[Federal Register Volume 65, Number 114 (Tuesday, June 13, 2000)]
[Rules and Regulations]
[Pages 37022-37025]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-14436]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-NM-208-AD; Amendment 39-11777; AD 2000-11-28]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 747-400 and 767-200 and -
300 Series Airplanes Powered by Pratt & Whitney Model PW4000 Series 
Engines

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 747-400 and 767-200 and -300 series 
airplanes, that requires repetitive inspections to detect damage and 
wear of the auxiliary track assembly of the thrust reverser, and 
corrective actions, if necessary. This amendment also requires eventual 
repair of the auxiliary track assembly, or replacement of the slider 
and liner or the entire assembly, with new, improved parts, which, when 
accomplished, would terminate the repetitive inspections. This 
amendment is prompted by reports of damage and wear to the auxiliary 
track assembly. The actions specified by this AD are intended to 
prevent a slider disengaging from the auxiliary track assembly, which 
could lead to separation of a portion of the thrust reverser from the 
airplane during flight, possible impact of separated portions on 
airplane structure, and consequent possible rapid decompression of the 
airplane, reduced controllability of the airplane, or reduced 
structural integrity of the fuselage.

DATES: Effective July 18, 2000.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of July 18, 2000.

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: Sulmo Mariano, Aerospace Engineer, 
Propulsion Branch, ANM-140S, FAA, Transport Airplane Directorate, 
Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, 
Washington 98055-4056; telephone (425) 227-2686; 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 747-400 and 
767-200 and -300 series airplanes was published in the Federal Register 
on October 19, 1999 (64 FR 56276). That action proposed to require 
repetitive inspections to detect damage and wear of the auxiliary track 
assembly of the thrust reverser, and corrective actions, if necessary. 
That action also proposed to require eventual replacement of the liner 
and slider, or the entire assembly, with new, improved parts, which, 
when accomplished, would terminate the repetitive inspections.

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.
    One commenter supports the proposed rule.

Request To Revise Certain Requirements in the Proposed AD

    Several commenters indicate that they disagree with the proposed 
replacement of the auxiliary track beam assembly, including 
installation of a new slider and liner, regardless of the amount of 
wear and/or damage to the track beam. The commenters request that 
repair of the track beam be allowed when the damage is within the 
allowable limits specified in the referenced service information. One 
commenter states that replacement of the track beam fitting is required 
only when the wear or damage is beyond repairable limits, as specified 
in Boeing Service Bulletin 747-78A2164, Revision 2, and Boeing Service 
Bulletin 767-78A0079, Revision 2. The commenter notes that replacement 
of the track beam fitting in and of itself does nothing to address the 
root cause of the excessive wear; however, the new design slider 
fitting and track liner do address and correct the root cause. A second 
commenter states that the service bulletins specify replacement of the 
track beam assembly if the track beam has any discrepancy AND the 
measurement of the gap is greater than 0.45 inch. If the track beam has 
any discrepancy and the gap measurement is less than 0.45 inch, only 
the slider and liner should be replaced. Another commenter states that 
replacement of the track beam assembly is necessary only when damage 
cannot be repaired by means of replacement of the liner, slider, and/or 
retainer bar.
    The FAA concurs with the commenters' requests. The FAA has 
coordinated this issue with the manufacturer, and has determined that 
if the damage to the track beam assembly is not beyond the repairable 
limits specified in the referenced service bulletins, a repair that 
involves replacement of the slider and liner and installation of a 
retainer bar, in lieu of replacement of the track beam assembly, is 
acceptable. Therefore, paragraphs (a) and (c) of this AD have been 
revised to specify measuring the auxiliary track beam dimensions in 
accordance with the Accomplishment Instructions of the referenced 
service bulletins, and to allow repair if the measurement is within the 
allowable limits.

Request To Revise Cost Impact Information

    One commenter states that the total number of U.S.-registered Model 
747-400 series airplanes affected by the proposed AD should be higher 
than the 12 airplanes shown in the cost impact section. The commenter 
indicates that it has 10 affected airplanes in its fleet and assumes 
that other operators also have Model 747-400 series airplanes that are 
affected by the proposal.
    The FAA concurs. The referenced service bulletin specifies a total 
of 36 Model 747-400 series airplanes of U.S.-registry that are powered 
by Pratt & Whitney PW4000 series engines. In light of this information, 
the FAA has revised the cost impact information, below, to specify that 
36 Model 747-400 series airplanes of U.S. registry will be affected by 
this AD.

