### 65503 Federal Register / Vol. 77, No. 209 / Monday, October 29, 2012 / Proposed Rules

the wiring, and do all associated actions, per the Accomplishment Instructions of Boeing Service Bulletin A3500, Revision 1, dated April 26, 2001. The associated actions include performing a general visual inspection of the area around each fuel boost pump and override pump for evidence of a fuel leak; finding the source of any fuel leak and repairing the affected area; replacing the conduit, if required; and performing a detailed visual inspection of the wiring installed in the conduit for evidence of electrical arcing or a fuel leak, or exposed copper wire. If replacement of the conduit is deferred per the Accomplishment Instructions of Boeing Service Bulletin A3500, Revision 1, dated April 26, 2001, repeat the inspection for fuel leaks every 500 flight hours until the conduit is replaced, and replace the conduit within 6,000 flight hours or 18 months, whichever occurs first.

(1) 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 under normally available lighting conditions such as daylight, hangar lighting, flashlight, or drop-light, 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.’’

(2) For the purposes of this AD, a detailed visual inspection is defined as: ‘‘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.’’
(h) Retained Repetitive Inspections

This paragraph restates the requirements of paragraph (b) of AD 2001–17–20, Amendment 39–12411 (66 FR 44954, August 27, 2001), with a new compliance time. After replacement of the wiring per paragraph (g) of this AD, repeat the detailed visual inspection of the wiring for the fuel boost pumps and override pumps for damage, such as evidence of electrical arcing or exposed copper wire, or evidence of a fuel leak. After the effective date of this AD, repeat the inspection one time at the earlier of the times specified in paragraphs (h)(1) and (h)(2) of this AD, per the Accomplishment Instructions of Boeing Service Bulletin A3500, Revision 1, dated April 26, 2001. If any electrical arcing or exposed copper wire or evidence of a fuel leak is detected during any inspection per this paragraph, before further flight, do the applicable corrective actions (including finding the source of any fuel leak and repairing the affected area, replacing the wiring, replacing the conduit, or installing new Teflon sleeving; as applicable) according to the Accomplishment Instructions of Boeing Service Bulletin A3500, Revision 1, dated April 26, 2001. Repeat the inspection thereafter at intervals not to exceed 15,000 flight hours. (1) Within 30,000 flight hours after the most recent inspection.

(2) At the later of the compliance times specified in paragraphs (h)(2)(i) and (h)(2)(ii) of this AD.

(i) Within 15,000 flight hours after the most recent inspection.

(ii) Within 3 years after the effective date of this AD.
(i) Credit for Previous Actions

This paragraph provides credit for the actions required by paragraph (g) of this AD, if those actions were performed before October 1, 2001 (the effective date of AD 2001–17–20, Amendment 39–12411 (66 FR 44954, August 27, 2001)), using Boeing Alert Service Bulletin A3500, dated July 27, 2000, which is not incorporated by reference in this AD. (j) Alternative Methods of Compliance (AMOCs)

(1) The Manager, Seattle Certification Office (ACO), FAA, has the authority to approve AMOCs for this AD, if requested using the procedures found in 14 CFR 39.19. In accordance with 14 CFR 39.19, send your request to your principal inspector or local Flight Standards District Office, as appropriate. If sending information directly to the manager of the ACO, send it to the attention of the person identified in the Related Information section of this AD. Information may be emailed to: 9-ANMSeattle-ACO-AMOC-Requests@faa.gov.

(2) Before using any approved AMOC, notify your appropriate principal inspector, or lacking a principal inspector, the manager of the local flight standards district office/ certificate holding district office.

(3) AMOCs approved previously in accordance with AD 2001–17–20, Amendment 39–12411 (66 FR 44954, August 27, 2001), are approved as AMOCs for this AD, except for AMOCS that change the inspection frequency.
(k) Related Information

(1) For more information about this AD, contact Rebel Nichols, Aerospace Engineer, Propulsion Branch, ANM–140S, Seattle Aircraft Certification Office (ACO), FAA, 1601 Lind Avenue SW., Renton, WA 98057– 3356; phone 425–917–6509; fax 425–917– 6590; email: Rebel.Nichols@faa.gov.

(2) For service information identified in this AD, contact Boeing Commercial Airplanes, Attention: Data & Services Management, P.O. Box 3707, MC 2H–65, Seattle, WA 98124–2207; telephone 206– 544–5000, extension 1; fax 206–766–5680; Internet https://www.myboeingfleet.com. You may review copies of the referenced service information at the FAA, Transport Airplane Directorate, 1601 Lind Avenue SW., Renton, WA. For information on the availability of this material at the FAA, call 425–227–1221.

