E6-6055. Airworthiness Directives; 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

AGENCY:

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

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

We propose to revise Airworthiness Directive (AD) 68-17-03, which applies to all Pilatus Aircraft Ltd. PC-6 series airplanes. AD 68-17-03 currently requires you to repetitively inspect the rudder end rib for cracks and replace the rudder end rib with a modified rudder end rib when you find cracks. Installing the modified rudder end rib terminates the repetitive inspection requirements of AD 68-17-03. Under a licensing agreement with Pilatus, Fairchild Republic Company (also identified as Fairchild Industries, Fairchild Heli Porter, or Fairchild-Hiller Corporation) produced Model PC-6 series airplanes (manufacturer serial numbers 2001 through 2092) in the United States. AD 68-17-03 was intended to apply to all affected serial numbers of Model PC-6 series airplanes listed on Type Certificate Data Sheet (TCDS) No. 7A15, including the Fairchild-produced airplanes. Consequently, this proposed AD would clarify that all models of the PC-6 airplane on TCDS No. 7A15 (including those models produced under the licensing agreement by Fairchild Republic Company) are included in the applicability. We are proposing this AD to detect and correct cracks in the rudder end rib, which could result in failure of the rudder end rib. This failure could result in loss of directional control.

DATES:

We must receive comments on this proposed AD by May 24, 2006.

ADDRESSES:

Use one of the following addresses to comment on this proposed AD:

• DOT Docket Web site: Go to http://dms.dot.gov and follow the instructions for sending your comments electronically.
• Government-wide rulemaking Web site: Go to http://www.regulations.gov and follow the instructions for sending your comments electronically.
• Mail: Docket Management Facility; U.S. Department of Transportation, 400 Seventh Street, SW., Nassif Building, Room PL-401, Washington, DC 20590-0001.
• Fax: [phone].
• Hand Delivery: Room PL-401 on the plaza level of the Nassif Building, 400 Seventh Street, SW., 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 Pilatus Aircraft Ltd., Customer Liaison Manager, CH-6371 Stans, Switzerland; telephone: [phone]; facsimile: [phone].

FOR FURTHER INFORMATION CONTACT:

Doug Rudolph, Aerospace Engineer, FAA, Small Airplane Directorate, 901 Locust, Room 301, Kansas City, Missouri 64106; telephone: [phone]; facsimile: [phone].

SUPPLEMENTARY INFORMATION:

Comments Invited

We invite you to send any written relevant data, views, or arguments regarding this proposed AD. Send your comments to an address listed under the ADDRESSES section. Include the docket number, “FAA-2006-24094; Directorate Identifier 2006-CE-20-AD” at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of the proposed AD. We will consider all comments received by the closing date and may amend the proposed AD in light of those comments.

We will post all comments we receive, without change, to http://dms.dot.gov,, including any personal information you provide. We will also post a report summarizing each substantive verbal contact we receive concerning this proposed AD.

Discussion

Fatigue cracks found in the bottom nose rib on the rudders of certain Model PC-6 series airplanes prompted us to issue AD 68-17-03, Amendment 39-634. AD 68-17-03 currently requires the following on all Pilatus Aircraft Ltd. (Pilatus) Model PC-6 series airplanes:

• Repetitively inspecting the rudder end rib for cracks;
• Replacing the rudder end rib with a modified rudder end rib when you find cracks; and
• Terminating the repetitive inspections when the modified rudder end rib is installed.

The Federal Office for Civil Aviation (FOCA), which is the airworthiness authority for Switzerland, notified the FAA of the need to revise AD 68-17-03 to address an unsafe condition that may exist or could develop on all Pilatus Model PC-6 series airplanes. The FOCA reports that clarification is needed to assure the applicability of AD 68-17-03 to all Model PC-6 series airplanes listed on Type Certificate Data Sheet (TCDS) No. 7A15, including those produced in the United States through a licensing agreement between Pilatus and Fairchild Republic Company (also identified as Fairchild Industries, Fairchild Heli Porter, or Fairchild-Hiller Corporation).

This condition, if not detected and corrected, could result in failure of the rudder end rib. This failure could result in loss of directional control.

Foreign Airworthiness Authority Information

The FOCA recently issued Swiss AD Number HB 2005-289, effective date August 23, 2005, to ensure the continued airworthiness of all Model PC-6 series airplanes listed on TC No. 7A15, including those produced in the United States under a licensing agreement with Pilatus and Fairchild Republic Company (also identified as Fairchild Industries, Fairchild Heli Porter, or Fairchild-Hiller Corporation).

The State of Design for Pilatus Model PC-6 series airplanes is Switzerland and the airplanes are type-certificated for operation in the United States under the provisions of section 21.29 of the Federal Aviation Regulations (14 CFR 21.29) and the applicable bilateral airworthiness agreement.

Under this bilateral airworthiness agreement, the FOCA has kept us informed of the situation described above.

FAA's Determination and Requirements of This Proposed AD

We are proposing this AD because we have examined the FOCA's findings, evaluated all information and determined the unsafe condition described previously is likely to exist or develop on other products of the same type design that are certificated for operation in the United States.

This proposed AD would revise AD 68-17-03 with a new AD that would retain all actions currently required by AD 68-17-03 and would clarify the applicability of the affected airplanes by:

• Identifying those airplanes produced in the United States through a licensing agreement with the Fairchild Republic Company; and
• Listing all Pilatus Model PC-6 series airplanes on TCDS No. 7A15 in the applicability section.

Costs of Compliance

We estimate that this proposed AD would affect 49 airplanes in the U.S. registry.

