05-11051. Airworthiness Directives; Boeing Model 737-100, -200, -200C, -300, -400, and -500 Series Airplanes

AGENCY:

Federal Aviation Administration (FAA), Department of Transportation (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 operators to examine the airplane's maintenance records to determine if the main landing gear (MLG) has been overhauled and if Titanine JC5A (also known as Desoto 823E508) corrosion-inhibiting compound (“C.I.C.”) was used during the overhaul. For airplanes for which the maintenance records indicate that further action is necessary, or for airplanes on which C.I.C. JC5A may have been used during manufacture, this proposed AD would require a one-time detailed inspection for discrepancies of certain components of the MLG, and corrective action if necessary. This proposed AD is prompted by twelve reports of severe corrosion on one or more of three components of the MLG. We are proposing this AD to prevent collapse of the MLG, or damage to hydraulic tubing or the aileron control cables, which could result in possible departure of the airplane from the runway and loss of control of the airplane.

DATES:

We must receive comments on this proposed AD by July 18, 2005.

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: [phone].
• 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 in person 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. This docket number is FAA-2005-21346; the directorate identifier for this docket is 2005-NM-031-AD.

FOR FURTHER INFORMATION CONTACT:

Nancy Marsh, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone [phone]; fax [phone].

SUPPLEMENTARY INFORMATION:

Comments Invited

We invite you to submit any relevant written data, views, or arguments regarding this proposed AD. Send your comments to an address listed under ADDRESSES. Include “Docket No. FAA-2005-21346; Directorate Identifier 2005-NM-031-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 Web site, 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.

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 [phone]) 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 twelve reports of severe corrosion on one or more of the following three components of the main landing gear (MLG) on the affected airplanes: The trunnion pin, the actuator beam, and the tee-bolt fitting. The manufacturer analyzed the corrosion and found that JC5A, a corrosion-inhibiting compound (C.I.C.), was used on the components. JC5A has been found to decompose in the presence of moisture. The decomposition can make chemical by-products that damage the primer, which is the primary protection for the titanium-cadmium (Ti-Cad) plating on the components. The Ti-Cad plating protects the base metal against corrosion.

Corrosion can cause a fracture of the trunnion pin or the actuator beam bolts. If the inboard end of the trunnion pin becomes disconnected, the side strut and reaction link will not be stable. Further, if the tee fitting attach bolt assembly fractures, the drag strut could become unstable. Either of these conditions could result in MLG collapse, and departure of the airplane from the runway.

Fractures in the trunnion pin or the actuator beam bolts can cause the actuator to move outboard during gear retraction. This outboard movement could damage the hydraulic tubing or the aileron control cables and could cause the flightcrew to lose control of the airplane.

Relevant Service Information

We have reviewed Boeing Service Bulletin 737-32A1367, Revision 1, dated December 23, 2004. The service bulletin describes procedures for a one-time detailed inspection for discrepancies (damage to the finish, indications of corrosion or pitting) of components of the MLG. These MLG components are the trunnion pins, the actuator beam bolts, the tee-bolt fitting, and certain adjacent parts indicated in the service bulletin. The airplanes to be inspected are those on which JC5A was applied during manufacture, or those on which JC5A was applied when the MLG was overhauled. The service bulletin does not include an inspection of the trunnion pins on Model 737-400 series airplanes due to the unique configuration of the Model 737-400.

If no discrepancy is found during the inspection, the service bulletin states that no more work is necessary.

If any discrepancy is found during the inspection, the service bulletin describes procedures for corrective action. The corrective action includes doing one of the following:

• For parts that have finish damage without corrosion or pitting, applying a new protective finish.
• For parts with corrosion or pitting, repair by removing the corrosion or pitting from the part, and applying a new protective finish, or replace the part with a serviceable part.
• For parts with corrosion or pitting that cannot be made serviceable after removing the corrosion or pitting, contact the manufacturer.

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. Therefore, we are proposing this AD, which would require the actions specified in the service bulletin, 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 specifies that you may contact the manufacturer for instructions on how to repair certain conditions, but this proposed AD would require you to repair those conditions in one of the following ways:

• Using a method that we approve; or
• Using data that meet the certification basis of the airplane, and that have been approved by an Authorized Representative for the Boeing Delegation Option Authorization Organization whom we have authorized to make those findings.

The service bulletin specifies additional compliance times after the original airplane delivery date; this proposed AD would require compliance within the specified compliance time after the date of issuance of the original standard Airworthiness Certificate or the date of issuance of the original Export Certificate of Airworthiness.

Although the service bulletin does not specify when to accomplish any necessary corrective actions, this proposed AD would require operators to do these corrective actions before further flight after the inspection.

Clarification of Procedures in the Service Bulletin

The procedures in the service bulletin state that airplanes must be inspected if they have had the MLG overhauled and C.I.C. JC5A was used during the last overhaul, or if the airplane was assembled in the factory during a time when JC5A was used by the manufacturer as an approved substitute C.I.C. Although the service bulletin does not have explicit procedures for doing so, this proposed AD would require that operators of certain groups of airplanes identified in the service bulletin examine airplane maintenance records to determine if the MLG has been overhauled and if C.I.C. JC5A has been applied to the MLG during overhaul. This AD also would require that operators inspect any airplane for which the maintenance records indicate that the MLG was overhauled, but for which it is unclear whether or not C.I.C. JC5A was used during the overhaul.

