[Federal Register Volume 64, Number 232 (Friday, December 3, 1999)]
[Proposed Rules]
[Pages 67807-67810]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-31435]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 99-NM-69-AD]
RIN 2120-AA64
Airworthiness Directives; Boeing Model 737-100, -200, -200C, -
300, -400, and -500 Series Airplanes
AGENCY: Federal Aviation Administration, DOT.
[[Page 67808]]
ACTION: Notice of proposed rulemaking (NPRM).
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SUMMARY: This document proposes the supersedure of an existing
airworthiness directive (AD), applicable to certain Boeing Model 737-
100, -200, -200C, -300, -400, and -500 series airplanes, that currently
requires a one-time inspection of the attachment nuts at each end
attachment of the elevator tab push rods to measure run-on torque
values, and corrective actions, if necessary. This action would add a
requirement to replace all existing bolts and attachment nuts at the
forward and aft end attachment of each elevator tab push rod with new
bolts and self-locking castellated nuts with cotter pins. This proposal
is prompted by reports of excessive high-frequency airframe vibration
during flight, with consequent structural damage to the elevator tab,
elevator, and stabilizer. The actions specified in this AD are intended
to prevent detachment of an elevator tab push rod due to a detached nut
at either end attachment of a push rod, which could result in excessive
high-frequency airframe vibration during flight; consequent structural
damage to the elevator tab, elevator, and horizontal stabilizer; and
reduced controllability of the airplane.
DATES: Comments must be received by January 18, 2000.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-114,
Attention: Rules Docket No. 99-NM-69-AD, 1601 Lind Avenue, SW., Renton,
Washington 98055-4056. Comments may be inspected at this location
between 9:00 a.m. and 3:00 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: Greg Schneider, Aerospace Engineer,
Airframe Branch, ANM-120S, FAA, Transport Airplane Directorate, Seattle
Aircraft Certification Office, 1601 Lind Avenue, SW., Renton,
Washington 98055-4056; telephone (425) 227-2028; 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-69-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-69-AD, 1601 Lind Avenue, SW., Renton, Washington
98055-4056.
Discussion
On February 26, 1999, the FAA issued AD 99-05-15, amendment 39-
11063 (64 FR 10935, March 8, 1999), applicable to certain Boeing Model
737-100, -200, -200C, -300, -400, and -500 series airplanes, to require
a one-time inspection of the attachment nuts at each end attachment of
the elevator tab push rods to measure run-on torque values, and
corrective actions, if necessary. That action was prompted by reports
of excessive high-frequency airframe vibration during flight, with
consequent structural damage to the elevator tab, elevator, and
stabilizer. The requirements of that AD are intended to prevent
detachment of an elevator tab push rod due to a detached nut at either
end attachment of a push rod, which could result in excessive high-
frequency airframe vibration during flight; consequent structural
damage to the elevator tab, elevator, and horizontal stabilizer; and
reduced controllability of the airplane.
In the preamble to AD 99-05-15, the FAA indicated that the actions
required by that AD were considered ``interim action'' until final
action is identified, at which time the FAA may consider further
rulemaking. Final action has been identified, and the FAA has
determined that further rulemaking action is indeed necessary; this AD
follows from that determination.
Actions Since Issuance of Previous Rule
Based upon a report of airframe vibration which resulted in severe
damage to the elevator, elevator tab push rods, and elevator tab, the
FAA has determined that a fastener installation which incorporates a
secondary locking feature should be installed at the elevator tab push
rod end attachments. The report indicated that airframe vibration was
initially caused by the absence of a bushing, which was not installed
during maintenance, in one of the elevator push rod attachments. Based
on this finding, it is concluded that vibration may occur as a result
of a single elevator tab push rod becoming disconnected. In addition, a
review of numerous reports has revealed that airframe vibration has
been caused by worn, loose, or missing parts at the elevator tab
attachments. To positively address the problem with the elevator tab
push rod end attachments becoming loose, the FAA finds it necessary to
mandate the new bolt, castellated nut, and cotter pin installation.
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 supersede AD 99-05-15 to continue to require a one-
time inspection of the attachment nuts at each end attachment of the
elevator tab push rods to measure run-on torque values. The proposed AD
would also require replacement of existing bolt and attachment nuts
with new bolts and self-locking castellated nuts that incorporate
cotter pins as a secondary locking feature. The actions would be
required to be accomplished in accordance with the service information
described previously in AD 99-05-15, except as discussed below.
