Airworthiness Directives; Boeing Model 747-400, 757, and 767 Series Airplanes

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 94-NM-140-AD]

Airworthiness Directives; Boeing Model 747-400, 757, and 767

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 Boeing Model 747-400, 757, and 767

series airplanes. This proposal would require a revision to the

Airplane Flight Manual that would advise flight crews to monitor the

engine indication and crew alerting system (EICAS) for ``status'' level

messages pertaining to impending engine fuel filter bypass. This

proposal also would require the installation of upgraded EICAS

computers that provide ``advisory'' level messages to indicate such

bypass conditions. This proposal is prompted by a finding that EICAS

computers currently installed on these airplanes do not provide an

appropriate indication to the flight crew of an impending engine fuel

filter bypass condition. The actions specified by the proposed AD are

intended to ensure that the flight crew is appropriately aware of

conditions involving a severely contaminated airplane fuel system and

the associated increased potential for engine power loss.

DATES: Comments must be received by July 19, 1995.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

Administration (FAA), Transport Airplane Directorate, ANM-103,

Attention: Rules Docket No. 94-NM-140-AD, 1601 Lind Avenue, SW.,

Renton, Washington 98055-4056. Comments may be inspected at this

location between 9 a.m. and 3 p.m., Monday through Friday, except

Federal holidays.

FOR FURTHER INFORMATION CONTACT: Jeff Duven, Aerospace Engineer,

Propulsion Branch, ANM-140S, Seattle Aircraft Certification Office,

FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton,

Washington 98055-4056; telephone (206) 227-2688; fax (206) 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

[[Page 27447]] 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 94-NM-140-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-103, Attention: Rules

Docket No. 94-NM-140-AD, 1601 Lind Avenue, SW., Renton, Washington

98055-4056.

Discussion

The FAA recently has learned that appropriate indication to the

flight crew of an impending engine fuel filter bypass condition is not

provided on Boeing Models 747-400 and 757 series airplanes, and on

Model 767 series airplanes powered by General Electric CF6-80A and CF6-

80C2 engines, Pratt & Whitney PW 4000 engines, and Rolls-Royce RB211-

524 engines. Such indication to the flight crew is required by part 25

of the Federal Aviation Regulations (14 CFR part 25), which establishes

the certification requirements for all transport category airplanes,

including the Models 747-400, 757, and 767.

Service experience has demonstrated that severe fuel contamination

can lead to fuel filter bypass, engine power loss, engine flameout, and

consequent airplane diversions. Fuel contaminants have been known to

adversely affect entire fuel systems on airplanes and, therefore, pose

a threat of complete loss of power on all engines. Clear indication to

the flight crew of an impending fuel filter bypass condition is

necessary in order to ensure that the flight crew is warned promptly of

conditions that could lead to a loss of power from one or more engines.

The engine indication and crew alerting system (EICAS) computers

installed on Model 747-400, 757, and 767 series airplanes use a multi-

level message system to provide indications of various conditions to

the flight crew. The levels of messages, in increasing order of

importance to the flight crew, are indicated as ``status,''

``advisory,'' ``caution,'' and ``warning.'' In general, ``status''

messages are used to ensure an acceptable airplane condition prior to

dispatch of the airplane. A ``status'' level message on the EICAS

computer is not considered to be an item that flight crews need to be

aware of during flight, or an item that would have any effect on the

flight planning considerations made by the flight crew.

The EICAS computers currently installed on all Model 747-400 and

757 series airplanes, and on certain Model 767 series airplanes, use a

``status'' level message to indicate impending engine fuel filter

bypass conditions. The FAA considers that this use of a ``status''

level message to indicate these conditions is an unsafe condition,

since such messages do not provide information to the flight crew at an

appropriate awareness level. Using a ``status'' level message to

indicate an impending engine fuel filter bypass condition could result

in the flight crew being unaware of a severely contaminated airplane

fuel system and the associated increased potential for engine power

loss. This condition, if not corrected, could result in the airplane

landing with reduced engine power, or the total loss of engine power

before the airplane is able to reach a suitable landing site.

It should be noted that the addressed unsafe condition pertains

only to situations involving gross fuel contaminants. Such contaminants

exceed the particulate size or concentration capabilities of what the

engine fuel filters are certified to handle. Additionally, the type of

gross fuel contaminants that are of concern do not include ice, which

can be eliminated by fuel heating. Contamination of airplane fuel

systems has occurred in the past and will likely occur in the future,

despite the many industry standards intended to maintain cleanliness of

the airplane fuel supply. Examples of such contamination found in

service include microbial growth, sealant, lint, metal particles, fuel

tank cleaning chemicals, and liquid fertilizer. There also have been

data indicating the existence of other contaminants in the fuel system

that, although unidentified, were severe enough to cause engine power

loss.

Since an unsafe condition has been identified that is likely to

exist on other products of this same type design, the proposed AD would

require, initially, a revision to the Limitations Section of the FAA-

approved Airplane Flight Manual (AFM) of affected airplanes that would

require the flight crew to respond to EICAS ``status'' level messages

that indicate impending engine fuel filter bypass conditions.

Information addressing the presence of multiple engine fuel filter

bypass messages would be contained in this AFM revision.

This proposed AD also would require the installation, on certain

airplanes, of upgraded EICAS computers that display an ``advisory''

level message to the flight crew to indicate that an impending engine

fuel filter bypass condition exists for each engine. Following

installation of the upgraded EICAS computers, the AFM information would

be required to be revised to be consistent with the displayed

information.

