevis bushings on the inboard and outboard sequence carriages of the 
wing foreflap for bushing migration, and corrective action, if 
necessary; replacement of existing bushings with new bushings, which 
would terminate the repetitive inspections; and replacement of the 
bushing markers with new markers, if necessary, to indicate the correct 
bushing orientation. For certain other airplanes, this proposal would 
require a one-time inspection to determine whether the bushings are in 
the correct orientation, and follow-on actions. This action is 
necessary to prevent the loss of an inboard trailing edge foreflap 
during flight, and subsequent damage to the airplane in flight. This 
action is intended to address the identified unsafe condition.

DATES: Comments must be received by February 19, 2002.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket 2001-NM-117-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. 2001-NM-117-AD'' in the subject line and need

[[Page 545]]

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: John Craycraft, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 
227-2782; 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:
     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.
     For each issue, state what specific change to the proposed 
AD is being requested.
     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 notice must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket 2001-NM-117-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 2001-NM-117-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-
4056.

Discussion

    The FAA has received a report indicating that an operator of a 
Boeing Model 747 series airplane with 22,141 total flight hours and 
7,268 total flight cycles discovered a broken lug on the inboard 
sequence carriage clevis of the wing foreflap during a routine check. 
Subsequently, another operator, with a Model 747 series airplane that 
had accumulated 5,790 total flight hours and 1,965 total flight cycles, 
found a cracked lug. In both cases, the bushing at the outboard lug had 
migrated out of place, resulting in bending loads on the lug. In one 
event, a Model 747 series airplane that had accumulated 114,036 total 
flight hours and 20,438 total flight cycles had the wing foreflap 
separate from the airplane during flight as a result of migrated 
bushings. The detached foreflap impacted the fuselage, creating a 5.5-
foot-by-3-foot hole in the main cabin during flight. No operational 
problems had been reported prior to the discovery of the cracked or 
broken lugs. Continued operation of the airplane without detecting and 
replacing migrated bushings could result in loss of an inboard trailing 
edge foreflap during flight, which could subsequently cause damage to 
the airplane in flight.

Explanation of Relevant Service Information

    The FAA has reviewed and approved Boeing Service Bulletin 747-57-
2166, Revision 5, dated May 13, 1993, which, for certain airplanes, 
describes procedures for a general visual inspection of the bushings of 
the clevis on the inboard and outboard sequence carriages of the 
inboard trailing edge foreflap to detect bushing migration, and 
corrective action, if necessary; repetitive inspections of the bushings 
until they have been replaced; replacement of the bushings with new 
bushings; and replacement of the markers installed on the airplane, if 
necessary, to ensure correct orientation of the bushings. For certain 
other airplanes, the service bulletin describes procedures for a one-
time general visual inspection to determine whether the bushings are in 
the correct orientation, and follow-on actions. If the bushings are 
correctly oriented, follow-on action involves replacement of the 
existing markers on the airplane with new markers, if applicable, to 
ensure that bushings are oriented correctly in future replacements. If 
the bushings are incorrectly oriented, follow-on actions in the service 
bulletin involve correction of the orientation and replacement of the 
existing markers with new markers. Accomplishment of the actions 
specified in the service bulletin is intended to adequately address the 
identified unsafe condition.

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 require accomplishment of the actions specified in 
the service bulletin described previously, except as discussed below.

