[Federal Register Volume 66, Number 132 (Tuesday, July 10, 2001)]
[Proposed Rules]
[Pages 35912-35914]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 01-17122]


 ========================================================================
 Proposed Rules
                                                 Federal Register
 ________________________________________________________________________
 
 This section of the FEDERAL REGISTER contains notices to the public of 
 the proposed issuance of rules and regulations. The purpose of these 
 notices is to give interested persons an opportunity to participate in 
 the rule making prior to the adoption of the final rules.
 
 ========================================================================
 

  Federal Register / Vol. 66, No. 132 / Tuesday, July 10, 2001 / 
Proposed Rules  

[[Page 35912]]



DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 95-NM-215-AD]


Airworthiness Directives; Boeing Model 737-100 and -200 Series 
Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Supplemental notice of proposed rulemaking; reopening of 
comment period.

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SUMMARY: This document revises an earlier proposed airworthiness 
directive (AD), applicable to certain Boeing Model 737-100 and -200 
series airplanes, that would have superseded an existing AD that 
currently requires various inspections for cracks in the outboard chord 
of the frame at body station (BS) 727 and in the outboard chord of 
stringer 18A; and repair or replacement of cracked parts. The proposed 
AD also would have required additional inspections for certain 
airplanes, and would have revised certain compliance times for all 
airplanes. That proposed AD was prompted by reports of fatigue cracks 
in those outboard chords. This new action revises the proposed AD by 
reducing the proposed initial inspection compliance times; simplifying 
and clarifying the repetitive inspection compliance times; and adding 
airplanes to the applicability. The actions specified by this new 
proposed AD are intended to detect and correct fatigue cracking, which 
could result in reduced structural integrity of the outboard chords, 
and consequent rapid decompression of the airplane.

DATES: Comments must be received by August 24, 2001.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 95-NM-215-AD, 1601 Lind Avenue, SW., 
Renton, Washington 98055-4056. Comments may be inspected at this 
location between 9:00 a.m. and 3:00 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. 95-NM-215-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: Scott Fung, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 
1601 Lind Avenue, SW., Renton, Washington; telephone (206) 227-1221; 
fax (206) 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 action must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 95-NM-215-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. 95-NM-215-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    A proposal to amend part 39 of the Federal Aviation Regulations (14 
CFR part 39) to add an airworthiness directive (AD), applicable to 
certain Boeing Model 737-100 and -200 series airplanes, was published 
as a notice of proposed rulemaking (NPRM) in the Federal Register on 
January 7, 1997 (62 FR 945). That NPRM proposed to supersede AD 95-12-
17, amendment 39-9268 (60 FR 36981, July 19, 1995), which is applicable 
to certain Boeing Model 737-100 and -200 series airplanes. That NPRM 
would have continued to require various inspections for cracks in the 
outboard chord of the frame at body station (BS) 727 and in the 
outboard chord of stringer 18A; and repair or replacement of cracked 
parts. That NPRM would have required additional inspections for certain 
airplanes, and would have revised certain compliance times for all 
airplanes. That NPRM was prompted by reports of fatigue cracks in the 
outboard chords. That condition, if not corrected, could result in 
reduced structural integrity of the outboard chords, and consequent 
rapid decompression of the airplane.

[[Page 35913]]

Comments

    Due consideration has been given to the comments received in 
response to the NPRM.

No Objection to the Proposed Rule

    Two commenters, both airline operators, advised that they did not 
have any objections to the proposed rule.

Request To Reduce the Threshold

    One commenter, the manufacturer, requests that the initial 
threshold compliance time for the proposed rule be changed from ``prior 
to 50,000 total flight cycles'' to ``prior to 35,000 total flight 
cycles.'' The commenter states that fleet data reviewed since the 
release of Boeing 737 Service Bulletin 737-53A1166 (the applicable 
service information specified in the proposed rule) shows that small 
cracks have been detected as early as 28,000 flight cycles. The 
commenter suggests that if there are no cracks found, the next 
inspection should be accomplished at 50,000 total flight cycles. The 
commenter states that the repetitive intervals of 4,500 flight cycles 
as specified in the proposed rule should be retained.
    The FAA partially agrees. For the reason the commenter stated, we 
concur that the threshold compliance time of paragraph (a) of the 
proposed rule should be reduced. However, based on the new reports of 
cracks, we have determined that the compliance time should be reduced 
to ``prior to the accumulation of 30,000 total flight cycles,'' and 
have revised this supplemental NPRM accordingly. This has the effect of 
retaining the initial compliance time specified in AD 95-12-17. We do 
not concur that, if no cracks are found, the next inspection should be 
accomplished only prior to 50,000 total flight cycles. Based on the new 
crack data that Boeing has provided, we find that, if there are no 
cracks found during an initial inspection that is performed prior to 
30,000 total flight cycles, waiting to perform the next inspection 
until 50,000 total flight cycles are accumulated could allow sufficient 
and ample time for cracking to develop. Therefore, we have determined 
that the previously proposed repetitive inspection interval of 4,500 
flight cycles should remain the same throughout this supplemental NPRM.

