E8-8911. Airworthiness Directives; Boeing Model 737-600, -700, -700C, -800, -900, and 900ER Series Airplanes

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

We propose to adopt a new airworthiness directive (AD) for certain Boeing Model 737-600, -700, -700C, -800, -900, and 900ER series airplanes. This proposed AD would require replacing the pushrods for the left and right elevator tab control mechanisms with new, improved pushrods. This proposed AD results from a report of a rod end fracture on a rudder Power Control Unit (PCU) control rod, which is similar to the ones used for the elevator tab pushrods. Analysis revealed that the fractured rod end had an incorrect hardness, which had probably occurred during the manufacture of the control rod. We are proposing this AD to prevent fracture of the elevator tab pushrod ends, which could result in excessive in-flight vibrations of the elevator tab, possible loss of the elevator tab, and consequent loss of controllability of the airplane.

DATES:

We must receive comments on this proposed AD by June 9, 2008.

ADDRESSES:

You may send comments by any of the following methods:

• Federal eRulemaking Portal: Go to http://www.regulations.gov. Follow the instructions for submitting comments.
• Fax: [phone].
• Mail: U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue, SE., Washington, DC 20590.
• Hand Delivery: U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue, SE., Washington, DC 20590, between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.

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

Examining the AD Docket

You may examine the AD docket on the Internet at http://www.regulations.gov; or in person at the Docket Management Facility between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The AD docket contains this proposed AD, the regulatory evaluation, any comments received, and other information. The street address for the Docket Office (telephone [phone]) is in the ADDRESSES section. Comments will be available in the AD docket shortly after receipt.

FOR FURTHER INFORMATION CONTACT:

Tamara Anderson, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone [phone]; fax [phone].

SUPPLEMENTARY INFORMATION:

Comments Invited

We invite you to send any written relevant data, views, or arguments about this proposed AD. Send your comments to an address listed under the ADDRESSES section. Include “Docket No. FAA-2008-0413; Directorate Identifier 2008-NM-003-AD” at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of this proposed AD. We will consider all comments received by the closing date and may amend this proposed AD because of those comments.

We will post all comments we receive, without change, to http://www.regulations.gov, including any personal information you provide. We will also post a report summarizing each substantive verbal contact we receive about this proposed AD.

Discussion

We have received a report of a rod end fracture on a rudder Power Control Unit (PCU) control rod, which is similar to the ones used for the elevator tab pushrods. An operator found a broken rudder PCU control rod during heavy maintenance of a Model 737-800 airplane. Analysis revealed that the fractured rod end had an incorrect hardness, which had probably occurred during the manufacture of the control rod. During the manufacturing process, specific areas of the control rods are to be masked off to prevent the application of the heat treatment/carburization process in those areas. But at different site locations of the supplier, the heat treatment/carburization process was done differently, which resulted in the application of the heat treatment/carburization process of some control rods in incorrect areas. This caused an incorrect hardness of the hollow shanks of the rod ends, and resulted in the occurrence of cracks at the time of manufacture. Further analysis revealed that all control rods made by the supplier were also affected by the incorrect manufacturing procedure. Subsequently, an improved design of the control rod was developed to change from hollow shank rod ends to solid shank rod ends, which would prevent the problems with the heat treatment/carburization process during manufacture. Fracture of the elevator tab pushrod ends could result in excessive in-flight vibrations of the elevator tab, possible loss of the elevator tab, and consequent loss of controllability of the airplane.

Relevant Service Information

We have reviewed Boeing Special Attention Service Bulletin 737-27-1284, dated November 28, 2007. The service bulletin describes procedures for replacing the pushrods for the left and right elevator tab control mechanism with new, improved pushrods. The service bulletin specifies doing the replacement within 4 years after the date on the service bulletin.

Other Related Rulemaking

On January 29, 2003, the FAA issued AD 2003-03-22, amendment 39-13047 (68 FR 5819, February 5, 2003), which applies to certain Boeing Model 737-600, -700, -700C, -800, and -900 series airplanes. AD 2003-03-22 requires accomplishing the modification in accordance with Boeing Alert Service Bulletin 737-55A1080, dated September 19, 2002, and Service Bulletin 737-27-1284 specifies prior or concurrent accomplishment of Service Bulletin 737-55A1080. AD 2003-03-22 requires installing speedbrake limitation placards in the flight compartment, and revising the Limitations Section of the Airplane Flight Manual to ensure the flightcrew is advised not to extend the speedbrake lever beyond the flight detent. For Model 737-600, -700, -700C, -800 series airplanes having line numbers 1 through 1174 inclusive, AD 2003-03-22 requires modifying the elevator and elevator tab assembly before the accumulation of 18,000 total flight cycles, or within 2 years after March 12, 2003, whichever occurs first.

