Airworthiness Directives; Boeing Model 727 Series Airplanes

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-NM-73-AD]

RIN 2120-AA64

Airworthiness Directives; Boeing Model 727 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 all Boeing Model 727 series

airplanes. This proposal would require a one-time

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detailed visual inspection of the fuselage skin and bonded doubler area

above the forward entry doorway to detect fatigue cracking or the

existence of certain repairs, and follow-on corrective actions, if

necessary. This action also would require a preventive modification or

full-sized repair doubler, as applicable. This proposal is prompted by

reports of fatigue cracking in the fuselage skin and bonded doublers in

the forward and aft corners above the forward entry doorway. The

actions specified by the proposed AD are intended to prevent such

fatigue cracking of the fuselage skin and bonded doubler, which could

result in reduced structural integrity and consequent loss of cabin

pressurization.

DATES: Comments must be received by January 21, 2000.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

Administration (FAA), Transport Airplane Directorate, ANM-114,

Attention: Rules Docket No. 99-NM-73-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.

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: Walter Sippel, Aerospace Engineer,

Airframe Branch, ANM-120S, FAA, Transport Airplane Directorate, Seattle

Aircraft Certification Office, 1601 Lind Avenue, SW., Renton,

Washington 98055-4056; telephone (425) 227-2774; 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 notice may be changed in

light of the comments received.

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 Number 99-NM-73-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. 99-NM-73-AD, 1601 Lind Avenue, SW., Renton, Washington

98055-4056.

Discussion

On February 18, 1994, the FAA issued AD 94-05-04, amendment 39-8842

(59 FR 13442, March 22, 1994), applicable to certain Boeing Model 727

series airplanes, to require incorporation of certain structural

modifications. That action was prompted by an evaluation by the Model

727 Structures Working Group, comprised of aircraft operators,

manufacturers, and the FAA. This Working Group evaluated Boeing service

bulletins that must be included as part of the ``Aging Airplane

Structural Modification Program.'' The actions specified by that AD are

intended to prevent degradation in the structural capabilities of the

affected airplanes. Those actions also reflect the FAA's decision that

long-term continued operational safety should be assured by actual

modification of the airframe rather than repetitive inspections.

Since the issuance of AD 94-05-04, the FAA has determined that

additional action (specified by Boeing Service Bulletin 727-53-0186,

Revision 1, dated May 21, 1992) is required to include certain

airplanes that are excluded in the applicability of that AD. Because AD

94-05-04 only requires modification of the airplane structure if no

cracking is detected in the fuselage skin and bonded doubler area above

the forward entry doorway, some airplanes do not have the full-sized

repair doubler installed. In addition, there is no mandatory

requirement to inspect airplanes on which the half- or full-sized

repair doubler has been installed to repair any crack that exceeds 2.5

inches or is located in the bear strap. Such conditions, if not

corrected, could result in a degradation in the structural capabilities

of the affected airplanes. In light of this, the FAA has determined

that corrective action is required for airplanes on which only a half-

sized repair doubler has been accomplished, or on which either a half-

or full-size repair doubler is found and any crack exceeds 2.5 inches

or is located in the bear strap. Accomplishment of the inspection and

corrective actions required by this AD is intended to ensure the

structural integrity of such airplanes, and to reduce the extent of

crack propagation (i.e., not to exceed 2.5 inches) in the fuselage skin

and bonded doublers above the upper area of the doorway. Such action

also reflects the FAA's decision that long-term continued operational

safety would be better assured by modification of the airframe, rather

than by repetitive inspections.

Explanation of Relevant Service Information

The FAA has reviewed and approved Boeing Service Bulletin 727-53-

0186, Revision 1, dated May 21, 1992, which describes procedures for

repetitive close (detailed) visual inspections to detect cracking of

the fuselage skin and bonded doubler area above the forward entry

doorway. Among other things, this service bulletin also describes

procedures for the accomplishment of either a preventive modification

(fabricating and installing a preventive modification doubler) or a

full-sized repair doubler of the upper area of the doorway skin.

