Airworthiness Directives; Boeing Model 757 Series Airplanes

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 94-NM-50-AD; Amendment 39-8899; AD 94-09-10]

Airworthiness Directives; Boeing Model 757 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

-----------------------------------------------------------------------

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

is applicable to all Boeing Model 757 series airplanes. This action

requires revising the Non-Normal Procedures Section of the FAA-approved

Airplane Flight Manual (AFM) to include procedures that will enable the

flight crew to identify fuel system leaks and to take appropriate

action to prevent further fuel loss. This amendment is prompted by

reports that flight crew procedures related to fuel system leaks are

not defined adequately in the FAA-approved AFM for these airplanes. The

actions specified in this AD are intended to ensure that the flight

crew is advised of the potential hazard related to fuel exhaustion due

to undetected leakage, and the procedures necessary to address it.

DATES: Effective May 11, 1994.

Comments for inclusion in the Rules Docket must be received on or

before June 27, 1994.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

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

Attention: Rules Docket No. 94-NM-50-AD, 1601 Lind Avenue SW., Renton,

Washington 98055-4056.

FOR FURTHER INFORMATION CONTACT: Tamra J. Elkins, Aerospace Engineer,

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

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

Washington 98055-4056; telephone (206) 227-2669; fax (206) 227-1181.

SUPPLEMENTARY INFORMATION: Several in-service incidents have occurred

on Model 757 series airplanes in which an engine fuel line has

fractured and a significant fuel leak has occurred. These fuel leaks

have occurred at locations within the engine fuel system upstream of

the fuel flow transmitter. Under these circumstances, sufficient fuel

may still be supplied to the engine, and the engine may operate

normally. In these instances, the flight crew would receive no

indication of abnormal fuel flow (i.e., fuel leakage) from the fuel

flow meter. If the flight crew fails to detect a fuel leak, appropriate

action would not be taken to prevent further fuel loss. This condition,

if not corrected, could result in fuel exhaustion due to undetected

fuel leakage.

In light of this information, the FAA finds that certain procedures

should be included in the FAA-approved Airplane Flight Manual (AFM) for

Model 757 series airplanes to enable the flight crew to detect fuel

system leaks and to take appropriate action. The FAA has determined

that such procedures currently are not defined adequately in the AFM

for these airplanes.

Since an unsafe condition has been identified that is likely to

exist or develop on other Boeing Model 757 series airplanes of the same

type design, this AD is being issued to ensure that flight crews are

advised of the potential hazard related to a significantly reduced or

exhausted airplane fuel supply, and of the procedures to address it.

This AD requires revising the Non-Normal Procedures Section of the AFM

to include procedures that will enable the flight crew to identify fuel

system leaks and to take appropriate action to prevent further fuel

loss.

This is considered to be interim action until final action is

identified, at which time the FAA may consider further rulemaking.

Since a situation exists that requires the immediate adoption of

this regulation, it is found that notice and opportunity for prior

public comment hereon are impracticable, and that good cause exists for

making this amendment effective in less than 30 days.

Comments Invited

Although this action is in the form of a final rule that involves

requirements affecting flight safety and, thus, was not preceded by

notice and an opportunity for public comment, comments are invited on

this rule. Interested persons are invited to comment on this 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 under the caption ``ADDRESSES.''

All communications received on or before the closing date for comments

will be considered, and this rule may be amended in light of the

comments received. Factual information that supports the commenter's

ideas and suggestions is extremely helpful in evaluating the

effectiveness of the AD action and determining whether additional

rulemaking action would be needed.

Comments are specifically invited on the overall regulatory,

economic, environmental, and energy aspects of the rule that might

suggest a need to modify the 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 that

summarizes each FAA-public contact concerned with the substance of this

AD 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-50-AD.'' The postcard will be date stamped and

returned to the commenter.

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.

The FAA has determined that this regulation is an emergency

regulation that must be issued immediately to correct an unsafe

condition in aircraft, and is not a ``significant regulatory action''

under Executive Order 12866. It has been determined further that this

action involves an emergency regulation under DOT Regulatory Policies

and Procedures (44 FR 11034, February 26, 1979). If it is determined

that this emergency regulation otherwise would be significant under DOT

Regulatory Policies and Procedures, a final regulatory evaluation will

be prepared and placed in the Rules Docket. A copy of it, if filed, 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, Safety.

Adoption of the Amendment

Accordingly, pursuant to the authority delegated to me by the

Administrator, the Federal Aviation Administration amends 14 CFR part

39 of the Federal Aviation Regulations 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:

94-09-10 Boeing: Amendment 39-8899. Docket 94-NM-50-AD.

Applicability: All Model 757 airplanes, certificated in any

category.

Compliance: Required as indicated, unless accomplished

previously.

To ensure that the flight crew is advised of the potential

hazard associated with fuel exhaustion due to undetected fuel

leakage, and of the procedures necessary to address it, accomplish

the following:

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

the Non-Normal Procedures Section of the FAA-approved Airplane

Flight Manual (AFM) to include the following procedures, which will

enable the flight crew to identify fuel system leaks and to take

appropriate action to prevent further fuel loss. This may be

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

``Flight Management Computer (FMC) Message Fuel QTY Error or Fuel

Disagree

Compare the Fuel Quantity Indicating System (FQIS) total fuel

quantity and the FMC calculated fuel remaining (based on fuel flow)

with estimated fuel usage data.

If a fuel leak is suspected, close the crossfeed valve and turn

off the center fuel pumps. Watch for any unusual decrease in fuel

tank quantity and/or a fuel imbalance to determine if fuel is being

lost.

If an engine fuel leak is confirmed (either visually or by

cockpit indications), shut down the affected engine to stop the leak

and retain fuel. After shutdown, fuel from the remaining center,

left, and right main tanks may be used for the operating engine. Use

FQIS to determine fuel remaining.''

(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: 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

Federal Aviation Regulations (FAR) 21.197 and 21.199 to operate the

airplane to a location where the requirements of this AD can be

accomplished.

(d) This amendment becomes effective on May 11, 1994.

Issued in Renton, Washington, on April 20, 1994.

S. R. Miller,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 94-9989 Filed 4-25-94; 8:45 am]

BILLING CODE 4910-13-U