[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