[Federal Register Volume 61, Number 251 (Monday, December 30, 1996)]
[Rules and Regulations]
[Pages 68566-68569]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-32053]
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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39
[Docket No. 96-NM-23-AD; Amendment 39-9860; AD 96-25-17]
RIN 2120-AA64
Airworthiness Directives; Boeing Model 737-300, -400, and -500
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 certain Boeing Model 737-300, -400, and -500 series
airplanes, that requires inspections to detect bent or damaged tie
links and washers of the elevator feel and centering unit, and
replacement of the centering unit with a new or serviceable unit, if
necessary. This amendment also provides an optional replacement of the
centering unit, which, if accomplished with the installation of
supports and a stop bolt, constitutes terminating action for the
repetitive inspections. This amendment is prompted by a report of high
control column forces that occurred during takeoff and landing. The
actions specified by this AD are intended to prevent such high forces,
which could result in restriction of elevator control during takeoff,
climbout, and landing.
DATES: Effective February 3, 1997.
The incorporation by reference of certain publications listed in
the regulations is approved by the Director of the Federal Register as
of February 3, 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 certain Boeing Model 737-300, -
400, and -500 series airplanes was published in the Federal Register on
June 26, 1996 (61 FR 33049). That action proposed to require repetitive
visual inspections to detect bent or damaged tie links of the elevator
centering unit, and replacement of the elevator centering unit with a
new or serviceable unit, if necessary.
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
One commenter supports the rule.
Request to Extend the Initial Inspection Compliance Time
Several commenters request that the proposed compliance time of 6
months for the initial inspection be extended to at least 12 or 15
months. The commenters express concern that there may be a shortage of
available tie link units to use as replacement units since the proposed
rule would require replacement of damaged tie links with new or
serviceable parts prior to further flight.
The FAA does not concur with the commenters' request to extend the
compliance time. Replacement of the feel and centering unit prior to
further flight is required only if the tie links have damage that
exceeds the limits as specified in Boeing Alert Service Bulletin 737-
27A1194. The manufacturer specifically devised the inspection plan
described in the service bulletin to address the concern of the
availability of an ample number of replacement tie link units. Damage
found to be within the service bulletin's specified limits requires
certain repetitive inspections until the elevator
[[Page 68567]]
feel and centering unit can be serviced or replaced. This is intended
to allow relief for the operators if a spare feel and centering unit is
not readily available. In developing an appropriate compliance time for
this proposal, the FAA considered the safety implications and the parts
availability, and finds no basis to extend the 6-month compliance time.
However, paragraph (f) of the final rule does provide affected
operators the opportunity to request an adjustment of the compliance
time if data are presented to justify such an extension.
Request to Revise Inspection Times and Mandate the Terminating
Action
Another commenter requests that:
1. The compliance time for the initial inspection be extended to 12
months,
2. Repetitive inspections be required every 12 months thereafter,
and
3. ``the modification'' specified in Boeing Alert Service Bulletin
737-27A1194 should be required to be installed within 2 years.
This commenter states that changing the elevator feel and centering
unit is labor-intensive and would require at least 8 hours to
accomplish. However, this commenter offered no data or technical basis
for revising the compliance times or for mandating the terminating
action provided in paragraph (e) of the proposed rule.
As for the commenter's request to extend the compliance time to
extend the compliance time of the initial and repetitive inspections,
the FAA does not concur. As previously explained, the FAA considered
the safety implications, parts availability, and maintenance schedules
when developing the compliance time. The commenter has offered no new
technical data that would indicate a need to revise the compliance
times. However, paragraph (f) of the final rule does provide affected
operators the opportunity to request an adjustment of the compliance
time if data are presented to justify such an extension.
As for the commenter's request to mandate ``the modification,'' the
FAA infers that the modification the commenter is referring to is that
of the feel and centering unit. (The referenced Boeing alert service
bulletin actually describes two different modifications: modification
of the supports and stop-bolt, and modification of the feel and
centering unit.) The FAA does not concur with this request. The
commenter offered no data to justify a compliance time of 2 years for
mandating the installation of this modification. The FAA considers
that, by providing the modification as an optional terminating action
for this AD, prudent operators may accomplish that action at a time of
their own discretion. Additionally, the optional terminating action
does not preclude any operator from installing the modification before
an arbitrary 2-year period, as suggested by the commenter. Further, the
FAA finds that the required inspections, and replacement action as
necessary, are both adequate and appropriate in addressing the subject
damage associated with the elevator feel and centering unit.
Request to Extend the Repetitive Inspection Interval
Two commenters state that, when the stop bolt and support are
installed, they will prevent excessive travel of the elevator feel
actuator and preclude further damage to the tie links. Therefore, one
of these commenters requests that, once the stop bolt and support are
installed, the repetitive inspection intervals be extended from those
intervals specified in proposed paragraph (c) (and specified in Figure
1 of Boeing Alert Service Bulletin 737-27A1194). This commenter, an
operator, proposes that the inspection intervals be increased to
coincide with the current maintenance schedules established for its
fleet of airplanes.
