03-4990. Airworthiness Directives; Boeing Model 737-100, -200, -200C, -300, -400, and -500 Series Airplanes

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

This document proposes the supersedure of an existing airworthiness directive (AD), applicable to all Boeing Model 737-100, -200, -200C, -300, -400, and -500 series airplanes, that currently requires repetitive inspections to find cracks, fractures, or corrosion of each carriage spindle of the left and right outboard mid-flaps; and corrective action, if necessary. This action would mandate the previously optional overhaul or replacement of the carriage spindles, which would end the repetitive inspections required by the existing AD. The actions specified by the proposed AD are intended to prevent severe flap asymmetry due to fractures of the carriage spindles on an outboard mid-flap, which could result in reduced control or loss of controllability of the airplane. This action is intended to address the identified unsafe condition.

DATES:

Comments must be received by April 18, 2003.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2002-NM-219-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Comments may be inspected at this location between 9 a.m. and 3 p.m., Monday through Friday, except Federal holidays. Comments may be submitted via fax to [phone]. Comments may also be sent via the Internet using the following address: [e-mail]. Comments sent via fax or the Internet must contain “Docket No. 2002-NM-219-AD” in the subject line and need not be submitted in triplicate. Comments sent via the Internet as attached electronic files must be formatted in Microsoft Word 97 for Windows or ASCII text.

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:

Sue Lucier, 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

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 action may be changed in light of the comments received.

Submit comments using the following format:

• Organize comments issue-by-issue. For example, discuss a request to change the compliance time and a request to change the service bulletin reference as two separate issues.
• For each issue, state what specific change to the proposed AD is being requested.
• Include justification (e.g., reasons or data) for each request.

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 action must submit a self-addressed, stamped postcard on which the following statement is made: “Comments to Docket Number 2002-NM-219-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-114, Attention: Rules Docket No. 2002-NM-219-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

Discussion

On October 22, 2002, the FAA issued AD 2002-22-05, amendment 39-12929 (67 FR 66316, October 31, 2002), applicable to all Boeing Model 737-100, -200, -200C, -300, -400, and -500 series airplanes, to require repetitive inspections to find cracks, fractures, or corrosion of each carriage spindle of the left and right outboard mid-flaps; and corrective action, if necessary. That action also provides for an optional action of overhaul or replacement of the carriage spindles, which would extend the repetitive inspection interval. The requirements of that AD are intended to prevent severe flap asymmetry due to fractures of the carriage spindles on an outboard mid-flap, which could result in reduced control or loss of controllability of the airplane.

Actions Since Issuance of Previous Rule

In the preamble to AD 2002-22-05, we specified that the actions required by that AD were considered “interim action” and that we were considering requiring the optional overhaul or replacement of the carriage spindles. We have now determined that it is necessary to require the overhaul or replacement of the carriage spindles, and this proposed AD follows from that determination.

Explanation of Relevant Service Information

The FAA has reviewed and approved Boeing Alert Service Bulletin 737-57A1218, Revision 3, dated July 25, 2002. (Boeing Alert Service Bulletin 737-57A1277, dated July 25, 2002, was referenced in the existing AD as the appropriate source of service information for accomplishment of the inspections to find discrepancies of each carriage spindle, and corrective action, if necessary.) Service Bulletin 737-57A1218 describes procedures for replacement or overhaul of each carriage spindle (two on each flap) of the left and right outboard mid-flaps. Such replacement or overhaul would end the repetitive inspections specified in Service Bulletin 737-57A1277. Accomplishment of the actions specified in Service Bulletin 737-57A1218 is intended to adequately address the identified unsafe condition.

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 supersede AD 2002-22-05 to continue to require repetitive inspections to find cracks, fractures, or corrosion of each carriage spindle of the left and right outboard mid-flaps; and corrective action, if necessary. This new action would mandate the previously optional overhaul or replacement of the carriage spindles, which would end the repetitive inspections required by the existing AD. The actions would be required to be accomplished in accordance with Service Bulletin 737-57A1218, Revision 3, except as discussed below.