We estimate the following costs to do the proposed inspection:

Labor cost	Parts cost	Total cost per airplane	Total cost on U.S. operators
1 work hour × $80 per hour = $80	Not applicable	$80	$80 × 49 = $3,920

We estimate the following costs to do any necessary replacements that would be required based on the results of the proposed inspection. We have no way of determining the number of airplanes that may need this replacement:

Labor cost	Parts cost	Total cost per airplane
9 work hours × $80 per hour = $720	$821	$1,541

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); 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.

Examining the AD Docket

Where Can I Go To View the Docket Information?

You may examine the AD docket that contains the proposed AD, the regulatory evaluation, any comments received, and other information on the Internet at http://dms.dot.gov;​; or in person at the Docket Management Facility between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The Docket Office (telephone [phone]) is located at the street address stated in the ADDRESSES section. Comments will be available in the AD docket shortly after receipt.

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.

§ 39.13

[Amended]

2. The FAA amends § 39.13 by removing Airworthiness Directive (AD) 68-17-03, Amendment 39-634, and adding the following new AD:

Pilatus Aircraft LTD: Docket No. FAA-2006-24094; Directorate Identifier 2006-CE-20-AD.

Comments Due Date

(a) We must receive comments on this proposed airworthiness directive (AD) action by May 24, 2006.

Affected ADs

(b) This AD revises AD 68-17-03, Amendment 39-634.

Applicability

(c) This AD affects the following airplane models, all manufacturer serial numbers (MSN), that are certificated in any category.

Note:

MSNs 2001 through 2092 were manufactured by Fairchild Republic Company (also identified as Fairchild Industries, Fairchild Heli Porter, and Fairchild-Hiller Corporation) in the United States under a license agreement and are covered by Type Certificate Data Sheet No. 7A15.

(1) PC-6

(2) PC-6-H1

(3) PC-6-H2

(4) PC-6/350

(5) PC-6/350-H1

(6) PC-6/350-H2

(7) PC-6/A

(8) PC-6/A-H1

(9) PC-6/A-H2

(10) PC-6/B-H2

(11) PC-6/B1-H2

(12) PC-6/B2-H2

(13) PC-6/B2-H4

(14) PC-6/C-H2

(15) PC-6/C1-H2

Unsafe Condition

(d) This AD results from fatigue cracks found in the bottom nose rib on the rudders of certain PC-6 airplanes. We are issuing this AD to detect and correct cracks in the rudder end rib, which could result in failure of the rudder. This failure could lead to loss of rudder control.

Compliance

(e) To address this problem, you must do the following:

Actions	Compliance	Procedures
(1) With the aid of a mirror, inspect the rudder end rib, part number (P/N) 6302.27 (or FAA-approved equivalent P/N) for crack(s)	Within the next 50 hours time-in-service (TIS) after August 19, 1968 (the effective date of AD 68-17-03). Repetitively inspect thereafter at intervals not to exceed 50 hours TIS	Follow Pilatus Service Bulletin No. 80, dated April 1968.
(2) If you detect crack(s) during any inspection required in paragraph (e)(1) of this AD, replace the rudder end rib with a modified rudder end rib assembly, P/N 6302.26 Pos. 2, channel reinforcement, P/N 113.40.06.002, and torque tube, P/N 113/40.06.003 (or FAA-approved equivalent P/Ns)	Before further flight after any inspection required in paragraph (e)(1) of this AD in which you find cracks. Installing the modified rudder end rib terminates the repetitive inspection requirement in paragraph (e)(1) of this AD	Follow Pilatus Service Bulletin No. 80, dated April 1968.
(3) 14 CFR 21.303 allows for replacement parts through parts manufacturer approval (PMA). The phrase “or FAA-approved equivalent part number” in this AD is intended to signify those parts that are PMA parts approved through identicality to the design of the part under the type certificate and replacement parts to correct the unsafe condition under PMA (other than identicality). If parts are installed that are identical to the unsafe parts, then the corrective actions of the AD affect these parts also. In addition, equivalent replacement parts to correct the unsafe condition under PMA (other than identicality) may also be installed provided they meet current airworthiness standards, which include those actions cited in this AD	Not applicable	Not applicable.
(4) Installing the modified rudder end rib assembly terminates the repetitive inspection requirement in paragraph (e)(1) of this AD	Not applicable	Not applicable.

Alternative Methods of Compliance (AMOCs)

(f) The Manager, Standards Office, Attn: Doug Rudolph, Aerospace Engineer, FAA, Small Airplane Directorate, 901 Locust, Room 301, Kansas City, Missouri 64106; telephone: [phone]; facsimile: [phone], has the authority to approve alternative methods of compliance (AMOCs) for this AD, if requested using the procedures found in 14 CFR 39.19.

(g) AMOCs approved for AD 68-17-03 are approved for this AD.

Related Information

(h) Swiss AD Number HB 2005-289, effective date August 23, 2005, also addresses the subject of this AD. To get copies of the documents referenced in this AD, contact Pilatus Aircraft Ltd., Customer Liaison Manager, CH-6371 Stans, Switzerland; telephone: [phone]; facsimile: [phone]. To view the AD docket, go to the Docket Management Facility; U.S. Department of Transportation, 400 Seventh Street, SW., Nassif Building, Room PL-401, Washington, DC, or on the Internet at http://dms.dot.gov. The docket number is Docket No. FAA-2006-24094; Directorate Identifier 2006-CE-20-AD.

Issued in Kansas City, Missouri, on April 17, 2006.

John R. Colomy,

Acting Manager, Small Airplane Directorate, Aircraft Certification Service.