[Federal Register Volume 64, Number 125 (Wednesday, June 30, 1999)]
[Rules and Regulations]
[Pages 34976-34979]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-16325]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 99-NM-133-AD; Amendment 39-11213; AD 99-13-51]
RIN 2120-AA64
Airworthiness Directives; Boeing Model 737-700 and -800 Series
Airplanes
AGENCY: Federal Aviation Administration, DOT.
ACTION: Final rule; request for comments.
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SUMMARY: This document publishes in the Federal Register an amendment
adopting Airworthiness Directive (AD) T99-13-51 that was sent
previously to all known U.S. owners and operators of certain Boeing
Model 737-700 and -800 series airplanes by individual telegrams. This
AD requires revising the Airplane Flight Manual (AFM) to prohibit
operation of the airplane under certain conditions; repetitive
inspections of the tab mast fitting of the elevator tab assemblies to
detect cracking; an elevator tab freeplay check; and corrective
actions, if necessary. This AD also provides for optional terminating
action for certain repetitive inspections. This AD requires installing
an additional fastener on the tab mast fitting, which terminates the
AFM revision and extends certain repetitive inspections. This action is
prompted by a report of a severe vibration incident on a Boeing Model
737-800 series airplane; inspection revealed fracturing of the elevator
tab mast fitting and excessive freeplay in the elevator tab. The
actions specified by this AD are intended to prevent reduced
controllability of the airplane due to excessive freeplay in the
elevator tab or a free tab.
DATES: Effective July 6, 1999, to all persons except those persons to
whom it was made immediately effective by telegraphic AD T99-13-51,
issued June 10, 1999, which contained the requirements of this
amendment.
The incorporation by reference of certain publications listed in
the regulations is approved by the Director of the Federal Register as
of July 6, 1999.
[[Page 34977]]
Comments for inclusion in the Rules Docket must be received on or
before August 30, 1999.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-114,
Attention: Rules Docket No. 99-NM-133-AD, 1601 Lind Avenue, SW.,
Renton, Washington 98055-4056.
The applicable service information 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; or at the
Office of the Federal Register, 800 North Capitol Street, NW., suite
700, Washington, DC.
FOR FURTHER INFORMATION CONTACT: Gregory L. 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: On June 10, 1999, the FAA issued telegraphic
AD T99-13-51, which is applicable to certain Boeing Model 737-700 and -
800 series airplanes.
Background
On June 2, 1999, the FAA received a report of a severe vibration
incident on a Boeing Model 737-800 series airplane, which had
accumulated 3,517 total flight hours and 1,284 total flight cycles. The
airplane was involved in a high-speed descent with speed brakes
extended while operating at an airspeed of 320 knots. During the
descent, severe vibration occurred at 250 knots. At 230 knots, the
speed brakes were retracted and the vibration stopped. The landing was
uneventful.
Inspection of the airplane revealed that the upper flange of the
right elevator tab mast fitting, to which the elevator tab push rods
are attached, was found fractured. The lower flange of the fitting was
not damaged. In addition, excessive freeplay in the elevator tab also
was observed and measured during the inspection.
Further analysis confirmed that the damage to the fitting was
aggravated by speed brake induced airframe vibrations. Such vibration
could lead to damage of the elevator tab mast fitting, excessive
freeplay in the tab, and consequent separation of the tab mast fitting
from the tab. Excessive freeplay in the tab could result in severe
airframe vibrations and consequent damage to the tab, elevator, and
horizontal stabilizer. Separation of the elevator tab mast fitting will
result in a free tab. These conditions, if not corrected, could result
in reduced controllability of the airplane.
Explanation of Relevant Service Information
The FAA has reviewed and approved Boeing Alert Service Bulletin
737-55A1068, dated June 9, 1999, which describes procedures for
repetitive high frequency eddy current (HFEC) inspections of the tab
mast fitting of the left and right elevator tab assembly to detect
cracking, and a one-time elevator tab freeplay check to detect
excessive freeplay of the elevator tab; and corrective actions, if
necessary. The alert service bulletin also describes procedures for
installing an additional high-strength fastener on the tab mast fitting
(time-limited modification).