Difference Between Service Information and Proposed AD

The service bulletin references Boeing 737 Overhaul Manual, chapter 57-53-35 (for Model 737-100, -200, and -200C series airplanes), and chapter 57-53-36 (for Model 737-300, -400, and -500 series airplanes), for the procedures for the overhaul specified in the proposed AD. Those chapters reference Boeing 737 Standard Overhaul Practices Manual (SOPM) chapter 20-42-09, titled, “Electro-deposited Nickel Plating,” for the nickel plating procedures. The amount of nickel plating required to restore functional capability and part geometry have made certain processing steps critical within the plating process for the spindle region of the flap carriage. The processing steps are specified in paragraph (d) of this AD, and are necessary to prevent structural failures of the carriage spindle due to hydrogen embrittlement. These processing steps have been identified by the manufacturer as critical details of the plating process, and Boeing Alert Service Bulletin 737-57A1218, Revision 3, is being revised to reflect these requirements.

Cost Impact

There are approximately 3,132 airplanes of the affected design in the worldwide fleet. The FAA estimates that 1,384 airplanes of U.S. registry would be affected by this proposed AD.

The inspections that are currently required by AD 2002-22-05 take approximately 10 work hours per airplane to accomplish, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of the currently required inspections on U.S. operators is estimated to be $830,400, or $600 per airplane.

It would take approximately 2 work hours per airplane to accomplish the new detailed inspection, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of the inspection proposed by this AD on U.S. operators is estimated to be $166,080, or $120 per airplane, per inspection cycle.

Should an operator be required to accomplish the overhaul, it would take approximately 32 work hours per airplane to accomplish, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of the overhaul proposed by this AD is estimated to be $1,920 per airplane.

Should an operator be required to accomplish the replacement, it would take approximately 32 work hours per airplane to accomplish, at an average labor rate of $60 per work hour. Required parts would cost approximately $45,000 per carriage spindle. Based on these figures, the cost impact of the replacement proposed by this AD is estimated to be $46,920 per spindle, per airplane.

The cost impact figures discussed above are based on assumptions that no operator has yet accomplished any of the current or proposed requirements of this AD action, and that no operator would accomplish those actions in the future if this AD were not adopted. The cost impact figures discussed in AD rulemaking actions represent only the time necessary to perform the specific actions actually required by the AD. These figures typically do not include incidental costs, such as the time required to gain access and close up, planning time, or time necessitated by other administrative actions.

Regulatory Impact

The regulations proposed herein 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. Therefore, it is determined that this proposal would not have federalism implications under Executive Order 13132.

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.

§ 39.13

[Amended]

2. Section 39.13 is amended by removing amendment 39-12929 (67 FR 66316, October 31, 2002), and by adding a new airworthiness directive (AD), to read as follows:

Boeing: Docket 2002-NM-219-AD. Supersedes AD 2002-22-05, Amendment 39-12929.

Applicability: All Model 737-100, -200, -200C, -300, -400, and -500 series airplanes; 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 severe flap asymmetry due to fractures of the carriage spindles on an outboard mid-flap, which could result in reduced control or loss of controllability of the airplane, accomplish the following:

Restatement of Requirements of AD 2002-22-05

Repetitive Inspections

(a) Do general visual and nondestructive test (NDT) inspections of each carriage spindle (two on each flap) of the left and right outboard mid-flaps to find cracks, fractures, or corrosion at the later of the times specified in paragraphs (a)(1) and (a)(2) of this AD, as applicable, per the Work Instructions of Boeing Alert Service Bulletin 737-57A1277, dated July 25, 2002. Repeat the inspections at least every 180 days until paragraph (b) or (c) of this AD is done, as applicable.

(1) Before the accumulation of 12,000 total flight cycles or 8 years in-service on new or overhauled carriage spindles, whichever is first.

