[Federal Register Volume 61, Number 184 (Friday, September 20, 1996)]
[Rules and Regulations]
[Pages 49409-49411]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-23851]



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 Rules and Regulations
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  Federal Register / Vol. 61, No. 184 / Friday, September 20, 1996 / 
Rules and Regulations  

[[Page 49409]]



DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 96-NM-223-AD; Amendment 39-9764; AD 96-19-17]
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 certain Boeing Model 757 series airplanes. This action 
requires a one-time inspection to detect discrepancies of the main 
battery shunt, and replacement with a serviceable part, if necessary. 
This action also requires inspection of certain wires, washers, and 
brass jam nuts to detect any discrepancy, and replacement with a 
serviceable part, if necessary. Additionally, this action requires 
inspection, and adjustment if necessary, of the torque and resistance 
of the installation of the main battery ground stud. This amendment is 
prompted by a report of interruption of electrical power during flight 
due to improper installation of the main battery shunt and ground stud 
connection of the main battery. The actions specified in this AD are 
intended to prevent such electrical power interruptions, which could 
result in loss of battery power to the source of standby power for the 
airplane.

DATES: Effective October 7, 1996.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of October 7, 1996.
    Comments for inclusion in the Rules Docket must be received on or 
before November 19, 1996.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 96-NM-223-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: Stephen S. Oshiro, Aerospace Engineer, 
Systems and Equipment Branch, ANM-130S, FAA, Seattle Aircraft 
Certification Office, 1601 Lind Avenue, SW., Renton, Washington; 
telephone (206) 227-2793; fax (206) 227-1181.

SUPPLEMENTARY INFORMATION: The FAA recently has received reports 
indicating that interruptions of electrical power have occurred during 
flight, which resulted in the loss of battery power to the hot battery 
bus (HBB) on a Boeing Model 767 series airplane. The HBB is the source 
of standby power to the airplane. Investigation revealed that the 
reported loss of power to the HBB occurred due to cracked shunts, 
improper installation of fasteners on the shunt studs, and improper 
torque of shunt fasteners. It appears that the improper installation of 
fasteners on the shunt studs and improper torque of shunt fasteners 
occurred during manufacture.
    Loose fasteners on the shunt studs can create an open circuit or 
high resistance in the connection of the main battery ground stud, 
which can cause an interruption of the battery charger and the loss of 
the HBB. The loss of the HBB and associated loads will cause multiple 
advisory level Engine Indication and Crew Alerting System (EICAS) 
messages; loss of power to the standby buses/loads during standby 
operation; and the potential loss of center bus power. Such loss of 
standby power could adversely affect the function of the following 
systems:
    1. the captain's standby instruments,
    2. flight control electronics,
    3. Very High Frequency (VHF) communications,
    4. thrust reverser control,
    5. standby ignition,
    6. passenger oxygen,
    7. fire detection and extinguishing, and
    8. wing and engine anti-ice systems, among others.
    Improper installation of the main battery shunt and ground stud 
connection of the main battery, if not corrected, could cause an 
interruption of electrical power and loss of battery power to the HBB 
during flight.
    The main battery shunts of the main equipment center on the Boeing 
Model 767 series airplanes are identical to those installed on the 
Boeing Model 757 series airplanes; therefore, both of these models may 
be subject to this same unsafe condition. The FAA has addressed this 
unsafe condition in Model 767 series airplanes with the issuance of AD 
96-19-10, amendment 39-9757, on September 6, 1996.

Explanation of Relevant Service Information

    The FAA has reviewed and approved Boeing Alert Service Bulletin 
757-24A0079, dated August 8, 1996, which describes procedures for 
inspection of the main battery shunt to detect contaminated fasteners, 
missing pressure washers or washers having an incorrect part number, or 
damage to the terminal posts or to the plastic base, and replacement of 
the main battery shunt, if necessary. The alert service bulletin also 
describes inspection of certain wires, washers, and brass jam nuts to 
detect any discrepancy, and replacement of any discrepant part with a 
serviceable part.
    Additionally, the alert service bulletin describes procedures for 
an inspection of the main battery ground stud to verify the torque and 
resistance, and adjustment of the torque and resistance, if necessary.

Explanation of the Requirements of the Rule

    Since an unsafe condition has been identified that is likely to 
exist or develop on Boeing Model 757 series airplanes, this AD is being 
issued to prevent interruption of electrical power during flight, which 
could result in loss of battery power to the source of standby power 
for the airplane. This AD requires inspection of the main battery

[[Page 49410]]

shunt to detect contaminated fasteners, missing pressure washers or 
washers having an incorrect part number, or damage to the terminal 
posts or to the plastic base, and replacement of the main battery 
shunt, if necessary. This AD also requires inspection of certain wires, 
washers, and brass jam nuts to detect any discrepancy, and replacement 
of any discrepant part with a serviceable part. Additionally, this AD 
requires an inspection of the main battery ground stud to verify the 
torque and electrical resistance, and adjustment of the torque and 
resistance, if necessary. The actions are required to be accomplished 
in accordance with the alert service bulletin described previously.

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 96-NM-223-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:

96-19-17  Boeing: Amendment 39-9764. Docket 96-NM-223-AD.

    Applicability: Model 757 series airplanes, as listed in Boeing 
Alert Service Bulletin 757-24A0079, dated August 8, 1996; 
certificated in any category.

    Note 1: This AD applies to each airplane identified in the 
preceding applicability provision, regardless of whether it has been 
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 interruptions of electrical power during flight, 
which could result in loss of battery power to the source of standby 
power for the airplane, accomplish the following:
    (a) Within 45 days after the effective date of this AD, 
accomplish the actions specified in paragraphs (a)(1), (a)(2) and 
(a)(3) of this AD, in accordance with Boeing Alert Service Bulletin 
757-24A0079, dated August 8, 1996.
    (1) Perform an inspection of the main battery shunt, to detect 
any contaminated fasteners, missing pressure washers or washers 
having an incorrect part number, or damage to terminal posts or to 
the plastic base. If any discrepancy is found, prior to further 
flight, replace the main battery shunt, in accordance with the alert 
service bulletin.
    (2) Perform an inspection of the wires, washers, and brass jam 
nuts to detect any contamination or damage. If any discrepancy is 
found, prior to further flight, replace the discrepant part with a 
serviceable part, in accordance with the alert service bulletin.
    (3) Inspect the torque and electrical resistance of the 
installation of the main battery ground stud, and adjust the torque 
and resistance of the ground stud, 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 757-24A0079, dated August 8, 1996. This 
incorporation by reference was approved by the Director of the 
Federal Register in

[[Page 49411]]

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 October 7, 1996.

    Issued in Renton, Washington, on September 11, 1996.
James V. Devany,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 96-23851 Filed 9-19-96; 8:45 am]
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