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###### Department of Transportation

###### Federal Aviation Administration

          - 14 CFR Part 39
          - [Docket No. FAA-2009-0622; Directorate Identifier 2009-CE-034-AD]
          - RIN 2120-AA64

# 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 the products listed above that would revise an existing AD. 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:

Findings of corrosion, wear and cracks in the upper wing strut fittings on some PC-6 aircraft have been reported in the past. It is possible that the spherical bearing of the wing strut fittings installed in the underwing can be loose in the fitting or cannot rotate because of corrosion. In this condition, the joint cannot function as designed and fatigue cracks may then develop. Undetected cracks, wear and/or corrosion in this area could cause failure of the upper attachment fitting, leading to failure of the wing structure and subsequent loss of control of the aircraft.

To address this problem, FOCA published AD TM-L Nr. 80.627-6/Index 72-2 and HB-2006-400 and EASA published AD 2007-0114 to require specific inspections and to obtain a fleet status. Since the issuance of AD 2007-0114, the reported data proved that it was necessary to establish and require repetitive inspections.

EASA published Emergency AD 2007-0241-E to extend the applicability and to require repetitive eddy current and visual inspections of the upper wing strut fitting for evidence of cracks, wear and/or corrosion and examination of the spherical bearing and replacement of cracked fittings. Collected data received in response to Emergency AD 2007-0241-E resulted in the issuance of EASA AD 2007-0241R1 that permitted extending the intervals for the repetitive eddy current and visual inspections from 100 Flight Hours (FH) to 300 FH and from 150 Flight Cycles (FC) to 450 FC, respectively. In addition, oversize bolts were introduced by Pilatus PC-6 Service Bulletin (SB) 57-005 R1 and the fitting replacement procedure was adjusted accordingly.

Based on fatigue test results, EASA AD 2007-0241R2 was issued to extend the repetitive inspection interval to 1100 FH or 12 calendar months, whichever occurs first, and to delete the related flight cycle intervals and the requirement for the “Mild Corrosion Severity Zone”. In addition, some editorial changes have been made for reasons of standardization and readability.

Revision 3 of this AD referred to the latest revision of the PC-6 Aircraft Maintenance Manual (AMM) Chapter 5 limitations which have included the same repetitive inspection intervals and procedures already mandated in the revision 2 of AD 2007-0241. Besides the inspections, in the latest revision of the PC-6 AMM, the replacement procedures for the fittings were included.

Additionally, EASA AD 2007-0241R3 introduced the possibility to replace the wing strut fitting with a new designed wing strut fitting. With this optional part replacement, in the repetitive inspection procedure the  1100 FH interval is deleted so that only calendar defined intervals of inspections remained applicable.

# DATES:

We must receive comments on this proposed AD by November 22, 2010.

# 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.                    

## 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:

                        Doug Rudolph, Aerospace Engineer, FAA, Small Airplane Directorate, 901 Locust, Room 301, Kansas City, Missouri 64106;                         *telephone:*                         (816) 329-4059;                         *fax:*                         (816) 329-4090.                    

# 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-2009-0622; Directorate Identifier 2009-CE-034-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

On August 18, 2009, we issued AD 2009-18-03, Amendment 39-15999 (74 FR 43636; August 27, 2009). That AD required actions intended to address an unsafe condition on the products listed above.

Since we issued AD 2009-18-03, Pilatus has updated their maintenance programs with new requirements and limitations. Another proposed AD action, Docket No. FAA-2010-1011, will require the incorporation of the updated maintenance requirements into the airworthiness limitations section of the instructions for continued airworthiness. Those updated maintenance requirements will include the repetitive inspections for the wing strut fittings and the spherical bearings currently included in AD 2009-18-03.

The European Aviation Safety Agency (EASA), which is the Technical Agent for the Member States of the European Community, has issued EASA AD No.: 2007-0241R4, dated August 31, 2010 (referred to after this as “the MCAI”), to correct an unsafe condition for the specified products. The MCAI states:

Findings of corrosion, wear and cracks in the upper wing strut fittings on some PC-6 aircraft have been reported in the past. It is possible that the spherical bearing of the wing strut fittings installed in the underwing can be loose in the fitting or cannot rotate because of corrosion. In this condition, the joint cannot function as designed and fatigue cracks may then develop. Undetected cracks, wear and/or corrosion in this area could cause failure of the upper attachment fitting, leading to failure of the wing structure and subsequent loss of control of the aircraft.

