[Federal Register Volume 64, Number 168 (Tuesday, August 31, 1999)]
[Rules and Regulations]
[Pages 47377-47382]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-22397]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97-NM-03-AD; Amendment 39-11271; AD 99-18-05]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 727 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment adopts a new airworthiness directive (AD), 
applicable to all Boeing Model 727 series airplanes, that requires 
repetitive inspections to detect cracks in the forward flange of the 
vertical beam of the aft pressure bulkhead at certain buttock lines, 
and installation of a splice repair, if necessary. The amendment also 
requires installation of a preventative modification on the vertical 
beam of the door frame in certain cases. This amendment is prompted by 
reports of fatigue cracks found in the vertical beam web and forward 
flange of the aft pressure bulkhead. The actions specified by this AD 
are intended to detect and correct

[[Page 47378]]

such fatigue cracking, which could result in the inability of the 
subject vertical beam to withstand the fail-safe loads, and consequent 
loss of cabin pressurization.

DATES: Effective October 5, 1999.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of October 5, 1999.

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: Walter Sippel, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 
1601 Lind Avenue, SW., Renton, Washington; telephone (425) 227-2774; 
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 all Boeing Model 727 series 
airplanes was published in the Federal Register on July 18, 1997 (62 FR 
38493). That action proposed to require repetitive inspections to 
detect cracks in the forward flange of the vertical beam of the aft 
pressure bulkhead at certain buttock lines, and installation of a 
splice repair, if necessary. That action also proposed to require 
installation of a preventative modification on the vertical beam of the 
door frames in certain cases.

Comments Received

    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due consideration has been given to 
the comments received.
    Two commenters support the proposed rule.

Request to Correct Service Information

    One commenter states that the last sentence under the heading 
``Explanation of Relevant Service Information'' of the proposed AD 
incorrectly references Boeing Service Bulletin 727-53-0055 as ``an 
additional source of service information for identical procedures to 
repair and modify the affected area.'' The commenter adds that Boeing 
Service Bulletin 727-53-0055 specifies a splice installation only if 
cracks are beyond repair/modification limits, whereas Boeing Service 
Bulletin 727-53-0210, dated April 1, 1993, specifies a splice repair 
and modification any time cracks are found.
    The FAA does not concur that the reference to Boeing Service 
Bulletin 727-53-0055 is incorrect in the proposed AD. Although Boeing 
Service Bulletins 727-53-0055 and 727-53-0210 specify an inspection of 
the vertical beam at different locations, both service bulletins 
specify the same procedures for accomplishing the preventative 
modification and the splice repair. In light of this, the FAA considers 
that the reference to Boeing Service Bulletin 727-53-0055 is correct. 
However, the ``Explanation of Relevant Service Information'' does not 
reappear in the final rule; therefore, no change to the final rule is 
necessary in this regard.