Request for Credit for Previously Accomplished Work

    One commenter requests credit for prior accomplishment of work done 
in

[[Page 37023]]

accordance with Boeing Service Bulletin 747-78A2164, dated June 19, 
1997, including Revision 1, dated February 5, 1998; and 767-78A0079, 
dated June 19, 1997, including Revision 1, dated February 5, 1998; 
which were previously issued revisions of the service bulletins 
referenced in the proposed rule as the appropriate sources of service 
information for accomplishment of the actions in the proposal. The 
commenter states that it incorporated the inspection and terminating 
actions described in the above service bulletins on two-thirds of its 
fleet beginning in June 1997. Additionally, the commenter states that 
the proposed rule requires different terminating action than the 
original and Revision 1 of the service bulletins specify.
    The FAA partially concurs with the commenter's request. The FAA has 
determined that there are significant differences between Revision 2 of 
the service bulletins and the original issue. The accomplishment 
instructions in Revision 2 provide more detailed information about how 
to perform the inspections, and are more specific regarding the extent 
of damage permitted before accomplishing repair work. Therefore, the 
FAA cannot give credit for work accomplished in accordance with the 
original issue of the service bulletin. However, for any procedure 
which an operator has accomplished previously, the operator may request 
approval of an alternative method of compliance in accordance with the 
provisions of paragraph (d) of this AD.
    Revision 1 of the service bulletin is essentially identical to 
Revision 2, which was cited in the proposed AD as the appropriate 
source of service information for accomplishment of the required 
actions. Revision 2 simply changes the recommended repetitive 
inspection interval for detection of no wear or damage. Therefore, this 
final rule has been revised to add a new NOTE 4 to include Revision 1 
of the referenced service bulletins as an additional source of service 
information for accomplishment of the actions.

Request To Extend Compliance Time and Revise Proposed Inspection

    One commenter states that the results of a survey of operators of 
Model 747 and 767 series airplanes powered by Pratt & Whitney PW4000 
series engines, which was conducted by the manufacturer in January 
1998, revealed that the most significant wear occurs on the lower 
auxiliary track assembly. The commenter recommends that the inspection 
only pertain to that assembly. The commenter also requests that the FAA 
extend the grace period for inspection of the upper and lower auxiliary 
track assemblies from 90 days to 18 months for the reason stated 
previously.
    The FAA does not concur with the commenter's requests. In 
developing an appropriate compliance time for this action, the FAA 
considered not only the degree of urgency associated with addressing 
the subject unsafe condition, but accomplishment of the required 
inspection within an interval of time that parallels normal scheduled 
maintenance for the majority of affected operators. However, under the 
provisions of paragraph (d) of the final rule, the FAA may approve 
requests for adjustments to the compliance time if data are submitted 
to substantiate that such an adjustment would provide an acceptable 
level of safety.
    In addition, the inspection required by paragraph (a) of the final 
rule is required to be accomplished in accordance with the inspection 
procedures specified in Boeing Service Bulletin 747-78A2164, Revision 
2, dated December 3, 1998; or Boeing Service Bulletin 767-78A0079, 
Revision 2, dated December 3, 1998; as applicable. Inspection of only 
the lower auxiliary track assembly is inadequate, in light of the fact 
that service experience accumulated over time has shown that excessive 
wear and damage are present in both the upper and lower auxiliary track 
assemblies. Therefore, no change to the final rule is necessary in this 
regard.

Other Related Service Information

    One commenter recommends that the FAA include the actions specified 
in Boeing Service Bulletins 767-78-0005, 767-78-0037, and 767-78-0039 
in the proposed rule as additional requirements. These service 
bulletins describe the replacement of the aluminum auxiliary slider 
fittings of the original design with new design steel fittings, on 
Model 767 series airplanes powered by General Electric CF6-80A and 
Pratt & Whitney JT9D-7R4D series engines. The commenter states that 
cracking of the aluminum fittings due to fatigue loading could result 
in breakage of the slider and subsequent separation of a portion of the 
thrust reverser from the airplane, which could lead to an unsafe 
condition similar to that addressed in the proposed AD.
    The FAA does not concur with the commenter's recommendation. The 
FAA has determined that since the suggested changes would alter the 
actions currently required by this AD, additional rulemaking would be 
required. The FAA finds that to delay this action would be 
inappropriate in light of the identified unsafe condition. However, the 
FAA will discuss this issue with the manufacturer at a later date; 
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 with the changes previously 
described. The FAA has determined that these changes will neither 
increase the economic burden on any operator nor increase the scope of 
the AD.

