Airworthiness Directives; Boeing Model 727-100, -100C, and -200 Series Airplanes

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-NM-74-AD]

RIN 2120-AA64

Airworthiness Directives; Boeing Model 727-100, -100C, and -200

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 727-100, -

100C, and -200 series airplanes. For certain airplanes, this proposal

would require a one-time inspection of certain fuselage circumferential

skin joints to determine the type of fasteners installed, and

replacement of any aluminum fasteners with steel fasteners, if

necessary; or modification of certain fuselage circumferential skin

joints; as applicable. For certain other airplanes, this proposal would

also require repetitive inspections to detect corrosion, sealant

deterioration, cracking, or disbonding; repair, if necessary; and

modification of certain fuselage circumferential skin joints. This

proposal is prompted by reports of corrosion between the body skins and

cold-bonded doublers at the fuselage circumferential skin joints. The

actions specified by the proposed AD are intended to prevent

delamination of the cold-bonded doublers, which could result in

corrosion of the body skins and doublers, and consequent reduced

structural capability of the fuselage circumferential skin joints.

DATES: Comments must be received by January 20, 2000.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

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

Attention: Rules Docket No. 99-NM-74-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: Walt 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-74-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-74-AD, 1601 Lind Avenue, SW., Renton, Washington

98055-4056.

Discussion

In 1990, the FAA issued AD 90-06-09, amendment 39-6488 (55 FR 8370,

March 7, 1990), which required incorporation of certain structural

modifications on certain Boeing Model 727 series airplanes, in

accordance with Boeing Document No. D6-54860, Revision C, dated

December 11, 1989, ``Aging Airplane Service Bulletin Structural

Modification Program--Model 727.'' One of those modifications was

replacement of countersunk fasteners installed at cold-bonded doublers

of fuselage circumferential skin joints at body stations (BS) 259, 360,

441, 481, and 681 with oversize, protruding-head fasteners. That AD was

prompted in part by reports of corrosion between the body skins and

cold-bonded doublers at the fuselage circumferential skin joints.

Delamination of the cold-bonded doublers allows moisture to enter voids

caused by the bond separation, which could result in corrosion of the

body skins and doublers, and consequent reduced structural capability

of the fuselage circumferential skin joints.

Since the issuance of AD 90-06-09, the airplane manufacturer has

notified the FAA that the incorrect fastener type was used in the

modification of the fuselage circumferential skin joints required by

that AD. Aluminum fasteners were used for that modification; the

airplane manufacturer now knows that aluminum fasteners reduce the

structural capability of the fuselage circumferential skin joints.

In 1990, the FAA also issued AD 90-26-09, amendment 39-6835 (55 FR

51403, December 14, 1990), which required repetitive inspections of

certain fuselage circumferential skin joints, and repair, if necessary,

in accordance with Boeing Service Bulletin 727-53-0084, Revision 4,

dated August 2, 1990. The modification of the fuselage circumferential

skin joints required by AD 90-06-09 was considered terminating action

for certain repetitive inspections required by AD 90-26-09.

Since the issuance of AD 90-26-09, the airplane manufacturer has

notified the FAA that certain airplanes were inadvertently not included

in the effectivity listing in paragraph I.A.1. of Boeing Service

Bulletin 727-53-0084, Revision 4, although they were included in the

effectivity statement in the summary of the service bulletin. The FAA

has determined that operators of those airplanes may not realize that

those airplanes are subject to AD 90-26-09. In addition, the airplane

manufacturer has notified the FAA that

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those same airplanes were also inadvertently not included in the

effectivity listing of Boeing Document No. D6-54860, Revision C, and

hence, were also omitted from the applicability of AD 90-06-09. Those

airplanes are subject to the same unsafe condition as the airplanes

that are included in the applicability statements of those two AD's.

Therefore, the FAA finds that additional rulemaking is necessary to

ensure that the unsafe condition is addressed on all affected

airplanes.

Explanation of Relevant Service Information

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

0084, Revision 4, dated August 2, 1990, which describes procedures for

repetitive inspections of the cold-bonded doublers of the fuselage

circumferential skin joints at BS 259, 360, 441, 481, and 681; and

repair, if necessary. The inspections include an external detailed

visual inspection to detect corrosion and sealant deterioration, a low

frequency eddy current (LFEC) inspection to detect corrosion, a high

frequency eddy current (HFEC) inspection to detect cracking, and an

internal detailed visual inspection to detect cracking, sealant

deterioration, or disbonding. The service bulletin also describes

procedures for modification of the cold-bonded doublers in those areas.

In addition, the service bulletin describes procedures for a one-time

inspection of the fuselage circumferential skin joints at BS 259, 360,

441, 481, and 681 to determine the type of fasteners installed, and

replacement of any aluminum fasteners with steel fasteners, if

necessary. Accomplishment of the actions specified in the service

bulletin is intended to adequately address the identified unsafe

condition.

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 Proposed Rule and Service Bulletin

Operators should note that, although the service bulletin specifies

that the manufacturer may be contacted for disposition of certain

repair conditions, this AD 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.

