[Federal Register Volume 61, Number 124 (Wednesday, June 26, 1996)]
[Proposed Rules]
[Pages 33048-33050]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-16244]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 96-NM-23-AD]
RIN 2120-AA64
Airworthiness Directives; Boeing Model 737-300, -400, and -500
Series Airplanes
AGENCY: Federal Aviation Administration, DOT.
ACTION: Notice of proposed rulemaking (NPRM).
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SUMMARY: This document proposes the adoption of a new airworthiness
directive (AD) that is applicable to certain Boeing Model 737-300, -
400, and -500 series airplanes. This proposal would require 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 action also would provide an
optional replacement of the centering unit, which, if accomplished with
the installation of supports and a stop bolt, would constitute
terminating action for the repetitive inspections. This proposal is
prompted by a report of high control column forces that occurred during
takeoff and landing. The actions specified by the proposed AD are
intended to prevent such high forces, which could result in restriction
of elevator control during takeoff, climbout, and landing.
DATES: Comments must be received by August 5, 1996.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-103,
Attention: Rules Docket No. 96-NM-23-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: 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:
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 96-NM-23-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-103, Attention: Rules
Docket No. 96-NM-23-AD, 1601 Lind Avenue, SW., Renton, Washington
98055-4056.
Discussion
The FAA has received a report of high control column forces during
takeoff and landing of a Model 737 series airplane. Investigation
revealed that the high forces were caused by bent tie links in the
elevator centering unit. Further investigation indicated that, when
hydraulic pressure is removed from the elevator feel actuator, the
actuator extends to its full length. If the control column is then
pulled back to the aft stop and then pushed forward with sufficient
force, the tie links in the centering unit can become bent. Bent tie
links can cause the elevator control forces to be higher than normal.
This will be noticeable when larger elevator inputs are necessary, such
as during takeoff and landing. This condition, if not corrected, could
result in restriction of elevator control during takeoff, climbout, and
landing.
Explanation of Relevant Service Information
The FAA has reviewed and approved Boeing Alert Service Bulletin
737-27A1194, dated February 1, 1996, which describes procedures for
repetitive visual inspections for bent or damaged tie links of the
elevator feel and centering unit, and replacement of the centering unit
with a new or serviceable unit, if necessary. The alert service
bulletin also describes procedures for installation of supports and a
stop-bolt on the elevator centering unit. Such installation eliminates
the need for repetitive inspections for airplanes on which no damaged
tie links or washers are found. The alert service bulletin also
indicates that replacement of the elevator centering unit with a new
unit, or one on which serviceable tie links, supports, and a stop-bolt
are installed, would eliminate the need for the repetitive inspections.
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 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. Replacement of the elevator centering unit with a new or
serviceable unit on which serviceable tie links, supports, and a stop-
bolt are installed constitutes terminating action for the repetitive
inspections. The actions would be required to be accomplished in
accordance with the alert service bulletin described previously.
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 would be affected by this
proposed AD, that it would take approximately 3 work hours per airplane
to accomplish the proposed actions, and that the average labor rate is
$60 per work hour. Required parts would cost approximately $140 per
airplane. Based on these figures, the cost impact of the proposed 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
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the proposed requirements of this AD action, and that no operator would
accomplish those actions in the future if this AD were not adopted.
Should an operator elect to replace the elevator centering unit
rather than continue the repetitive inspections, it would take
approximately 10 work hours per airplane to accomplish the replacement,
at an average labor rate of $60 per work hour. Required parts would
cost approximately $640 per airplane. Based on these figures, the cost
impact of the replacement is estimated to be $1,240 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 adding the following new
airworthiness directive:
Boeing: 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
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 1, 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 1, 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 the limits specified in Figure 1 of Boeing Alert Service
Bulletin 737-27A1194, dated February 1, 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 limits
specified in Figure 1 of Boeing Alert Service Bulletin 737-27A1194,
dated February 1, 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 Service Bulletin 737-27A1194,
dated February 1, 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.
Issued in Renton, Washington, on June 19, 1996.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 96-16244 Filed 6-25-96; 8:45 am]
BILLING CODE 4910-13-U