Additional Changes to the NPRM

    Since the issuance of the original NPRM, the FAA has determined 
that a new group of airplanes (i.e., for airplanes that have 
accumulated less than 27,000 total flight cycles) were inadvertently 
excluded in the original NPRM. Therefore, that group of airplanes has 
been included and addressed in paragraph (c) of this supplemental NPRM.
    Also, we have determined that the various repetitive inspection 
times specified in the original NPRM should be combined into a single 
repetitive interval not to exceed 4,500 flight cycles. That single 
repetitive compliance time will continue to provide an adequate level 
of safety and should make it simpler and easier for operators to 
schedule their fleets for required maintenance.

Conclusion

    Since these changes expand the scope of the originally proposed 
rule, the FAA has determined that it is necessary to reopen the comment 
period to provide additional opportunity for public comment.

Cost Impact

    There are approximately 999 Model 737-100 and -200 series airplanes 
of the affected design in the worldwide fleet. The FAA estimates that 
296 airplanes of U.S. registry would be affected by this proposed AD.
    The actions that are currently required by AD 95-12-17 take 
approximately 4 work hours per airplane to accomplish, at an average 
labor rate of $60 per work hour. Based on these figures, the cost 
impact on U.S. operators of the actions currently required is estimated 
to be $71,040, or $240 per airplane, per inspection cycle.
    This proposed AD specifies inspection requirements for airplanes 
that were omitted inadvertently from the existing AD. However, the 
costs associated with the inspections for those airplanes were included 
previously in the cost impact on U.S. operators for accomplishment of 
AD 95-12-17. Therefore, the FAA estimates that no additional costs 
would be required for accomplishment of the proposed requirements of 
this AD for those airplanes.
    The cost impact figures discussed above are based on assumptions 
that no operator has yet accomplished any of the current or proposed 
requirements of this AD action, and that no operator would accomplish 
those actions in the future if this AD were not adopted.
    Should an operator elect to accomplish the optional terminating 
action that would be provided by this proposed AD, it would take 
approximately 50 work hours to accomplish, at an average labor rate of 
$60 per work hour. Required parts would cost approximately $3,680 per 
airplane. Based on these figures, the cost impact of this optional 
terminating action is estimated to be $6,680 per airplane.

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 39-9268 (60 FR 
36981, July 19, 1995), and by adding a new airworthiness directive 
(AD), to read as follows:

Boeing: Docket 95-NM-215-AD. Supersedes AD 95-12-17, Amendment 39-
9268.

    Applicability: Model 737-100 and -200 series airplanes, line 
numbers 1 through 999 inclusive; 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

[[Page 35914]]

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 (g) 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 detect and correct fatigue cracking, which could result in 
reduced structural integrity of the outboard chords, and consequent 
rapid decompression of the airplane., accomplish the following:

Restatement of AD 95-12-17

Inspections of the Outboard Chord

    (a) For airplanes on which the body station (BS) 727 frame upper 
outboard chord has been replaced in accordance with Boeing Service 
Bulletin 737-53-1088: Prior to the accumulation of 30,000 total 
flight cycles since replacement of the upper outboard chord, or 
within 4,500 flight cycles after August 18, 1995, the effective date 
of AD 95-12-17 (60 FR 36981, July 19, 1995), whichever occurs later, 
perform close visual, pulse echo shear wave (PESW), and high 
frequency eddy current (HFEC) inspections to detect cracks in the 
outboard chord of the frame at BS 727 and in the outboard chord of 
stringer 18A; in accordance with Part I of the Accomplishment 
Instructions of either Boeing Alert Service Bulletin 737-53A1166, 
dated June 30, 1994; or Boeing Service Bulletin 737-53A1166, 
Revision 1, dated May 25, 1995.