Requests to Revise the Cost Estimate

    Three commenters request that the cost estimate in the proposed AD 
be revised.
    One commenter estimates that access to the affected area and 
removal and installation of the lavatories and walls would require 80 
hours for a fleet cost of $389,000 for the inspection, total out-of-
service costs of $1,285,380, additional inspection costs of $728,382 
because of a disruption of normal ``C'' checks, and an inspection-only 
cost of $2,402,762. The commenter adds that the proposed AD requires 
inspections within 1,500 flight cycles, which would not allow the 
airplane to be scheduled into normal ``C'' checks and would necessitate 
its removal from service for approximately 90 days.
    Another commenter estimates approximately 10 hours for the 
inspections. This estimate is based on 4 hours to gain access to the 
inspection area, 2 hours to accomplish the inspection, and 4 hours to 
close up the inspection area, with a cost per airplane of approximately 
$600 and a fleet cost of $632,400.
    Another commenter estimates 200 hours (two mechanics for 5 working 
days) to remove/replace the lavatories and perform the inspections. The 
commenter states that, because the proposed initial inspection interval 
of 1,500 flight cycles is 500 flight cycles less than its current ``C'' 
check interval, 25 percent of its Model 727 fleet would need to be 
removed from service on a ``special route'' basis and flown to a 
maintenance base to accomplish the inspection. The commenter adds that 
this schedule disruption and the downtime added to routine ``C'' check 
visits would severely impact operations and result in unnecessary 
expense and burden.
    The FAA does not concur with the commenters' requests to revise the 
cost estimate in the AD. The FAA based its estimate on the cost 
estimate recommended in Boeing Service Bulletin 727-53-0210, dated 
April 1, 1993; as revised by Notice of Status Change 727-53-0210 NSC 1, 
dated June 17, 1993; and Notice of Status Change 727-53-0210 NSC 2, 
dated September 21, 1995. In that service bulletin, the time for 
removal and installation of lavatories is not included in the estimate 
because those times vary significantly based on the type of lavatories 
installed and whether lavatory galleys are installed (freighters have 
neither), and whether or not other inspections are being accomplished.
    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, where safety considerations allow, the FAA attempts to 
impose compliance times that generally coincide with operators' 
maintenance schedules. However, because operators' schedules vary 
substantially, the FAA is unable to accommodate every operator's 
optimal scheduling in each AD. Each AD does allow individual operators 
to obtain approval for extensions of compliance times, based on a 
showing that the extension will not affect safety adversely. Therefore, 
the FAA does not consider it appropriate to attribute to the AD, the 
costs associated with the type of special scheduling that might 
otherwise be required. Furthermore, because the FAA generally attempts 
to impose compliance times that coincide with operators' scheduled 
maintenance, the FAA considers it inappropriate to attribute the cost 
associated with aircraft ``downtime'' to the cost of the AD, because, 
normally, compliance with the AD will not necessitate any additional 
downtime beyond that of a regularly scheduled maintenance hold. Even 
if, in some cases, additional downtime is necessary for some airplanes, 
the FAA does not possess sufficient information to evaluate the number 
of airplanes that may be so affected or the amount of additional 
downtime that may be

[[Page 47379]]

required. No change to the final rule is necessary in this regard.

Request to Revise Compliance Time

    One commenter requests revising Note 2 [following paragraph (a)(2) 
of the proposed AD]. The commenter states that Note 2 does not agree 
with the service bulletin. The commenter considers that if the splice 
repair has been accomplished, the inspection threshold should be 20,000 
flight cycles since installation of the splice repair; whereas, if the 
splice repair has not been accomplished, the threshold should be 20,000 
flight cycles from time of delivery.
    The FAA agrees with the commenter's remark that Note 2 of the 
proposed AD does not correspond with the service bulletin, and has 
removed the note from this final rule. In reviewing this comment, the 
FAA notes that the compliance time specified in the proposed AD differs 
from the service bulletin. However, the FAA's intent was that the 
compliance times coincide with the service bulletin.
    Further, the FAA notes that the splice repair or the preventative 
modification may have been installed independently on the left and 
right vertical beams. In such cases, in order to allow those beams to 
be inspected independently, the FAA has revised the final rule to 
specify compliance times from the time of installation of the splice 
repair or preventative modification of the vertical beams. The 
compliance times in paragraphs (a)(1) and (a)(2) of this AD have been 
revised to coincide with the service bulletin, as follows:
     For any vertical beam on which neither the preventative 
modification nor the splice repair have been accomplished, paragraph 
(a)(1) of this AD requires an inspection prior to the accumulation of 
20,000 total flight cycles, or within 1,500 flight cycles after the 
effective date of this AD, whichever occurs later.
     For any vertical beam on which the preventative 
modification has not been accomplished and the splice repair has been 
accomplished, paragraph (a)(2) of this AD requires an inspection prior 
to the accumulation of 20,000 flight cycles since installation of the 
splice repair, or within 1,500 flight cycles after the effective date 
of this AD, whichever occurs later.

