### 73739 Federal Register / Vol. 78, No. 236 / Monday, December 9, 2013 / Proposed Rules

DOE is also interested in comments on other relevant issues that participants believe would affect energy conservation standards for these products, applicable test procedures, or the preliminary determination on the scope of coverage. DOE invites all interested parties, whether or not they participate in the public meeting, to submit in writing by January 23, 2014, comments and information on matters addressed in the Framework Document and on other matters relevant to DOE’s consideration of coverage of and standards for GSLs.

The public meeting will be conducted in an informal, facilitated, conference style. There shall be no discussion of proprietary information, costs or prices, market shares, or other commercial matters regulated by U.S. antitrust laws. A court reporter will record the proceedings of the public meeting, after which a transcript will be available for purchase from the court reporter and placed on the DOE Web site at: http:// www1.eere.energy.gov/buildings/ appliance

_standards/ product.aspx?productid=82.

After the public meeting and the close of the comment period on the Framework Document, DOE will collect data, conduct the analyses as discussed in the Framework Document and at the public meeting, and review the public comments it receives.

DOE considers public participation to be a very important part of the process for determining whether to establish or amend energy conservation standards and, if so, in setting those standards. DOE actively encourages the participation and interaction of the public during the comment period at each stage of the rulemaking process. Beginning with the Framework Document, and during each subsequent public meeting and comment period, interactions with and among members of the public provide a balanced discussion of the issues to assist DOE in the standards rulemaking process. Accordingly, anyone who wishes to participate in the public meeting, receive meeting materials, or be added to the DOE mailing list to receive future notices and information about this rulemaking should contact Ms. Brenda Edwards at (202) 586–2945, or via email
at Brenda.Edwards@ee.doe.gov.

Issued in Washington, DC, on December 2,
2013. Kathleen B. Hogan, Deputy Assistant Secretary for Energy Efficiency, Energy Efficiency and Renewable Energy.
[FR Doc. 2013–29166 Filed 12–6–13; 8:45 am]

**BILLING CODE 6450–01–P DEPARTMENT OF TRANSPORTATION** 

**Federal Aviation Administration**

**14 CFR Part 39**

**[Docket No. FAA–2013–0981; Directorate Identifier 2013–NM–032–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 Airworthiness Directives (ADs) 97–11– 07 and AD 99–18–23, which apply to all The Boeing Company Model MD–90–30 airplanes. AD 97–11–07 and AD 99–18– 23 currently require revising the Airworthiness Limitations Section (ALS) of the Instructions for Continued Airworthiness to incorporate certain compliance times for principal structural elements (PSE) inspections and replacement times for safe-life limited parts. Since we issued AD 97– 11–07 and AD 99–18–23, an analysis of data identified a need to introduce a new PSE requirement for the rear spar caps of the horizontal stabilizer. This proposed AD would require revising the maintenance or inspection program to incorporate the new PSE requirement and its associated inspections. We are proposing this AD to detect and correct fatigue cracking of PSEs and certain safe-life limited parts, which could adversely affect the structural integrity of the airplane.

**DATES :**  We must receive comments on this proposed AD by January 23, 2014.

**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, 3855 Lakewood Boulevard, MC D800–0019, Long Beach, CA 90846–0001; telephone 206–544–5000, extension 2; fax 206– 766–5683; Internet https:// www.myboeingfleet.com. You may view this referenced service information at the FAA, Transport Airplane Directorate, 1601 Lind Avenue SW., Renton, Washington. 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 :**  Roger Durbin, Airframe Branch, ANM– 120L, FAA, Los Angeles Aircraft Certification Office (ACO), 3960 Paramount Boulevard, Lakewood, California 90712–4137; phone: (562) 627–5233; fax: (562) 627–5210; email: roger.durbin@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–2013–0981; Directorate Identifier 2013–NM–032–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 May 16, 1997, we issued AD 97– 11–07, Amendment 39–10036 (62 FR 27941, May 22, 1997), for all The Boeing Company Model MD–90–30 airplanes. AD 97–11–07 requires revising the Airworthiness Limitations Section of the Instructions for Continued Airworthiness (MD–90–30 Airworthiness Limitations Instructions