The FAA does not concur. The commenter provided no substantiating
evidence to justify extending the repetitive inspection intervals; and
the FAA does not consider it appropriate to revise provisions in an AD
to accommodate a single operator's maintenance schedule. The FAA has
determined that the repetitive inspection interval described in Boeing
Alert Service Bulletin 737-27A1194 (the appropriate service information
for this AD) will ensure that any damage to the tie links is identified
and corrected in a timely manner. However, paragraph (f) of the final
rule does provide affected operators the opportunity to request an
adjustment of the compliance time if data are presented to justify such
an extension.
Request to Clarify Damage Limits
One commenter, the manufacturer, states that the phrase ``* * * and
damage is within limits specified in Figure 1 * * *'', as used in
paragraphs (c) and (d) of the proposal is confusing. The manufacturer
notes that Figure 1 of Boeing Alert Service Bulletin 737-27A1194, which
is referenced as the appropriate source of service information in the
proposal, has two action paths: One path depicts actions to follow if
damage is within acceptable limits (which starts an inspection
program); the other path depicts actions to follow if damage is outside
the acceptable limits (which specifies replacement of the unit). The
manufacturer requests that the phrase be clarified to read ``* * * and
damage is within acceptable limits as specified in Figure 1 * * *''.
The FAA concurs and has revised paragraphs (c) and (d) of the AD
accordingly.
Request to Clarify the Unsafe Condition
The manufacturer also suggests that the wording, ``Since an unsafe
condition has been identified that is likely to exist or develop * *
*.'', which appeared in the preamble to the notice, be changed. The
manufacturer requests that this language be revised to specify that a
``possible unsafe condition'' has been identified. The manufacturer
states that this change of wording is warranted, since the worst
scenario that has been identified is ``high control column forces''
and, even in that situation, an airplane still would be controllable.
The FAA does not concur with the commenter's suggestion. First, all
unsafe conditions are ``possible'' events that ``could occur.'' In
fact, they are described in the regulations as conditions that are
``likely to exist or develop'' in aircraft. Second, as for this
specific AD, in the event that the tie links were to become bent, it
could lead to the elevator control forces being higher than normal,
thus restricting the elevator control. This would be especially
noticeable when larger elevator inputs are necessary, such as during
takeoff, climb, and landing. The FAA considers this restriction of
elevator control during these critical flight regimes to be an unsafe
condition. (Further, since that language is not repeated in this final
rule, no change is necessary.)
Request to Refer to Terminating Action
The manufacturer requests that reference to ``see paragraph (e) for
terminating action'' be added to paragraph (c)(2) of the proposed rule.
The FAA does not concur. The FAA finds that it is unnecessary to
reference paragraph (e) for operators who may be required to accomplish
paragraph (c)(2) of the AD, since the terminating action specified in
paragraph (e) of this AD is not a required terminating action.
Request to Change the Date of the Referenced Alert Service Bulletin
Additionally, the manufacturer requests that the release date of
Boeing Alert Service Bulletin 737-27A1194 be changed from February 1,
1996, as specified in the proposed rule, to the actual release date of
February 8, 1996.
[[Page 68568]]
The FAA concurs. The FAA notes that the subject alert service
bulletin dated February 1, 1996, has been replaced with the February 8,
1996, version. The FAA has revised the final rule accordingly.
Additional Sources of Service Information
Since the issuance of the proposed rule, the FAA has reviewed and
approved Boeing Notices of Status Change (NSC) 737-27A1194 NSC 01,
dated March 7, 1996, and 737-27A1194 NSC 02, dated April 4, 1996; and
Boeing Alert Service Bulletin 737-27A1194, Revision 1, dated September
26, 1996. The NSC's and service bulletin revision provide further
clarification of the inspection and modification procedures required by
this AD. Therefore, the FAA has revised the AD to cite those documents
as additional sources of service information.
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 1,618 Boeing Model 737-300, -400, and -500
series airplanes of the affected design in the worldwide fleet. The FAA
estimates that 684 airplanes of U.S. registry will be affected by this
AD, that it will take approximately 3 work hours per airplane to
accomplish the required actions, and that the average labor rate is $60
per work hour. Required parts will cost approximately $140 per
airplane. Based on these figures, the cost impact of the AD on U.S.
operators is estimated to be $218,880, or $320 per airplane.
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 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:
96-25-17 Boeing: Amendment 39-9860. Docket 96-NM-23-AD.