Cost Impact

    There are approximately 254 airplanes of the affected design in the 
worldwide fleet. The FAA estimates that 36 Model 747-400 series 
airplanes and 46 Model 767-200 and -300 series airplanes of U.S. 
registry will be affected by this AD.
    It will take approximately 4 work hours per engine to accomplish 
the required repetitive inspections, at an average labor rate of $60 
per work hour. Based on these figures, the cost impact of the AD on 
U.S. operators of Model 747-400 series airplanes (4 engines per 
airplane) is estimated to be $34,560, or $960 per airplane, per 
inspection cycle. The cost impact of the AD on U.S. operators of Model 
767 series airplanes (2 engines per airplane) is estimated to be 
$22,080, or $480 per airplane, per inspection cycle.
    Should an operator be required to accomplish the replacement of the 
auxiliary track assembly, it would take approximately 220 work hours 
per auxiliary track assembly to accomplish the replacement, at an 
average labor rate of $60 per work hour. Required parts would cost 
approximately $30,090. Based on these figures, the cost impact of this 
replacement is estimated to be $43,290 per assembly. There are four 
auxiliary track assemblies per engine.
    Should an operator be required to accomplish the replacement of the 
liner and slider, it would take approximately 8 work hours per 
auxiliary track assembly to accomplish the replacement, at an average 
labor rate of $60 per work hour. Required parts would be provided at no 
cost by the airplane manufacturer. Based on these figures, the cost 
impact of this replacement is estimated to be $480 per assembly. There 
are four auxiliary track assemblies per engine.
    The cost impact figures discussed above are based on assumptions 
that no

[[Page 37024]]

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 AD were not adopted.

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:

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:

2000-11-28  Boeing: Amendment 39-11777. Docket 99-NM-208-AD.

    Applicability: Model 747-400 series airplanes powered by Pratt & 
Whitney PW4000 series engines, line numbers 696 through 1100 
inclusive; and Model 767-200 and -300 series airplanes powered by 
Pratt & Whitney PW4000 series engines, line numbers 1 through 646 
inclusive; 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 (d) 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 a slider disengaging from the auxiliary track 
assembly, which could lead to separation of a portion of the thrust 
reverser from the airplane during flight, possible impact of 
separated portions on airplane structure, and consequent possible 
rapid decompression of the airplane, reduced controllability of the 
airplane, or reduced structural integrity of the fuselage, 
accomplish the following:

Initial Inspection

    (a) Prior to the accumulation of 3,000 total flight cycles, or 
within 90 days after the effective date of this AD, whichever occurs 
later, perform a detailed visual inspection of the upper and lower 
auxiliary track assemblies on each thrust reverser half of each 
engine to detect missing segments of the track lip; to detect signs 
that the slider has disengaged from the track; to detect cracks, 
gouges, and wear of the liner; and measure the auxiliary track beam 
dimensions; in accordance with the Accomplishment Instructions of 
Boeing Service Bulletin 747-78A2164, Revision 2, dated December 3, 
1998 (for Model 747-400 series airplanes); or Boeing Service 
Bulletin 767-78A0079, Revision 2, dated December 3, 1998 (for Model 
767 series airplanes); as applicable.

    Note 2: For the purposes of this AD, a detailed visual 
inspection is defined as: ``An intensive visual examination of a 
specific structural area, system, installation, or assembly to 
detect damage, failure, or irregularity. Available lighting is 
normally supplemented with a direct source of good lighting at 
intensity deemed appropriate by the inspector. Inspection aids such 
as mirror, magnifying lenses, etc., may be used. Surface cleaning 
and elaborate access procedures may be required.''

Repetitive Inspections/Corrective Actions

    (1) If no discrepancy is detected, repeat the detailed visual 
inspection thereafter at intervals not to exceed 3,000 flight cycles 
or 7,000 flight hours, whichever occurs earlier, until paragraph (b) 
or (c), as applicable, has been accomplished.
    (2) If the auxiliary track lip has a missing segment of 3 inches 
or longer, or longitudinal cracks at the base of the lip, or other 
indications that the slider has disengaged from the track in the 
forward 4 inches, prior to further flight, repair in accordance with 
Part A of the Accomplishment Instructions of the applicable service 
bulletin. Repeat the detailed visual inspection thereafter at the 
applicable intervals specified in Part A of the Accomplishment 
Instructions of the applicable service bulletin, until paragraph (c) 
of this AD has been accomplished.
    (3) If the auxiliary track lip has a missing segment of 3 inches 
or longer, or longitudinal cracks at the base of the lip, or other 
indications that the slider has disengaged from the track AFT of the 
forward four inches, accomplish paragraphs (a)(3)(i) or (a)(3)(ii) 
of this AD.
    (i) Prior to further flight, repair in accordance with Part B of 
the Accomplishment Instructions of the applicable service bulletin. 
Repeat the detailed visual inspection thereafter at the applicable 
intervals specified in Part B of the Accomplishment Instructions of 
the applicable service bulletin, until paragraph (c) of this AD has 
been accomplished.
    (ii) Accomplish both paragraphs (a)(3)(ii)(A) and (a)(3)(ii)(B) 
of this AD:
    (A) Prior to further flight, deactivate the associated thrust 
reverser in accordance with Section 78-2 of Boeing Document 
D6U10151, ``Boeing 747-400 Dispatch Deviations Guide,'' Revision 11, 
dated March 31, 1998 (for Model 747-400 series airplanes); or 
Section 78-2 of Boeing Document D630T002, ``Boeing 767 Dispatch 
Deviations Guide,'' Revision 19, dated May 14, 1999 (for Model 767 
series airplanes); as applicable. No more than one thrust reverser 
on any airplane may be deactivated under the provisions of the 
paragraph.

