Airworthiness Directives; Boeing Model 747 Series Airplanes Equipped With General Electric CF6-45 or CF6-50 Engines or Pratt & Whitney JT9D Series Engines

DEPARTMENT OF TRANSPORTATION

14 CFR Part 39

[Docket No. 94-NM-52-AD; Amendment 39-9126; AD 95-02-07]

Airworthiness Directives; Boeing Model 747 Series Airplanes

Equipped With General Electric CF6-45 or CF6-50 Engines or Pratt &

Whitney JT9D Series Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment adopts a new airworthiness directive (AD),

applicable to certain Boeing Model 747 series airplanes, that requires

installation of a seal on the wing front spar at each engine strut.

This amendment is prompted by a report of a fire that occurred due to

fuel leakage from the fuel line coupling in the engine strut area along

the wing front spar while the airplane was on the ground after engine

shutdown. The actions specified by this AD are intended to ensure that

fuel is contained within the strut drainage area and channeled away

from ignition sources.

DATES: Effective March 16, 1995. -

The incorporation by reference of certain publications listed in

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

of March 16, 1995.

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: G. Michael Collins, Aerospace

Engineer, Propulsion Branch, ANM-140S, FAA, Transport Airplane

Directorate, Seattle Aircraft Certification Office, 1601 Lind Avenue,

SW., Renton, Washington 98055-4056; telephone (206) 227-2689; fax (206)

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 certain Boeing Model 747 series

airplanes was published in the Federal Register on June 9, 1994 (59 FR

29744). That action proposed to require installation of a seal on the

wing front spar at each engine strut. -

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 state that the one reported incident was an

``isolated incident'' and is not characteristic of industry findings.

One commenter also states that the incident was not a safety-of-flight

issue since the reported fire occurred while the airplane was on the

ground. Because of this, these commenters request that the FAA withdraw

the proposed rule. The FAA does not concur. As explained in detail in

the preamble to the proposed rule, airflow when the airplane is in

flight or airflow from the engine running when the airplane is on the

ground does prevent fuel from leaking onto hot engine surface. However,

a potential unsafe condition still exists because fire can occur after

engine shutdown as a result of the fuel dripping onto the hot engine

surface. The reported fire demonstrates that the design of the

flammable fluid drainage system does not adequately separate the fuel

leak from the hot surface of the engine following engine shutdown. The

FAA has determined that the actions required by this AD are warranted

in order to address that unsafe condition.

Several commenters contend that the proposed installation of a seal

on the wing front spar at each engine will not prevent a fuel leak from

occurring. One commenter states that individual modifications, such as

the proposed modification, should only be required as part of a more

comprehensive program of modifications that will address all known fuel

system leakage problems. (The commenter did not, however, provide any

specific details of a program.) Another commenter states that periodic

replacement of the O-rings in the fitting would prevent the leakage of

fuel; therefore, the proposed installation is not necessary. Because of

these items, these commenters request that the rule not be issued. The

FAA does not concur. Each incident report and each modification

presented to correct causes of fuel leakage incidents is evaluated by

the FAA. Both the effectiveness of the modification and the economic

impact to accomplish corrective action required by an AD are

considered. The FAA has determined that the installation required by

this AD will improve the drainage system and prevent future fires that

could be caused by fuel leakage from the fuel line (Wiggins) coupling

in the engine strut area. Scheduled replacement of the O-rings may

reduce the potential for fuel leaks caused by worn or aged O-rings, but

it will not eliminate all causes of fuel leakage in the area of the

modification.

One commenter states that the seal described in the proposed rule

will be replaced during an anticipated ``Boeing Model 747 strut

modification program,'' and that installing the seal before modifying

the strut area would provide a short-lived increase in safety. This

commenter, therefore, considers the proposed installation to be

unwarranted. The FAA does not concur. The planned strut modification

program does not include a requirement for incorporation of the

installation required by this AD, nor has a compliance time for the

strut modifications been established; it is likely that the compliance

time may be a period of three to five years. Although the planned strut

modifications may require the removal and reinstallation of the seal

installation required by this AD, the risk of a fire occurring before

the planned strut modification program is implemented outweighs the

convenience of waiting to install the seal until the strut modification

is accomplished. The installation required by this AD can be

incorporated during normal scheduled maintenance periods, thereby

reducing the costs associated with this installation since access to

this area will be necessitated in order to accomplish other scheduled

maintenance actions.