Costs of Compliance

There are about 3,132 airplanes of the affected design in the worldwide fleet. The following table provides the estimated costs for U.S. operators to comply with this proposed AD.

Estimated Costs

Action	Work hours	Average labor rate per hour	Parts	Cost per airplane	Number of U.S.-registered airplanes	Fleet cost
Records examination	1	$65	None	$65	1,748	$113,620

For airplanes that require a detailed inspection, we estimate that the inspection would take about 3 work hours per airplane to accomplish, at an average labor rate of $65 per work hour. Based on these figures, we estimate that the detailed inspection would cost about $195 per airplane.

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 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.

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 airworthiness directive (AD):

Boeing: Docket No. FAA-2005-21346; Directorate Identifier 2005-NM-031-AD.

Comments Due Date

(a) The Federal Aviation Administration (FAA) must receive comments on this AD action by July 18, 2005.

Affected ADs

(b) None.

Applicability

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

Unsafe Condition

(d) This AD was prompted by twelve reports of severe corrosion on one or more of three components of the main landing gear (MLG). We are issuing this AD to prevent collapse of the MLG, or damage to hydraulic tubing or the aileron control cables, which could result in possible departure of the airplane from the runway and loss of control 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.

Service Bulletin Reference

(f) The term “service bulletin,” as used in this AD, means the Accomplishment Instructions of Boeing Alert Service Bulletin 737-32A1367, Revision 1, dated December 23, 2004.

Records Examination and Compliance Times

(g) For all airplanes: Before the inspection required by paragraph (h) of this AD, examine the airplane records to determine if the MLG has been overhauled, and, for any overhauled MLG, if JC5A corrosion inhibiting compound (C.I.C.) was used on the trunnion pin or other parts of the MLG.

(1) For airplanes identified in the service bulletin as Group 2 and Group 4: If records indicate conclusively that the MLG has not been overhauled, no further action is required by this paragraph or paragraph (h) of this AD.

(2) For airplanes identified in the service bulletin as Group 1, Group 2, Group 3, and Group 4: If records indicate conclusively that the MLG has been overhauled and that C.I.C. JC5A was not used on the trunnion pins or other parts of the MLG during the overhaul, no further action is required by this paragraph or paragraph (h) of this AD.

Inspection and Corrective Action

(h) For all airplanes, except as provided by paragraph (g)(1) and (g)(2) of this AD: At the applicable compliance time in paragraph (h)(1) or (h)(2) of this AD, do a detailed inspection for discrepancies of the applicable MLG components specified in the service bulletin. Do all applicable corrective actions before further flight after the inspection. Do all the actions in accordance with the service bulletin, except as required by paragraph (i) of this AD.

(1) For airplanes identified in the service bulletin as Group 1 and Group 3 for which records indicate conclusively that the MLG has not been overhauled: Inspect at the later of the times in paragraph (h)(1)(i) and (h)(1)(ii) of this AD.

(i) Within 48 months after the date of issuance of the original Airworthiness Certificate or the date of issuance of the original standard Export Certificate of Airworthiness, whichever occurs later.

(ii) Within 6 months after the effective date of this AD.

(2) For airplanes identified in the service bulletin as Group 1, Group 2, Group 3, and Group 4 for which records indicate conclusively that the MLG has been overhauled, and for which records indicate conclusively that C.I.C. JC5A was used during the last overhaul; and for airplanes for which records do not show conclusively which C.I.C. compound was used during the last overhaul: Inspect at the later of the times in paragraph (h)(2)(i) or (h)(2)(ii) of this AD.

(i) Within 48 months after the landing gear was installed.

(ii) Within 6 months after the effective date of this AD.

Note 1:

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

Contact ACO or DOA for Certain Corrective Actions

(i) If any discrepancy is found during any inspection required by this AD, and the service bulletin specifies to contact Boeing for appropriate action: Before further flight, do the action according to a method approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA; or according to data meeting the certification basis of the airplane approved by an Authorized Representative for the Boeing Delegation Option Authorization Organization (DOA) who has been authorized by the Manager, Seattle ACO, to make those findings. For a repair method to be approved, the approval must specifically refer to this AD.

Use of JC5A Prohibited

(j) As of the effective date of this AD, no person may use C.I.C. JC5A on an MLG component on any airplane.

Actions Done According to Previous Revision of Service Bulletin

(k) Actions done before the effective date of this AD in accordance with Boeing Alert Service Bulletin 737-32A1367, dated August 19, 2004, are considered acceptable for compliance with the corresponding action specified in this AD.

Alternative Methods of Compliance (AMOCs)

(l)(1) The Manager, Seattle ACO, FAA, has the authority to approve AMOCs for this AD, if requested in accordance with the procedures found in 14 CFR 39.19.

(2) 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 DOA 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, and the approval must specifically refer to this AD.

Issued in Renton, Washington, on May 26, 2005.

Ali Bahrami,

Manager, Transport Airplane Directorate, Aircraft Certification Service.