Applicability: Model 737-300, -400 and -500 series airplanes
through line position 2764, 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
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 (f) 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 restriction of elevator control during takeoff,
climbout, and landing, due to higher than normal elevator control
forces caused by damaged tie links in the elevator centering unit,
accomplish the following:
(a) Within 6 months after the effective date of this AD: Perform
a visual inspection to detect any bent or damaged tie links of the
elevator feel and centering unit, in accordance with Boeing Alert
Service Bulletin 737-27A1194, dated February 8, 1996, as revised by
Boeing Notice of Status Change 737-27A1194 NSC 01, dated March 7,
1996, and Boeing Notice of Status Change 737-27A1194 NSC 02, dated
April 4, 1996; or Boeing Alert Service Bulletin 737-27A1194,
Revision 1, dated September 26, 1996.
(b) If no tie link is found to be broken, bent, or damaged
during the inspection required by paragraph (a) of this AD:
Accomplish either paragraph (b)(1) or (b)(2) of this AD, in
accordance with Boeing Alert Service Bulletin 737-27A1194, dated
February 8, 1996, as revised by Boeing Notice of Status Change 737-
27A1194 NSC 01, dated March 7, 1996, and Boeing Notice of Status
Change 737-27A1194 NSC 02, dated April 4, 1996; or Boeing Alert
Service Bulletin 737-27A1194, Revision 1, dated September 26, 1996.
(1) Prior to further flight, install supports and a stop-bolt on
the elevator centering unit. Once this installation is accomplished,
no further action is required by this AD. Or
(2) Repeat the inspection required by paragraph (a) of this AD
thereafter at intervals not to exceed 1,000 flight cycles.
Installation of supports and a stop-bolt in accordance with the
alert service bulletin, constitutes terminating action for the
repetitive inspections required by this AD, provided that no damage
is detected during any inspection required by paragraph (a) of this
AD.
(c) If any tie link is found to be bent or damaged during the
inspection required by paragraph (a) of this AD, and damage is
within acceptable limits as specified in Figure 1 of Boeing Alert
Service Bulletin 737-27A1194, dated February 8, 1996, Boeing Notice
of Status Change 737-27A1194 NSC 01, dated March 7, 1996, and Boeing
Notice of Status Change 737-27A1194 NSC 02, dated April 4, 1996; or
as specified in Boeing Alert Service Bulletin 737-27A1194, Revision
1, dated September 26, 1996: Accomplish paragraphs (c)(1) and (c)(2)
of this AD in accordance with the alert service bulletin:
(1) Repeat the inspection required by paragraph (a) of this AD
thereafter at intervals not to exceed those specified in Figure 1 of
the alert service bulletin. And
(2) Within 6 months after the effective date of this AD, install
supports and a stop-bolt on the elevator centering unit. This
installation does not terminate the repetitive inspection
requirements of this paragraph.
(d) If any tie link is found to be bent or damaged during any
inspection required by this AD, and the damage is beyond the
acceptable limits as specified in Figure 1 of Boeing Alert Service
Bulletin 737-27A1194, dated February 8, 1996, Boeing Notice of
Status Change 737-27A1194 NSC 01, dated
[[Page 68569]]
March 7, 1996, and Boeing Notice of Status Change 737-27A1194 NSC
02, dated April 4, 1996; or Boeing Alert Service Bulletin 737-
27A1194, Revision 1, dated September 26, 1996: Prior to further
flight, replace the elevator centering unit with a new or
serviceable unit and accomplish either paragraph (d)(1) or (d)(2) of
this AD in accordance with the alert service bulletin:
(1) Install supports and a stop-bolt on the elevator centering
unit; or
(2) Repeat the inspection required by paragraph (a) of this AD
thereafter at intervals not to exceed 1,000 flight cycles until the
installation specified in paragraph (d)(1) of this AD is
accomplished.
(e) Replacement of the elevator centering unit with a unit in
which the tie links have been inspected and determined to be
acceptable and in which supports and a stop-bolt have been
installed, in accordance with Boeing Alert Service Bulletin 737-
27A1194, dated February 8, 1996, as revised by Boeing Notice of
Status Change 737-27A1194 NSC 01, dated March 7, 1996, and Boeing
Notice of Status Change 737-27A1194 NSC 02, dated April 4, 1996; or
Boeing Alert Service Bulletin 737-27A1194, Revision 1, dated
September 26, 1996, constitutes terminating action for the
requirements of this AD.
(f) 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.
(g) 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.
(h) The actions shall be done in accordance with Boeing Alert
Service Bulletin 737-27A1194, dated February 8, 1996, as revised by
Boeing Notice of Status Change 737-27A1194 NSC 01, dated March 7,
1996, and Boeing Notice of Status Change 737-27A1194 NSC 02, dated
April 4, 1996; or in accordance with Boeing Alert Service Bulletin
737-27A1194, Revision 1, dated September 26, 1996. 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.
(i) This amendment becomes effective on February 3, 1997.
Issued in Renton, Washington, on December 11, 1996.
James V. Devany,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 96-32053 Filed 12-27-96; 8:45 am]
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