[Federal Register Volume 64, Number 201 (Tuesday, October 19, 1999)]
[Proposed Rules]
[Pages 56276-56279]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-27273]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-NM-208-AD]
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: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the adoption of a new airworthiness 
directive (AD) that is applicable to certain Boeing Model 747-400 and 
767-200 and -300 series airplanes. This proposal would require 
repetitive inspections to detect damage and wear of the auxiliary track 
assembly of the thrust reverser, and corrective actions, if necessary. 
This proposal would also

[[Page 56277]]

require eventual replacement of the liner and slider, or the entire 
assembly, with new, improved parts, which, when accomplished, would 
terminate the repetitive inspections. This proposal is prompted by 
reports of damage and wear to the auxiliary track assembly. The actions 
specified by the proposed 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: Comments must be received by December 3, 1999.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 99-NM-208-AD, 1601 Lind Avenue, SW., 
Renton, Washington 98055-4056. Comments may be inspected at this 
location between 9 a.m. and 3 p.m., Monday through Friday, except 
Federal holidays.
    The service information referenced in the proposed rule 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.

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:

Comments Invited

    Interested persons are invited to participate in the making of the 
proposed 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 above. All 
communications received on or before the closing date for comments, 
specified above, will be considered before taking action on the 
proposed rule. The proposals contained in this notice may be changed in 
light of the comments received.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the proposed 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 summarizing each FAA-public contact concerned with 
the substance of this proposal will be filed in the Rules Docket.
    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this notice must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 99-NM-208-AD.'' The postcard will be date stamped and 
returned to the commenter.

Availability of NPRMs

    Any person may obtain a copy of this NPRM by submitting a request 
to the FAA, Transport Airplane Directorate, ANM-114, Attention: Rules 
Docket No. 99-NM-208-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    The FAA has received reports indicating that damage and wear was 
found on the upper and lower auxiliary track assemblies of the thrust 
reverser halves on Boeing Model 747 and 767 series airplanes equipped 
with Pratt & Whitney Model PW4000 series engines. Further investigation 
revealed that the damage and wear is caused by loss of the Rulon J tape 
on the slider of the auxiliary track assembly. This condition, if not 
corrected, could result in 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.

Explanation of Relevant Service Information

    The FAA has reviewed and approved Boeing Service Bulletin 747-
78A2164, Revision 2, dated December 3, 1998 (for Model 747-400 series 
airplanes), and Boeing Service Bulletin 767-78A0079, Revision 2, dated 
December 3, 1998 (for Model 767-200 and -300 series airplanes). These 
service bulletins describe procedures for repetitive inspections of the 
auxiliary track assembly of the thrust reverser 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 to measure the auxiliary track liner gap. The service 
bulletins also describe procedures for temporary repairs and repetitive 
inspections of those repairs, if necessary. The service bulletins 
describe procedures for replacement of the liner and slider with a new, 
improved liner and slider, installation of a retainer bar, and 
replacement of the auxiliary track assembly with a new, improved 
assembly. Such modifications eliminate the need for repetitive 
inspections. Accomplishment of the actions specified in the applicable 
service bulletin is intended to adequately address the identified 
unsafe condition.

Explanation of Requirements of Proposed Rule

    Since an unsafe condition has been identified that is likely to 
exist or develop on other products of this same type design, the 
proposed AD would require accomplishment of the actions specified in 
the applicable service bulletin described previously, except as 
discussed below.

Differences Between Proposed Rule and Service Bulletins

    Operators should note that this proposed AD would mandate, at 
various compliance times depending on the findings during the 
repetitive inspections, the replacement of the liner and slider, or the 
entire auxiliary track assembly, with new, improved parts. Such 
replacement is described in the service bulletins as optional 
terminating action for the repetitive inspections.
    The FAA has determined that long-term continued operational safety 
will be better assured by design changes to remove the source of the 
problem, rather than by repetitive inspections. Long-term inspections 
may not be providing the degree of safety assurance necessary for the 
transport airplane fleet. This, coupled with a better understanding of 
the human factors associated with numerous continual inspections, has 
led the FAA to consider placing less emphasis on inspections and more 
emphasis on design improvements. The proposed replacement requirement 
is consistent with these conditions.
    The service bulletins describe, for certain damage or wear detected 
on the auxiliary track assembly, replacement of the liner and slider 
with a new, improved liner and slider, installation of a retainer bar, 
and a one-time inspection of the repair as a permanent repair. The 
service bulletins state that such actions would eliminate the need for 
the repetitive inspections. The proposed AD would only allow this 
repair as a temporary repair and would

[[Page 56278]]

require eventual replacement of the repaired auxiliary track assembly 
with a new, improved assembly. The FAA has determined that this repair 
would not prevent excessive damage and wear in the future because the 
cause of that damage and wear is related to how the parts mate during 
installation, and, therefore, such repair would not prevent the subject 
unsafe condition.

Cost Impact

    There are approximately 254 airplanes of the affected design in the 
worldwide fleet. The FAA estimates that 12 Model 747-400 series 
airplanes and 46 Model 767-200 and -300 series airplanes of U.S. 
registry would be affected by this proposed AD.
    It would take approximately 4 work hours per engine to accomplish 
the proposed repetitive inspection, at an average labor rate of $60 per 
work hour. Based on these figures, the cost impact of the proposed AD 
on U.S. operators of Model 747-400 series airplanes (4 engines per 
airplane) is estimated to be $11,520, or $960 per airplane, per 
inspection cycle. The cost impact of the proposed 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 proposed 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 proposed 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 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 proposed herein would 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 
proposal would not have sufficient federalism implications to warrant 
the preparation of a Federalism Assessment.
    For the reasons discussed above, I certify that this proposed 
regulation: (1) Is not a ``significant regulatory action'' under 
Executive Order 12866; (2) is not a ``significant rule'' under the DOT 
Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); 
and (3) if promulgated, 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 copy of the draft 
regulatory evaluation prepared for this action is contained in the 
Rules Docket. A copy of it may be obtained by contacting the Rules 
Docket at the location provided under the caption ADDRESSES.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Safety.

The Proposed Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration proposes to amend 
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:

Boeing: 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 to measure the auxiliary track 
liner gap; 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.

    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.

[[Page 56279]]

    (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 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.
    (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 Part A of 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 Part A of 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.
    (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: Replace the auxiliary track assembly with a new, 
improved assembly (including a new 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 
(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.

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 4: 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.

    Issued in Renton, Washington, on October 13, 1999.
D.L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 99-27273 Filed 10-18-99; 8:45 am]
BILLING CODE 4910-13-U