    Note 3: The airplane may be operated for up to 30 days in 
accordance with the provisions and limitations specified in the 
operator's FAA-approved Master Minimum Equipment List, provided that 
no more than one thrust reverser on the airplane is inoperative.

    (B) Within 30 days after deactivation of any thrust reverser in 
accordance with paragraph (a)(3)(ii)(A) of this AD, the thrust 
reverser must be repaired in accordance with the Accomplishment 
Instructions of the applicable service bulletin; once this is 
accomplished, the thrust reverser may then be reactivated. Repeat 
the detailed visual inspection thereafter at the applicable 
intervals specified in the Accomplishment Instructions of the 
applicable service bulletin, until paragraph (c) of this AD has been 
accomplished.

Terminating Action

    (b) For any auxiliary track assembly on which no discrepancy is 
detected during any detailed visual inspection required by paragraph 
(a) of this AD: Replace the liner and slider of the auxiliary track 
assembly with a new, improved liner and slider, in accordance with 
Part A of the Accomplishment Instructions of Boeing Service Bulletin 
747-78A2164, Revision 2, dated December 3, 1998 (for Model 747-400 
series airplanes); or Boeing Service Bulletin 767-78A0079, Revision 
2, dated December 3, 1998 (for Model 767 series airplanes); as 
applicable; at the later of the times specified in paragraphs (b)(1) 
and (b)(2) of this AD. Such action constitutes terminating action 
for the requirements of this AD for that assembly.

[[Page 37025]]

    (1) Within 6,000 flight cycles, 14,000 flight hours, or 5 years 
after the date of the first inspection, whichever occurs earliest; 
or
    (2) Within 4 years after the effective date of this AD.
    (c) For any auxiliary track assembly on which any discrepancy is 
detected during any detailed visual inspection required by paragraph 
(a) of this AD: Repair the auxiliary track assembly (replace the 
slider and liner and install a retainer bar), or replace with a new, 
improved assembly (including a new liner and slider), as applicable, 
in accordance with the Accomplishment Instructions of Boeing Service 
Bulletin 747-78A2164, Revision 2, dated December 3, 1998 (for Model 
747-400 series airplanes); or Boeing Service Bulletin 767-78A0079, 
Revision 2, dated December 3, 1998 (for Model 767 series airplanes); 
as applicable; at the later of the times specified in paragraphs 
(c)(1) and (c)(2) of this AD. Such action constitutes terminating 
action for the requirements of this AD for that assembly.
    (1) Within 4,500 flight cycles, 10,000 flight hours, or 3 years 
after the date of the first repair, whichever occurs earliest; or
    (2) Within 2 years after the effective date of this AD.

    Note 4: Inspections and repairs accomplished prior to the 
effective date of this AD in accordance with Boeing Service Bulletin 
747-78A2164, Revision 1, or Boeing Service Bulletin 767-78A0079, 
Revision 1, both dated February 5, 1998; are considered acceptable 
for compliance with the applicable actions specified in this AD.

Alternative Methods of Compliance

    (d) 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 5: 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

    (e) 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

    (f) Except as provided by paragraph (a)(3)(ii)(A) of this AD, 
the actions shall be done in accordance with Boeing Service Bulletin 
747-78A2164, Revision 2, dated December 3, 1998; or Boeing Service 
Bulletin 767-78A0079, Revision 2, dated December 3, 1998; 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.
    (g) This amendment becomes effective on July 18, 2000.

    Issued in Renton, Washington, on June 2, 2000.
Donald L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 00-14436 Filed 6-12-00; 8:45 am]
BILLING CODE 4910-13-P