[Federal Register Volume 59, Number 114 (Wednesday, June 15, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-14360]


[[Page Unknown]]

[Federal Register: June 15, 1994]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 94-NM-81-AD; Amendment 39-8939; AD 94-12-11]

 

Airworthiness Directives; Boeing Model 747-400 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This amendment adopts a new airworthiness directive (AD) that 
is applicable to all Boeing Model 747-400 series airplanes. This action 
requires revising the Airplane Flight Manual 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 June 30, 1994.
    Comments for inclusion in the Rules Docket must be received on or 
before August 15, 1994.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 94-NM-81-AD, 1601 Lind Avenue SW., Renton, 
Washington 98055-4056.

    Information concerning this rulemaking action may be examined at 
the FAA, Transport Airplane Directorate, 1601 Lind Avenue SW., Renton, 
Washington.

FOR FURTHER INFORMATION CONTACT: Jon Regimbal, Aerospace Engineer, 
Propulsion Branch, ANM-140S, FAA, Transport Airplane Directorate, 
Seattle Aircraft Certification Office, 1601 Lind Avenue SW., Renton, 
Washington 98055-4056; telephone (206) 227-2687; fax (206) 227-1181.

SUPPLEMENTARY INFORMATION: On March 21, 1994, a Boeing Model 747-400 
diverted from its intended destination airport because of indications 
that insufficient fuel remained to complete the scheduled leg of the 
flight. During landing and rollout, a large amount of fuel was spilled 
on the runway; additionally, during application of reverse thrust, fuel 
sprayed on the airplane. With such fuel leakage, the potential for a 
large fire existed during and after landing; however, the fuel did not 
ignite and no injuries occurred.
    Investigation of this incident revealed that a major fuel leak had 
developed much earlier in the flight, and that approximately 35,000 
lbs. of fuel had been lost. The operator of the incident airplane 
pointed out that, had a similar scenario occurred on the same flight 
leg in the opposite direction, the airplane's fuel supply would have 
been exhausted prior to reaching a suitable airport.
    The fuel apparently had leaked from a cracked fuel tube within the 
engine nacelle. The cause of the cracking currently is under 
investigation by the engine manufacturer (and may be the subject of 
future rulemaking, if warranted). The fuel leak was located upstream of 
the fuel flow meter. Under these circumstances, sufficient fuel may 
still be supplied to the engine, and the engine may operate normally. 
In this particular incident, the flight crew received no immediate 
indication of abnormal fuel flow (i.e., excessive fuel flow on one 
engine) from the fuel flow meter. The ``FUEL DISAGREE--PROG 2/2'' 
Flight Management System--Control Display Unit (FMS-CDU) message and 
the ``FUEL IMBALANCE'' Engine Indication and Crew Alerting System 
(EICAS) message were displayed some time after the fuel began leaking. 
However, because there currently are no explicit instructions in the 
Airplane Flight Manual (AFM) or the Operations Manual relative to 
actions that should be taken during situations such as these, the 
flight crew did not initiate procedures to isolate the leak and retain 
the remaining fuel on the airplane.
    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 AFM for Model 747-400 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 747-400 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 necessary 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.
    The applicability of this AD action is limited to only Model 747-
400 series airplane. While Model 747-100, -200, -300, SP, and SR series 
airplanes have a similar fuel delivery system to that of the Model 747-
400, the indication systems and flight crew procedures for monitoring 
fuel usage are significantly different for these models. These models 
were designed to be operated by three flight crew members and, in the 
event of a similar fuel leak on one of these airplanes, the flight 
engineer would detect the fuel leak and recommend shutdown of the 
appropriate engine prior to the loss of such a large quantity of fuel.
    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-81-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 that it 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 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:

94-12-11 Boeing: Amendment 39-8939. Docket 94-NM-81-AD.

    Applicability: All Model 747-400 series 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.

In-Flight Fuel Leak

    If the Flight Management Computer System (FMCS) message ``FUEL 
DISAGREE--PROG 2/2'' or ``INSUFFICIENT FUEL'' is displayed:
    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, turn off the stabilizer tank pump 
switches, ifinstalled, the center wing tank pump switches, and the 
tank 2 and 3 override pump switches, and close all crossfeed valves 
(tank-to-engine fuel feed configuration). 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 
flight deck indications), shut down the affected engine to stop the 
leak and retain the remaining fuel. After shutdown of the affected 
engine, resume normal fuel management procedures. All remaining fuel 
can be used for the operating engines. 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 
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) This amendment becomes effective on June 30, 1994.

    Issued in Renton, Washington, on June 8, 1994.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 94-14360 Filed 6-14-94; 8:45 am]
BILLING CODE 4910-13-U