In addition, the alert service bulletin references removing and
replacing the cracked tab mast fitting with a new, improved fitting.
Such replacement, if accomplished, eliminates the need for the
repetitive inspections.
Explanation of Requirements of the Rule
Since the unsafe condition described is likely to exist or develop
on other airplanes of the same type design, this airworthiness
directive is issued to require revising the Limitations Section of the
FAA-approved Airplane Flight Manual (AFM) to prohibit operation of the
airplane at certain airspeeds with the speed brakes extended, and at
certain altitudes.
This AD also requires repetitive HFEC inspections of the tab mast
fitting of the left and right elevator tab assembly to detect cracking,
and a one-time elevator tab freeplay check to detect excessive freeplay
of the elevator tab; and corrective actions, if necessary. This AD also
provides for optional terminating action for the repetitive HFEC
inspections.
Certain actions are required to be accomplished in accordance with
the alert service bulletin described previously.
Additionally, this AD requires installing an additional high-
strength fastener on the tab mast fitting (time-limited modification).
Such installation terminates the AFM revision and allows extension of
the repetitive interval for accomplishment of the HFEC inspections.
It should be noted that, although this AD prohibits the deployment
of the spoilers at speeds in excess of 310 knots indicated airspeed
(IAS), the FAA recognizes that under emergency circumstances, previous
pilot training and human factors could result in deployment of the
spoilers at such speeds notwithstanding the AFM prohibition. In this
event, this AD requires accomplishment of the HFEC inspection of the
tab mast fitting and of the check of the tab for freeplay prior to
further flight after landing.
Since it was found that immediate corrective action was required,
notice and opportunity for prior public comment thereon were
impracticable and contrary to the public interest, and good cause
existed to make the AD effective immediately by individual telegrams
issued on June 10, 1999, to all known U.S. owners and operators of
Boeing Model 737-700 and -800 series airplanes. These conditions still
exist, and the AD is hereby published in the Federal Register as an
amendment to section 39.13 of the Federal Aviation Regulations (14 CFR
39.13) to make it effective to all persons.
Interim Action
In the preamble to AD T99-13-51, the FAA indicated that the actions
required by that AD were considered to be interim action and that the
FAA may consider further rulemaking to require replacement of the tab
mast fitting with a new, improved fitting.
Comments Invited
Although this action is in the form of a final rule that involves
requirements affecting flight safety and, thus, was not preceded by
notice and an opportunity for public comment, comments are invited on
this rule. Interested persons are invited to comment on this 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 under the caption ADDRESSES. All
communications received on or before the closing date for comments will
be considered, and this rule may be amended in light of the comments
received. Factual information that supports the commenter's ideas and
suggestions is extremely helpful in evaluating the effectiveness of the
AD action and determining whether additional rulemaking action would be
needed.
Comments are specifically invited on the overall regulatory,
economic, environmental, and energy aspects of the rule that might
suggest a need to modify the 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 that
[[Page 34978]]
summarizes each FAA-public contact concerned with the substance of this
AD will be filed in the Rules Docket.
Commenters wishing the FAA to acknowledge receipt of their comments
submitted in response to this rule must submit a self-addressed,
stamped postcard on which the following statement is made: ``Comments
to Docket Number 99-NM-133-AD.'' The postcard will be date stamped and
returned to the commenter.
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.
The FAA has determined that this regulation is an emergency
regulation that must be issued immediately to correct an unsafe
condition in aircraft, and that it is not a ``significant regulatory
action'' under Executive Order 12866. It has been determined further
that this action involves an emergency regulation under DOT Regulatory
Policies and Procedures (44 FR 11034, February 26, 1979). If it is
determined that this emergency regulation otherwise would be
significant under DOT Regulatory Policies and Procedures, a final
regulatory evaluation will be prepared and placed in the Rules Docket.
A copy of it, if filed, 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:
99-13-51 Boeing: Amendment 39-11213. Docket 99-NM-133-AD.