Operators should also note that, for those airplanes on which

modification of cold-bonded doublers of certain fuselage

circumferential skin joints has already been accomplished, this AD

proposes only to mandate the one-time inspection of the joints to

determine the type of fastener installed, and replacement of any

aluminum fasteners with steel fasteners, if necessary; or modification

of certain fuselage circumferential skin joints; as applicable.

Operators should also note that this proposed AD would require the

repetitive inspections and modification of the cold-bonded doublers of

certain fuselage circumferential skin joints for only certain

airplanes. These airplanes were inadvertently omitted from the

applicability of AD 90-26-09.

The service bulletin recommends accomplishing the repetitive

internal visual inspections every 30 months if the repetitive HFEC

inspection is accomplished every 48 months, or accomplishing the

repetitive internal visual inspections every 48 months if the

repetitive HFEC inspection is accomplished every 15 months. In

developing an appropriate compliance time for this AD, the FAA

considered not only the manufacturer's recommendation, but the degree

of urgency associated with addressing the subject unsafe condition, the

average utilization of the affected fleet, and the time necessary to

perform the inspections. In light of all of these factors, the FAA

finds a 48-month compliance time for both the internal visual

inspection and the HFEC inspection to be warranted, in that it

represents an appropriate interval of time allowable for affected

airplanes to continue to operate without compromising safety. This

compliance time is consistent with that specified in AD 90-26-09.

Cost Impact

There are approximately 549 airplanes of the affected design in the

worldwide fleet. Based on a records review, the FAA estimates that only

374 of those airplanes are still in service. The FAA estimates that 280

airplanes of U.S. registry still in service would be affected by this

proposed AD.

The number of airplanes that would be subject to the proposed one-

time inspection to determine the type of fasteners installed is

unknown. For affected airplanes, it would take approximately 45 work

hours per airplane to accomplish the proposed one-time inspection, at

an average labor rate of $60 per work hour. Based on these figures, the

cost impact of this proposed inspection on U.S. operators is estimated

to be $2,700 per airplane.

The FAA estimates that 3 airplanes of U.S. registry would be

required to perform the external detailed visual inspection of certain

fuselage circumferential skin joints that is proposed in this AD

action. It would take approximately 8 work hours per airplane to

accomplish this proposed inspection, at an average labor rate of $60

per work hour. Based on these figures, the cost impact of this proposed

inspection on U.S. operators is estimated to be $1,440, or $480 per

airplane, per inspection cycle.

The FAA estimates that 3 airplanes of U.S. registry would be

required to perform the internal detailed visual inspection of certain

fuselage circumferential skin joints that is proposed in this AD

action. It would take approximately 12 work hours per airplane to

accomplish this proposed inspection, at an average labor rate of $60

per work hour. Based on these figures, the cost impact of this proposed

inspection on U.S. operators is estimated to be $2,160, or $720 per

airplane, per inspection cycle.

The FAA estimates that 3 airplanes of U.S. registry would be

required to perform the LFEC inspection of certain fuselage

circumferential skin joints that is proposed in this AD action. It

would take approximately 100 work hours per airplane to accomplish this

proposed inspection, at an average labor rate of $60 per work hour.

Based on these figures, the cost impact of this proposed inspection on

U.S. operators is estimated to be $18,000, or $6,000 per airplane, per

inspection cycle.

The FAA estimates that 3 airplanes of U.S. registry would be

required to perform the HFEC inspection of certain fuselage

circumferential skin joints that is proposed in this AD action. It

would take approximately 24 work hours per airplane to accomplish this

proposed inspection, at an average labor rate of $60 per work hour.

Based on these figures, the cost impact of this proposed inspection on

U.S. operators is estimated to be $4,320, or $1,440 per airplane, per

inspection cycle.

For affected airplanes, it would take approximately 192 work hours

per airplane to accomplish the proposed modification of the cold-bonded

doublers of certain fuselage circumferential skin joints, at an average

labor rate of $60 per work hour. Required parts would cost

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approximately $1,250. Based on these figures, the cost impact of this

proposed modification on U.S. operators is estimated to be $12,770 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-74-AD.

Applicability: Model 727-100, -100C, and -200 series airplanes;

line numbers 1 through 549 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 (g)(1)

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 delamination of the cold-bonded doublers, which could

result in corrosion of the body skins and doublers, and consequent

reduced structural capability of the fuselage circumferential skin

joints, accomplish the following:

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

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.''

One-Time Inspection/Replacement

(a) For airplanes on which the modification specified in Boeing

Service Bulletin 727-53-0084, Revision 2, dated June 5, 1972, and

the additional actions (including additional fastener replacement

locations) specified in Boeing Document No. D6-54860, Revision C,

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

Structural Modification Program--Model 727''; or the modification

specified in Boeing Service Bulletin 727-53-0084, Revision 3, dated

September 28, 1989; HAS been accomplished: Within 36 months after

the effective date of this AD, perform a one-time inspection of the

fuselage circumferential skin joints to determine the type of

fastener installed, in accordance with Figure 7 of the Boeing

Service Bulletin 727-53-0084, Revision 4, dated August 2, 1990.