Differences Between Proposed Rule and Service Bulletin

    Operators should note that this proposed AD would require, within 5 
years, the bushing replacement described in Boeing Service Bulletin 
747-57-2166, Revision 5, as terminating action for the repetitive 
inspections. (Incorporation of the terminating action is optional in 
the service bulletin.) The FAA has determined that long-term continued 
operational safety will be better assured by design changes to remove 
the source of the problem, rather than by repetitive inspections. Long-
term inspections may not provide the degree of safety assurance 
necessary for the transport airplane fleet. This, coupled with a better 
understanding of the human factors associated with numerous continual 
inspections, has led the FAA to consider placing less emphasis on 
inspections and more emphasis on design improvements. The proposed 
replacement requirement is consistent with these conditions.
    Operators also should note that, for airplanes on which the 
bushings have been replaced prior to the effective date of this AD in 
accordance with Boeing Service Bulletin 747-57-2166, Revision 4, dated 
December 6, 1990, or prior revisions, this proposed AD would require 
accomplishment of an inspection to determine whether the bushings are 
correctly oriented, and follow-on actions. This proposed AD would 
differ from the service bulletin in that, if any bushing is incorrectly 
oriented, the follow-on actions would involve accomplishment of the 
repetitive inspections for bushing migration and eventual replacement 
of the bushings with new bushings.

[[Page 546]]

    Operators should also note that the number of airplanes to which 
this AD is applicable is larger than that published in the service 
bulletin. Additional line numbers of airplanes have been included, as 
advised in Boeing Service Letter 747-SL-57-77, dated November 18, 1993. 
However, the FAA has further learned that the Boeing 747SP flaps are of 
a different design and are excluded from the proposed rule.

Cost Impact

    There are approximately 589 airplanes of the affected design in the 
worldwide fleet. The FAA estimates that 222 airplanes of U.S. registry 
would be affected by this proposed AD, that it would take approximately 
7 work hours per airplane to accomplish the proposed actions, and that 
the average labor rate is $60 per work hour. Required parts costs would 
be negligible. Based on these figures, the cost impact of the proposed 
AD on U.S. operators is estimated to be $93,240, or $420 per airplane.
    The cost impact figure discussed above is 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 adding the following new 
airworthiness directive:

Boeing: Docket 2001-NM-117-AD.

    Applicability: Model 747-100, -100B, -100B SUD, -200B, -200C, -
200F, -300, -400, -400D, and -400F series airplanes; and Model 747SR 
series airplanes; certificated in any category; line numbers 1 
through 1009, except 968, 999, 1004, and 1007.

    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 (e) 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 the loss of an inboard trailing edge foreflap during 
flight, and subsequent damage to the airplane in flight, accomplish 
the following:

Inspections (Bushings Not Yet Replaced)

    (a) For airplanes on which the bushings have not been replaced 
prior to the effective date of this AD in accordance with Boeing 
Service Bulletin 747-57-2166, Revision 4, dated December 6, 1990, or 
prior revisions: Prior to the accumulation of 5,000 total flight 
cycles, or within 1,200 flight cycles after the effective date of 
this AD, whichever occurs later, perform a general visual inspection 
of the bushings of the clevis on the inboard and outboard sequence 
carriages, flap tracks 3, 4, 5, and 6 of the inboard trailing edge 
foreflap, for bushing migration, in accordance with Boeing Service 
Bulletin 747-57-2166, Revision 5, dated May 13, 1993.


    Note 2: For the purposes of this AD, a general visual inspection 
is defined as: ``A visual examination of an interior or exterior 
area, installation, or assembly to detect obvious damage, failure, 
or irregularity. This level of inspection is made under normally 
available lighting conditions such as daylight, hangar lighting, 
flashlight, or drop-light, and may require removal or opening of 
access panels or doors. Stands, ladders, or platforms may be 
required to gain proximity to the area being checked.''


    (1) For each nondiscrepant bushing (with no migration): Repeat 
the inspection of that bushing at intervals not to exceed 1,200 
flight cycles, until the terminating action required by paragraph 
(c) of this AD has been accomplished.
    (2) For any discrepant bushing: Prior to further flight, replace 
the discrepant bushing with a new bushing and, if applicable, 
replace the bushing marker with a new marker, in accordance with 
Boeing Service Bulletin 747-57-2166, Revision 5, dated May 13, 1993. 
No further action is required by this AD for that bushing only.

    Note 3: It is not necessary to replace the marker if the marker 
installed on the airplane shows the correct bushing orientation 
(flange reversed, as shown in NEW CONFIGURATION, Figure 1, of Boeing 
Service Bulletin 747-57-2166, Revision 5, dated May 13, 1993).

