Airworthiness Directives; Boeing Model 747 Series Airplanes

DEPARTMENT OF TRANSPORTATION

14 CFR Part 39

[Docket No. 93-NM-174-AD; Amendment 39-8989; AD 94-15-18]

Airworthiness Directives; Boeing Model 747 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment supersedes an existing airworthiness directive

(AD), applicable to certain Boeing Model 747 series airplanes, that

currently requires that the FAA-approved maintenance inspection program

include inspections which will give no less than the required damage

tolerance rating (DTR) for each Structural Significant Item (SSI). This

amendment requires the inclusion of additional airplanes to the

candidate fleet. This amendment is prompted by a recommendation from

the Airworthiness Assurance Working Group, Model 747 Structures Task

Group. The actions specified by this AD are intended to ensure the

continued structural integrity of the total Boeing Model 747 fleet.

DATES: Effective September 12, 1994.

The incorporation by reference of certain publications listed in

the regulations is approved by the Director of the Federal Register as

of September 12, 1994.

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: Steven Fox, Aerospace Engineer,

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

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

98055-4056; telephone (206) 227-2777; fax (206) 227-1181.

SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal

Aviation Regulations (14 CFR part 39) by superseding AD 93-06-01,

amendment 39-8526 (58 FR 19571, April 15, 1993), which is applicable to

certain Boeing Model 747 series airplanes, was published in the Federal

Register on January 4, 1994 (59 FR 265). The action proposed to require

that the FAA-approved maintenance inspection program be revised to

include inspections which will give no less than the required damage

tolerance rating (DTR) for each Structural Significant Item (SSI). That

action was prompted by a recommendation from the Airworthiness

Assurance Working Group, Model 747 Structures Task Group (STG). The

requirements of that AD are intended to ensure the continued structural

integrity of the total Boeing Model 747 fleet.

Interested persons have been afforded an opportunity to participate

in the making of this amendment. Due consideration has been given to

the comments received.

One commenter supports the proposed rule.

Several commenters request that the selection of airplanes in the

candidate fleet be determined by the STG, which is comprised of

representatives from various operators, the FAA, and Boeing. The FAA

does not concur. The FAA has determined that retired airplanes, hull

losses, or parked airplanes that are in the current candidate fleet

must be replaced with in-service airplanes to maintain the candidate

fleet size of 117 in-service airplanes. In selecting replacement

airplanes for the candidate fleet, the FAA evaluates, among other

factors, age and service history of in-service airplanes. The FAA will

continue to consider recommendations from the STG for replacement

airplanes; however, the responsibility for determining the suitability

of airplanes for the candidate fleet ultimately rests with the FAA.

One commenter questions the validity for including Boeing Model

747SR series airplanes in the Supplemental Structural Inspection

Document (SSID) candidate fleet. This commenter states that the FAA's

justification for including these airplanes was based upon the

conversion of these airplanes from passenger operations to cargo

operations, which the commenter alleges is incorrect. The commenter

further states that the FAA needs to consider the inclusion of

airplanes based upon maintenance requirements, especially airplanes

that have been modified in accordance with supplemental type

certificates (STC). The FAA does not concur. The FAA points out that it

included certain Boeing Model 747SR series airplanes because these

airplanes were no longer operated as Model 747SR series airplanes (at

low gross weights and at reduced engine thrusts), not because they were

converted from passenger operations to cargo operations. Since those

airplanes are now operated similarly to other airplanes that are in the

Boeing Model 747 SSID candidate fleet and that are operated as both

freighter and passenger airplanes, the FAA has determined that they,

too, should be included in the SSID candidate fleet. As noted above,

the FAA considers many factors when selecting airplanes for inclusion

into the candidate fleet, including age and service history of the

airplane, which may be affected by modifications that were performed in

accordance with STC's.

Since AD 86-19-01 requires structural inspections and repairs or

replacements on certain Model 747-100SR series airplanes, a number of

commenters request that AD 86-19-01, Amendment 39-5395 (51 FR 29212,

August 15, 1986), be revised to exclude Model 747SR series airplanes

that are now included in this rulemaking action to avoid redundant

requirements for inspection. One of these commenters requests that the

requirement to inspect SSI's, required by AD 86-19-01, be exempt from

the requirements of this AD. The FAA concurs. The FAA will, in a

separate rulemaking action, revise AD 86-19-01 to exclude Model 747-

100SR series airplanes that have been included in this final rule.

One commenter requests an extension in the compliance time until

such time that a review of the damage tolerance rating (DTR) check

forms has been completed and a revised SSID has been issued. The FAA

does not concur. To extend the compliance time for this action would be

inappropriate, since the FAA has determined that an unsafe condition

exists and that inspections must be conducted to ensure continued

safety. Additional rulemaking may be considered, however, once the DTR

check forms have been reviewed and incorporated into the revised SSID.

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 as proposed.