                        To address this problem, FOCA published AD TM-L Nr. 80.627-6/Index 72-2 and HB-2006-400 and EASA published AD 2007-0114 to require specific inspections and to                               ( print page 62006)                            obtain a fleet status. Since the issuance of AD 2007-0114, the reported data proved that it was necessary to establish and require repetitive inspections.                    

EASA published Emergency AD 2007-0241-E to extend the applicability and to require repetitive eddy current and visual inspections of the upper wing strut fitting for evidence of cracks, wear and/or corrosion and examination of the spherical bearing and replacement of cracked fittings. Collected data received in response to Emergency AD 2007-0241-E resulted in the issuance of EASA AD 2007-0241R1 that permitted extending the intervals for the repetitive eddy current and visual inspections from 100 Flight Hours (FH) to 300 FH and from 150 Flight Cycles (FC) to 450 FC, respectively. In addition, oversize bolts were introduced by Pilatus PC-6 Service Bulletin (SB) 57-005 R1 and the fitting replacement procedure was adjusted accordingly.

Based on fatigue test results, EASA AD 2007-0241R2 was issued to extend the repetitive inspection interval to 1100 FH or 12 calendar months, whichever occurs first, and to delete the related flight cycle intervals and the requirement for the “Mild Corrosion Severity Zone”. In addition, some editorial changes have been made for reasons of standardization and readability.

Revision 3 of this AD referred to the latest revision of the PC-6 Aircraft Maintenance Manual (AMM) Chapter 5 limitations which have included the same repetitive inspection intervals and procedures already mandated in the revision 2 of AD 2007-0241. Besides the inspections, in the latest revision of the PC-6 AMM, the replacement procedures for the fittings were included.

Additionally, EASA AD 2007-0241R3 introduced the possibility to replace the wing strut fitting with a new designed wing strut fitting. With this optional part replacement, in the repetitive inspection procedure the  1100 FH interval is deleted so that only calendar defined intervals of inspections remained applicable.

The aim of this new revision is to only mandate the initial inspection requirement and consequently to limit its applicability to aeroplanes which are not already in compliance with EASA AD 2007-0241R3. All aeroplanes which are in compliance with EASA AD 2007-0241R3 have to follow the repetitive inspection requirements as described in Pilatus PC-6 AMM Chapter 04-00-00, Document Number 01975, Revision 12 and the Airworthiness Limitations (ALS) Document Number 02334 Revision 1 mandated by EASA AD 2010-0176. Therefore the repetitive inspection requirements corresponding paragraphs have been deleted in this new EASA AD revision. The paragraph numbers of EASA AD 2007-0241R numbering has been maintained for referencing needs. 

The proposed AD would require actions that are intended to address the unsafe condition described in the MCAI. You may obtain further information by examining the MCAI in the AD docket.

## 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.

## Differences Between This Proposed AD and the MCAI or Service Information

We have reviewed the MCAI and related service information and, in general, agree with their substance. But we might have found it necessary to use different words from those in the MCAI to ensure the AD is clear for U.S. operators and is enforceable. In making these changes, we do not intend to differ substantively from the information provided in the MCAI and related service information.

We might also have proposed different actions in this AD from those in the MCAI in order to follow FAA policies. Any such differences are highlighted in a NOTE within the proposed AD.

## Costs of Compliance

We estimate that this proposed AD will affect 50 products of U.S. registry. We also estimate that it would take about 7 work-hours per product to comply with the basic requirements of this proposed AD. The average labor rate is $85 per work-hour.

Based on these figures, we estimate the cost of the proposed AD on U.S. operators to be $29,750, or $595 per product.

In addition, we estimate that any necessary follow-on actions would take about 30 work-hours and require parts costing $5,000, for a cost of $7,550 per product. We have no way of determining the number of products that may need these actions.

## 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.

We prepared a regulatory evaluation of the estimated costs to comply with this proposed AD and placed it in the AD docket.

# 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 

2. The FAA amends § 39.13 by removing Amendment 39-15999 (74 FR 43636; August 27, 2009), and adding the following new AD:

**Pilatus Aircraft Ltd.:**                                 Docket No. FAA-2009-0622; Directorate Identifier 2009-CE-034-AD.                                      ( print page 62007)    

## Comments Due Date

(a) We must receive comments by November 22, 2010.

