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Proposed Rule

Airworthiness Directives; Boeing Model 737-100, -200, -200C, -300, -400, and -500 Series Airplanes

Document Details

Information about this document as published in the Federal Register.

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AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

The FAA proposes to adopt a new airworthiness directive (AD) for all Boeing Model 737-100, -200, -200C, -300, -400, and -500 series airplanes. This proposed AD would require repetitive inspections for discrepancies of the elevator tab control rod assemblies and/or damage to the surrounding structure, and related corrective action. This proposed AD is prompted by reports indicating loose jam nuts and/or thread wear at the rod ends on the elevator tab control rod assembly. We are proposing this AD to find and fix excessive freeplay in the tab control mechanism, which could result in elevator tab flutter and consequent loss of controllability of the airplane.

DATES:

We must receive comments on this proposed AD by September 24, 2004.

ADDRESSES:

Use one of the following addresses to submit comments on this proposed AD.

  • DOT Docket Web site: Go to http://dms.dot.gov and follow the instructions for sending your comments electronically.
  • Government-wide rulemaking Web site: Go to http://www.regulations.gov and follow the instructions for sending your comments electronically.
  • Mail: Docket Management Facility, U.S. Department of Transportation, 400 Seventh Street SW., Nassif Building, room PL-401, Washington, DC 20590.
  • By fax: (202) 493-2251.
  • Hand Delivery: Room PL-401 on the plaza level of the Nassif Building, 400 Seventh Street SW., Washington, DC, between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.

For service information identified in this proposed AD, contact Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124-2207.

You can examine the contents of this AD docket on the Internet at http://dms.dot.gov, or at the Docket Management Facility, U.S. Department of Transportation, 400 Seventh Street SW., room PL-401, on the plaza level of the Nassif Building, Washington, DC.

Start Further Info

FOR FURTHER INFORMATION CONTACT:

Kenneth Frey, Aerospace Engineer, Systems and Equipment Branch, ANM-130S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 917-6468; fax (425) 917-6590.

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SUPPLEMENTARY INFORMATION:

Docket Management System (DMS)

The FAA has implemented new procedures for maintaining AD dockets electronically. As of May 17, 2004, new AD actions are posted on DMS and assigned a docket number. We track each action and assign a corresponding directorate identifier. The DMS AD docket number is in the form “Docket No. FAA-2004-99999.” The Transport Airplane Directorate identifier is in the form “Directorate Identifier 2004-NM-999-AD.” Each DMS AD docket also lists the directorate identifier (“Old Docket Number”) as a cross-reference for searching purposes.

Comments Invited

We invite you to submit any written relevant data, views, or arguments regarding this proposed AD. Send your comments to an address listed under ADDRESSES. Include “Docket No. FAA-2004-18814; Directorate Identifier 2003-NM-286-AD” in the subject line of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of the proposed AD. We will consider all comments submitted by the closing date and may amend the proposed AD in light of those comments.

We will post all comments we receive, without change, to http://dms.dot.gov, including any personal information you provide. We will also post a report summarizing each substantive verbal contact with FAA personnel concerning this proposed AD. Using the search function of that website, anyone can find and read the comments in any of our dockets, including the name of the individual who sent the comment (or signed the comment on behalf of an association, business, labor union, etc.). You can review DOT's complete Privacy Act Statement in the Federal Register published on April 11, 2000 (65 FR 19477-78), or you can visit http://dms.dot.gov.

We are reviewing the writing style we currently use in regulatory documents. We are interested in your comments on whether the style of this document is clear, and your suggestions to improve the clarity of our communications that affect you. You can get more information about plain language at http://www.faa.gov/​language and http://www.plainlanguage.gov.

Examining the Docket

You can examine the AD docket on the Internet at http://dms.dot.gov, or in person at the Docket Management Facility office between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The Docket Management Facility office (telephone (800) 647-5227) is located on the plaza level of the Nassif Building at the DOT street address stated in the ADDRESSES section. Comments will be available in the AD docket shortly after the DMS receives them.

Discussion

We have received several reports indicating loose jam nuts and/or thread wear at the rod ends on the elevator tab control rod assembly on certain Boeing Model 737-100, -200, -200C, -300, -400, and -500 series airplanes. If the jam nuts of the elevator tab control rod are not properly torqued, the control rod ends can loosen and the threads at the rod end can become worn, causing increased freeplay in the tab control loop. Airframe vibration can occur if there is sufficient freeplay. Additionally, if both control rods on one side of the airplane loosen, significant damage can be done to the elevator tab, elevator, and horizontal stabilizer. Excessive freeplay in the elevator tab control mechanism, if not found and Start Printed Page 48425fixed, could result in elevator tab flutter and consequent loss of controllability of the airplane.

Related AD

On April 30, 2001, we issued AD 2001-09-51, amendment 39-12251 (66 FR 31141, June 11, 2001). That AD is applicable to certain Boeing Model 737-600, -700, -700C, and -800 series airplanes. That AD requires inspection of the small jam nut on the elevator tab control rods to detect inspection putty and to determine its condition; a torque check of the small and large jam nuts on the tab control rod, if necessary; and corrective actions, as applicable. For certain airplanes, that AD also requires a one-time inspection for torque of the small and large jam nuts on the tab control rods; and corrective actions, as applicable.