The upgraded EICAS installation would not be required for Model 767

airplanes powered by Pratt & Whitney JT9D engines, since those

airplanes are currently equipped with EICAS computers that provide the

level of indications that are otherwise proposed in this notice.

However, the AFM for those airplanes does not contain appropriate

information addressing these messages. Therefore, this proposed AD

would require revising the Limitations Section of that AFM to include

information addressing the situation where multiple advisory level

messages are present, indicating that multiple engine fuel filters are

in an impending bypass condition.

There are approximately 1,378 Model 747-400, 757, and 767 series

airplanes of the affected design in the worldwide fleet. The FAA

estimates that 588 airplanes of U.S. registry would be affected by this

proposed AD.

The proposed initial revision to the AFM would take approximately 1

work hour per airplane to accomplish, at an average labor rate of $60

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

proposed action on U.S. operators is estimated to be $35,280, or $60

per airplane.

The FAA currently has no specific cost estimates associated with

the proposed installation of upgraded EICAS computers, since the

upgrade has not been developed yet. The FAA has been advised, however,

that the manufacturer is planning other changes to these EICAS

computers that are [[Page 27448]] necessary to provide for global

positioning system (GPS) navigation capability and other enhanced

features. The proposed compliance time of four years for the EICAS

installation requirements of this AD will allow a portion of the EICAS

computers installed on airplanes affected by this AD to have the

required EICAS message upgrade made coincidentally with those other

planned EICAS changes, thereby reducing the costs and scheduling impact

of such changes on operators. As indicated earlier in this preamble,

the FAA specifically invites the submission of comments and other data

regarding the economic aspect of this proposal.

The proposed revision to the AFM that would be required subsequent

to the installation of the upgraded EICAS computers would take

approximately 1 work hour per airplane to accomplish, at an average

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

impact of this proposed action on U.S. operators is estimated to be

$35,280, or $60 per airplane.

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. 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:

Boeing: Docket 94-NM-140-AD.

Applicability: All Model 747-400, 757, and 767 series airplanes;

certificated in any category.

Compliance: Required as indicated, unless accomplished

previously.

To ensure that the flight crew is appropriately aware of

conditions involving a severely contaminated airplane fuel system

and the associated increased potential for engine power loss,

accomplish the following:

(a) For all Model 747-400 series airplanes: Within 60 days after

the effective date of this AD, revise the Limitations Section of the

FAA-approved Airplane Flight Manual (AFM) to include the following

statement. This may be accomplished by inserting a copy of this AD

in the AFM.

``Respond to the EICAS STATUS CUE by checking for the following

status level messages(s):

ENG 1 FUEL FILT

ENG 2 FUEL FILT

ENG 3 FUEL FILT

ENG 4 FUEL FILT

If more than one of these impending fuel filter bypass messages

is displayed, airplane fuel system contamination may be present,

which can result in erratic engine operation and engine flameout.''

(b) For all Model 757 series airplanes, and Model 767 series

airplanes powered by General Electric CF6-80A and CF6-80C2 engines,

Pratt & Whitney PW 4000 engines, and Rolls-Royce RB211-524 engines:

Within 60 days after the effective date of this AD, revise the

Limitations Section of the FAA-approved Airplane Flight Manual (AFM)

to include the following statement. This may be accomplished by

inserting a copy of this AD in the AFM.

``Respond to the EICAS STATUS CUE by checking for the following

status level messages(s):

R ENG FUEL FILT

L ENG FUEL FILT

If more than one of these impending fuel filter bypass messages

is displayed, airplane fuel system contamination may be present,

which can result in erratic engine operation and engine flameout.''

(c) For Model 767 series airplanes powered by Pratt & Whitney

JT9D engines: Within 60 days after the effective date of this AD,

revise the Limitations Section of the FAA-approved Airplane Flight

Manual (AFM) to include the following statement. This may be

accomplished by inserting a copy of this AD in the AFM.

``If both of the following EICAS advisory level messages for

impending fuel filter bypass are displayed, and engine fuel icing is

not suspected (based on the fuel temperature being too high or

because engine fuel heat has been selected ``on''), airplane fuel

system contamination may be present, which can result in erratic

engine operation and engine flameout:

R ENG FUEL FILT

L ENG FUEL FILT''

(d) For all Model 747-400 series airplanes; all Model 757 series

airplanes; and Model 767 series airplanes powered by General

Electric CF6-80A and CF6-80C2 engines, Pratt & Whitney PW 4000

engines, and Rolls-Royce RB211-524 engines: Accomplish the

requirements of paragraph (d)(1) and (d)(2) of this AD:

(1) Within 4 years after the effective date of this AD, install

an upgraded engine indication and crew alerting system (EICAS)

computer that will provide ``advisory'' level messages to the flight

crew to indicate an impending engine fuel filter bypass condition

for each engine. The installation shall be accomplished in

accordance with a method approved by the Manager, Seattle Aircraft

Certification Office (ACO), FAA, Transport Airplane Directorate.

(2) Coincidental with the installation required by paragraph

(d)(1) of this AD, remove the AFM revisions required by paragraphs

(a) and (b) of this AD, and revise the Limitations Section of the

AFM to advise the flight crew that impending engine fuel filter

bypass advisory level messages for multiple engines may indicate

contamination of the airplane fuel system, which can result in

erratic engine operation and engine flameout. The revision to the

Limitations Section must be approved by the Manager, Seattle ACO,

FAA, Transport Airplane Directorate.

(e) 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 Operations 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.

(f) 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 May 18, 1995. Original Signed By:

Darrell M. Pederson,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 95-12710 Filed 5-23-95; 8:45 am]

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