Applicability: Model 737-700 and -800 series airplanes having
line numbers 1 through 190, 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 (g) 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 due to
excessive freeplay in the elevator tab or a free tab, accomplish the
following:
Airplane Flight Manual (AFM) Revision
(a) Within 24 clock hours after the effective date of this AD,
revise the Limitations Section of the FAA-approved AFM to include
the following information. This may be accomplished by inserting a
copy of this AD into the AFM.
Do not operate the airplane at speeds in excess of 310 knots
indicated airspeed (IAS) with speed brakes extended. Do not operate
the airplane above FL 390.
(b) In the event of deployment of the speed brakes at speeds in
excess of 310 knots indicated airspeed (IAS), prior to further
flight after landing, accomplish the requirements of paragraph (c)
of this AD.
Inspection and Check
(c) Within 10 days after the effective date of this AD, perform
a high frequency eddy current (HFEC) inspection of the tab mast
fitting of the left and right elevator tab assembly to detect
cracking, and a one-time elevator tab freeplay check to detect
freeplay of the elevator tab, in accordance with Boeing Alert
Service Bulletin 737-55A1068, dated June 9, 1999.
(1) If no cracking is found in the elevator tab mast fitting,
repeat the HFEC inspection thereafter at intervals not to exceed 15
days, until accomplishment of the actions required by paragraph (d)
of this AD.
(2) If any cracking is found in the elevator tab mast fitting,
prior to further flight, accomplish the requirements of paragraph
(e) of this AD.
(3) If any freeplay is found that is outside the limits
specified in the alert service bulletin, prior to further flight,
perform corrective actions in accordance with the alert service
bulletin.
Note 2: Boeing Alert Service Bulletin 737-55A1068, dated June 9,
1999, references Boeing Model 737-600/-700/-800 Maintenance Manual
(AMM), Subjects 27-09-91, 27-31-00, and 51-21-99; 737 Nondestructive
Test (NDT) Manual D6-37239, Part 6, Subject 55-00-00; 737 Structural
Repair Manual (SRM) Subject 51-20-81; and Operations Manual Service
Bulletin D6-27370-TBC (``Elevator Tab Operational Limitations''),
dated June 10, 1999; as additional sources of service information to
accomplish certain requirements of this AD.
Time-Limited Modification
(d) Within 90 days after the effective date of this AD, install
an additional high-strength fastener on the elevator tab mast
fitting in accordance with Boeing Alert Service Bulletin 737-
55A1068, dated June 9, 1999. Accomplishment of this modification
constitutes terminating action for the requirements of paragraph (b)
of this AD. Following accomplishment of the installation, the AFM
revision required by paragraph (a) of this AD may be removed from
the AFM. Following accomplishment of the installation, repeat the
HFEC inspection required by paragraph (c) of this AD thereafter at
intervals not to exceed 90 days until accomplishment of paragraph
(e) of this AD.
Replacement
(e) Replacement of the elevator tab mast fitting with a new,
improved fitting in accordance with a method approved by the
Manager, Seattle Aircraft Certification Office (ACO), FAA, Transport
Airplane Directorate, constitutes terminating action for the
requirements of this AD.
Spares
(f) As of receipt of this AD, no elevator tab mast fitting, part
numbers (P/N) 185A400-1 or 185A400-2, shall be installed on any
airplane.
Alternative Methods of Compliance
(g) 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 ACO. 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 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
(h) 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.
Incorporation by Reference
(i) The inspections, check, and time-limited modification shall
be done in accordance with Boeing Alert Service Bulletin 737-
55A1068, dated June 9, 1999. This incorporation by reference was
approved by the Director of the Federal
[[Page 34979]]
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.
(j) This amendment becomes effective on July 6, 1999, to all
persons except those persons to whom it was made immediately
effective by telegraphic AD T99-13-51, issued on June 10, 1999,
which contained the requirements of this amendment.
Issued in Renton, Washington, on June 22, 1999.
D. L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 99-16325 Filed 6-29-99; 8:45 am]
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