### 73740 Federal Register / Vol. 78, No. 236 / Monday, December 9, 2013 / Proposed Rules

(ALI)) to add principle structural elements (PSE) requirements. AD 97– 11–07 resulted from analysis of data that identified reduced initial inspection thresholds, reduced repetitive inspection intervals for PSEs, and other PSEs to be added to the ALI. We issued AD 97–11–07 to detect and correct fatigue cracking, which could result in reduced structural integrity or reduced controllability of the airplane.

On August 27, 1999, we issued AD 99–18–23, Amendment 39–11289 (64 FR 48284, September 3, 1999), for all The Boeing Company Model MD–90–30 airplanes. AD 99–18–23 requires revising the Airworthiness Limitations Section of the Instructions for Continued Airworthiness (MD–90–30 Airworthiness Limitations Instructions (ALI)) to incorporate certain replacement times for safe-life limited parts. AD 99–18–23 resulted from analysis of data that identified reduced replacement times for certain safe-life limited parts. We issued AD 99–18–23 to prevent fatigue cracking of various safe-life limited parts, which could adversely affect the structural integrity of airplanes. Actions Since Existing AD Was Issued

Since we issued AD 97–11–07, Amendment 39–10036 (62 FR 27941, May 22, 1997), and AD 99–18–23, Amendment 39–11289 (64 FR 48284, September 3, 1999), an analysis of data identified the need to introduce a new principle structural elements (PSE) requirement for the rear spar of the horizontal stabilizer and its associated inspections.

Relevant Service Information

We reviewed Boeing MD–90 Airworthiness Limitations Instructions (ALI) Report No. MDC–94K9000, Revision 6, dated September 2011. For information on the procedures and compliance times, see this service information at http:// www.regulations.gov by searching for Docket No. FAA–2013–0981.

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.

This AD requires revisions to certain operator maintenance documents to include new actions (e.g., inspections). Compliance with these actions is required by 14 CFR 91.403(c). For airplanes that have been previously modified, altered, or repaired in the areas addressed by this AD, the operator may not be able to accomplish the actions described in the revisions. In this situation, to comply with 14 CFR 91.403(c), the operator must request approval for an alternative method of compliance according to paragraph (n) of this proposed AD. The request should include a description of changes to the required actions that will ensure the continued damage tolerance of the affected structure.
Proposed AD Requirements

This proposed AD would retain all of the requirements of AD 97–11–07, Amendment 39–10036 (62 FR 27941, May 22, 1997), and AD 99–18–23, Amendment 39–11289 (64 FR 48284, September 3, 1999). This proposed AD would require revising the maintenance program to incorporate the new PSE requirement and its associated inspections.
Costs of Compliance

We estimate that this proposed AD affects 52 airplanes of U.S. registry.

We estimate the following costs to comply with this proposed AD:



### E STIMATED 

### COSTS

Action Labor cost Parts cost Cost per product Cost on U.S. operators

Revise airworthiness limitations [retained actions from AD 97–11–07, Amendment 39– 10036 (62 FR 27941, May 22, 1997). 1 work-hour × $85 per hour = $85 ................. $0 $85 $35,445

Revise airworthiness limitations [retained actions from AD 99–18–23, Amendment 39– 11289 (64 FR 48284, September 3, 1999). 1 work-hour × 85 per hour = 85 ..................... 0 85 35,445

Revise airworthiness limitations [new proposed action]. 1 work-hour × 85 per hour = 85 ..................... 0 85 35,445

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),

(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.


