Airworthiness Directives; Boeing Model 737, 747, and 777 Series Airplanes

[Federal Register Volume 66, Number 112 (Monday, June 11, 2001)]
[Rules and Regulations]
[Pages 31129-31131]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 01-13998]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2000-NM-156-AD; Amendment 39-12254; AD 2001-11-11]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 737, 747, and 777 Series 
Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment adopts a new airworthiness directive (AD), 
applicable to certain Boeing Model 737, 747, and 777 series airplanes, 
that requires replacement of the seat track fittings on all passenger 
seats with new, improved fittings. The actions specified by this AD are 
intended to prevent unrestrained movement of the passenger seats during 
high forward deceleration of the airplane, which could result in injury 
to the passengers or crew members during an emergency landing.

DATES: Effective July 16, 2001.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of July 16, 2001.

ADDRESSES: 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 Federal 
Aviation Administration (FAA), Transport Airplane Directorate, Rules 
Docket, 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: Jan Risheim, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 
1601 Lind Avenue, SW., Renton, Washington; telephone (425) 227-1675; 
fax (425) 227-1181.

SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal 
Aviation Regulations (14 CFR part 39) to include an airworthiness 
directive (AD) that is applicable to certain Boeing Model 737, 747, and 
777 series airplanes was published in the Federal Register on December 
22, 2000 (65 FR 80794). That action proposed to require replacement of 
the seat track fittings on all passenger seats with new, improved 
fittings.

[[Page 31130]]

Comments

    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due consideration has been given to 
the comments received from one commenter.

Change Unsafe Condition and Paragraph (a) of Proposed Rule

    A single commenter asks that the unsafe condition in the proposed 
rule which states, ``To prevent unrestrained movement of the passenger 
seats during high forward deceleration of the airplane, which could 
result in injury to the passengers or crew members during an emergency 
landing,'' be changed to read, ``To verify that during seat 
installation no over-torque on seat track fitting shear bolts 
occurred.'' The commenter also asks that paragraph (a) of the proposed 
rule be changed to read, ``Within 1 month after the effective date of 
this AD: Inspect all the seat track fittings on all the passenger seats 
as specified in the applicable component maintenance manual under the 
section titled, `Troubleshooting,' following the troubleshooting 
procedure therein.''
    The commenter states that if the old fitting is properly installed 
(i.e., the maximum allowable torque value is not exceeded, and the 
shear plunger is correctly engaged), no risk of unrestrained movement 
of the passenger seat under any circumstances, including high forward 
deceleration, can occur. The commenter notes that this has been 
demonstrated during the certification process of the seat, and found 
acceptable by all involved airworthiness authorities. To date there is 
no evidence that such an occurrence is even possible, provided that the 
installation specifications of the seat manufacturer are fully 
accomplished. The commenter also states that if the new improved 
fitting is used, but the maximum allowable torque value is exceeded, 
then an unrestrained movement of the passenger seat is possible exactly 
as with the old fitting in the same condition. The commenter concludes 
that issuance of an airworthiness directive requiring the replacement 
of old fittings with new, improved fittings having a higher maximum 
torque value only, is ineffective to prevent unrestrained seat 
movement. Additionally, the origin of the eventual safety problem 
resides in the application on the shear bolt of high torque value, 
exceeding the maximum allowable torque specified by the seat 
manufacturer.
    The FAA does not concur. As stated in the proposed rule, the 
manufacturer reported that the shear plunger screws of certain seat 
track fittings broke during installation. Analysis of the broken screws 
revealed that various modifications had weakened the shear plunger 
screws. Further analysis revealed that high torque during seat 
installation resulted in broken shear plunger screws and subsequent 
disengagement of the shear plunger from the seat track. Additionally, 
the manufacturer found that the threads used to attach the shear 
plunger screws to the seat track were filled with coating that was used 
on the exterior of the screws, which increases the torque required to 
install the screw. This information indicates that the torque required 
to install the shear plunger screws is very close to the strength of 
the screw, and as the seats are moved for maintenance or interior 
reconfigurations, breaking of the shear plunger screws is to be 
expected. The new, improved design of the seat track fitting corrects 
the deficiencies in the existing design, and is necessary to correct 
the unsafe condition specified in this final rule. Therefore, no change 
to the final rule is necessary.

