[Federal Register Volume 61, Number 250 (Friday, December 27, 1996)]
[Rules and Regulations]
[Pages 68135-68139]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-32048]


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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 95-NM-244-AD; Amendment 39-9861; AD 96-25-18]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 767 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 all Boeing Model 767 series airplanes, that requires 
inspections of the components of the leading edge outboard slat; 
replacement of the control rod end, if necessary; and various follow-on 
actions. This amendment is prompted by reports of skewed panels of the 
outboard leading edge slat due to failure of a corroded rotary actuator 
or the control rod. The actions specified by this 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: Effective January 31, 1997.

[[Page 68136]]

    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of January 31, 1997.

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: 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: 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 all Boeing Model 767 series 
airplanes was published in the Federal Register on December 13, 1995 
(60 FR 63992). That action proposed to require inspections of the 
components of the leading edge outboard slat; replacement of the 
control rod end, if necessary; and various follow-on actions.
    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due consideration has been given to 
the comments received.

Support for the Proposal

    Two commenters support the proposed rule.

Request To Revise the Description of the Addressed Unsafe Condition

    One commenter notes that the description of the cause of the 
addressed unsafe condition that appeared in the Summary and Discussion 
sections of the preamble to the notice states 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 * * * .'' The commenter suggests that a more accurate 
description of the cause would be ``* * * failure of a corroded rotary 
actuator, due to excessive loads caused by the incorrect clearance of 
the overtravel stop, or failure of the control rod.''
    The FAA concurs and has revised the appropriate sections of this 
preamble to specify this language.

Requests To Extend the Compliance Time for Inspections Performed 
Previously

    Several commenters request that the compliance time for paragraphs 
(a), (b), and (c) of the proposal be revised to allow credit for visual 
inspections performed previously within 6,000 hours time-in-service, or 
18 months, whichever occurs later. One commenter submitted an identical 
request, but for inspections performed previously within 5,500 hours 
time-in-service. Two other commenters narrowed this request to apply to 
only paragraph (b) of the proposal. These commenters state that, as the 
NPRM is currently worded, it penalizes operators who promptly started 
accomplishing Boeing Service Bulletin 767-27A0137 after its issuance on 
May 18, 1995. These commenters assert that their suggested compliance 
times will coincide with the repetitive inspection requirements of the 
proposal.
    The FAA concurs with the commenters' request to allow credit for 
all inspections accomplished prior to the effective date of this AD. 
The FAA has re-reviewed the recommended compliance time in the subject 
service bulletin and the proposed AD. The FAA does not intend that 
operators be penalized for accomplishing the actions specified in 
Boeing Service Bulletin 767-27A0137 in an expeditious manner. Although 
the service bulletin recommends that credit be allowed only for 
inspections accomplished previously within 3,000 hours time-in-service, 
the FAA finds that no data exist to warrant limiting credit for such 
inspections to 3,000 hours. Therefore, the FAA has removed the phrase 
``unless previously accomplished within the last 3,000 hours time-in-
service prior to the effective date of this AD'' from paragraphs (a), 
(b), and (c) of the final rule. In the case of this AD, if the initial 
inspection has been accomplished prior to the effective date of the AD, 
this AD does not require that it be repeated. However, the AD does 
require that repetitive inspections be conducted thereafter at 
intervals not to exceed 6,000 hours time-in-service, and that other 
follow-on actions be accomplished when indicated.

Request to Extend the Compliance Time for Slat Adjustment

    One commenter requests that the compliance time for adjustment of 
the stop clearance, as specified in paragraph (a)(2) of the proposal, 
be extended from the proposed 500 hours time-in-service to 3,000 hours 
time-in-service. This commenter asserts that the time for accomplishing 
this adjustment of the slats with incorrect clearance at the overtravel 
stop should not be more stringent than the time for accomplishing the 
replacement of the rotary actuator if no clearance is found to exist 
(specified in proposed paragraph (a)(3) as 3,000 hours time-in-
service).
    The FAA does not concur with the commenter's request to extend the 
compliance time for the slat adjustment; nor does the FAA agree that 
the compliance time for adjustment of the slats is more stringent than 
that for replacement of the actuator and gearbox. Paragraph (a)(2) of 
the AD requires the proper adjustment of the stop clearance within 500 
flight hours after the initial inspection if that inspection reveals 
that some clearance exists, but not the correct clearance; the 
inspection is then to be repeated thereafter at intervals of 6,000 
hours time-in-service. However, the FAA points out that paragraph 
(a)(3) of the AD requires adjustment of the stop clearance immediately 
(prior to further flight) if the inspection reveals that no clearance 
exists; after this adjustment is accomplished, the replacement of the 
actuator and gearbox is required within 3,000 hours time-in-service. 
For cases where some clearance exists, the FAA finds a compliance time 
of 500 flight hours to be appropriate and warranted, since some 
clearance may continue to deteriorate until no clearance exists.