FAA's Determination and Requirements of This Proposed AD

We are proposing this AD because we evaluated all relevant information and determined the unsafe condition described previously is likely to exist or develop in other products of the same type design. This proposed AD would require accomplishing the actions specified in the service information described previously.

Costs of Compliance

We estimate that this proposed AD would affect 715 airplanes of U.S. registry. We also estimate that it would take about 4 work-hours per product to comply with this proposed AD. The average labor rate is $80 per work-hour. Required parts would cost about $8,036 per product. Based on these figures, we estimate the cost of this proposed AD to the U.S. operators to be $5,974,540, or $8,356 per product.

Authority for This Rulemaking

Title 49 of the United States Code specifies the FAA's authority to issue rules on aviation safety. Subtitle I, section 106, describes the authority of the FAA Administrator. “Subtitle VII: Aviation Programs,” describes in more detail the scope of the Agency's authority.

We are issuing this rulemaking under the authority described in “Subtitle VII, Part A, Subpart III, Section 44701: General requirements.” Under that section, Congress charges the FAA with promoting safe flight of civil aircraft in air commerce by prescribing regulations for practices, methods, and procedures the Administrator finds necessary for safety in air commerce. This regulation is within the scope of that authority because it addresses an unsafe condition that is likely to exist or develop on products identified in this rulemaking action.

Regulatory Findings

We 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 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. 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.

You can find our regulatory evaluation and the estimated costs of compliance in the AD Docket.

List of Subjects in 14 CFR Part 39

• Air transportation
• Aircraft
• Aviation safety
• Safety

The Proposed Amendment

Accordingly, under the authority delegated to me by the Administrator, the FAA proposes to amend 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.

§ 39.13

[Amended]

2. The FAA amends § 39.13 by adding the following new AD:

Boeing: Docket No. FAA-2008-0413; Directorate Identifier 2008-NM-003-AD.

Comments Due Date

(a) We must receive comments by June 9, 2008.

Affected ADs

(b) None.

Applicability

(c) This AD applies to Boeing Model 737-600, -700, -700C, -800, -900, and 900ER series airplanes, certificated in any category; line numbers 1 through 2196 inclusive.

Unsafe Condition

(d) This AD results from a report of a rod end fracture on rudder Power Control Unit (PCU) control rod, which is similar to the ones used for the elevator tab pushrods. Analysis revealed that the fractured rod end had an incorrect hardness, which had probably occurred during the manufacture of the control rod. We are issuing this AD to prevent fracture of the elevator tab pushrod ends, which could result in excessive in-flight vibrations of the elevator tab, possible loss of the elevator tab, and consequent loss of controllability of the airplane.

Compliance

(e) Comply with this AD within the compliance times specified, unless already done.

Pushrod Replacement

(f) At the time specified in paragraph 1.E., “Compliance,” of Boeing Special Attention Service Bulletin 737-27-1284, dated November 28, 2007; except, where the service bulletin specifies a compliance time after the date on the service bulletin, this AD requires compliance within the specified compliance time after the effective date of this AD: Replace the pushrods for the left and right elevator tab control mechanisms with new, improved pushrods by doing all the actions in accordance with the Accomplishment Instructions of Boeing Special Attention Service Bulletin 737-27-1284, dated November 28, 2007.

Parts Installation

(g) As of the effective date of this AD, no person may install a pushrod assembly, part number 65-45166-24, on any airplane.

Alternative Methods of Compliance (AMOCs)

(h)(1) The Manager, Seattle Aircraft Certification Office (ACO), FAA, ATTN: Tamara Anderson, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle ACO, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone [phone]; fax [phone]; has the authority to approve AMOCs for this AD, if requested using the procedures found in 14 CFR 39.19.

(2) To request a different method of compliance or a different compliance time for this AD, follow the procedures in 14 CFR 39.19. Before using any approved AMOC on any airplane to which the AMOC applies, notify your appropriate principal inspector (PI) in the FAA Flight Standards District Office (FSDO), or lacking a PI, your local FSDO.

(3) An AMOC that provides an acceptable level of safety may be used for any repair required by this AD, if it is approved by an Authorized Representative for the Boeing Commercial Airplanes Delegation Option Authorization Organization who has been authorized by the Manager, Seattle ACO, to make those findings. For a repair method to be approved, the repair must meet the certification basis of the airplane.

Issued in Renton, Washington, on April 15, 2008.

Ali Bahrami,

Manager, Transport Airplane Directorate, Aircraft Certification Service.