Request to Extend Compliance Time for Inspections

    One commenter requests an inspection interval of 4,000 flight 
cycles, with repeat inspections every 4,000 flight cycles if the 
preventative modification has not been accomplished. The commenter 
states that the 4,000 flight cycle limit would allow the operator to 
remove the lavatories, accomplish the inspection, and install the 
preventative modification during scheduled corrosion (R-check) visits. 
The commenter adds that these corrosion visits are of sufficient 
duration to absorb the additional work without undue impact, and that 
its current fleet plans include the initial inspection and installation 
of the preventative modification during the same visit. The commenter 
considers that the 4,000 flight cycles for the initial inspection is 
justified from a technical standpoint because it has been conducting 
routine intensified inspections and repairs of the aft pressure 
bulkhead vertical beam at scheduled heavy maintenance visits since 
1988. The commenter also states that the inspection interval of 1,500 
flight cycles is 500 flight cycles less than its current ``C-check'' 
interval. The commenter adds that, unless the inspection intervals are 
increased, 25% of its 727 fleet would be removed from service on a 
``special route'' basis and flown to base maintenance. The commenter 
considers that this schedule disruption and the additional downtime 
added to routine C-checks would severely impact operations and result 
in unnecessary expense and burden, whereas inspection intervals of 
4,000 flight cycles would allow sufficient time to accomplish the work 
without undue impact.
    The FAA does not concur with the commenter's request to revise the 
compliance times, as described. The grace period for the initial 
inspection and the inspection intervals specified in this AD were 
determined based on engineering analysis of crack growth rates and the 
type of detection methods used. The compliance times proposed by the 
commenter do not ensure that cracking will be detected in a timely 
manner.
    Another commenter requests that the initial inspection threshold 
required by paragraph (a)(1) of the proposed AD be increased from 
``18,500 total flight cycles'' to ``30,000 total flight cycles.'' The 
commenter states that the two reports of cracks have both occurred at 
48,000 and 48,500 flight cycles. The commenter adds that it considers 
the inspection threshold of 18,500 flight cycles to be premature 
because cracking did not occur before 48,000 flight cycles.
    The FAA does not concur that the inspection threshold required by 
paragraph (a)(1) of the final rule, should be increased to 30,000 total 
flight cycles. While Boeing Service Bulletin 727-53-0210 specifies that 
cracks occurred at thresholds exceeding 48,000 flight cycles, the FAA 
considers that the extent of such cracking was unsafe. In developing an 
appropriate compliance time for this AD, the FAA considered the degree 
of urgency associated with addressing the subject unsafe condition, the 
average utilization of the affected fleet, the time necessary to 
perform the inspection, and the practical aspects of performing the 
inspections. In consideration of these factors, the FAA finds that the 
compliance time required by paragraph (a)(1) of this AD represents an 
appropriate threshold for accomplishment of the inspection in a timely 
manner within the fleet and still maintain an adequate level of safety. 
The FAA considers that the inspections can be accomplished within an 
interval of time that parallels normal scheduled maintenance for a 
majority of affected operators, and within an appropriate interval to 
prevent the initiation and propagation of fatigue cracking in the 
vertical beam web and forward flange of the aft pressure bulkhead.
    Because the objective of the proposed inspections is to detect and 
correct these cracks before the extent of the cracking found on those 
airplanes, the FAA has determined that the inspection threshold 
specified in paragraph (a)(1) of the AD is appropriate. No change was 
made to the final rule in this regard.

Request to Defer Accomplishment of Modification on Both Frames

    One commenter states that operators should have the option of 
``terminating the inspection'' on both frames. The FAA infers that the 
commenter requests that the repair be required for cracked door frames 
only, and that operators be allowed to accomplish the modification at a 
time established by the operator. The FAA has determined that an 
appropriate level of safety can be assured by accomplishment of both 
the repair and modification on all cracked door frames prior to further 
flight, as recommended by the manufacturer. Additionally, repetitive 
inspections of uncracked door frames must be accomplished at the 
intervals specified in this AD. Paragraphs (b) and (c) of this AD have 
been revised accordingly.

Request to Change Installation Requirement for Splice Repair

    One commenter requests that an operator should be allowed to 
install the splice repair only (not the preventative modification) on a 
cracked door frame, followed by repeat inspections beginning at 18,500 
flight cycles.
    The FAA does not concur that an adequate level of safety can be 
ensured

[[Page 47380]]

by requiring only the splice repair and continued inspection beginning 
at 18,500 flight cycles after repair of the cracked vertical beam. The 
FAA points out that the commenter provided no technical justification 
for accomplishing only the repair with repetitive inspections of a 
cracked vertical beam; the FAA considers cracking in the forward flange 
of the vertical beam of the aft pressure bulkhead to be a significant 
safety issue.
    In developing the appropriate actions (i.e., repair, modification, 
and repetitive inspections) for this AD, the FAA considered not only 
those safety issues but the recommendations of the manufacturer, the 
availability of parts, and the practical aspect of accomplishing the 
required inspections within an interval of time that parallels normal 
scheduled maintenance for the majority of affected operators. The FAA 
considers that the repair, modification, and repetitive inspections 
required by the proposed AD are necessary to ensure the timely 
detection of cracking.
    To further clarify the required repetitive inspection intervals of 
uncracked vertical beams and the required actions for cracked vertical 
beams, paragraphs (b)(1)(i) and (b)(1)(ii) have been added, and 
paragraphs (b), (b)(1), (b)(2), and (c) have been revised in the final 
rule.