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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:

■ a. Removing airworthiness directive (AD) 97–11–07, Amendment 39–10036 (62 FR 27941, May 22, 1997), and AD 99–18–23, Amendment 39–11289 (64 FR 48284, September 3, 1999), and

■ b. Adding the following new AD:
The Boeing Company: Docket No. FAA– 2013–0981; Directorate Identifier 2013–NM– 032–AD.
(a) Comments Due Date

The FAA must receive comments on this AD action by January 23, 2014.

(b) Affected ADs

This AD supersedes AD 97–11–07, Amendment 39–10036 (62 FR 27941, May 22, 1997), and AD 99–18–23, Amendment 39– 11289 (64 FR 48284, September 3, 1999).
(c) Applicability

This AD applies to all The Boeing Company Model MD–90–30 airplanes, certificated in any category.
(d) Subject

Air Transport Association (ATA) of America Code 51, Standard Practices/ Structures; Code 55, Stabilizers.

(e) Unsafe Condition

This AD was prompted by an analysis of data that identified a need to introduce a new principal structural elements (PSE) requirement for the rear spar caps of the horizontal stabilizer. We are issuing this AD to detect and correct fatigue cracking of PSEs and certain safe-life limited parts, which could adversely affect the structural integrity of the airplane.
(f) Compliance

Comply with this AD within the compliance times specified, unless already done.
(g) Retained Revision of Airworthiness Limitations of Principal Structural Elements

This paragraph restates the requirements of paragraph (a) of AD 97–11–07, Amendment 39–10036 (62 FR 27941, May 22, 1997). Within 180 days after June 26, 1997 (the effective date of AD 97–11–07, Amendment 39–10036 (62 FR 27941, May 22, 1997)), revise the Airworthiness Limitations Section of the Instructions for Continued Airworthiness (Airworthiness Limitations Instructions (ALI), McDonnell Douglas Report No. MDC–94K9000, dated November 1994) to incorporate the Item, Location, and Inspection Interval of principal structural elements identified in paragraphs (g)(1) through (g)(3) of this AD. This may be accomplished by inserting a copy of Revision 1 of the ALI, dated January 1995; or a copy of this AD into the ALI.

(1) For Item 53.30.02.3 at Skin Panels, STA 237 to 1395 Fuselage Skin in Constant Section from Longeron 3 Left to Longeron 3 Right: Initial Interval at 60,000 landings. Repeat the inspection thereafter at intervals not to exceed 11,000 landings.

(2) For Item 53.30.02.4 at Skin Panels, STA 237 to 1395 Fuselage Hoop Skin Splice in Constant Section from Longeron 5 Left to Longeron 5 Right: Initial Interval at 60,000 landings. Repeat the inspection thereafter at intervals not to exceed 30,000 landings.

(3) For Item 54.10.04.1 at Thrust Bulkhead, Pylon—STA Yn 170.5—Rear Spar and Engine Thrust Support Fitting (Upper and Lower): Initial Interval at 15,000 landings. Repeat the inspection thereafter at intervals not to exceed 4,500 landings.

(h) Retained Revision of Airworthiness Limitations

(1) This paragraph restates the requirements of paragraph (b) of AD 97–11– 07, Amendment 39–10036 (62 FR 27941, May 22, 1997). Within 180 days after June 26, 1997 (the effective date of AD 97–11–07, Amendment 39–10036 (62 FR 27941, May 22, 1997)), revise the Airworthiness Limitations Section of the Instructions for Continued Airworthiness (Airworthiness Limitations Instructions (ALI), McDonnell Douglas Report No. MDC–94K9000, dated November 1994) to incorporate the Item, Location, and Inspection Interval of principal structural element specified in paragraph (h)(2) of this AD. This may be accomplished by inserting a copy of Revision 2 to the ALI, dated July 1996, or a copy this AD into the ALI or Airworthiness Limitations Section.

(2) For Item 55.13.01.1 at Plates/Skin— Upper STA Xh 27.2 Left to Xh 27.2 Right— Upper Aft Skin Plank with Integral Stringers from Xh 7.234 to Xh 26.859: Initial Interval at 60,000 landings. Repeat the inspection thereafter at intervals not to exceed 8,100 landings.