Several commenters request that the FAA extend the proposed

compliance time for the installation. Some of the commenters request

the compliance time be extended from the proposed 12 months to as much

as 48 months. This would permit ample time to accomplish the

installation during scheduled maintenance periods. One of these

commenters requests that the compliance time be extended to coincide

with the planned strut modification program to reduce the additional

cost to the operators. The FAA concurs that the compliance time may be

extended somewhat. In [[Page 8293]] developing an appropriate

compliance time for this AD action, the FAA considered not only the

degree of urgency associated with addressing the subject unsafe

condition, but the practical aspect of incorporating the required

installation into affected operators' scheduled maintenance visits,

when the airplanes would be located at a base where facilities and

trained personnel would be readily available, if necessary. The FAA has

reviewed data submitted by the manufacturer as to recommended

installation time, and concurs with the commenters' requests for an

extension. The FAA has determined that extending the compliance time

from 12 months to 18 months will not compromise safety. Paragraph (a)

of the final rule has been revised accordingly.

As a result of recent communications with the Air Transport

Association (ATA) of America, the FAA has learned that, in general,

some operators may misunderstand the legal effect of AD's on airplanes

that are identified in the applicability provision of the AD, but that

have been altered or repaired in the area addressed by the AD. The FAA

points out that all airplanes identified in the applicability provision

of an AD are legally subject to the AD. If an airplane has been altered

or repaired in the affected area in such a way as to affect compliance

with the AD, the owner or operator is required to obtain FAA approval

for an alternative method of compliance with the AD, in accordance with

the paragraph of each AD that provides for such approvals. A note has

been added to this final rule to clarify this requirement.

Additionally, the FAA has recently reviewed the figures it has used

over the past several years in calculating the economic impact of AD

activity. In order to account for various inflationary costs in the

airline industry, the FAA has determined that it is necessary to

increase the labor rate used in these calculations from $55 per work

hour to $60 per work hour. The economic impact information, below has

been revised to reflect this increase in the specified hourly labor

rate.

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.

There are approximately 610 Boeing Model 747 series airplanes of

the affected design in the worldwide fleet. The FAA estimates that 183

airplanes of U.S. registry will be affected by this AD, that it will

take approximately 14 work hours per airplane to accomplish the

required actions, and that the average labor rate is $60 per work hour.

Required parts will cost approximately $57 per airplane. Based on these

figures, the total cost impact of the AD on U.S. operators is estimated

to be $164,151, or $897 per airplane.

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 adding the following new

airworthiness directive:

95-02-07 Boeing: Amendment 39-9126. Docket 94-NM-52-AD.

Applicability: Model 747 series airplanes, equipped with General

Electric CF6-45 or CF6-50 engines, or Pratt & Whitney JT9D series

engines; as listed in Boeing Service Bulletin 747-28-2160, Revision

1, dated December 16, 1993; 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 use the authority

provided in paragraph (b) to request approval from the FAA. This

approval may address either no action, if the current configuration

eliminates the unsafe condition; or different actions necessary to

address the unsafe condition described in this AD. Such a request

should include an assessment of the effect of the changed

configuration on the unsafe condition addressed by this AD. In no

case does the presence of any modification, alteration, or repair

remove any airplane from the applicability of this AD.

Compliance: Required as indicated, unless accomplished

previously.

To ensure that fuel is contained within the strut drainage area

and channeled away from ignition sources, accomplish the following:

(a) Within 18 months after the effective date of this AD,

install a seal on the wing front spar at each engine strut in

accordance with Boeing Service Bulletin 747-28-2160 dated July 23,

1992, or Revision 1, dated December 16, 1993.

(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 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 2: Information concerning the existence of approved

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

obtained from the Seattle ACO.

(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.

(d) The installation shall be done in accordance with Boeing

Service Bulletin 747-28-2160, dated July 23, 1992, or Boeing Service

Bulletin 747-28-2160, Revision 1, dated December 16, 1993. 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

[[Page 8294]] 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.

(e) This amendment becomes effective on March 16, 1995.

Issued in Renton, Washington, on January 19, 1995.

Darrell M. Pederson,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 95-1846 Filed 2-13-95; 8:45 am]

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