Certain Other Inspections

    (b) For airplanes on which the BS 727 frame outboard chord has 
not been replaced or on which only the lower outboard chord has been 
replaced in accordance with Boeing Service Bulletin 737-53-1088: 
Perform close visual, PESW, and HFEC inspections to detect cracks in 
the outboard chord of the frame at BS 727 and in the outboard chord 
of stringer 18A; in accordance with Part I of the Accomplishment 
Instructions of either Boeing Alert Service Bulletin 737-53A1166, 
dated June 30, 1994; or Boeing Service Bulletin 737-53A1166, 
Revision 1, dated May 25, 1995; at the times specified in paragraph 
(b)(1), (b)(2), (b)(3), (b)(4), or (b)(5) of this AD. Thereafter, 
repeat the inspections at intervals not to exceed 4,500 flight 
cycles.
    (1) For airplanes that have accumulated 27,000 or more total 
flight cycles, but fewer than 50,000 total flight cycles, as of 
August 18, 1995: Perform the inspections within 4,500 flight cycles 
after August 18, 1995.
    (2) For airplanes that have accumulated 50,000 or more total 
flight cycles, but fewer than 60,000 total flight cycles, as of 
August 18, 1995: Perform the inspections within 2,500 flight cycles 
after August 18, 1995.
    (3) For airplanes that have accumulated 60,000 or more total 
flight cycles, as of August 18, 1995: Perform the inspections within 
1,500 flight cycles after August 18, 1995.
    (4) For airplanes that have accumulated 70,000 or more total 
flight cycles as of August 18, 1995: Perform the inspections within 
500 flight cycles or within 90 days after August 18, 1995.

New Requirements of This AD

    (c) For any airplane that had accumulated less than 27,000 total 
flight cycles as of August 18, 1995 (the effective dated of AD-95-
12-17): Within 4,500 flight cycles after the effective date of this 
AD, perform close visual, pulse echo shear wave (PESW), and high 
frequency eddy current (HFEC) inspections to detect cracks in the 
outboard chord of the frame at BS 727 and in the outboard chord of 
stringer 18A; in accordance with Part I of the Accomplishment 
Instructions of either Boeing Alert Service Bulletin 737-53A1166, 
dated June 30, 1994; or Boeing Service Bulletin 737-53A1166, 
Revision 1, dated May 25, 1995. Thereafter, repeat the inspections 
at intervals not to exceed 4,500 flight cycles.
    (d) If any crack is found in the outboard chord of stringer 18A 
during any inspection required by this AD, prior to further flight, 
repair in accordance with either paragraph (d)(1) or (d)(2) of this 
AD.
    (1) Repair in accordance with Boeing Service Bulletin 737-
53A1166, Revision 1, dated May 25, 1995; or
    (2) Repair in accordance with a method approved by the Manager, 
Seattle Aircraft Certification Office (ACO), FAA; or in accordance 
with data meeting the type certification basis of the airplane 
approved by a Boeing Company Designated Engineering Representative 
who has been authorized by the Manager, Seattle ACO, to make such 
findings. For a repair method to be approved by the Manager, Seattle 
ACO, as required by this paragraph, the Manager's approval letter 
must specifically reference this AD.
    (e) If any crack is found in the outboard chord of the frame at 
BS 727 during any inspection required by this AD: Accomplish 
paragraph (e)(1) or (e)(2) of this AD, as applicable, in accordance 
with either Boeing Alert Service Bulletin 737-53A1166, dated June 
30, 1994; or Boeing Service Bulletin 737-53A1166, Revision 1, dated 
May 25, 1995. Thereafter, repeat the inspections required by either 
paragraph (a) or (b) of this AD, as applicable, at intervals not to 
exceed 4,500 flight cycles.
    (1) If any crack extends from the forward edge of the chord or 
from the forward fastener hole, but does not extend past the second 
fastener hole, accomplish either paragraph (e)(1)(i) or (e)(1)(ii) 
of this AD.
    (i) Prior to further flight, install the time-limited repair. 
Prior to the accumulation of 4,500 flight cycles or within 18 months 
after accomplishment of the repair, whichever occurs first, replace 
the outboard chord. Or
    (ii) Prior to further flight, replace the outboard chord.

    Note 2: Boeing Alert Service Bulletin 737-53A1166 references 
Boeing Service Bulletin 737-53-1088 as an additional source of 
service information for procedures to replace the chord.

    (2) If any crack extends from the forward edge of the chord, or 
from the forward fastener hole, and extends past the second fastener 
hole, prior to further flight, replace the outboard chord in 
accordance with either the original issue or Revision 1 of the 
service bulletin.
    (f) Accomplishment of the actions specified in paragraph (f)(1) 
or (f)(2) of this AD in accordance with either Boeing Alert Service 
Bulletin 737-53A1166, dated June 30, 1994, or Boeing Service 
Bulletin 737-53A1166, Revision 1, dated May 25, 1995, constitutes 
terminating action for the requirements of this AD.
    (1) For airplanes on which no crack is found: Install the 
preventative modification.
    (2) For airplanes on which any crack is found: Prior to further 
flight, replace the cracked chord and install the preventative 
modification.

Alternative Methods of Compliance

    (g) 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

    (h) 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 July 2, 2001.
Vi L. Lipski,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 01-17122 Filed 7-9-01; 8:45 am]
BILLING CODE 4910-13-U