## Affected ADs

(b) This AD revises AD 2009-18-03, Amendment 39-15999.

## Applicability

(c) This AD applies to Pilatus Aircraft Ltd. Models PC-6, PC-6-H1, PC-6-H2, PC-6/350, PC-6/350-H1, PC-6/350-H2, PC-6/A, PC-6/A-H1, PC-6/A-H2, PC-6/B-H2, PC-6/B1-H2, PC-6/B2-H2, PC-6/B2-H4, PC-6/C-H2, and PC-6/C1-H2 airplanes, all manufacturer serial number (MSN), and MSN 2001 through 2092, certificated in any category. These airplanes are also identified as Fairchild Republic Company PC-6 airplanes, Fairchild Industries PC-6 airplanes, Fairchild Heli Porter PC-6 airplanes, or Fairchild-Hiller Corporation PC-6 airplanes.

## Subject

(d) Air Transport Association of America (ATA) Code 57: Wings.

## Reason

(e) The mandatory continuing airworthiness information (MCAI) states:

Findings of corrosion, wear and cracks in the upper wing strut fittings on some PC-6 aircraft have been reported in the past. It is possible that the spherical bearing of the wing strut fittings installed in the underwing can be loose in the fitting or cannot rotate because of corrosion. In this condition, the joint cannot function as designed and fatigue cracks may then develop. Undetected cracks, wear and/or corrosion in this area could cause failure of the upper attachment fitting, leading to failure of the wing structure and subsequent loss of control of the aircraft.

To address this problem, FOCA published AD TM-L Nr. 80.627-6/Index 72-2 and HB-2006-400 and EASA published AD 2007-0114 to require specific inspections and to obtain a fleet status. Since the issuance of AD 2007-0114, the reported data proved that it was necessary to establish and require repetitive inspections.

EASA published Emergency AD 2007-0241-E to extend the applicability and to require repetitive eddy current and visual inspections of the upper wing strut fitting for evidence of cracks, wear and/or corrosion and examination of the spherical bearing and replacement of cracked fittings. Collected data received in response to Emergency AD 2007-0241-E resulted in the issuance of EASA AD 2007-0241R1 that permitted extending the intervals for the repetitive eddy current and visual inspections from 100 Flight Hours (FH) to 300 FH and from 150 Flight Cycles (FC) to 450 FC, respectively. In addition, oversize bolts were introduced by Pilatus PC-6 Service Bulletin (SB) 57-005 R1 and the fitting replacement procedure was adjusted accordingly.

Based on fatigue test results, EASA AD 2007-0241R2 was issued to extend the repetitive inspection interval to 1100 FH or 12 calendar months, whichever occurs first, and to delete the related flight cycle intervals and the requirement for the “Mild Corrosion Severity Zone”. In addition, some editorial changes have been made for reasons of standardization and readability.

Revision 3 of this AD referred to the latest revision of the PC-6 Aircraft Maintenance Manual (AMM) Chapter 5 limitations which have included the same repetitive inspection intervals and procedures already mandated in the revision 2 of AD 2007-0241. Besides the inspections, in the latest revision of the PC-6 AMM, the replacement procedures for the fittings were included.

Additionally, EASA AD 2007-0241R3 introduced the possibility to replace the wing strut fitting with a new designed wing strut fitting. With this optional part replacement, in the repetitive inspection procedure the  1100 FH interval is deleted so that only calendar defined intervals of inspections remained applicable.

The aim of this new revision is to only mandate the initial inspection requirement and consequently to limit its applicability to aeroplanes which are not already in compliance with EASA AD 2007-0241R3. All aeroplanes which are in compliance with EASA AD 2007-0241R3 have to follow the repetitive inspection requirements as described in Pilatus PC-6 AMM Chapter 04-00-00, Document Number 01975, Revision 12 and the Airworthiness Limitations (ALS) Document Number 02334 Revision 1 mandated by EASA AD 2010-0176. Therefore the repetitive inspection requirements corresponding paragraphs have been deleted in this new EASA AD revision. The paragraph numbers of EASA AD 2007-0241R numbering has been maintained for referencing needs.

The proposed AD would require actions that are intended to address the unsafe condition described in the MCAI.

