[Federal Register Volume 61, Number 227 (Friday, November 22, 1996)]
[Rules and Regulations]
[Pages 59319-59321]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-29726]


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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 96-NM-255-AD; Amendment 39-9829; AD 96-24-03]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 747-400 ``Combi'' 
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), 
applicable to certain Boeing 747-400 series airplanes in the ``combi'' 
configuration. This action requires replacing the decompression panels 
that are located in the smoke barrier between the passenger and main 
deck cargo compartment, with new panels of an improved design. This 
amendment is prompted by reports indicating that normal pressurization 
cycles are causing premature tearing or opening of these decompression 
panels. The actions specified in this AD are intended to prevent 
increased airflow in the cargo compartment caused by the tearing or 
opening of these panels; this condition, if not corrected, could result 
in delayed fire detection and reduced effectiveness of the cargo 
compartment fire suppression system.

DATES: Effective December 9, 1996.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of December 9, 1996.
    Comments for inclusion in the Rules Docket must be received on or 
before January 21, 1997.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 96-NM-255-AD, 1601 Lind Avenue, SW., 
Renton, Washington 98055-4056.
    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 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.

FOR FURTHER INFORMATION CONTACT: Susan Letcher, Aerospace Engineer, 
Systems and Equipment Branch, ANM-130S, FAA, Seattle Aircraft 
Certification Office, 1601 Lind Avenue, SW., Renton, Washington; 
telephone (206) 227-2670; fax (206) 227-1181.

SUPPLEMENTARY INFORMATION: The FAA has received at least four reports 
indicating that tearing and inadvertent opening of the decompression 
(``blow-out'') panels located in the smoke barrier between the 
passenger and main deck cargo compartment have occurred on Boeing Model 
747-400 ``combi'' airplanes. One operator reported that the 
decompression panel on one of its airplanes tore and inadvertently 
opened during service. A subsequent survey indicated that three other 
operators had experienced similar in-service incidents. Investigation 
has revealed that fatigue associated with normal pressurization cycles 
is causing the premature tearing of the decompression panels.
    Tearing and subsequent opening of these decompression panels allows 
additional air to flow into the cargo compartment. In the event of a 
fire in the cargo compartment, the additional airflow would dilute the 
smoke and, consequently, result in delayed detection of the fire. 
Additionally, the increased airflow would dilute the cargo compartment 
fire suppression agent below effective concentrations and, thus, 
degrade the capability of the system to suppress a fire.
    This condition is significant specifically for airplanes that are 
equipped with a ``90-minute fire suppression system'' installed in 
accordance with ``Option 4'' of paragraph (b)(4) of AD 93-07-15, 
amendment 39-8547 (58 FR 21243, April 20, 1993). That AD requires 
various actions that are intended to minimize the hazards associated 
with a fire occurring in the main deck Class B cargo compartment. 
Paragraph (b)(4) of AD 93-07-15 requires, among other things, 
installing a cargo compartment fire extinguishing system in the Class B 
cargo compartment that

    * * * provides an initial fire extinguishant concentration of at 
least 5% of the empty compartment volume of Halon 1301 or 
equivalent, and a fire suppression extinguishant concentration of at 
least 3% of the empty compartment volume of Halon 1301 or 
equivalent, for a period of time not less than 90 minutes.

    If additional air flows into the cargo compartment through a torn 
or open panel and dilutes the amount of

[[Page 59320]]

extinguishant, it would reduce the effectiveness of the 90-minute fire 
suppression system.

Explanation of Relevant Service Information

    Boeing has issued Alert Service Bulletin 747-25A3064, dated 
December 21, 1995, which describes procedures for replacing the 
currently-installed decompression panels with new panels of an improved 
design. The new panels are more resistant to tearing and inadvertent 
opening.

Explanation of Requirements of the Rule

    Since an unsafe condition has been identified that is likely to 
exist or develop on other airplanes of the same type design, this AD is 
being issued to prevent tearing and inadvertent opening of the 
decompression panels that are located in the smoke barrier between the 
passenger and main deck cargo compartment. This AD requires the 
replacement of certain panels with new panels having an improved 
design. The actions are required to be accomplished in accordance with 
the service bulletin described previously.
    This AD is applicable only to airplanes that are equipped with a 
90-minute fire suppression system, which is specified as ``Option 4'' 
in paragraph (b)(4) of AD 93-07-15.

Cost Impact

    None of the Model 747-400 ``Combi'' airplanes affected by this 
action are on the U.S. Register. All airplanes included in the 
applicability of this rule currently are operated by non-U.S. operators 
under foreign registry; therefore, they are not directly affected by 
this AD action. However, the FAA considers that this rule is necessary 
to ensure that the unsafe condition is addressed in the event that any 
of these subject airplanes are imported and placed on the U.S. Register 
in the future.
    Should an affected airplane be imported and placed on the U.S. 
Register in the future, it would require approximately 1 work hour to 
accomplish the required actions, at an average labor charge of $60 per 
work hour. Required parts would cost approximately $14,000 per 
airplane. Based on these figures, the cost impact of this AD would be 
$14,060 per airplane.

Determination of Rule's Effective Date

    Since this AD action does not affect any airplane that is currently 
on the U.S. register, it has no adverse economic impact and imposes no 
additional burden on any person. Therefore, prior notice and public 
procedures hereon are unnecessary and the amendment may be made 
effective in less than 30 days after publication in the Federal 
Register.

Comments Invited

    Although this action is in the form of a final rule and was not 
preceded by notice and 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 rule must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 96-NM-255-AD.'' The postcard will be date stamped and 
returned to the commenter.

Regulatory Impact

    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. 106(g), 40113, 44701.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by adding the following new 
airworthiness directive:

96-24-03 Boeing: Amendment 39-9829. Docket 96-NM-255-AD.

    Applicability: Model 747-400 ``combi'' airplanes; as listed in 
Boeing Alert Service Bulletin 747-25A3064, dated December 21, 1995; 
on which a 90-minute fire suppression system specified in paragraph 
(b)(4) of AD 93-07-15, amendment 39-8547, has been installed; 
certificated in any category.

    Note 1: This AD applies to each airplane identified in the 
preceding applicability provision, regardless of whether it has been 
otherwise 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 request approval for an 
alternative method of compliance in accordance with paragraph (b) of 
this AD. The request should include an assessment of the effect of 
the modification, alteration, or repair on the unsafe condition 
addressed by this AD; and, if the unsafe condition has not been 
eliminated, the request should include specific proposed actions to 
address it.

    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent increased airflow in the cargo compartment caused by 
the tearing or opening of the decompression panels, which could 
result in delayed fire detection and reduced effectiveness of the 
fire suppression system, accomplish the following:
    (a) Within 90 days after the effective date of this AD, replace 
the decompression

[[Page 59321]]

(``blow-out'') panels in the smoke barrier above the cargo/passenger 
partition, with improved panels, in accordance with Boeing Alert 
Service Bulletin 747-25A3064, dated December 21, 1995.
    (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 replacement shall be done in accordance with Boeing 
Alert Service Bulletin 747-25A3064, dated December 21, 1995. 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.
    (e) This amendment becomes effective on December 9, 1996.

    Issued in Renton, Washington, on November 14, 1996.
James V. Devany,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 96-29726 Filed 11-21-96; 8:45 am]
BILLING CODE 4910-13-U