Requests to Clarify the Repetitive Inspection Intervals

    One commenter requests that paragraph (a)(2) of the proposed AD, 
which specifies repetitive inspections at intervals not to exceed 6,000 
flight cycles, be divided into two sections, one for airplanes 
inspected at 3,000 flight cycles and another for airplanes inspected at 
6,000 flight cycles. The commenter states that, for airplanes with the 
modification accomplished previously, paragraph (a)(2) requires 
repetitive inspections thereafter at intervals not to exceed 6,000 
flight cycles; however, paragraph (b)(2) requires such inspections at 
intervals not to exceed 3,000 flight cycles. The commenter considers 
that the FAA's intent was to require such inspections thereafter at 
intervals not to exceed 3,000 flight cycles for airplanes that do not 
have preventative modifications installed.
    Another commenter states that the actions required by paragraphs 
(a)(2) and (b)(2) seem to conflict. That commenter suggests changing 
the wording in those paragraphs to clarify that repetitive inspections 
are not to exceed 3,000 flight cycles for unmodified structure or 6,000 
flight cycles for modified structure.
    The FAA concurs. The FAA agrees that clarification of the number of 
repetitive inspection intervals specified in paragraphs (a)(2) and 
(b)(2) of the proposed AD is necessary. The FAA also agrees that it is 
necessary to distinguish between the number of flight cycles required 
for modified and unmodified structures in the final rule. In light of 
this, the FAA has deleted the repetitive inspections specified in 
paragraph (a)(2) of the proposed AD, and has specified the repetitive 
inspection intervals required for modified and unmodified structures in 
paragraphs (b)(1)(i) and (b)(1)(ii) of the final rule.

Request to Allow Repair/Modification During D-Check

    One commenter requests that the repair and modification required by 
the proposed AD be accomplished during ``D-check'' opportunities 
because the actions required could exceed 200 hours and possibly 4 
days.
    The FAA does not concur. The FAA points out that the compliance 
times specified in the AD for the repair and preventative modification 
were based on the information included in Boeing Service Bulletin 727-
53-0210, and that it considers these estimates appropriate. The FAA has 
determined that continued flight with unmodified structure, which has 
begun to crack and is likely to continue cracking, does not provide an 
acceptable level of safety. In light of these considerations, no change 
has been made to the final rule in this regard.

Request to Correct Typographical Error

    Two commenters request a correction to paragraph (c) of the NPRM to 
delete a reference to paragraph (a)(3). The FAA agrees that paragraph 
(a)(3) did not exist in the NPRM and that a reference to that paragraph 
should not have been included in paragraph (c) of the NPRM. However, 
the final rule now includes a paragraph (a)(3), which is appropriately 
referenced in paragraph (c) of this final rule.

Request to Permit ``Industry-Accepted Shop Practices''

    One commenter requests including a statement in the final rule 
allowing the use of industry-accepted shop practices in lieu of 
processes and finishes (e.g., primer, paint, or sealant) that are 
specified by the original equipment manufacturer (OEM) and that have no 
effect on the intent of the AD. The commenter states that industry-
accepted shop practices would allow operators to use equivalent methods 
and types of finishes without first having to seek approval from the 
FAA for an alternative method of compliance.
    The FAA does not concur with the request to allow the use of 
industry-accepted shop practices instead of the alternative method of 
compliance required by paragraph (d) of the proposed AD. The FAA points 
out that such practices could vary from operator to operator and, thus, 
make it impossible to ensure the appropriate level of safety required. 
In light of this, the FAA has determined that it is unacceptable to 
delegate an undefined practice. This final rule requires that the 
actions be accomplished in accordance with the procedures specified in 
Boeing Service Bulletin 727-53-0210. An industry-accepted shop practice 
may be used only if approved as an alternative method of compliance in 
accordance with paragraph (d) of the final rule. No change has been 
made to paragraph (d) of the final rule.