Relevant Service Information

We have reviewed and approved Boeing Alert Service Bulletin 737-27A1266, dated September 18, 2003, which describes procedures for a one-time inspection of the elevator tab control rod assemblies for discrepancies, which includes the following, as specified in Part I of the Accomplishment Instructions of the service bulletin:

  • Inspect for missing or damaged inspection putty.
  • Inspect for binding of the control rod.
  • Inspect for inadequate clearance between the rod end bearing and the clevis of the tab mast fitting; damage to the control rod, tab mast fitting, or tab control mechanism clevises.
  • Inspect for damage to the elevator tab control rod assemblies and/or damage to the surrounding structure.

The service bulletin also describes procedures for related corrective action, which includes the following, as specified in Part II of the Accomplishment Instructions of the service bulletin:

  • Adjust the control rod.
  • Adjust the space between the rod and bearing to provide adequate clearance.
  • Tighten the jam nuts until correct torque is obtained.
  • Replace damaged components with new components.
  • Realign the rod ends.

The service bulletin also describes procedures for operational tests and a flight test, if necessary, after the corrective action is done. Affected airplanes are separated into Groups 1, 2, and 3, and the Accomplishment Instructions of the service bulletin provide the inspection/corrective action procedures for each group.

Accomplishing the actions specified in the service information is intended to adequately address the unsafe condition.

FAA's Determination and Requirements of the Proposed AD

We have evaluated all pertinent information and identified an unsafe condition that is likely to exist or develop on other airplanes of this same type design. The proposed AD would require you to perform the actions using the service bulletin described previously, except as discussed under “Differences Between the Proposed AD and the Service Bulletin.”

Differences Between the Proposed AD and the Service Bulletin

The service bulletin recommends doing a one-time inspection of the elevator tab control rod assemblies. However, we have determined that a one-time inspection would not address the identified unsafe condition, which could occur again after the one-time inspection is done. Therefore, in conjunction with the manufacturer, we have determined that this proposed AD would require repetitive inspections at intervals not to exceed 4,500 flight cycles or 6,000 flight hours, whichever is first. We find that doing repetitive inspections allows affected airplanes to continue to operate without compromising safety.

The service bulletin refers only to an inspection for discrepancies of the elevator tab control rod assemblies and/or damage to the surrounding structure. We have determined that the inspection should be described as a “detailed inspection.” Note 1 in this proposed AD defines this type of inspection.

Costs of Compliance

This proposed AD would affect about 1,078 airplanes of U.S. registry and 2,878 airplanes worldwide. The proposed inspection would take about 2 work hours per airplane, at an average labor rate of $65 per work hour. Based on these figures, the estimated cost of the proposed AD for U.S. operators is $140,140, or $130 per airplane, per inspection cycle.

Regulatory Findings

We have determined that this proposed AD would not have federalism implications under Executive Order 13132. This proposed AD would not have a substantial direct effect 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.

For the reasons discussed above, I certify that the 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. 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.

We prepared a regulatory evaluation of the estimated costs to comply with this proposed AD. See the ADDRESSES section for a location to examine the regulatory evaluation.

Start List of Subjects

List of Subjects in 14 CFR Part 39

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The Proposed Amendment

Accordingly, under the authority delegated to me by the Administrator, the FAA proposes to amend 14 CFR part 39 as follows:

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PART 39—AIRWORTHINESS DIRECTIVES

1. The authority citation for part 39 continues to read as follows:

Start Authority

Authority: 49 U.S.C. 106(g), 40113, 44701.

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[Amended]

2. The FAA amends § 39.13 by adding the following new airworthiness directive (AD):

Boeing: Docket No. FAA-2004-18814; Directorate Identifier 2003-NM-286-AD.

Comments Due Date

(a) The Federal Aviation Administration (FAA) must receive comments on this AD action by September 24, 2004.

Affected ADs

(b) None.

Applicability

(c) This AD applies to all Model 737-100, -200, -200C, -300, -400, and -500 series airplanes; certificated in any category.

Unsafe Condition

(d) This AD was prompted by reports indicating loose jam nuts and/or thread wear at the rod ends on the elevator tab control rod assembly. We are issuing this AD to find and fix excessive freeplay in the elevator tab control mechanism, which could result in elevator tab flutter and consequent loss of controllability of the airplane.

Compliance

(e) You are responsible for having the actions required by this AD performed within the compliance times specified, unless the actions have already been done.

Repetitive Inspections

(f) Within 4,500 flight cycles or 6,000 flight hours after the effective date of this AD, Start Printed Page 48426whichever is first: Do a detailed inspection for discrepancies of the elevator tab control rod assemblies and/or damage to the surrounding structure, including corrective action, by doing all the actions in the Accomplishment Instructions of Boeing Alert Service Bulletin 737-27A1266, dated September 18, 2003. Do any related corrective action before further flight, in accordance with the service bulletin. Repeat the inspection thereafter at intervals not to exceed 4,500 flight cycles or 6,000 flight hours, whichever is first.

Note 1:

For the purposes of this AD, a detailed inspection is: “An intensive visual examination of a specific structural area, system, installation, or assembly to detect damage, failure, or irregularity. Available lighting is normally supplemented with a direct source of good lighting at intensity deemed appropriate by the inspector. Inspection aids such as mirror, magnifying lenses, etc., may be used. Surface cleaning and elaborate access procedures may be required.”

Alternative Methods of Compliance (AMOCs)

(g) The Manager, Seattle Aircraft Certification Office, FAA, has the authority to approve AMOCs for this AD, if requested in accordance with the procedures found in 14 CFR 39.19.

Start Signature

Issued in Renton, Washington, on August 3, 2004.

Ali Bahrami,

Manager, Transport Airplane Directorate, Aircraft Certification Service.

End Signature End Part End Supplemental Information

[FR Doc. 04-18221 Filed 8-9-04; 8:45 am]

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