Issued in Renton, Washington, on October 22, 2012. Kalene C. Yanamura, Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.

[FR Doc. 2012–26480 Filed 10–26–12; 8:45 am]

**BILLING CODE 4910–13–P DEPARTMENT OF TRANSPORTATION** 

**Federal Aviation Administration**

**14 CFR Part 39**

**[Docket No. FAA–2012–1148; Directorate Identifier 2012–CE–039–AD]** 

**RIN 2120–AA64**

**Airworthiness Directives; Diamond Aircraft Industries GmbH Airplanes** 

**AGENCY :**  Federal Aviation Administration (FAA), Department of Transportation (DOT).

**ACTION :**  Notice of proposed rulemaking (NPRM).

**SUMMARY :**  We propose to adopt a new airworthiness directive (AD) for Diamond Aircraft Industries GmbH Models DA 42, DA 42 M–NG, and DA 42 NG airplanes. This proposed AD results from mandatory continuing airworthiness information (MCAI) originated by an aviation authority of another country to identify and correct an unsafe condition on an aviation product. The MCAI describes the unsafe condition as overextension of the main landing gear (MLG) shock absorber that could lead to the MLG jamming in the gear bay and result in damage to the aircraft or occupant injury. We are issuing this proposed AD to require actions to address the unsafe condition on these products.

**DATES :**  We must receive comments on this proposed AD by December 13,
2012.

**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 proposed AD, contact DiamondAircraft Industries GmbH, N.A. OttoStra+ e 5, A–2700 Wiener Neustadt, Austria, telephone: +43 2622 26700; fax: +43 2622 26780; email: office@diamond-air.at; Internet: http:// www.diamond-air.at. You may review copies of the referenced service information at the FAA, Small Airplane


### 65504 Federal Register / Vol. 77, No. 209 / Monday, October 29, 2012 / Proposed Rules

Directorate, 901 Locust, Kansas City, Missouri 64106. For information on the availability of this material at the FAA, call (816) 329–4148. 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 :**  Mike Kiesov, Aerospace Engineer, FAA, Small Airplane Directorate, 901 Locust, Room 301, Kansas City, Missouri 64106; telephone: (816) 329–4144; fax: (816) 329–4090; email: mike.kiesov@faa.gov

. **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–2012–1148; Directorate Identifier 2012–CE–039–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:// 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

The European Aviation Safety Agency (EASA), which is the Technical Agent for the Member States of the European Community, has issued AD No.: 2012– 0174, dated September 4, 2012 (referred to after this as ‘‘the MCAI’’), to correct an unsafe condition for the specified products. The MCAI states:

An incident was reported where a Diamond DA 42 experienced main landing gear (MLG) extension problems during approach, with the left hand (LH) MLG not down. An uneventful landing was made with minor damage to the aeroplane and no injuries to occupants. Subsequent investigation results showed that the affected MLG leg shock absorber, P/ N D60–3277–10–00, had overextended, resulting in the MLG being jammed in the gear bay. The overextension had been caused by a retaining nut in the MLG shock absorber which had loosened itself during operation.

This condition, if not corrected, could inhibit proper extension of the MLG, possibly resulting in damage to the aeroplane and injury to occupants.

Prompted by the reported event, Diamond Aircraft Industries (DAI) published Recommended Service Bulletin (RSB) 42– 089/RSB 42NG–017 which includes Working Instruction (WI) WI–RSB–089/WI–RSB 42NG–017 (published as a single document) to recommend operators to modify the affected dampers to P/N D60–3277–10–00

_ 01 standard, which incorporates installation of a new retaining nut and a new seal system for the MLG damper that is more durable and can withstand a greater temperature range.

Since that RSB was issued, further analysis has shown that the risk of a MLG failing to extend is greater than was initially determined. Consequently, DAI issued Mandatory Service Bulletin MSB 42–095/ MSB 42NG–026 to alert aeroplane owners and operators accordingly. The new MSB contains the same instructions as the earlier RSB, but is no longer ‘at owner’s discretion’.

For the reasons described above, this AD requires modification of the affected MLG leg shock absorber, P/N D60–3277–10–00. This AD also prohibits installation of unmodified P/N D60–3277–10–00 MLG leg shock absorbers.

You may obtain further information by examining the MCAI in the AD docket.

