05-11703. 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), DOT.

ACTION:

Supplemental notice of proposed rulemaking (NPRM); Reopening of the comment period.

SUMMARY:

The FAA proposes to revise an earlier proposed airworthiness directive (AD) that applies to all Pilatus Aircraft Ltd. (Pilatus) (also identified as Fairchild Republic Company and Fairchild Heli Porter) Model PC-6 airplanes. The earlier NPRM proposed to require you to repetitively inspect the stabilizer-trim attachment and structural components for cracks, corrosion, and discrepancies and replace any defective part with a new part. The earlier NPRM also proposed to require you to replace all Fairchild connecting pieces with a Pilatus connecting piece. The earlier NPRM resulted from mandatory continuing airworthiness information (MCAI) issued by the airworthiness authority for Switzerland. This proposed AD would retain the actions from the earlier NPRM and would require you to replace fittings without an index after the part number (P/N) with an improved part. This proposed AD results from incorporating revised manufacture service information to include a procedure for replacing certain fittings with an improved part and to correct the allowable limits of the actuator attachment hole diameters. This proposed AD also clarifies the applicability. Since this action imposes an additional burden over that proposed in the NPRM, we are reopening the comment period to allow the public the chance to comment on this additional action.

DATES:

We must receive any comments on this proposed AD by July 13, 2005.

ADDRESSES:

Use one of the following to submit comments 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 20590-001.
• 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.

To get the service information identified in this proposed AD, contact Pilatus Aircraft Ltd., Customer Liaison Manager, CH-6371 Stans, Switzerland; telephone: [phone]; facsimile: [phone].

To view the comments on this proposed AD, go to http://dms.dot.gov. The docket number is FAA-2005-20515; Directorate Identifier 2005-CE-09-AD.

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

How do I comment on this proposed AD? We invite you to submit any written relevant data, views, or arguments regarding this proposal. Send your comments to an address listed under ADDRESSES. Include the docket number, “FAA-2005-20515; Directorate Identifier 2005-CE-09-AD” at the beginning of your 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 with FAA personnel concerning this proposed rulemaking. Using the search function of our docket web site, anyone can find and read the comments received into any of our dockets, including the name of the individual who sent the comment (or signed the comment on behalf of an association, business, labor union, etc.). This is docket number FAA-2005-20515. You may review the DOT's complete Privacy Act Statement in the Federal Register published on April 11, 2000 (65 FR 19477-78) or you may visit http://dms.dot.gov.

Are there any specific portions of this proposed AD I should pay attention to? We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of this proposed AD. If you contact us through a nonwritten communication and that contact relates to a substantive part of this proposed AD, we will summarize the contact and place the summary in the docket. We will consider all comments received by the closing date and may amend this proposed AD in light of those comments and contacts.

Docket Information

Where can I go to view the docket information? You may view the AD docket that contains this proposal, any comments received, and any final disposition in person at the DMS Docket Offices between 9 a.m. and 5 p.m. (eastern standard time), Monday through Friday, except Federal holidays. The Docket Office (telephone [phone]) is located on the plaza level of the Department of Transportation NASSIF Building at the street address stated in ADDRESSES. You may also view the AD docket on the Internet at http://dms.dot.gov. The comments will be available in the AD docket shortly after the DMS receives them.

Discussion

What is the background of the subject matter? The Federal Office for Civil Aviation (FOCA), which is the airworthiness authority for Switzerland, recently notified FAA that an unsafe condition may exist on all Pilatus Model PC-6 airplanes. The FOCA reports that the lower attachment bracket of the horizontal stabilizer actuator broke which resulted in an emergency landing outside the airport.

The FOCA also reports two other instances of total failure of the stabilizer trim attachment on in-service airplanes.

What is the potential impact if FAA took no action? If not detected and corrected, defects in the stabilizer-trim attachment and surrounding structural components could cause the stabilizer-trim attachment to fail. This failure could lead to loss of control of the airplane.

Has FAA taken any action to this point? We issued a proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an AD that would apply to all Pilatus Model PC-6 airplanes. This proposal was published in the Federal Register as a notice of proposed rulemaking (NPRM) on March 24, 2005 (70 FR 15019). The NPRM proposed to require you to:

—Inspect the stabilizer-trim attachment and structural components (the fitting, the connecting piece, the bearing fork, the bearing support assembly, and the auxiliary frame, as applicable) for cracks and corrosion;

—Inspect the diameters of the boltholes on the fittings, auxiliary frame, and connecting piece (as applicable) for discrepancies;

—Replace any cracked, corroded, or defective part with a new part; and

—Replace all Fairchild connecting pieces with a Pilatus connecting piece.

Was the public invited to comment? The FAA encouraged interested persons to participate in developing this amendment. The following presents the comments received on the proposal and FAA's response to each comment:

Comment Issue No. 1: Incorporate Revised Service Bulletin

What is the commenter's concern? Pilatus has revised the original service bulletin to include a requirement to replace fittings, part number (P/N) 116.40.06.033 without an index of “A” or “B” with an improved part, P/N 116.40.06.112.