Inspection (Bushings Replaced)

    (b) For airplanes on which the bushings have been replaced prior 
to the effective date of this AD in accordance with Boeing Service 
Bulletin 747-57-2166, Revision 4, dated December 6, 1990, or 
previous revisions: Prior to the accumulation of 5,000 total flight 
cycles, or within 1,200 flight cycles after the effective date of 
this AD, whichever occurs later, perform a one-time general visual 
inspection of the bushings of the clevis on the inboard and outboard 
sequence carriages, flap tracks 3, 4, 5, and 6 of the inboard 
trailing edge foreflap, to determine whether the bushings are 
oriented correctly, in accordance with Boeing Service Bulletin 747-
57-2166, Revision 5, dated May 13, 1993.
    (1) For each bushing that is oriented correctly: Within 5 years 
after the effective date of this AD, replace the markers installed 
on the airplane with new markers, as applicable, in accordance with 
Boeing Service Bulletin 747-57-2166, Revision 5, dated May 13, 1993.


    Note 4: It is not necessary to replace the marker if the marker 
installed on the airplane shows the correct bushing orientation 
(flange reversed, as shown in NEW CONFIGURATION, Figure 1, of Boeing 
Service Bulletin 747-57-2166, Revision 5, dated May 13, 1993).

    (2) For any bushing that is oriented incorrectly: Prior to 
further flight, perform a general visual inspection of the bushing 
for bushing migration, in accordance with Boeing Service Bulletin 
747-57-2166, Revision 5, dated May 13, 1993.

[[Page 547]]

    (i) For each nondiscrepant bushing (with no migration), repeat 
the inspection specified by paragraph (b)(2) of this AD at intervals 
not to exceed 1,200 flight cycles, until the terminating action 
required by paragraph (c) of this AD has been accomplished.
    (ii) For any discrepant bushing: Prior to further flight, 
replace the discrepant bushing with a new bushing and, if 
applicable, replace the bushing marker with a new marker, in 
accordance with the service bulletin. No further action is required 
by this paragraph for that bushing only.

    Note 5: It is not necessary to replace the marker if the marker 
installed on the airplane shows the correct bushing orientation 
(flange reversed, as shown in NEW CONFIGURATION, Figure 1, of Boeing 
Service Bulletin 747-57-2166, Revision 5, dated May 13, 1993).

Terminating Action

    (c) Within 5 years after the effective date of this AD, replace 
the existing bushings of the clevis on the inboard and outboard 
sequence carriages, in flap tracks 3, 4, 5, and 6 of the inboard 
trailing edge foreflap, in accordance with Boeing Service Bulletin 
747-57-2166, Revision 5, dated May 13, 1993. Replacement of the 
bushings in accordance with Boeing Service Bulletin 747-57-2166, 
Revision 4, dated December 6, 1990, or earlier, is acceptable, 
provided the bushings are inspected as required by paragraph (b) of 
this AD and found to be in the correct orientation. Also, as 
applicable, before further flight, replace the markers installed on 
the airplane with new markers in accordance with Boeing Service 
Bulletin 747-57-2166, Revision 5. Replacement of all bushings, and 
markers as applicable, terminates the requirements of this AD.

    Note 6: It is not necessary to replace the marker if the marker 
installed on the airplane shows the correct bushing orientation 
(flange reversed, as shown in NEW CONFIGURATION, Figure 1, of Boeing 
Service Bulletin 747-57-2166, Revision 5, dated May 13, 1993).

Spares

    (d) As of the effective date of this AD, no person shall install 
on any airplane a carriage and toggle assembly unless it has been 
modified in accordance with Boeing Service Bulletin 747-57-2166, 
Revision 5, dated May 13, 1993.

Alternative Methods of Compliance

    (e) 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 7: 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

    (f) 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 December 28, 2001.
Vi L. Lipski,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 02-207 Filed 1-3-02; 8:45 am]
BILLING CODE 4910-13-U