Relevant Service Information

Diamond Aircraft Industries GmbH has issued the following service information:

• Mandatory Service Bulletin MSB 42–095, MSB 42NG–026, dated November 11, 2011;

• Recommended Service Bulletin RSB 42–089/1, RSB 42NG–017/1, dated April 19, 2011;

• Page 202 through page 211 of CHAPTER 32 LANDING GEAR in Diamond Aircraft DA 42 Series AMM, Doc # 7.02.01, Rev. 2, dated June 30, 2008;

• Page 201 through page 213 in Temporary Revision AMM–TR–OA  ̈ M 42–195 of Diamond Aircraft DA 42 AMM, Doc # 7.02.01, dated July 14, 2010; and

• Page 203 through page 214 of CHAPTER 32 LANDING GEAR in Diamond Aircraft DA 42 NG AMM, Doc # 7.02.15, Rev. 1, dated October 15,
2009.

The actions described in this service information are intended to correct the unsafe condition identified in the MCAI. FAA’s Determination and Requirements of the Proposed AD

This product has been approved by the aviation authority of another country, and is approved for operation in the United States. Pursuant to our bilateral agreement with this State of Design Authority, they have notified us of the unsafe condition described in the MCAI and service information referenced above. We are proposing this AD because we evaluated all information and determined the unsafe condition exists and is likely to exist or develop on other products of the same type design. Costs of Compliance

We estimate that this proposed AD will affect 175 products of U.S. registry. We also estimate that it would take about 2 work-hours per product to comply with the basic requirements of this proposed AD. The average labor rate is $85 per work-hour. Required parts would cost about $115 per product.

Based on these figures, we estimate the cost of the proposed AD on U.S. operators to be $49,875, or $285 per product.

According to the manufacturer, some of the costs of this proposed AD may be covered under warranty, thereby reducing the cost impact on affected individuals. We do not control warranty coverage for affected individuals. As a result, we have included all costs in our cost estimate. 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


### 65505 Federal Register / Vol. 77, No. 209 / Monday, October 29, 2012 / Proposed Rules

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),

(3) Will not affect intrastate aviation in Alaska, and

(4) 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. List of Subjects in 14 CFR Part 39

Air transportation, Aircraft, Aviation safety, Incorporation by reference, 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:

Diamond Aircraft Industries GmbH: Docket No. FAA–2012–1148; Directorate Identifier 2012–CE–039–AD.

(a) Comments Due Date

We must receive comments by December 13, 2012.
(b) Affected ADs

None. (c) Applicability

This AD applies to Diamond Aircraft Industries GmbH Models DA 42, DA 42 M– NG, and DA 42 NG airplanes, all serial numbers, certificated in any category.
(d) Subject

Air Transport Association of America (ATA) Code 32: Landing Gear.

(e) Reason

This AD was prompted by mandatory continuing airworthiness information (MCAI) originated by an aviation authority of another country to identify and correct an unsafe condition on an aviation product. The MCAI describes the unsafe condition as overextension of the main landing gear (MLG) shock absorber. We are issuing this AD to prevent the MLG jamming in the gear bay, which could result in damage to the aircraft or occupant injury.
(f) Actions and Compliance

Unless already done, do the following actions:

(1) Within the next 200 hours time-inservice (TIS) after the effective date of this AD or within the next 12 months after the effective date of this AD, whichever occurs first, modify the left hand (LH) and right hand (RH) MLG leg shock absorbers part number (P/N) D60–3277–10–00 (no P/N change necessary) following Diamond Aircraft Industries GmbH Mandatory Service Bulletin MSB 42–095, MSB 42NG–026, dated November 11, 2011, or replace each MLG leg shock absorber P/N D60–3277–10–00 with a modified unit P/N D60–3277–10–00–01, following, as applicable: Diamond Aircraft Industries GmbH Recommended Service Bulletin RSB 42–089/1, RSB 42NG–017/1, dated April 19, 2011; page 202 through page 211 of CHAPTER 32 LANDING GEAR in Diamond Aircraft DA 42 Series AMM, Doc # 7.02.01, Rev. 2, dated June 30, 2008; page 201 through page 213 in Temporary Revision AMM–TR–OA  ̈ M 42–195 of Diamond Aircraft DA 42 AMM, Doc # 7.02.01, dated July 14, 2010; and page 203 through page 214 of CHAPTER 32 LANDING GEAR in Diamond Aircraft DA 42 NG AMM, Doc # 7.02.15, Rev. 1, dated October 15, 2009.