Pilatus Service Bulletin No. 147, dated May 1985, requires you to inspect P/N 116.40.06.033 for cracks and to replace all cracked P/Ns 116.40.06.033 with an improved part, P/N 116.40.06.112. If no cracks are found, P/N 116.40.06.033 without an index of “A” or “B” can remain installed provided it is repetitively inspected for cracks every 100 hours time-in-service (TIS).

Pilatus Service Bulletin No. 147, dated May 1985, states that P/N 116.40.06.033 with an Index A is not subject to the 100-hour repetitive inspection.

Pilatus PC-6 Service Bulletin No. 53-001, Rev. No. 1, dated June 1, 2005, terminates the 100-hour repetitive inspection specified in Service Bulletin No. 147. The 100-hour repetitive inspection is terminated by requiring you to replace all P/Ns 116.40.06.033 without an index of “A” or “B” with an improved part, P/N 116.40.04.112.

Pilatus requests the actions in the revised service bulletin be included in the proposed AD action.

What is FAA's response to the concern? We agree with the commenter.

It is FAA's policy that reliance on critical repetitive inspections on airplanes utilized in commuter service for hire carries an unnecessary safety risk when a design change exists that could eliminate or, in certain instances, reduce the number of those critical inspections. In determining what inspections are critical, the FAA considers (1) The safety consequences of the airplane if the known problem is not detected by the inspection; (2) the reliability of the inspection such as the probability of not detecting the known problem; (3) whether the inspection area is difficult to access; and (4) the possibility of damage to an adjacent structure as a result of the problem.

The fitting is considered a critical structural component. Requiring replacement of all P/Ns 116.40.06.033 without an index of “A” or “B” with a P/N 116.40.06.112 terminates the 100-hour repetitive inspection specified in Pilatus Service Bulletin No. 147, dated May 1985.

We have confirmed with Pilatus that replacing P/Ns 116.40.06.033 without an index of “A” or “B” with a P/N 116.40.06.033 with an index of “A” or “B” also terminates the 100-hour repetitive inspection specified in Pilatus Service Bulletin No. 147, dated May 1985.

Since a design change exists that reduces the number of critical inspections, we will change this proposed AD to include this action.

Including this action imposes an additional burden over that proposed in the earlier NPRM. We are reopening the comment period to allow the public the opportunity to comment on this additional action.

Comment Issue No. 2: Change the Repetitive Inspection Intervals

What is the commenter's concern? The commenter states that repetitive dye-penetrant inspection of all affected parts at 100-hour TIS intervals could cause more damage. Dye-penetrant inspections require considerable paint stripping.

The Aircraft Maintenance Manual (AMM) for these airplanes currently requires a repetitive dye-penetrant inspection on the affected parts every 3,500 hours TIS or every 7 years, whichever occurs first.

The commenter requests the repetitive inspection intervals be changed to every 3,500 hours TIS or every 7 years, whichever occurs first, to coincide with the AMM.

What is FAA's response to the concern? We agree that the repetitive 100-hour TIS inspections could cause additional damage to the affected parts. The FAA's intent was to mandate the repetitive inspections of the AMM. The NPRM inadvertently carried 100 hours TIS as the repetitive interval. The correct interval for the repetitive inspection is 3,500 hours TIS.

The AMM specifies the inspection every 3,500 hours TIS or every 7 years, whichever occurs first. However, the only way we can ensure that all operators follow this AMM specification is through an AD. Therefore, we will make this change in the proposed AD action to ensure the inspections are done.

Comment Issue No. 3: Clarify the Applicability of the Affected Airplanes

What is the commenter's concern? A commenter states that it is not clear whether the proposed AD applied to Fairchild built Model PC-6 airplanes or to both Pilatus and Fairchild built Model PC-6 airplanes.

Also, it is unclear whether the proposed AD applies only to Model PC-6 airplanes or to all PC-6 series airplanes.

The commenter requests clarification on the applicability of the affected airplanes.

What is FAA's response to the concern? We agree with commenter that the applicability may be unclear.

Fairchild Republic Company and Fairchild Heli Porter manufactured certain Model PC-6 airplanes under the license agreement shown on the United States (U.S.) type certificate data sheet (TCDS) No. 7A15, which is currently held by Pilatus Aircraft Ltd.

This proposed AD applies to all PC-6 series airplanes, including those built by Fairchild Republic Company and Fairchild Heli Porter.

We will change the proposed AD action to clarify the applicability.

What events have caused FAA to issue a supplemental NPRM? In addition to the changes noted above, the manufacturer revised the service information to include a requirement for replacing the fitting without an index after the part number with an improved part and to correct the allowable limits of the actuator attachment hole diameters.