Explanation of Changes Made to the Proposal

    Operators should note that the following changes were made to this 
AD to clarify certain terminology:
     The term ``aft fuselage bulkhead,'' which was used in the 
proposed AD, has been changed to ``aft pressure bulkhead'' in the final 
rule. This change was made in the Summary and throughout this AD to 
correlate with the term used in Boeing Service Bulletin 727-53-0210 and 
because it more accurately describes the bulkhead.
     The term ``close visual inspections,'' as specified in 
certain paragraphs of the proposed AD, has been changed to ``detailed 
visual inspections.'' This terminology is considered to be technically 
equivalent. This change was made in paragraphs (b)(1)(i), (b)(1)(ii), 
(b)(2), and (c) of the final rule. In addition, Note 2 has been added 
to the final rule, following paragraph (a)(3), to include the 
definition of a ``detailed visual inspection.''

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 1,560 Model 727 series airplanes of the 
affected design in the worldwide fleet. The FAA

[[Page 47381]]

estimates that 1,054 airplanes of U.S. registry will be affected by 
this AD.
    It will take approximately 2 work hours per airplane to accomplish 
the required inspections, at an average labor rate of $60 per work 
hour. Based on these figures, the cost impact of the inspection 
required by this AD on U.S. operators is estimated to be $126,480, or 
$120 per airplane, per inspection cycle.
    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.
    Should an operator be required to accomplish the preventative 
modification, it will take approximately 100 work hours per airplane to 
accomplish, at an average labor rate of $60 per work hour. The cost of 
required parts could range between $910 and $1,042 per preventative 
modification kit (2 kits per airplane). Based on these figures, the 
cost impact of the preventative modification required by this AD on 
U.S. operators is estimated to be between $7,820, and $8,084 per 
airplane.
    Should an operator be required to accomplish the splice repair, it 
will take approximately 148 work hours per airplane to accomplish, at 
an average labor rate of $60 per work hour. Required parts will cost 
approximately $3,545 per airplane ($1,756 for the splice repair kit on 
the left side, and $1,789 for the splice repair kit on the right side). 
Based on these figures, the cost impact of the splice repair required 
by this AD on U.S. operators is estimated to be $12,425 per airplane.

Regulatory Impact

    The regulations adopted herein will not have substantial direct 
effects 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, in accordance with Executive Order 12612, it is 
determined that this final rule does not have sufficient federalism 
implications to warrant the preparation of a Federalism Assessment.
    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:

99-18-05  Boeing: Amendment 39-11271. Docket 97-NM-03-AD.

    Applicability: All Model 727 airplanes, 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 (d) 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 in the forward flange of 
the vertical beam of the aft pressure bulkhead, which could result 
in the inability of the subject vertical beam to withstand the fail-
safe loads, and consequent loss of cabin pressurization, accomplish 
the following:

Initial Inspections

    (a) Perform a detailed visual inspection and a high frequency 
eddy current (HFEC) inspection to detect cracks in the forward 
flange of the vertical beam at left and right buttock line 17.8 from 
water lines 265 through 288 inclusive, in accordance with Boeing 
Service Bulletin 727-53-0210, dated April 1, 1993, as revised by 
Notice of Status Change 727-53-0210 NSC 1, dated June 17, 1993, and 
Notice of Status Change 727-53-0210 NSC 2, dated September 21, 1995; 
at the time specified in paragraph (a)(1), (a)(2), or (a)(3) of this 
AD, as applicable.
    (1) For any vertical beam on which neither the preventative 
modification nor the splice repair have been accomplished, as 
specified in Boeing Service Bulletin 727-53-0210, dated April 1, 
1993; or Boeing Service Bulletin 727-53-0055, Revision 6, dated 
February 28, 1986, Revision 7, dated March 5, 1987, Revision 8, 
dated December 17, 1987, or Revision 9, dated August 3, 1989: 
Inspect prior to the accumulation of 20,000 total flight cycles, or 
within 1,500 flight cycles after the effective date of this AD, 
whichever occurs later.
    (2) For any vertical beam on which the preventative modification 
has not been accomplished and the splice repair has been 
accomplished, as specified in Boeing Service Bulletin 727-53-0210, 
dated April 1, 1993, or Boeing Service Bulletin 727-53-0055, 
Revision 6, dated February 28, 1986, Revision 7, dated March 5, 
1987, Revision 8, dated December 17, 1987, or Revision 9, dated 
August 3, 1989: Inspect prior to the accumulation of 20,000 flight 
cycles since installation of the splice repair, or within 1,500 
flight cycles after the effective date of this AD, whichever occurs 
later.
    (3) For any vertical beam on which the preventative modification 
has been accomplished and the splice repair has or has not been 
accomplished, as specified in Boeing Service Bulletin 727-53-0210, 
dated April 1, 1993, or Boeing Service Bulletin 727-53-0055, 
Revision 6, dated February 28, 1986, Revision 7, dated March 5, 
1987, Revision 8, dated December 17, 1987, or Revision 9, dated 
August 3, 1989: Inspect prior to the accumulation of 40,000 flight 
cycles since installation of the preventative modification, or 
within 1,500 flight cycles after the effective date of this AD, 
whichever occurs later.