(i) Retained Restriction on Alternative Inspections and Inspection Intervals

This paragraph restates the restriction on alternative inspections and inspection intervals required by paragraph (c) of AD 97– 11–07, Amendment 39–10036 (62 FR 27941, May 22, 1997). Except as provided by paragraphs (l) and (n) of this AD:

After the actions required by paragraphs (g) and (h) of this AD have been accomplished, no alternative inspections or inspection intervals may be approved for the parts specified in paragraphs (g) and (h) of this AD.
(j) Retained Revision of Airworthiness Limitations of Safe-Life Limited Parts:

This paragraph restates the requirements of paragraph (a) of AD 99–18–23, Amendment 39–11289 (64 FR 48284, September 3, 1999). Within 180 days after October 8, 1999 (the effective date of AD 99–18–23, Amendment 39–48284 (64 FR 48284, September 3, 1999)), revise the Airworthiness Limitations Section of the Instructions for Continued Airworthiness (Airworthiness Limitations Instructions (ALI), McDonnell Douglas Report No. MDC–94K9000, dated November 1994) to incorporate the Part Number, Item, and Mandatory Replacement Time of certain safe-life limited parts by inserting a copy of Revision 3, to the ALI, dated November 1997, into the ALI.

(k) Retained Restriction on Alternative Inspections and Inspection Intervals

This paragraph restates the restriction on alternative inspections and inspection intervals required by paragraph (b) of AD 99– 18–23, Amendment 39–11289 (64 FR 48284, September 3, 1999). Except as provided by paragraphs (l) and (n) of this AD: After the actions required by paragraph (j) of this AD have been accomplished, no alternative replacement times for the safe-life limited parts specified in McDonnell Douglas ALI Report No. MDC–94K9000, Revision 3, dated November 1997.
(l) New Requirements of This AD: Revision of the Maintenance Program

(1) Within 180 days after the effective date of this AD, revise the maintenance or inspection program, as applicable, to incorporate the tasks specified in Airworthiness Limitations Instructions (ALI), Boeing Report No. MDC–94K9000, Revision 6, dated September 2011. The compliance times for the initial and repetitive intervals for the tasks are stated in Airworthiness Limitations Instructions (ALI), Boeing Report No. MDC–94K9000, Revision 6, dated September 2011. Doing the revision required by this paragraph terminates the revisions required by paragraphs (g), (h), and (j) of this AD.
(m) No Alternative Actions or Intervals

After accomplishing the revision required by paragraph (l) of this AD, no alternative actions (e.g., inspections) or intervals may be used unless the actions or intervals are approved as an alternative method of compliance (AMOC) in accordance with the procedures specified in paragraph (n) of this AD.
(n) Alternative Methods of Compliance (AMOCs)

(1) The Manager, Los Angeles Aircraft 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 paragraph (o) of this AD.

(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) An AMOC that provides an acceptable level of safety may be used for any repair required by this AD if it is approved by Boeing Commercial Airplanes Organization Designation Authorization (ODA) that has been authorized by the Manager, Los Angeles


### 73742 Federal Register / Vol. 78, No. 236 / Monday, December 9, 2013 / Proposed Rules

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.

(4) AMOCs approved for AD 97–11–07, Amendment 39–10036 (62 FR 27941, May 22, 1997), and AD 99–18–23, Amendment 39– 11289 (64 FR 48284, September 3, 1999), are approved as AMOCs for the corresponding provisions of this AD.

(o) Related Information

(1) For more information about this AD, contact Roger Durbin, Airframe Branch, ANM–120L, FAA, Los Angeles Aircraft Certification Office (ACO), 3960 Paramount Boulevard, Lakewood, California 90712– 4137; phone: (562) 627–5233; fax: (562) 627– 5210; email: roger.durbin@faa.gov.

