Airworthiness Directives; Boeing Model 727 and 727C Series Airplanes

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-NM-293-AD]

RIN 2120-AA64

Airworthiness Directives; Boeing Model 727 and 727C Series

Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the adoption of a new airworthiness

directive (AD) that is applicable to certain Boeing Model 727 and 727C

series airplanes. This proposal would require one-time inspections of

the exterior body skin located at the forward corners of the mid-galley

door hinge cutouts to detect cracking, and corrective actions, if

necessary. This proposal also would require modification of the body

skin of the mid-galley door hinge cutouts. This proposal is prompted by

a report indicating that, during fatigue testing on a Boeing Model 727

series airplane, a crack was found in the body skin at the lower

forward corners of the mid-galley door hinge cutouts due to cabin

pressurization cycles. The actions specified by the proposed AD are

intended to prevent such fatigue cracking of the body skin, which could

result in reduced structural integrity of the fuselage and consequent

loss of cabin pressurization.

DATES: Comments must be received by January 6, 2000.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

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

Attention: Rules Docket No. 98-NM-293-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 Linda 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 98-NM-293-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. 98-NM-293-AD, 1601 Lind Avenue, SW., Renton, Washington

98055-4056.

Discussion

The FAA has received reports indicating that, during fatigue

testing on a Boeing Model 727 series airplane, a crack was found in the

body skin at the lower forward corners of the mid-galley door hinge

cutouts. The crack was attributed to fatigue induced by cabin

pressurization cycles. Such cracking, if not corrected, could result in

reduced structural integrity of the fuselage and consequent loss of

cabin pressurization.

Other Related Rulemaking

On January 16, 1990, the FAA issued AD 90-06-09, amendment 39-6488

(55 FR 8370, March 7, 1990), applicable to certain Boeing Model 727

series airplanes, which currently requires the incorporation of certain

structural modifications specified by Boeing Document No. D6-54860,

Revision C, dated December 11, 1989, ``Aging Airplane Service Bulletin

Structural Modification Program--Model 727.'' That Boeing document

references numerous Boeing service bulletins that specify various

modification actions that are mandated by AD 90-06-09. That AD was

prompted by reports of incidents involving fatigue cracking and

corrosion in transport category airplanes that were approaching or had

exceeded their design life goal. The actions required by that AD are

intended to prevent a degradation in the structural capabilities of the

affected airplanes, which could result in structural failure. That

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

operational safety should be assured by actual modification of the

airframe rather than repetitive inspection.

Since issuance of that AD, the FAA has determined that the same

unsafe condition addressed in that AD may exist on certain additional

Model 727 and 727C series airplanes. The FAA was advised that three

Model 727 and 727C series airplanes (line numbers 153, 290, and 339)

were omitted inadvertently from the applicability of AD 90-06-09

because those airplanes had been excluded inadvertently from the

effectivity of Section I.A. of Boeing Service Bulletin 727-53-0054,

Revision 1, dated November 16, 1989. Therefore, these additional

airplanes are also subject to the same unsafe condition addressed in AD

90-06-09.

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Explanation of Relevant Service Information

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

0054,

Revision 1, which describes a modification to the corners of the

hinge cutouts and provides a top kit and instructions for installing

doublers. Procedures include a close (detailed) visual inspection and a

high-frequency eddy current (HFEC) inspection of the forward upper and

lower corners of the mid-galley door hinge cutouts for cracks in the

body skin. If no cracks are found, procedures specify either a

modification, which includes modifying cutout corners and installing

doublers, or a reinspection at ``C'' check intervals until

accomplishment of the modification. If cracks are within specified

repair limits, procedures include stop-drilling cracks, modifying

cutout corners, and installing doublers. If cracks exceed specified

repair limits, procedures specify contacting the manufacturer for

repair instructions. Accomplishment of the modification is intended to

increase the fatigue life of the body skin adjacent to the forward

corners of the mid-galley door hinge cutouts.

The procedures specified by Revision 1 of the service bulletin are

essentially the same as those procedures included in Boeing Document

D6-54860, Revision C, as cited in AD 90-06-09, and the procedures

specified in the original issue of Boeing Service Bulletin 727-53-0054.

Accomplishment of the actions specified in AD 90-06-09 is

acceptable for compliance with the requirements of this proposed AD.

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

Revision 1 of the service bulletin described previously, except as

described below in the Differences section of this AD.