Requests to Defer Initial Inspections

    Two commenters request that the compliance time for the initial 
inspections be deferred until Model 767 series airplanes have 
accumulated 10,000 total hours time-in-service, as recommended in 
Boeing Service Bulletin 767-27A0137, Revision 1, dated November 30, 
1995. One of these commenters states that the history of the Model 767 
fleet has shown that, for airplanes that have accumulated 10,000 total 
hours time-in-service or less, the amount and location of corrosion in 
the rotary actuators does not adversely affect their strength or 
function.
    The FAA concurs with the commenters' request to defer the initial 
inspections. The FAA has reviewed and approved Revision 1 of Boeing 
Service Bulletin 767-27A0137, dated November 30, 1995, as discussed 
below. The FAA has revised the compliance time of the initial 
inspection requirements of paragraphs (a), (b), and (c) of the final 
rule to state ``prior the accumulation of 10,500 total hours time-in-
service since date of manufacture, or within 500

[[Page 68137]]

hours time-in-service after the effective date of this AD, whichever 
occurs later . . .'' to coincide with the recommendations of the 
service bulletin.

Requests to Reference Boeing Service Bulletin 767-27A0137

    Several commenters request that the FAA reference Boeing Service 
Bulletin 767-27A0137, Revision 1, dated November 30, 1995, as the 
appropriate source of service information for accomplishing the actions 
required by the proposal.
    These commenters point out that, even though the proposal 
references the Boeing 767 Airplane Maintenance Manual (AMM), Chapter 
27-81-20, as the appropriate source of service information, the 
proposed actions and compliance times of the proposal appear to be 
consistent with the recommendations of Boeing Service Bulletin 767-
27A0137. Two of these commenters point out that the procedures 
described in the Boeing 767 AMM for accomplishing the inspection 
requirements of the proposal are not as detailed as those described in 
Boeing Service Bulletin 767-27A0137. The commenters contend that 
referencing the subject service bulletin will eliminate the operators' 
confusion as to which slats are to be inspected.
    One of these commenters states that many operators have already 
accomplished the recommendations of Boeing Service Bulletin 767-
27A0137, since it has been available for some time now. However, 
without specific reference to this service bulletin in the proposal, 
operators will be hesitant to indicate compliance with the AD without 
first submitting a request for an alternative method of compliance.
    The FAA concurs with the commenters' request to reference Boeing 
Service Bulletin 767-27A0137 as the appropriate source of service 
information. The FAA has reviewed and approved Boeing Service Bulletin 
767-27A0137, Revision 1, dated November 30, 1995. The service bulletin 
describes procedures for:
    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.
    The final rule has been revised to include this service bulletin as 
an additional source of appropriate service information. The final rule 
also has been revised to indicate the specific numbers of the outboard 
leading edge slats that are to be inspected.
    Operators should note that although the Boeing service bulletin 
indicates that certain procedures may be accomplished in accordance 
with an ``operator's equivalent procedure,'' this AD does not permit 
such procedures to be used unless they have been approved as an 
alternative method of compliance under the provisions of paragraph (d) 
of the final rule. Since procedures may vary from operator to operator, 
the FAA would have no way of knowing whether an ``equivalent'' 
procedure would provide an acceptable level of safety unless it has 
been reviewed and verified in accordance with the alternative method of 
compliance approval process. New NOTES 3, 4, and 5 have been added to 
this final rule to clarify this information.

Request to Reference Original Version of Service Bulletin

    Two commenters request that the proposed rule be revised to cite 
the original version of Boeing Alert Service Bulletin 767-27A0137, 
dated May 18, 1995, as an additional source of service information for 
accomplishing the actions specified in the AD. The FAA concurs and has 
revised the final rule to include a new ``NOTE 2'' to clarify this 
point.

Request to Revise the Reference to ``New'' Actuator

    Several commenters note that paragraphs (b)(1)(i), (b)(2)(i), and 
(b)(2)(ii) of the proposal specify replacement of the actuator with a 
``new'' actuator having part number
(P/N) 256T2120-5 or later. One of these commenters suggests that, in 
lieu of the word ``new,'' the language in the AD should use the term 
``serviceable,'' which would be a more accurate description. This same 
commenter states that a serviceable actuator, having P/N 256T2120-5 or 
later, is sufficient when it has been inspected according to the 
Component Maintenance Manual.
    The FAA concurs with this suggestion and has revised the relevant 
wording of the final rule.