(2) For service information identified in this AD, contact Boeing Commercial Airplanes, Attention: Data & Services Management, 3855 Lakewood Boulevard, MC D800–0019, Long Beach, CA 90846–0001; telephone 206–544–5000, extension 2; fax 206–766–5683; Internet https:// www.myboeingfleet.com. You may view this referenced service information at the FAA, Transport Airplane Directorate, 1601 Lind Avenue SW., Renton, Washington. For information on the availability of this material at the FAA, call 425–227–1221.

Issued in Renton, Washington, on November 29, 2013. John P. Piccola, Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.
[FR Doc. 2013–29317 Filed 12–6–13; 8:45 am]

**BILLING CODE 4910–13–P**

**DEPARTMENT OF TRANSPORTATION**

**Federal Aviation Administration**

**14 CFR Part 39**

**[Docket No. FAA–2013–0980; Directorate Identifier 2013–NM–129–AD]** 

**RIN 2120–AA64**

**Airworthiness Directives; EADS CASA (Type Certificate Previously Held by**  **Construcciones Aeronauticas, S.A.) 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 EADS CASA (Type Certificate Previously Held by Construcciones Aeronauticas, S.A.) Model CN–235–300 airplanes. This proposed AD was prompted by reports of reduced thickness of the center fuselage lower skin panel. This proposed AD would require a detailed inspection to determine the presence of panel thickness reduction, and repetitive nondestructive testing (NDT) inspections and repair if necessary. We are proposing this AD to detect and correct a reduced thickness of lower panel joints, which could result in reduced fatigue and damage tolerant characteristics of the lower panel joint to the adjacent side panels and lead to failure of the center fuselage lower skin panel, resulting in loss of control of the airplane.

**DATES :**  We must receive comments on this proposed AD by January 23, 2014.

**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, between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.

For service information identified in this proposed AD, contact EADS–CASA, Military Transport Aircraft Division (MTAD), Integrated Customer Services (ICS), Technical Services, Avenida de Arago  ́ n 404, 28022 Madrid, Spain; telephone +34 91 585 55 84; fax +34 91 585 55 05; email MTA.TechnicalService@casa.eads.net; Internet http://www.eads.net. You may view this 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 Operations office 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 Operations 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 :**  Shahram Daneshmandi, Aerospace Engineer, International Branch, ANM– 116, Transport Airplane Directorate, FAA, 1601 Lind Avenue SW., Renton, Washington 98057–3356; telephone (425) 227–1112; fax (425) 227–1149.

**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–2013–0980; Directorate Identifier 2013–NM–129–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 based on 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

The European Aviation Safety Agency (EASA), which is the Technical Agent for the Member States of the European Community, has issued EASA Airworthiness Directive 2013–0131, dated June 25, 2013 (referred to after this as the Mandatory Continuing Airworthiness Information, or ‘‘the MCAI’’), to correct an unsafe condition for the specified products. The MCAI
states:

During delivery of a spare centre fuselage lower skin panel to a CN–235 aeroplane operator, a reduced thickness of the spare panel was identified. The affected panel is used as the lower part of the fuselage between Frame (FR) FR13 and FR21, and from Stringer (STR) 24 left hand (LH) side to STR24 right hand (RH) side. Several CN–235 aeroplanes could have been delivered with a reduced thickness panel.

This condition, if not detected and corrected, could result in reduced fatigue and damage tolerant characteristics of the lower panel joint to the adjacent side panels and lead to failure of the part.

To address this potentially unsafe condition, EADS–CASA issued All Operator Letter (AOL) 235–024 to provide instructions to determine correct centre fuselage lower panel configuration by accomplishing a detailed visual inspection (DVI) of affected fuselage area [for any cracking].

For the reason described above, this [EASA] AD requires a one-time inspection of the affected panel thickness at STR24 LH and STR24 RH. In case a nonconforming panel is found to be installed, this [EASA] AD requires repetitive Non Destructive Testing (NDT) inspections and, depending on findings, the accomplishment of applicable corrective action(s).