Airworthiness Directives: Boeing Model 737-300, -400, and -500 Series Airplanes

Federal Register: March 26, 2008 (Volume 73, Number 59)

Proposed Rules

Page 15959-15961

From the Federal Register Online via GPO Access [wais.access.gpo.gov]

DOCID:fr26mr08-31

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration 14 CFR Part 39

Docket No. FAA-2008-0357; Directorate Identifier 2008-NM-005-AD

RIN 2120-AA64

Airworthiness Directives; Boeing Model 737-300, -400, and -500

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 all

Boeing Model 737-300, -400, and -500 series airplanes. This proposed AD would require repetitive inspections for discrepancies of the fuse pins of the inboard and outboard midspar fittings of the nacelle strut, and corrective actions if necessary. This proposed AD results from a report of corrosion damage of the chrome runout on the head side found on all four midspar fuse pins of the nacelle strut. Additionally, a large portion of the chrome plate was missing from the corroded area of the shank. We are proposing this AD to detect and correct discrepancies of the fuse pins of the inboard and outboard midspar fittings of the nacelle strut, which could result in reduced structural integrity of the fuse pins and consequent loss of the strut and separation of the engine from the airplane.

DATES: We must receive comments on this proposed AD by May 12, 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: 202-493-2251.

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 800-647-5527) is in the

ADDRESSES section. Comments will be available in the AD docket shortly after receipt.

FOR FURTHER INFORMATION CONTACT: Allen Rauschendorfer, Aerospace

Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft

Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98057- 3356; telephone (425) 917-6432; fax (425) 917-6590.

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-2008-0357;

Directorate Identifier 2008-NM-005-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 corrosion damage of the chrome runout on the head side found on all four midspar fuse pins of the nacelle strut on a Model 737-300 airplane. Additionally, a large portion of the chrome plate was missing from the corroded area of the shank. The airplane had a total of 28,621 flight cycles. This condition, if not corrected, could result in discrepancies of the fuse pins of the inboard and outboard midspar fittings of the nacelle strut, reduced structural integrity of the fuse pins, and consequent loss of the strut and separation of the engine from the airplane.

Relevant Service Information

We have reviewed Boeing Special Attention Service Bulletin 737-54- 1044, dated December 10, 2007. The service bulletin describes procedures for

Page 15960

repetitive detailed inspections for discrepancies (cracking, pitting, corrosion, or chrome plate damage) of the fuse pins of the left- and right-side inboard and outboard midspar fittings of the nacelle strut, and corrective actions if necessary. The corrective actions include blending out pitting or corrosion damage, inspecting blended areas to make sure all damage was removed, and repairing or replacing damaged fuse pins with new or serviceable fuse pins.

The compliance time specified in the service bulletin is the latest of the following: Within 180 months from the date of issuance of the original standard certificate of airworthiness or original export certificate of airworthiness, within 180 months from date of previous pin replacement, or within 24 months after the effective date of the service bulletin. The repetitive interval is not to exceed 60 months.

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.

Interim Action

We consider this proposed AD interim action. The manufacturer is currently developing a modification that will address the unsafe condition identified in this AD. Once this modification is developed, approved, and available, we might consider additional rulemaking.

Costs of Compliance

We estimate that this proposed AD would affect 616 airplanes of

U.S. registry. We also estimate that it would take about 4 work-hours per product to comply with the inspection in this proposed AD. The average labor rate is $80 per work-hour. Based on these figures, we estimate the cost of this proposed AD to the U.S. operators to be

$197,120, or $320 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.

Sec. 39.13 [Amended] 2. The FAA amends Sec. 39.13 by adding the following new AD:

Boeing: Docket No. FAA-2008-0357; Directorate Identifier 2008-NM- 005-AD.

Comments Due Date

(a) We must receive comments by May 12, 2008.

Affected ADs

(b) None.

Applicability

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

Unsafe Condition

(d) This AD results from a report of corrosion damage of the chrome runout on the head side found on all four midspar fuse pins of the nacelle strut. Additionally, a large portion of the chrome plate was missing from the corroded area of the shank. We are issuing this AD to detect and correct damage of the fuse pins of the inboard and outboard midspar fittings of the nacelle strut, which could result in reduced structural integrity of the fuse pins and consequent loss of the strut and separation of the engine from the airplane.

Compliance

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

Repetitive Inspections/Corrective Actions

(f) At the applicable time specified in paragraph 1.E.,

``Compliance'' of Boeing Special Attention Service Bulletin 737-54- 1044, dated December 10, 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: Do a detailed inspection for discrepancies of the fuse pins of the inboard and outboard midspar fittings of the nacelle strut by doing all the actions, including all applicable corrective actions, in accordance with the

Accomplishment Instructions of the service bulletin. Do all applicable corrective actions before further flight. Repeat the inspection at the time specified in paragraph 1.E. of the service bulletin.

Alternative Methods of Compliance (AMOCs)

(g)(1) The Manager, Seattle Aircraft Certification Office (ACO),

FAA, ATTN: Allen Rauschendorfer, Aerospace Engineer, Airframe

Branch, ANM-120S, FAA, Seattle ACO, 1601 Lind Avenue, SW., Renton,

Washington 98057-3356; telephone (425) 917-6432; fax (425) 917-6590; 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

Page 15961

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 March 19, 2008.

Dionne Palermo,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

FR Doc. E8-6106 Filed 3-25-08; 8:45 am

BILLING CODE 4910-13-P