(2) Modification of an airplane following Diamond Aircraft Industries GmbH Recommended Service Bulletin RSB 42–089/ 1, RSB 42NG–017/1, dated April 19, 2011, following working instruction WI–MSB 42– 095, MSB 42NG–026, dated November 11, 2011, as referenced in Diamond Aircraft Industries GmbH Mandatory Service Bulletin MSB 42–095, MSB 42NG–026, dated November 11, 2011, is acceptable to comply with the requirement of paragraph (f)(1) of this AD.

(3) After the effective date of this AD, do not install an MLG leg shock absorber P/N D60–3277–10–00 on the airplane, unless the shock absorber has been modified following Diamond Aircraft Industries GmbH Mandatory Service Bulletin MSB 42–095, MSB 42NG–026, dated November 11, 2011, or following Diamond Aircraft Industries GmbH Recommended Service Bulletin RSB 42–089/1, RSB 42NG–017/1, dated April 19, 2011; and following working instruction WI– MSB 42–095, MSB 42NG–026, dated November 11, 2011, as referenced in Diamond Aircraft Industries GmbH Mandatory Service Bulletin MSB 42–095, MSB 42NG–026, dated November 11, 2011.
(g) Other FAA AD Provisions

The following provisions also apply to this AD:

(1) Alternative Methods of Compliance (AMOCs): The Manager, Standards Office, FAA, has the authority to approve AMOCs for this AD, if requested using the procedures found in 14 CFR 39.19. Send information to ATTN: Mike Kiesov, Aerospace Engineer, FAA, Small Airplane Directorate, 901 Locust, Room 301, Kansas City, Missouri 64106; telephone: (816) 329–4144; fax: (816) 329– 4090; email: mike.kiesov@faa.gov. 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.

(2) Airworthy Product: For any requirement in this AD to obtain corrective actions from a manufacturer or other source, use these actions if they are FAA-approved. Corrective actions are considered FAA-approved if they are approved by the State of Design Authority (or their delegated agent). You are required to assure the product is airworthy before it is returned to service.

(3) Reporting Requirements: For any reporting requirement in this AD, a federal agency may not conduct or sponsor, and a person is not required to respond to, nor shall a person be subject to a penalty for failure to comply with a collection of information subject to the requirements of the Paperwork Reduction Act unless that collection of information displays a current valid OMB Control Number. The OMB Control Number for this information collection is 2120–0056. Public reporting for this collection of information is estimated to be approximately 5 minutes per response, including the time for reviewing instructions, completing and reviewing the collection of information. All responses to this collection of information are mandatory. Comments concerning the accuracy of this burden and suggestions for reducing the burden should be directed to the FAA at: 800 Independence Ave. SW., Washington, DC 20591, Attn: Information Collection Clearance Officer, AES–200.

(h) Related Information

Refer to MCAI European Aviation Safety Agency (EASA) AD No.: 2012–0174, dated September 4, 2012; Diamond Aircraft Industries GmbH Mandatory Service Bulletin MSB 42–095, MSB 42NG–026, dated November 11, 2011; Diamond Aircraft Industries GmbH Recommended Service Bulletin RSB 42–089/1, RSB 42NG–017/1, dated April 19, 2011; page 202 through page 211 of CHAPTER 32 LANDING GEAR in Diamond Aircraft DA 42 Series AMM, Doc # 7.02.01, Rev. 2, dated June 30, 2008; page 201 through page 213 in Temporary Revision AMM–TR–OA  ̈ M 42–195 of Diamond Aircraft DA 42 AMM, Doc # 7.02.01, dated July 14, 2010; and page 203 through page 214 of CHAPTER 32 LANDING GEAR in Diamond Aircraft DA 42 NG AMM, Doc # 7.02.15, Rev. 1, dated October 15, 2009, for related information. For service information related to this AD, contact Diamond Aircraft Industries GmbH, N.A. Otto-Stra+ e 5, A–2700 Wiener Neustadt, Austria, telephone: +43 2622 26700; fax: +43 2622 26780; email: office@diamond-air.at; Internet: http:// www.diamond-air.at. You may review copies of the referenced service information at the FAA, Small Airplane Directorate, 901 Locust, Kansas City, Missouri 64106. For information on the availability of this material at the FAA, call (816) 329–4148.


