[Federal Register Volume 60, Number 239 (Wednesday, December 13, 1995)]
[Proposed Rules]
[Pages 63991-63993]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-30354]



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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 95-NM-244-AD]


Airworthiness Directives; Boeing Model 767 Series Airplanes

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 all Boeing Model 767 series 
airplanes. This proposal would require inspections of the components of 
the leading edge outboard slat; replacement of the control rod end, if 
necessary; and various follow-on actions. This proposal is prompted by 
reports of skewed panels of the outboard leading edge slat due to 
either corrosion of the rotary actuator, cracking of the control rod, 
or incorrect clearance of the overtravel stop of the outboard leading 
edge slat. The actions specified by the proposed AD are intended to 
prevent such conditions, which could result in reduced controllability 
of the airplane and damage to or cracking of the leading edge slats or 
the fixed leading edge of the wing.

DATES: Comments must be received by January 24, 1996.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 95-NM-244-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.
    This information may be examined at the FAA, Transport Airplane 
Directorate, 1601 Lind Avenue SW., Renton, Washington.

FOR FURTHER INFORMATION CONTACT: Kristin Larson, Aerospace Engineer, 
Systems and Equipment Branch, ANM-130S, FAA, Seattle Aircraft 
Certification Office, 1601 Lind Avenue SW., Renton, Washington; 
telephone (206) 227-1760; fax (206) 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 95-NM-244-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-103, Attention: Rules 
Docket No. 95-NM-244-AD, 1601 Lind Avenue SW., Renton, Washington 
98055-4056.
Discussion
    The FAA has received reports of skewed panels of the outboard 
leading edge slat on several Boeing Model 767 series airplanes. 
Investigation revealed that the cause of the skewed panels is 
attributed to either corrosion of the rotary actuator, cracking of the 
control rod, or incorrect clearance of the overtravel stop of the 
outboard leading edge slat. These conditions, if not detected and 
corrected in a timely manner, could result in reduced controllability 
of the airplane and damage to or cracking of the leading edge slats or 
the fixed leading edge of the wing.
    Since an unsafe condition has been identified that is likely to 
exist or develop on other products of this same type design, the FAA 
has determined that an airworthiness directive (AD) is warranted to 
require the following inspections and follow-on actions of the affected 
airplanes. These actions are necessary in order to ensure that the 
unsafe condition is corrected, and to provide an acceptable level of 
safety:
    1. A visual inspection to verify proper clearance of the overtravel 
stop;
    2. Adjustment of the stop clearance, and replacement of the rotary 
actuator and adjacent offset gearbox, if necessary;
    3. Repetitive visual inspections to detect external signs of 
internal corrosion of the rotary actuator of the outboard leading edge 
slat;
    4. Replacement of a certain earlier model rotary actuator with a 
certain later model rotary actuator, for certain airplanes;
    5. Visual inspection(s) to verify proper installation of the 
control rods of the outboard leading edge slats; and
    6. Tightening of the bolts or installing a new lockwire, if any 
bolt is loose or any lockwire is missing.
    This proposed AD would require that these actions be accomplished 
at specific times and in accordance with the procedures specified in 
the Boeing 767 Airplane Maintenance Manual (AMM), Chapter 27-81-20.
    This is considered to be interim action. The manufacturer has 
advised that it currently is developing a modification that will 
positively address the unsafe condition that is the subject of this AD. 
Once this modification is developed, approved, and available, the FAA 
may consider additional rulemaking.
    There are approximately 612 Model 767 series airplanes of the 
affected design in the worldwide fleet. The FAA estimates that 213 
airplanes of U.S. registry would be affected by this proposed AD, that 
it would take approximately 14 work hours per airplane to accomplish 
the proposed actions, and that the average labor rate is $60 per work 
hour. Based on these figures, the cost impact of the proposed AD on 
U.S. operators is estimated to be $178,920, or $840 per airplane, per 
inspection cycle.
    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 AD were not adopted.
    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

[[Page 63993]]

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 USC 106(g), 40101, 40113, 44701.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by adding the following new 
airworthiness directive:

Boeing: Docket 95-NM-244-AD.

