Airworthiness Directives; Boeing Model 757 Series Airplanes

[Federal Register Volume 62, Number 80 (Friday, April 25, 1997)]
[Rules and Regulations]
[Pages 20098-20100]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-10661]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97-NM-73-AD; Amendment 39-10002; AD 97-09-06]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 757 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 757 series airplanes. This action 
requires repetitive inspections to detect damage of the tubes of the 
fire extinguishing and smoke detection systems, and duct support 
brackets of the auxiliary power unit (APU); and corrective actions, if 
necessary. This amendment is prompted by reports of incidents in which 
the tubes of the fire extinguishing and smoke detection systems chafed 
against the stiffener rings and support brackets of the pneumatic duct 
of the APU. The actions specified in this AD are intended to detect and 
correct such chafing, which could result in a hole in the tube of the 
fire extinguishing system and consequently, could prevent the proper 
distribution of the fire extinguishing agent within the aft cargo 
compartment in the event of a fire. Such chafing also could result in a 
hole in the smoke detection system, which could result in the delay of 
detection of a fire in the aft cargo compartment.

DATES: Effective May 15, 1997.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of May 12, 1997.
    Comments for inclusion in the Rules Docket must be received on or 
before June 24, 1997.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 97-NM-73-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: Clayton R. Morris, Jr., Aerospace 
Engineer, Systems and Equipment Branch, ANM-130S, FAA, Seattle Aircraft 
Certification Office, 1601 Lind Avenue, SW., Renton, Washington; 
telephone (206) 227-2794; fax (206) 227-1181.

SUPPLEMENTARY INFORMATION: The FAA has received several reports of 
incidents in which the tubes of the fire extinguishing and smoke 
detection systems of the aft cargo compartment chafed against the 
stiffener rings and support brackets of the pneumatic duct of the 
auxiliary power unit (APU). These incidents occurred on Boeing Model 
757 series airplanes. Investigation revealed that thermal growth of the 
pneumatic duct of the APU caused the stiffener rings to contact the 
tubes. Such thermal growth also can cause a stiffener ring to contact a 
support bracket of the pneumatic duct of the APU, which could 
eventually break the support bracket. A broken support bracket could 
chafe the tubes of the fire extinguishing and smoke detection systems 
of the aft cargo compartment. Chafing of the subject tubes could 
eventually create a hole in the tubes.

[[Page 20099]]

Unsafe Conditions

    A hole in the tubes of the fire extinguishing system, if not 
detected and corrected, could prevent the proper distribution of the 
fire extinguishing agent within the aft cargo compartment in the event 
of a fire. In addition, such a hole could release the fire 
extinguishing agent outside of the aft cargo compartment, which could 
migrate through the return air grilles in the passenger cabin. 
Localized hazardous concentrations of a fire extinguishing agent could 
cause deleterious physiological effects on the passengers and crew.
    Additionally, a hole in the tubes of the smoke detection system, if 
not detected and corrected, could result in the delay of detection of a 
fire in the aft cargo compartment.

Explanation of Relevant Service Information

    The FAA has reviewed and approved Boeing Alert Service Bulletin 
757-26A0040, dated March 27, 1997. The alert service bulletin describes 
procedures for repetitive detailed visual inspections to detect damage 
of the tubes of the fire extinguishing and smoke detection systems, and 
support brackets of the pneumatic duct of the APU. The alert service 
bulletin also describes procedures for replacing, repairing, or 
splicing (as applicable) any damaged part.

Explanation of the Requirements of the Rule

    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 detect and correct chafing of 
the tubes of the fire extinguishing and smoke detection systems. Such 
chafing could result in a hole in a tube of the fire extinguishing 
system, and consequently prevent the proper distribution of the fire 
extinguishing agent within the aft cargo compartment in the event of a 
fire. Such chafing also could result in a hole in a tube of the smoke 
detection system, which could result in the delay of detection of a 
fire in the aft cargo compartment. This AD requires repetitive detailed 
visual inspections to detect damage of the tubes of the fire 
extinguishing and smoke detection systems, and support brackets of the 
pneumatic duct of the APU; and corrective actions, if necessary. The 
actions are required to be accomplished in accordance with the alert 
service bulletin described previously.

Interim Action

    This is considered to be interim action until final action is 
identified, at which time the FAA may consider further rulemaking.

Determination of Rule's Effective Date

    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 rule must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 97-NM-73-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.
    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, 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:

97-09-06  Boeing: Amendment 39-10002. Docket 97-NM-73-AD.

    Applicability: All Model 757 series airplanes, 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

[[Page 20100]]

been eliminated, the request should include specific proposed 
actions to address it.

    Compliance: Required as indicated, unless accomplished 
previously.
    To detect and correct chafing of the tubes of the fire 
extinguishing and smoke detection systems, which could prevent the 
proper distribution of the fire extinguishing agent within the aft 
cargo compartment in the event of a fire, or could result in the 
delay of detection of a fire in the aft cargo compartment, 
accomplish the following:
    (a) Prior to the accumulation of 10,000 flight hours, or within 
60 days after the effective date of this AD, whichever occurs later, 
accomplish paragraphs (a)(1), (a)(2), and (a)(3) of this AD, in 
accordance with Boeing Alert Service Bulletin 757-26A0040, dated 
March 27, 1997. Repeat all inspections thereafter at intervals not 
to exceed 10,000 flight hours.
    (1) Perform a detailed visual inspection to detect damage of the 
tubes of the fire extinguishing system between stations 1300 and 
1580, as applicable, in accordance with the alert service bulletin. 
If any damaged tube is detected, prior to further flight, repair or 
replace it with a new tube, in accordance with the alert service 
bulletin.
    (2) Perform a detailed visual inspection to detect damage of the 
tubes of the smoke detection system between stations 1300 and 1580, 
in accordance with the alert service bulletin.
    (i) If any damage is detected, and the damage is within the 
limits specified in the alert service bulletin, prior to further 
flight, repair it in accordance with the alert service bulletin.
    (ii) If any damage is detected, and the damage is outside the 
limits specified in the alert service bulletin, prior to further 
flight, splice any damaged tube or replace it with a new tube, in 
accordance with the alert service bulletin.
    (3) Perform a detailed visual inspection to detect damage of the 
support brackets of the pneumatic duct of the auxiliary power unit 
(APU) at stations 1380, 1460, and 1540, in accordance with the alert 
service bulletin. If any damage is detected, prior to further 
flight, repair any damaged duct support bracket, or replace it with 
a new duct support bracket, in accordance with the alert service 
bulletin.
    (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 actions shall be done in accordance with Boeing Alert 
Service Bulletin 757-26A0040, dated March 27, 1997. 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 May 12, 1997.

    Issued in Renton, Washington, on April 18, 1997.
James V. Devany,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 97-10661 Filed 4-24-97; 8:45 am]
BILLING CODE 4910-13-U

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