(1) If no aluminum fasteners are found, no further action is

required by this AD.

(2) If any aluminum fastener is found, prior to further flight,

replace with a steel fastener, in accordance with Boeing Service

Bulletin 727-53-0084, Revision 4, dated August 2, 1990.

Modification

(b) For airplanes listed in Boeing Document No. D6-54860,

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

Bulletin Structural Modification Program--Model 727'' on which the

modification specified in Boeing Service Bulletin 727-53-0084,

Revision 2, dated June 5, 1972, and the additional actions specified

in Boeing Document No. D6-54860, Revision C, dated December 11,

1989; or the modification specified in Boeing Service Bulletin 727-

53-0084, Revision 3, dated September 28, 1989; has not been

accomplished prior to the effective date of this AD: Prior to the

accumulation of 60,000 total flight cycles, modify the fuselage

circumferential skin joints in accordance with Part IV of the

Accomplishment Instructions of Boeing Service Bulletin 727-53-0084,

Revision 4, dated August 2, 1990. Such action constitutes

terminating action for the modification in that area required by AD

90-06-09.

Repetitive Inspections

(c) For airplanes having line numbers 153, 339, 416, and 540:

Accomplish the requirements of paragraphs (c)(1), (c)(2), and (c)(3)

of this AD at the compliance time specified in those paragraphs.

(1) Within 15 months after the effective date of this AD,

perform an external detailed visual inspection and a low frequency

eddy current (LFEC) inspection of the fuselage circumferential skin

joints to detect corrosion or sealant deterioration, in accordance

with Parts II.A. and II.B. of the Accomplishment Instructions of

Boeing Service Bulletin 727-53-0084, Revision 4, dated August 2,

1990. Repeat the external detailed visual inspection thereafter at

intervals not to exceed 15 months, and repeat the LFEC inspection

thereafter at intervals not to exceed 30 months.

(2) Within 3,000 flight cycles or 30 months after the effective

date of this AD, whichever occurs first, perform a high frequency

eddy current (HFEC) inspection of the fuselage circumferential skin

joints to detect cracking, in accordance with Part II.D. of the

Accomplishment Instructions of Boeing Service Bulletin 727-53-0084,

Revision 4, dated August 2, 1990. Repeat the HFEC inspection

thereafter at intervals not to exceed 4,000 flight cycles or 48

months, whichever occurs first, until accomplishment of paragraph

(f) of this AD.

(3) Within 48 months after the effective date of this AD,

perform an internal detailed visual inspection of the fuselage

circumferential skin joints to detect cracking, disbonding, or

sealant deterioration; in accordance with Part II.C. of the

Accomplishment Instructions of Boeing Service Bulletin 727-53-0084,

Revision 4, dated August 2, 1990. Repeat the internal detailed

visual inspection thereafter at intervals not to exceed 48 months.

Repair

(d) For airplanes having line numbers 153, 339, 416, and 540: If

any discrepancy is detected during any inspection required by

paragraph (c) of this AD, accomplish paragraph (d)(1) or (d)(2) of

this AD, as applicable.

(1) If any corrosion, cracking, or disbonding is detected during

any inspection required by paragraph (c) of this AD, prior to

further flight, repair in accordance with Part III of the

Accomplishment Instructions of Boeing Service Bulletin 727-53-0084,

Revision 4, dated August 2, 1990, except as provided by paragraph

(e) of this AD. No

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further action is required by this AD for that area.

(2) If the sealant has deteriorated but no corrosion, cracking,

or disbonding is detected during any inspection required by

paragraph (c) of this AD, prior to further flight, reseal in

accordance with Figure 5 or 6, as applicable, of Boeing Service

Bulletin 727-53-0084, Revision 4, dated August 2, 1990.

(e) Where the service bulletin specifies that the manufacturer

may be contacted for disposition of certain repair conditions, 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 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 a

Boeing DER, as required by this paragraph, the approval letter must

specifically reference this AD.

Modification

(f) For airplanes having line numbers 153, 339, 416, and 540:

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, modify the fuselage circumferential skin joints in

accordance with Part IV of the Accomplishment Instructions of Boeing

Service Bulletin 727-53-0084, Revision 4, dated August 2, 1990. Such

action constitutes terminating action for the requirements of

paragraph (c)(2) of this AD.

Alternative Methods of Compliance

(g)(1) 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.

(2) An alternative method of compliance for paragraph (f) of

this AD that provides an acceptable level of safety may be used 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.

Note 3: Information concerning the existence of approved

alternative methods of compliance with this AD, if any, may be

obtained from the Seattle ACO.

Special Flight Permits

(h) Special flight permits may be issued in accordance with sections

21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197

and 21.199) to operate the airplane to a location where the

requirements of this AD can be accomplished.

Issued in Renton, Washington, on November 30, 1999.

D. L. Riggin,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 99-31477 Filed 12-3-99; 8:45 am]

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