### 65506 Federal Register / Vol. 77, No. 209 / Monday, October 29, 2012 / Proposed Rules

Issued in Kansas City, Missouri, on October 22, 2012. James E. Jackson, Acting Manager, Small Airplane Directorate, Aircraft Certification Service.
[FR Doc. 2012–26499 Filed 10–26–12; 8:45 am]

**BILLING CODE 4910–13–P**

**DEPARTMENT OF TRANSPORTATION**

**Federal Aviation Administration**

**14 CFR Part 39**

**[Docket No. FAA–2012–1109; Directorate Identifier 2011–NM–172–AD]** 

**RIN 2120–AA64**

**Airworthiness Directives; The Boeing Company Airplanes** 

**AGENCY :**  Federal Aviation Administration (FAA), DOT.

**ACTION :**  Notice of proposed rulemaking (NPRM).

**SUMMARY :**  We propose to supersede an existing airworthiness directive (AD) that applies to certain The Boeing Company Model 757–200 and –200PF series airplanes. The existing AD currently requires modification of the nacelle strut and wing structure, and repair of any damage found during the modification. Since we issued that AD, a compliance time error involving the optional threshold formula was discovered, which could allow an airplane to exceed the acceptable compliance time for addressing the unsafe condition. This proposed AD would specify a maximum compliance time limit that overrides the optional threshold formula results. We are proposing this AD to prevent fatigue cracking in primary strut structure and consequent reduced structural integrity of the strut.

**DATES :**  We must receive comments on this proposed AD by December 13,
2012.

**ADDRESSES :**  You may send comments, using the procedures found in 14 CFR 11.43 and 11.45, 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: Deliver to Mail address above 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, Attention: Data & Services Management, P.O. Box 3707, MC 2H–65, Seattle, WA 98124–2207; phone: 206–544–5000, extension 1; fax: 206–766–5680; Internet: https:// www.myboeingfleet.com. You may review copies of the referenced service information at the FAA, Transport Airplane Directorate, 1601 Lind Avenue SW., Renton, WA. For information on the availability of this material at the FAA, call 425–227–1221. 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 (phone: 800–647–5527) is in the

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

**FOR FURTHER INFORMATION CONTACT :**  Nancy Marsh, Aerospace Engineer, Airframe Branch, ANM–120S, Seattle Aircraft Certification Office (ACO), FAA, 1601 Lind Avenue SW., Renton, WA 98057–3356; phone: 425–917–6440; fax: 425–917–6590; email: Nancy.Marsh@faa.gov.

**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–2012–1109; Directorate Identifier 2011–NM–172–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

On August 29, 2003, we issued AD 2003–18–05, Amendment 39–13296 (68 FR 53496, September 11, 2003), for certain Model 757 series airplanes powered by Pratt & Whitney engines. That AD requires modification of the nacelle strut and wing structure, and repair of any damage found during the modification. That AD resulted from reports indicating that the actual operational loads applied to the nacelle are higher than the analytical loads that were used during the initial design. Subsequent analysis and service history, which included numerous reports of fatigue cracking on certain strut and wing structure, indicated that fatigue cracking can occur on the primary strut structure before an airplane reaches its design service objective. We issued that AD to prevent fatigue cracking in primary strut structure and consequent reduced structural integrity of the strut. Actions Since Existing AD (68 FR 53496, September 11, 2003) Was Issued

Since we issued AD 2003–18–05, Amendment 39–13296 (68 FR 53496, September 11, 2003), an error in the optional threshold formula of the compliance time was discovered. If the optional threshold formula is used, it could result in an unacceptable compliance time for addressing the unsafe condition.

Relevant Service Information

AD 2003–18–05, Amendment 39– 13296 (68 FR 53496, September 11, 2003), refers to Boeing Service Bulletin 757–54–0034, dated May 14, 1998; or Revision 1, dated October 11, 2001; as the appropriate source of service information for modifying the nacelle strut and wing structure. Boeing has since revised this service bulletin. We reviewed Boeing Service Bulletin 757– 54–0034, Revision 2, dated May 7, 2009. This service bulletin specifies a compliance time that limits the results from the optional threshold compliance time formula to within eight years from the issuance date of this service bulletin.

FAA’s Determination

We are proposing this AD because we evaluated all the relevant information and determined the unsafe condition described previously is likely to exist or develop in other products of the same type design. Proposed AD Requirements

This proposed AD would retain all requirements of AD 2003–18–05, Amendment 39–13296 (68 FR 53496, September 11, 2003). This proposed AD would reduce certain compliance times. The optional threshold formula method is limited to within eight years after the effective date of the AD. This proposed