There are approximately 128 Boeing Model 747 series airplanes of

the affected design in the worldwide fleet. The FAA estimates that 87

airplanes of U.S. registry and 8 U.S. operators will be affected by

this AD. Incorporation of the SSID program into an operator's

maintenance program, as required by AD 93-06-01, and retained in this

AD, is estimated to necessitate 1,000 work hours (per operator) at an

average labor rate of $55 per work hour. Based on these figures, the

total cost to the 8 affected U.S. operators to incorporate the SSID

program is estimated to be $440,000, or $55,000 per U.S. operator.

The recurring inspections cost, as required by AD 93-06-01, and

retained in this AD, is estimated to be 1,275 work hours per airplane

at an average labor rate of $55 per work hour. Based on these figures,

the annual recurring cost required by AD 93-06-01, and retained in this

AD, is estimated to be $6,100,875 for the affected U.S. fleet, or

$70,125 per airplane.

Since no new operators have been added by this AD, there will be no

new costs associated with incorporating the SSID program into an

operator's maintenance program. Therefore, the future economic cost

impact of this AD on U.S. operators is now only the cost of the

recurring inspections for these additional airplanes.

The number of required work hours for the recurring inspections in

this AD, as indicated above, is presented as if the accomplishment of

the actions were to be conducted as ``stand alone'' action. However, in

actual practice, these actions, for the most part, will be accomplished

coincidentally or in combination with normally scheduled airplane

inspections and other maintenance program tasks. Therefore, the actual

number of necessary additional work hours will be minimal in many

instances. Additionally, any costs associated with special airplane

scheduling will be minimal.

The total 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.

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. App. 1354(a), 1421 and 1423; 49 U.S.C.

106(g); and 14 CFR 11.89.

Sec. 39.13 [Amended]

2. Section 39.13 is amended by removing amendment 39-8526 (58 FR

19571, April 15, 1993), and by adding a new airworthiness directive

(AD), amendment 39-8989, to read as follows:

94-15-18 Boeing: Amendment 39-8989. Docket 93-NM-174-AD. Supersedes

AD 93-06-01, Amendment 39-8526.

Applicability: Model 747 series airplanes, as listed in Section

3.0 of Boeing Document No. D6-35022, Volumes 1 and 2, ``Supplemental

Structural Inspection Document (SSID) for Model 747 Airplanes,''

Revision E, dated June 17, 1993; and manufacturer's line numbers 42,

174, 221, 231, 234, 239, 242, and 254; certificated in any category.

Compliance: Required as indicated, unless accomplished

previously.

To ensure the continued structural integrity of the total Boeing

Model 747 fleet, accomplish the following:

(a) For airplanes listed in Boeing Document No. D6-35022,

Volumes I and II, ``Supplemental Structural Inspection Document

(SSID),'' Revision D, dated February 1992: Within 12 months after

May 17, 1993 (the effective date of AD 93-06-01, Amendment 39-8526),

incorporate a revision into the FAA-approved maintenance inspection

program which provides no less than the required Damage Tolerance

Rating (DTR) for each Structural Significant Item (SSI) listed in

Boeing Document No. D6-35022, Revision D, dated February 1992. (The

required DTR value for each SSI is listed in the document.) The

revision to the maintenance program shall include Sections 5.0 and

6.0 of the SSID and shall be implemented in accordance with the

procedures contained in those sections. Revision to the maintenance

program shall be in accordance Revision D of the SSID, until

Revision E of the SSID is incorporated into the FAA-approved

maintenance inspection program in accordance with the requirements

of paragraph (b) of this AD.

(b) For airplanes listed in Boeing Document No. D6-35022,

Volumes 1 and 2, ``Supplemental Structural Inspection Document

(SSID) for Model 747 Airplanes,'' Revision E, dated June 17, 1993;

and manufacturer's line numbers 42, 174, 221, 231, 234, 239, 242,

and 254: Within 12 months after the effective date of this AD,

replace the revision of the FAA-approved maintenance inspection

program required by paragraph (a) of this AD with a revision that

provides no less than the required DTR for each SSI listed in Boeing

Document No. D6-35022, Volumes 1 and 2, ``Supplemental Structural

Inspection Document (SSID) for Model 747 Airplanes,'' Revision E,

dated June 17, 1993. (The required DTR value for each SSI is listed

in the document.) The revision to the maintenance program shall

include Sections 5.0 and 6.0 of the SSID and shall be implemented in

accordance with the procedures contained in those sections.

(c) Cracked structure must be repaired, prior to further flight,

in accordance with an FAA-approved method.

(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: Information concerning the existence of approved

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

obtained from the Seattle ACO.

(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.

(f) The incorporation of the revision shall be done in

accordance with Boeing Document No. D6-35022, Volumes 1 and 2,

``Supplemental Structural Inspection Document (SSID) for Model 747

Airplanes,'' Revision E, dated June 17, 1993, which contains the

following list of effective pages:

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Revision letter

Page No. shown on page

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List of Active Pages-............................. E

Pages 1 through 21.1 .............................

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(Note: The issue date is indicated only on the title page of

Volume 1.) 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 September 12, 1994.

Issued in Renton, Washington, on July 22, 1994.

Darrell M. Pederson,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 94-18454 Filed 8-10-94; 8:45 am]

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