Request to Revise the Cost Impact Statement

    One commenter questions the FAA's cost estimate presented in the 
preamble to the notice. The commenter points out that the cost estimate 
did not include the cost of replacement of the rotary actuators, having 
part number (P/N) 256T2120-3 or earlier, with a new rotary actuator, 
having P/N 256T2120-5 or later.
    The FAA finds that clarification of the costs associated with the 
requirements of this AD is necessary. The FAA points out that the 
economic analysis of the AD is usually limited only to the cost of 
actions actually required by the rule. It does not consider the costs 
of ``on condition'' actions (e.g., ``replace if any sign of internal 
corrosion is detected''), since those actions would be required to be 
accomplished, regardless of AD direction, in order to correct an unsafe 
condition identified in an airplane, and to ensure operation of that 
airplane in an airworthy condition, as required by the Federal Aviation 
Regulations.

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 612 Model 767 series airplanes of the 
affected design in the worldwide fleet. The FAA estimates that 213 
airplanes of U.S. registry will be affected by this AD, that it will 
take approximately 14 work hours per airplane to accomplish the 
required inspections, and that the average labor rate is $60 per work 
hour. Based on these figures, the cost impact of the 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 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 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

[[Page 68138]]

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.
    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:

96-25-18  Boeing: Amendment 39-9861. 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 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 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:

    Note 2: Actions specified in this AD that were accomplished 
prior to the effective date of this AD in accordance with Boeing 
Alert Service Bulletin 767-27A0137, dated May 18, 1995, are 
considered acceptable for compliance.

    (a) Prior to the accumulation of 10,500 total hours time-in-
service, or within 500 hours time-in-service after the effective 
date of this AD, whichever occurs later: Perform a visual inspection 
to verify proper clearance of the overtravel stop of the outboard 
leading edge slats 2, 3, 4, 5, 8, 9, 10, and 11, in accordance with 
Part I of Boeing Service Bulletin 767-27A0137, Revision 1, dated 
November 30, 1995, or Chapter 27-81-20 of the Boeing 767 Airplane 
Maintenance Manual (AMM).

    Note 3: Although the Boeing service bulletin indicates that the 
actions required by this paragraph may be accomplished in accordance 
with the ``operator's equivalent procedure,'' this AD does not 
permit use of an ``operator's equivalent procedure'' unless it has 
been approved as an alternative method of compliance in accordance 
with paragraph (d) of this AD.

    (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 service bulletin or 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 service bulletin or 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 service bulletin or 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) Prior to the accumulation of 10,500 total hours time-in-
service, or within 500 hours time-in-service after 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 slats 2, 3, 4, 5, 8, 9, 10, and 11, in accordance with 
Part II of the Boeing Service Bulletin 767-27A0137, Revision 1, 
dated November 30, 1995, or Chapter 27-81-20 of the Boeing 767 AMM.

    Note 4: Although the Boeing service bulletin indicates that the 
actions required by this paragraph may be accomplished in accordance 
with the ``operator's equivalent procedure,'' this AD does not 
permit use of an ``operator's equivalent procedure'' unless it has 
been approved as an alternative method of compliance in accordance 
with paragraph (d) of this AD.

    (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 serviceable rotary actuator having P/N 256T2120-5 or later, 
in accordance with the service bulletin or AMM. 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 serviceable rotary actuator having P/N 256T2120-5 or later, 
in accordance with the service bulletin or AMM. 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 
serviceable rotary actuator having P/N 256T2120-5 or later, in 
accordance with the service bulletin or AMM. 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) Prior to the accumulation of 10,500 total hours time-in-
service, or within 500 hours time-in-service after 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 2, 3, 4, 5, 8, 9, 
10, and 11, in accordance with Part III of the Boeing Service 
Bulletin 767-27A0137, Revision 1, dated November 30, 1995; or 
Chapter 27-81-20 of the Boeing 767 AMM.

    Note 5: Although the Boeing service bulletin indicates that the 
actions required by this paragraph may be accomplished in accordance 
with the ``operator's equivalent procedure,'' this AD does not 
permit use of an ``operator's equivalent procedure'' unless it has 
been approved as an alternative method of compliance in accordance 
with paragraph (d) of this AD.

    (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

[[Page 68139]]

with the service bulletin or 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 6: 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.
    (f) The inspections and replacements shall be done in accordance 
with Boeing Service Bulletin 767-27A0137, Revision 1, dated November 
30, 1995. 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 January 31, 1997.

    Issued in Renton, Washington, on December 11, 1996.
John J. Hickey,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 96-32048 Filed 12-26-96; 8:45 am]
BILLING CODE 4910-13-U