Airworthiness Directives; Boeing Model 727 Series Airplanes

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]

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