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 the Service Information and the Proposed AD

Operators should note that the service bulletin recommends a visual

inspection for cracks ``at 40,000 cycles'' for airplanes that have not

yet accumulated 40,000 total flight cycles, and an inspection ``within

3,000 flight cycles'' for airplanes that have accumulated more than

40,000 total flight cycles. The service bulletin also recommends a

repetitive inspection interval of 3,000 flight cycles, and

accomplishment of either a preventive

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modification or a full-sized repair doubler prior to the accumulation

of 60,000 total flight cycles. However, paragraph (a) of this proposed

AD requires accomplishment of a one-time detailed visual inspection and

either the preventive modification or full-sized repair doubler ``prior

to the accumulation of 60,000 total flight cycles.'' This proposed AD

does not require repetitive inspections prior to modification or

repair. The FAA points out that cracks in the fuselage skin and bonded

doubler area above the forward entry doorway have not been found to be

a safety factor prior to the accumulation of 60,000 total flight

cycles. Therefore, the FAA considers that accomplishment of the actions

required by paragraph (a) of this proposed AD would provide an adequate

level of operational safety.

Operators also should note that the service bulletin specifies

three repair options, which include a procedure for installing a half-

sized repair doubler in the forward corner or aft area of the doorway

skin. However, this proposed AD requires installing a full-sized repair

doubler rather than a half-sized repair doubler.

Operators also should note that the service bulletin specifies

contacting the manufacturer if any repair was previously accomplished

for cracking that exceeded 2.5 inches, or if a crack was repaired in

the bear strap. However, this proposed AD requires that such repairs be

accomplished in accordance with a method approved by the 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 FAA to make such

findings.

Operators also should note that, although the service bulletin

specifies a ``close visual inspection,'' this proposed AD requires a

``detailed visual inspection.''

Other Relevant Rulemaking

Accomplishment of certain actions required by this proposed AD

would constitute terminating action for the requirements specified in

paragraph (a) of AD 94-05-04 with respect to the modification specified

in Boeing Service Bulletin 727-53-0186, dated April 27, 1989. This

service bulletin is one of many service bulletins referenced in Boeing

Document D6-54860, Revision G, Appendix A.3, dated March 5, 1993. All

other service bulletins referenced in that document still apply.

Cost Impact

There are approximately 1,429 airplanes of the affected design in

the worldwide fleet. The FAA estimates that 887 airplanes of U.S.

registry would be affected by this proposed AD.

The FAA estimates that it would take approximately 1 work hour per

airplane to accomplish the inspection of the fuselage skin and bonded

doubler area, and that the average labor rate is $60 per work hour.

Based on these figures, the cost impact of the proposed AD on U.S.

operators is estimated to be $53,220, or $60 per airplane.

The FAA estimates that it would take approximately 27 work hours

per airplane to accomplish the preventive modification or full-sized

repair doubler, and that the average labor rate is $60 per work hour.

Required parts would cost approximately $979 per airplane. Based on

these figures, the cost impact of the proposed AD on U.S. operators is

estimated to be $2,305,313, or $2,599 per airplane.

The cost impact figures discussed above are based on assumptions

that no operator has yet accomplished any of the proposed requirements

of this AD action, and that no operator would accomplish those actions

in the future if this AD were not adopted.

Regulatory Impact

The regulations proposed herein would 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

proposal would not have sufficient federalism implications to warrant

the preparation of a Federalism Assessment.

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 99-NM-73-AD.

Applicability: All Model 727 series 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 (c) 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 fatigue cracking of the fuselage skin and bonded

doubler area above the forward entry doorway, which could result in

reduced structural integrity and consequent loss of cabin

pressurization, accomplish the following:

Detailed Visual Inspection

(a) Prior to the accumulation of 60,000 total flight cycles, or

within 3,000 flight cycles after the effective date of this AD,

whichever occurs later: Perform a one-time detailed visual

inspection of the fuselage skin and bonded doubler area above the

forward entry doorway to detect fatigue cracking or the existence of

a previous repair, in accordance with Boeing Service Bulletin 727-

53-0186, Revision 1, dated May 21, 1992.