    Applicability: All Model 767 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 use the authority 
provided in paragraph (d) of this AD to request approval from the 
FAA. This approval may address either no action, if the current 
configuration eliminates the unsafe condition; or different actions 
necessary to address the unsafe condition described in this AD. Such 
a request should include an assessment of the effect of the changed 
configuration on the unsafe condition addressed by this AD. In no 
case does the presence of any modification, alteration, or repair 
remove any airplane from the applicability of this AD.
    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent reduced controllability of the airplane and damage to 
or cracking of the leading edge slats or the fixed leading edge of 
the wing, accomplish the following:
    (a) Within 500 hours time-in-service after the effective date of 
this AD, unless previously accomplished within the last 3,000 hours 
time-in-service prior to the effective date of this AD: Perform a 
visual inspection to verify proper clearance of the overtravel stop, 
in accordance with the Boeing 767 Airplane Maintenance Manual (AMM), 
Chapter 27-81-20.
    (1) If proper clearance exists, repeat the inspection for proper 
clearance thereafter at intervals not to exceed 6,000 hours time-in-
service or 18 months, whichever occurs later.
    (2) If clearance exists, but is incorrect, at the next 
convenient maintenance interval, but no later than 500 flight hours 
after accomplishment of the inspection, adjust the stop clearance 
for the slats in accordance with the AMM. Repeat the inspection for 
proper clearance thereafter at intervals not to exceed 6,000 hours 
time-in-service or 18 months, whichever occurs later.
    (3) If no clearance exists (i.e., stop contact), prior to 
further flight, adjust the stop clearance for the slats in 
accordance with the AMM. After the adjustment, within 3,000 hours 
time-in-service or 1,500 flight cycles after accomplishing the 
inspection required by paragraph (a) of this AD, whichever occurs 
later, replace the rotary actuator and adjacent offset gearbox in 
accordance with the AMM. After replacement, repeat the inspection 
for proper clearance at intervals not to exceed 6,000 hours time-in-
service or 18 months, whichever occurs later.
    (b) Within 500 hours time-in-service after the effective date of 
this AD, unless previously accomplished within the last 3,000 hours 
time-in-service prior to the effective date of this AD, perform a 
visual inspection to detect external signs of internal corrosion of 
the rotary actuator of the outboard leading edge slat, in accordance 
with the Boeing 767 Airplane Maintenance Manual (AMM), Chapter 27-
81-20.
    (1) If no sign of internal corrosion is detected, accomplish 
paragraph (b)(1)(i) or (b)(1)(ii) of this AD, as applicable.
    (i) For airplanes on which a rotary actuator having part number 
(P/N) 256T2120-3 or earlier is installed: Within 4,000 flight hours 
after the effective date of this AD, replace that rotary actuator 
with a new rotary actuator having P/N 256T2120-5 or later. After 
replacement, repeat the inspection of the rotary actuator at 
intervals not to exceed 6,000 flight hours or 18 months, whichever 
occurs later.
    (ii) For airplanes on which a rotary actuator having P/N 
256T2120-5 or later is installed: Repeat the inspection of the 
rotary actuator thereafter at intervals not to exceed 6,000 flight 
hours or 18 months, whichever occurs later.
    (2) If any sign of internal corrosion is detected, accomplish 
paragraph (b)(2)(i) or (b)(2)(ii) of this AD, as applicable.
    (i) For airplanes on which a rotary actuator having part number 
(P/N) 256T2120-3 or earlier is installed: Within 4,000 flight hours 
after the effective date of this AD, replace that rotary actuator 
with a new rotary actuator having P/N 256T2120-5 or later. After 
replacement, repeat the inspection of the rotary actuator at 
intervals not to exceed 6,000 flight hours or 18 months, whichever 
occurs later.
    (ii) For airplanes on which a rotary actuator having P/N 
256T2120-5 or later is installed: Within 6,000 flight hours or 18 
months after accomplishing the initial inspection required by 
paragraph (b) of this AD, replace that rotary actuator with a new 
rotary actuator having P/N 256T2120-5 or later. After replacement, 
repeat the inspection required of the rotary actuator at intervals 
not to exceed 6,000 flight hours or 18 months, whichever occurs 
later.
    (c) Within 500 hours time-in-service after the effective date of 
this AD, unless previously accomplished within the last 3,000 hours 
time-in-service prior to the effective date of this AD, perform a 
visual inspection to verify proper installation (including loose 
bolts and missing lockwires) of the control rods of the outboard 
leading edge slats, in accordance with the Boeing 767 Airplane 
Maintenance Manual (AMM), Chapter 27-81-20.
    (1) If all control rods are installed properly, repeat the 
inspection to verify proper installation thereafter at intervals not 
to exceed 6,000 flight hours or 18 months, whichever occurs later.
    (2) If any bolt is loose or any lockwire missing, prior to 
further flight, tighten the bolt or install a new lockwire, in 
accordance with the AMM. Repeat the inspection to verify proper 
installation thereafter at intervals not to exceed 6,000 flight 
hours or 18 months, whichever occurs later.
    (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 2: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Seattle ACO.

    (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 December 7, 1995.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 95-30354 Filed 12-12-95; 8:45 am]
BILLING CODE 4910-13-U