[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

[[Page 33050]]

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