    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.''

Repetitive Inspections and Corrective Action

    (b) If no crack is detected during any inspection required by 
paragraph (a)(1), (a)(2), or (a)(3) of this AD, accomplish either 
paragraph (b)(1) or (b)(2) of this AD, as applicable, in accordance 
with Boeing Service Bulletin 727-53-0210, dated April 1, 1993, as 
revised by Notice of Status Change 727-53-0210 NSC 1, dated June 17, 
1993, and Notice of Status Change 727-53-0210 NSC 2, dated September 
21, 1995.
    (1) For any vertical beam on which the preventative modification 
has not been accomplished, as specified in paragraphs (a)(1) and 
(a)(2) of this AD, accomplish either paragraph (b)(1)(i) or 
(b)(1)(ii) of this AD in accordance with the service bulletin.

[[Page 47382]]

    (i) Prior to further flight, install the preventative 
modification. Prior to the accumulation of 40,000 flight cycles 
following accomplishment of a preventative modification, accomplish 
the detailed visual and HFEC inspections specified in paragraph (a) 
of this AD for any modified area. Repeat those inspections 
thereafter at intervals not to exceed 6,000 flight cycles for that 
modified area. Or
    (ii) Repeat the detailed visual and HFEC inspections specified 
in paragraph (a) of this AD for any unmodified area at intervals not 
to exceed 3,000 flight cycles.
    (2) For any vertical beam on which the preventative modification 
has been accomplished, repeat the detailed visual and HFEC 
inspections specified in paragraph (a) of this AD thereafter at 
intervals not to exceed 6,000 flight cycles.
    (c) If any crack is detected during any inspection required by 
paragraph (a)(1), (a)(2), or (a)(3) of this AD, prior to further 
flight, install a splice repair and preventative modification to all 
cracked door frames, in accordance with Boeing Service Bulletin 727-
53-0210, dated April 1, 1993, as revised by Notice of Status Change 
727-53-0210 NSC 1, dated June 17, 1993, and Notice of Status Change 
727-53-0210 NSC 2, dated September 21, 1995. Prior to the 
accumulation of 40,000 flight cycles following accomplishment of the 
preventative modification, accomplish the detailed visual and HFEC 
inspections specified in paragraph (a) of this AD. Repeat those 
inspections specified in paragraph (a) for that repaired and 
modified area thereafter at intervals not to exceed 6,000 flight 
cycles.

Alternative Method of Compliance

    (d) 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, Transport Airplane Directorate. 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

    (e) 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

    (f) The actions shall be done in accordance with Boeing Service 
Bulletin 727-53-0210, dated April 1, 1993, as revised by Notice of 
Status Change 727-53-0210 NSC 1, dated June 17, 1993, and Notice of 
Status Change 727-53-0210 NSC 2, dated September 21, 1995. 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.
    (g) This amendment becomes effective on October 5, 1999.

    Issued in Renton, Washington, on August 23, 1999.
Vi L. Lipski,
Acting Manager,
Transport Airplane Directorate,
Aircraft Certification Service.
[FR Doc. 99-22397 Filed 8-30-99; 8:45 am]
BILLING CODE 4910-13-U