Differences Between Proposed Rule and Service Letter
Operators should note that Boeing Service Letter 737-SL-27-118-A,
dated November 14, 1997, describes the actions specified by this
proposed AD as a design improvement that may be accomplished at any
time by the
[[Page 67809]]
operator. The service letter, therefore, does not provide a recommended
timeframe for accomplishing the replacement of the existing bolts and
attachment nuts with new bolts and self-locking castellated nuts that
incorporate the installation of cotter pins as a secondary locking
feature. The FAA has determined that an unspecified interval would not
address the identified unsafe condition in a timely manner. In
developing an appropriate compliance time for this AD, the FAA
considered not only the manufacturer's recommendation, but the degree
of urgency associated with addressing the subject unsafe condition, the
average utilization of the affected fleet, and the time necessary to
perform the replacement (4 hours). In light of all of these factors,
the FAA finds a 12-month compliance time for completing the required
actions to be warranted, in that it represents an appropriate interval
of time allowable for affected airplanes to continue to operate without
compromising safety.
Cost Impact
There are approximately 2,742 airplanes of the affected design in
the worldwide fleet. The FAA estimates that 1,106 airplanes of U.S.
registry would be affected by this proposed AD.
The new replacement that is proposed in this AD action would take
approximately 4 work hours per airplane to accomplish, at an average
labor rate of $60 per work hour. Required parts would cost
approximately $560 per airplane. Based on these figures, the cost
impact of the proposed requirements of this AD on U.S. operators is
estimated to be $884,800, or $800 per airplane.
The cost impact figure discussed above is based on assumptions that
no operator has yet accomplished any of the current or proposed
requirements of this AD action, and that no operator would accomplish
those actions in the future if this AD were not adopted.
The one-time inspection required by AD 99-05-15 was required to be
accomplished within 90 days after the effective date of that AD (March
23, 1999). Since the 90-day compliance time has past, the FAA assumes
that all airplanes currently on the U.S. Register have been inspected.
Therefore, there is no future cost impact of this requirement on
current U.S. operators of these airplanes.
However, should an affected airplane be imported and placed on the
U.S. Register in the future, it would take approximately 4 work hours
per airplane to accomplish the one-time inspection, at an average labor
rate of $60 per work hour. Based on these figures, the cost impact of
the proposed inspection requirement on U.S. operators is estimated to
be $240 per airplane.
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 removing amendment 39-11063 (64 FR
10935, March 8, 1999), and by adding a new airworthiness directive
(AD), to read as follows:
Boeing: Docket 99-NM-69-AD. Supersedes AD 99-05-15, Amendment 39-
11063.
Applicability: Model 737-100, -200, -200C, -300, -400, and -500
series airplanes, line numbers 1 through 2939 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 (c)(1)
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 detachment of an elevator tab push rod due to a
detached nut at either end attachment of a push rod, which could
result in excessive high-frequency airframe vibration during flight;
consequent structural damage to the elevator tab, elevator, and
horizontal stabilizer; and reduced controllability of the airplane;
accomplish the following:
Restatement of Requirements of AD 99-05-15
One-Time Inspection
(a) Within 90 days after March 23, 1999 (the effective date of
AD 99-05-15, amendment 39-11063), perform a one-time inspection of
all attachment nuts at each end of each elevator tab push rod to
measure the run-on torque values of the nuts, in accordance with
Boeing Alert Service Bulletin 737-27A1205, dated August 28, 1997.
(1) If the run-on torque value of any end attachment nut is
within the limits specified in the alert service bulletin, prior to
further flight, ensure that the final seating torque of the
attachment nuts is within the torque values specified in the alert
service bulletin.
(2) If the run-on torque value of any end attachment nut is
outside the limits specified in the alert service bulletin, prior to
further flight, replace all existing bolts and attachment nuts at
each end of each elevator tab push rod with new bolts and self-
locking castellated nuts that have cotter pins installed as a
secondary locking feature, in accordance with Boeing Service Letter
737-SL-27-118-A, dated November 14, 1997, and ensure that the final
seating torque of the nuts is within the torque values specified in
the service letter.
Note 2: Accomplishment of the inspection and ensuring adequate
final seating torque values, prior to the effective date of this AD,
in accordance with Boeing All-Base Telex M-7272-97-0897, dated
February 13, 1997, are considered acceptable for compliance with the
actions specified in paragraphs (a) and (a)(1) of this AD for only
the forward attachment nuts.
Replacement
(b) Within 12 months after the effective date of this AD,
replace all existing bolts and attachment nuts at the forward and
aft end attachment of each elevator tab push rod
[[Page 67810]]
with new bolts and self-locking castellated nuts that have cotter
pins installed as a secondary locking feature, in accordance with
Boeing Service Letter 737-SL-27-118-A, dated November 14, 1997.
Alternative Methods of Compliance
(c)(1) 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.
(2) Alternate methods of compliance, approved previously in
accordance with AD 99-05-15, amendment 39-11063, are not considered
to be approved as alternate methods of compliance with this AD.
Note 3: 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
(d) Special flight permits may be issued in accordance with
Secs. 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 November 29, 1999.
D.L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 99-31435 Filed 12-2-99; 8:45 am]
BILLING CODE 4910-13-U