## Actions and Compliance

(f) Unless already done, do the following actions:

                                (1)                                 *For airplanes that have not had both wing strut fittings replaced within the last 100 hours time-in-service (TIS) before September 26, 2007 (the effective date of AD 2007-19-14), or have not been inspected using an eddy current inspection method following Pilatus Aircraft Ltd. Pilatus PC-6 Service Bulletin No. 57-004, dated April 16, 2007, within the last 100 hours TIS before September 26, 2007 (the effective date of AD 2007-19-14):*                                 Before further flight after either September 26, 2007 (the effective date of AD 2007-19-14), or October 1, 2009 (the effective date of AD 2009-18-03), visually inspect the upper wing strut fittings and examine the spherical bearings following the Pilatus Aircraft Ltd. Pilatus PC-6 Service Bulletin No. 57-005, REV No. 2, dated May 19, 2008.                            

                                (2)                                 *For all airplanes:*                                 Within 25 hours TIS after September 26, 2007 (the effective date of AD 2007-19-14), or within 30 days after September 26, 2007 (the effective date of AD 2007-19-14), whichever occurs first, visually and using eddy current methods, inspect the upper wing strut fittings and examine the spherical bearings following Pilatus Aircraft Ltd. Pilatus PC-6 Service Bulletin No. 57-005, REV No. 2, dated May 19, 2008.                            

(3) You may also take “unless already done” credit for any inspection specified in paragraphs (f)(1) or (f)(2) of this AD if done before October 1, 2009 (the effective date retained from AD 2009-18-03) following Pilatus Aircraft Ltd. Pilatus PC-6 Service Bulletin No. 57-005, dated August 30, 2007; or Pilatus Aircraft Ltd. Pilatus PC-6 Service Bulletin No. 57-005, REV No. 1, dated November 19, 2007.

                                (4)                                *For all airplanes:*                                 If during any inspection required by paragraphs (f)(1) or (f)(2) of this AD you find cracks in the upper wing strut fitting or the spherical bearing is not in conformity, before further flight, replace the cracked upper wing strut fitting and/or the nonconforming spherical bearing following Chapter 57-00-02 of Pilatus Aircraft Ltd. Pilatus PC-6 Aircraft Maintenance Manual, dated November 30, 2008.                            

# Note 1:

 Another proposed AD action, Docket No. FAA-2010-1011, proposes to require the incorporation of the updated maintenance requirements into the airworthiness limitations section of the instructions for continued airworthiness. Those updated maintenance requirements include the repetitive inspections for the wing strut fittings and the spherical bearings currently included in AD 2009-18-03.

## FAA AD Differences

# Note 2: 

This AD differs from the MCAI and/or service information as follows: No differences.

## Other FAA AD Provisions

(g) 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:*                                 Doug Rudolph, Aerospace Engineer, FAA, Small Airplane Directorate, 901 Locust, Room 301, Kansas City, Missouri 64106;                                 *telephone:*                                 (816) 329-4059;                                 *fax:*                                 (816) 329-4090. 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, under the provisions of the Paperwork Reduction Act (44 U.S.C. 3501*et seq.*), the Office of Management and Budget (OMB) has approved the information collection requirements and has assigned OMB Control Number 2120-0056.                            

## Related Information

                                (h) Refer to MCAI EASA AD No.: 2007-0241R4, dated August 31, 2010; Pilatus Aircraft Ltd. Pilatus PC-6 Service Bulletin No. 57-005, REV No. 2, dated May 19, 2008;                                       ( print page 62008)                                    Pilatus Aircraft Ltd. Pilatus PC-6 Service Bulletin No. 57-005, REV No. 1, dated November 19, 2007; Pilatus Aircraft Ltd. Pilatus PC-6 Service Bulletin No. 57-005, dated August 30, 2007; Pilatus Aircraft Ltd. Pilatus PC-6 Service Bulletin No. 57-004, dated April 16, 2007; and Chapter 57-00-02 of Pilatus Aircraft Ltd. Pilatus PC-6 Aircraft Maintenance Manual, dated November 30, 2008, for related information.                            

Issued in Kansas City, Missouri, on September 30, 2010.

John Colomy,

Acting Manager, Small Airplane Directorate, Aircraft Certification Service.

[FR Doc. 2010-25289 Filed 10-6-10; 8:45 am]

BILLING CODE 4910-13-P