Corrective Action

(1) If no crack or repair is detected, prior to further flight,

perform the preventive modification in accordance with the service

bulletin. No further action is required by this AD.

(2) If any crack but no repair is detected, prior to further

flight, accomplish the actions required by paragraph (a)(2)(i),

(a)(2)(ii), or (a)(2)(iii), as applicable.

(i) If any crack is less than or equal to 2.5 inches, perform

the full-sized repair doubler in accordance with Boeing Service

Bulletin

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727-53-0186, Revision 1, dated May 21, 1992. Accomplishment of this

action constitutes terminating action for the requirements of this

AD.

(ii) If any crack exceeds 2.5 inches, repair in accordance with

a method approved by the Manager, Seattle Aircraft Certification

Office (ACO), FAA, Transport Airplane Directorate; or in accordance

with data meeting the type certification basis of the airplane

approved by a Boeing Company Designated Engineering Representative

(DER) 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, or the Boeing DER, as required by this paragraph, the

approval letter must specifically reference this AD.

(iii) If any crack in the bear strap is detected, repair in

accordance with a method approved by the Manager, Seattle Aircraft

Certification Office (ACO), FAA, Transport Airplane Directorate; or

in accordance with data meeting the type certification basis of the

airplane approved by a Boeing Company DER 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, or the Boeing DER, as

required by this paragraph, the approval letter must specifically

reference this AD.

(3) If any repair is found, accomplish paragraph (a)(3)(i),

(a)(3)(ii), or (a)(3)(iii), of this AD, as applicable.

(i) If a full-sized repair doubler is found, as specified by

Boeing Service Bulletin 727-53-0186, dated April 27, 1989, or

Revision 1, dated May 21, 1992, and any crack is less than or equal

to 2.5 inches, no further action is required by this AD.

(ii) If a half-sized repair doubler is found, as specified by

Boeing Service Bulletin 727-53-0186, dated April 27, 1989, or

Revision 1, dated May 21, 1992, and any crack is less than or equal

to 2.5 inches and is not in the bear strap: Prior to further flight,

perform the full-sized repair doubler in accordance with Boeing

Service Bulletin 727-53-0186, Revision 1, dated May 21, 1992. No

further action is required by this AD.

(iii) If a half-sized or full-sized repair doubler is found, as

specified by the service bulletin, and any crack exceeds 2.5 inches

or is located in the bear strap: Prior to further flight, repair in

accordance with a method approved by the Manager, Seattle Aircraft

Certification Office (ACO), FAA, Transport Airplane Directorate; or

in accordance with data meeting the type certification basis of the

airplane approved by a Boeing Company DER 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, or the Boeing DER, as

required by this paragraph, the approval letter must specifically

reference this AD.

Note 2: For the purposes of this AD, a detailed visual

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 an

intensity deemed appropriate by the inspector. Inspection aids such

as mirrors, magnifying lenses, etc. may be used. Surface cleaning

and elaborate access procedures may be required.''

Terminating Action for AD 94-05-04

(b) Accomplishment of the requirements of this AD constitutes

terminating action for the requirements of paragraph (a) of AD 94-

05-04, amendment 39-8842 (which are required to be accomplished in

accordance with Appendices A.3, B.3, and C.3 of Boeing Document

Number D6-54860, ``Aging Airplane Service Bulletin Structural

Modification and Inspection Program--Model 727,'' Revision G, dated

March 5, 1993), with respect to the modification specified in Boeing

Service Bulletin 727-53-0186, dated April 27, 1989. All other

service bulletins referenced in Boeing Document Number D6-54860

still apply.

Alternative Methods of Compliance

(c) 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, 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

(d) Special flight permits may be issued in accordance with

Secs. 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.

D.L. Riggin,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 99-31680 Filed 12-6-99; 8:45 am]

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