Since this AD expands the applicability of AD 90-06-09, the FAA has

considered a number of factors in determining whether to issue a new AD

or to supersede the ``old'' AD. Although the three additional airplanes

included in the applicability of this proposed AD were inadvertently

omitted from Boeing Service 727-53-0054, numerous other service

bulletins referenced in Boeing Document No. D6-54860, Revision C,

(cited in AD 90-06-09) included those additional airplanes in the

effectivity. The FAA also has considered the entire fleet size that

would be affected by superseding AD 90-06-09 and the consequent

workload associated with revising maintenance record entries. In light

of this, the FAA has determined that a less burdensome approach is to

issue a separate AD applicable only to these additional airplanes. This

proposed AD would not supersede AD 90-06-09; airplanes listed in the

applicability of AD 90-06-09 are required to continue to comply with

the requirements of that AD. This proposed AD is a separate AD action,

and is applicable only to Boeing Model 727 and 727C series airplanes,

line numbers 153, 290, and 339; certificated in any category.

Differences Between Proposed AD and Relevant Service Information

Operators should note that the proposed AD differs from Boeing

Service Bulletin 727-53-0054, Revision 1, as follows:

The effectivity of Revision 1 includes Model 727-100

series airplanes, line positions 1 through 474 inclusive. However, the

applicability of this proposal includes Model 727 and 727C series

airplanes, line numbers 153, 290, and 339 inclusive, which were

inadvertently omitted from AD-90-06-09.

Although Revision 1 specifies that, in certain cases,

repetitive inspections may be performed in lieu of a modification, this

proposal does not allow such action. Instead, this proposal would

require accomplishment of a repair and modification if cracking is

detected, or a modification if no cracking is detected. The FAA has

determined that long-term continued operational safety will be better

assured by design changes to remove the source of the problem, rather

than by repetitive inspections. Long-term inspections may not be

providing the degree of safety assurance necessary for the transport

airplane fleet. This, coupled with a better understanding of the human

factors associated with numerous continual inspections, has led the FAA

to consider placing less emphasis on inspections and more emphasis on

design improvements. The proposed repair and modification requirement

is in consonance with these conditions.

Paragraph III.C. of the Accomplishment Instructions of

Revision 1 specifies that if any crack is found that is greater than

1.00 inch, the manufacturer must be contacted for repair instructions.

However, this proposal requires the repair of those conditions to 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.

Figure 1 of Revision 1 specifies a ``close visual

inspection'' of the body skin at the forward corners of mid-galley door

hinge cutouts. However, this AD would require a ``detailed visual

inspection'' of the body skin at those locations.

Cost Impact

There are approximately 1,516 airplanes of the affected design in

the worldwide fleet. The FAA estimates that 3 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 required inspections of the body skin at the

corners of the mid-galley door hinge cutouts, and that the average

labor rate is $60 per work hour. Based on these figures, the cost

impact of the required inspections on U.S. operators is estimated to be

$180, or $60 per airplane.

The FAA also estimates that it would take approximately 28 work

hours per airplane to accomplish the repair and modification, and that

the average labor rate is $60 per work hour. Required parts would cost

approximately $1,023 per airplane. Based on these figures, the cost

impact of the proposed AD on U.S. operators is estimated to be $8,109,

or $2,703 per airplane.

The cost impact figure discussed above is based on assumptions that

no operator has yet accomplished any of the proposed requirements of

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

the future if this 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

[[Page 63755]]

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 98-NM-293-AD.

Applicability: Model 727 and 727C series airplanes, line numbers

153, 290, and 339 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 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 (b) 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 body skin at the forward

corners of the mid-galley door hinge cutouts, which could result in

reduced structural integrity of the fuselage and consequent loss of

cabin pressurization, accomplish the following:

One-Time Inspections

(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 and a high frequency eddy current inspection of the

exterior body skin located adjacent to the forward corners of the

mid-galley door hinge cutouts for cracking in accordance with Boeing

Service Bulletin 727-53-0054, Revision 1, dated November 16, 1989.

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

inspection is defined as: ``An intensive 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.''

Repairs and Modification

(1) If no cracking is found during any inspection, prior to

further flight, modify the body skin at the forward corners of the

mid-galley door hinge cutouts, in accordance with Boeing Service

Bulletin 727-53-0054, Revision 1, dated November 16, 1989. No

further action is required by this AD.

(2) If any cracking is found during any inspection, prior to

further flight, accomplish the requirements of either paragraph

(a)(2)(i) or (a)(2)(ii) of this AD, as applicable.

(i) If any crack is less than or equal to 1.00 inch, accomplish

the repair and modification in accordance with Boeing Service

Bulletin 727-53-0054, Revision 1, dated November 16, 1989. No

further action is required by this AD.

(ii) If any crack is greater than 1.00 inch, accomplish the

repair and modification 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 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. No further action is required by this AD.

Note 3: Accomplishment of the actions required by AD 90-06-09,

amendment 39-6488, is considered acceptable for compliance with this

AD.

Alternative Method of Compliance

(b) 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 4: 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

(c) 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 November 16, 1999.

D.L. Riggin,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 99-30372 Filed 11-19-99; 8:45 am]

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