Conclusion

    After careful review of the available data, including the comments 
noted above, the FAA has determined that air safety and the public 
interest require the adoption of the rule as proposed.

Cost Impact

    There are approximately 46 Model 737, 747, and 777 series airplanes 
of the affected design in the worldwide fleet.
    For Model 737 series airplanes (2 U.S.-registered airplanes): It 
will take approximately 10 work hours per airplane to accomplish the 
replacement, at an average labor rate of $60 per work hour. Required 
parts will cost approximately $15,100 per airplane. Based on these 
figures, the cost impact of the replacement required by this AD on U.S. 
operators is estimated to be $31,400, or $15,700 per airplane.
    The cost impact figure discussed above is based on assumptions that 
no operator has yet accomplished any of the proposed requirements of 
this AD action, and that no operator would accomplish those actions in 
the future if this proposed AD were not adopted. The cost impact 
figures discussed in AD rulemaking actions represent only the time 
necessary to perform the specific actions actually required by the AD. 
These figures typically do not include incidental costs, such as the 
time required to gain access and close up, planning time, or time 
necessitated by other administrative actions.
    Currently, there are no affected Model 747 series airplanes on the 
U.S. Register. However, should an affected airplane be imported and 
placed on the U.S. Register in the future, it requires approximately 29 
work hours to accomplish the replacement, at an average labor rate of 
$60 per work hour. Required parts will cost approximately $43,000. 
Based on these figures, the cost impact of the replacement required by 
this AD will be $44,740 per airplane.
    Currently, there are no affected Model 777 series airplanes on the 
U.S. Register. However, should an affected airplane be imported and 
placed on the U.S. Register in the future, it requires approximately 24 
work hours to accomplish the replacement, at an average labor rate of 
$60 per work hour. Required parts will cost approximately $36,400. 
Based on these figures, the cost impact of the replacement required by 
this AD will be $37,840 per airplane.

Regulatory Impact

    The regulations adopted herein will not have a substantial direct 
effect 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, it 
is determined that this final rule does not have federalism 
implications under Executive Order 13132.
    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:

[[Page 31131]]

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:

2001-11-11 Boeing: Amendment 39-12254. Docket 2000-NM-156-AD.

    Applicability: Model 737, 747, and 777 series airplanes; 
certificated in any category; as specified in the Boeing service 
bulletins listed in Table 1. below:

                         Table 1.--Applicability
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For Model 737 series airplanes............  737-25-1371, Revision 2,
                                             dated December 9, 1999;
For Model 737 series airplanes............  737-25-1407, dated December
                                             9, 1999;
For Model 747 series airplanes............  747-25-3196, Revision 1,
                                             dated May 13, 1999; or
For Model 777 series airplanes............  777-25-0111, Revision 1,
                                             dated December 13, 1999;
------------------------------------------------------------------------


    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 unrestrained movement of the passenger seats during 
high forward deceleration of the airplane, which could result in 
injury to the passengers or crew members during an emergency 
landing, accomplish the following:

Replacement

    (a) Within 18 months after the effective date of this AD: 
Replace all the seat track fittings on all the passenger seats with 
new, improved fittings, in accordance with the Accomplishment 
Instructions specified in Boeing Service Bulletin 737-25-1371; 
Revision 2 or 737-25-1407, both dated December 9, 1999 (for Model 
737 series airplanes); Boeing Service Bulletin 747-25-3196, Revision 
1, dated May 13, 1999 (for Model 747 series airplanes); or Boeing 
Service Bulletin 777-25-0111, Revision 1, dated May 13, 1999 (for 
Model 777 series airplanes); as applicable.

Alternative Methods of Compliance

    (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. 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.

Special Flight Permits

    (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.

Incorporation by Reference

    (d) The replacement shall be done in accordance with Boeing 
Service Bulletin 737-25-1371, Revision 2, dated December 9, 1999; 
Boeing Service Bulletin 737-25-1407, dated December 9, 1999; Boeing 
Service Bulletin 747-25-3196, Revision 1, dated May 13, 1999; or 
Boeing Service Bulletin 777-25-0111, Revision 1, dated May 13, 1999; 
as applicable. 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.

Effective Date

    (e) This amendment becomes effective on July 16, 2001.

    Issued in Renton, Washington, on May 25, 2001.
Vi L. Lipski,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 01-13998 Filed 6-8-01; 8:45 am]
BILLING CODE 4910-13-U

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