(2) Within 90 days after November 15, 2002 (the effective date of AD 2002-22-05, amendment 39-12929).

Note 2:

For the purposes of this AD, a general visual inspection is defined as: “A visual examination of an interior or exterior area, installation, or assembly to detect obvious damage, failure, or irregularity. This level of inspection is made from within touching distance unless otherwise specified. A mirror may be necessary to enhance visual access to all exposed surfaces in the inspection area. This level of inspection is made under normally available lighting conditions such as daylight, hangar lighting, flashlight, or droplight and may require removal or opening of access panels or doors. Stands, ladders, or platforms may be required to gain proximity to the area being checked.”

Corrective Action

(b) If any crack, fracture, or corrosion is found during any inspection required by paragraph (a) of this AD: Before further flight, do the applicable actions for that spindle as specified in paragraph (b)(1) or (b)(2) of this AD, per the Work Instructions of Boeing Alert Service Bulletin 737-57A1277, dated July 25, 2002. Then repeat the inspections required by paragraph (a) of this AD every 12,000 flight cycles or 8 years, whichever is first, on the overhauled or replaced spindle only.

(1) If any corrosion is found in the carriage spindle, overhaul the spindle.

(2) If any crack or fracture is found in the carriage spindle, replace with a new or overhauled carriage spindle.

Note 3:

Although Boeing Alert Service Bulletin 737-57A1277, dated July 25, 2002, recommends that operators report inspection findings of any crack or fracture in the carriage spindle to the manufacturer, this AD does not contain such a reporting requirement.

New Requirements of This AD

Overhaul or Replacement

(c) Overhaul or replace, as applicable, all four carriage spindles (two on each flap) of the left and right outboard mid-flaps at the applicable time specified in paragraph (c)(1) or (c)(2) of this AD, per the Work Instructions of Boeing Alert Service Bulletin 737-57A1218, Revision 3, dated July 25, 2002. Then repeat the applicable overhaul or replacement every 12,000 flight cycles or 8 years, whichever is first. Accomplishment of this paragraph ends the repetitive inspections required by paragraphs (a) and (b) of this AD.

(1) For Model 737-100, -200, and -200C series airplanes, overhaul or replace at the later of the times specified in paragraphs (c)(1)(i) and (c)(1)(ii) of this AD.

(i) Before the accumulation of 12,000 total flight cycles on the carriage spindle, or within 8 years since overhaul of the spindle or installation of a new spindle, whichever is first.

(ii) Within 1 year after the effective date of this AD.

(2) For Model 737-300, -400, and -500 series airplanes, overhaul or replace at the later of the times specified in paragraphs (c)(2)(i) and (c)(2)(ii) of this AD.

(i) Before the accumulation of 12,000 total flight cycles on the carriage spindle, or within 8 years since overhaul of the spindle or installation of a new spindle, whichever is first.

(ii) Within 2 years after the effective date of this AD.

(d) During accomplishment of any overhaul required by paragraph (c) of this AD, use the procedures specified in paragraphs (d)(1) and (d)(2) of this AD during application of the nickel plating of the carriage spindle in addition to those specified in Boeing 737 Standard Overhaul Practices Manual, Chapter 20-42-09.

(1) Begin the hydrogen embrittlement relief bake within 10 hours after application of the plating, or less than 24 hours after the current was first applied to the part, whichever is first.

(2) The maximum thickness of the nickel plating that is deposited in any one plating/baking cycle must not exceed 0.020 inch.

(e) Overhauling or replacing the carriage spindles before the effective date of this AD, in accordance with Boeing Alert Service Bulletin 737-57A1277, dated July 25, 2002, is considered acceptable for compliance with the overhaul or replacement specified in paragraph (c) of this AD.

Alternative Methods of Compliance

(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 ACO. 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 4:

Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Seattle ACO.

Special Flight Permits

(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 February 26, 2003.

Ali Bahrami,

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.