FAA's Determination and Requirements of This Proposed AD

What has FAA decided? After examining the circumstances and reviewing all available information related to the incidents described above, we have determined that:

—The unsafe condition referenced in this document exists or could develop on other Pilatus Model PC-6 airplanes of the same type design that are on the U.S. registry;

—We should change the NPRM to incorporate the concerns addressed by the commenters and incorporate the revised service information; and

—We should take AD action to correct this unsafe condition.

The Supplemental NPRM

How will the changes to the NPRM impact the public? Proposing to require you to replace fittings without an index after the part number with a different part goes beyond the scope of what was originally proposed in the NPRM. Therefore, we are reopening the comment period and allowing the public the chance to comment on these additional actions.

What are the provisions of the supplemental NPRM? The proposed AD would require you to:

—Inspect the stabilizer-trim attachment and structural components (the fitting, the connecting piece, the bearing fork, the bearing support assembly, and the auxiliary frame, as applicable) for cracks and corrosion;

—Inspect the diameters of the boltholes on the fittings, auxiliary frame, and connecting piece (as applicable) for discrepancies;

—Replace any cracked, corroded, or defective part with a new part;

—Replace all Fairchild connecting pieces, P/N 6232.0026.XX with a Pilatus connecting piece. The Fairchild part has a rivet in the middle that is not on the Pilatus part; and

—Replace all fittings, P/N 116.40.06.033 without an index after the P/N with an improved part, P/N 116.40.06.033 with an index after the P/N or P/N 116.40.06.112.

How does the revision to 14 CFR part 39 affect this proposed AD? On July 10, 2002, we published a new version of 14 CFR part 39 (67 FR 47997, July 22, 2002), which governs FAA's AD system. This regulation now includes material that relates to altered products, special flight permits, and alternative methods of compliance. This material previously was included in each individual AD. Since this material is included in 14 CFR part 39, we will not include it in future AD actions.

Costs of Compliance

How many airplanes would this proposed AD impact? We estimate that this proposed AD affects 41 airplanes in the U.S. registry.

What would be the cost impact of this proposed AD on owners/operators of the affected airplanes? We estimate the following costs to do the proposed inspections:

Labor cost	Parts cost	Total cost per airplane	Total cost on U.S. operators
11 work hours × $65 per hour = $715	Not applicable	$715	$715 × 41 = $29,315.

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

Labor cost	Parts cost	Total cost per airplane to replace all parts
10 work hours × $65 = $650	$2,000 to replace all parts	$650 + $2,000 = $2,650.

Authority for This Rulemaking

What authority does FAA have for issuing this rulemaking action? 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 AD.

Regulatory Findings

Would this proposed AD impact various entities? 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.

Would this proposed AD involve a significant rule or regulatory action? For the reasons discussed above, I certify that this proposed AD:

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 summary of the costs to comply with this proposed AD (and other information as included in the Regulatory Evaluation) and placed it in the AD Docket. You may get a copy of this summary by sending a request to us at the address listed under ADDRESSES. Include “AD Docket FAA-2005-20515; Directorate Identifier 2005-CE-09-AD” in your request.

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 Federal Aviation Administration 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 airworthiness directive (AD):

Pilatus Aircraft Ltd.: Docket No. FAA-2005-20515; Directorate Identifier 2005-CE-09-AD.

When is the Last Date I Can Submit Comments on This Proposed AD?

(a) We must receive comments on this proposed airworthiness directive (AD) by July 13, 2005.

What Other ADs Are Affected By This Action?

(b) None.

What Airplanes Are Affected by This AD?

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

Note 1:

These airplanes are also identified as Fairchild Republic Company PC-6 series airplanes and Fairchild Heli Porter PC-6 series airplanes.

Models

(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

What Is the Unsafe Condition Presented in This AD?

(d) This AD is the result of mandatory continuing airworthiness information (MCAI) issued by the airworthiness authority for Switzerland. We are issuing this proposed AD to detect and correct cracks in the stabilizer-trim attachment and surrounding structural components, which could result in failure of the stabilizer-trim attachment. This failure could lead to loss of control of the airplane.

What Must I Do To Address This Problem?

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

Actions	Compliance	Procedures
(1) Inspect the following:
(i) the stabilizer-trim attachment and structural components (fitting, connecting piece, bearing fork, bearing support assembly, and auxiliary frame, as applicable) for cracks and corrosion; and (ii) the diameters of the actuator attachment bolt holes on the fittings, auxiliary frame, and connecting piece (as applicable) for discrepancies	Within the next 100 hours time-in-service (TIS) after the effective date of this AD. Repetitively inspect thereafter at intervals not-to-exceed 3,500 hours TIS or 7 years, whichever occurs first	Follow Pilatus PC-6 Service Bulletin No. 53-001, Rev. No. 1, dated June 1, 2005.
(2) If cracks are found during any inspection required in paragraph (e)(1)(i) of this AD, replace the defective part with a new part	Replace the defective part before further flight after the inspection in which cracks are found. After each replacement, continue with the repetitive inspection requirement in paragraph (e)(1) of this AD	Follow Pilatus PC-6 Service Bulletin No. 53-001, Rev. No. 1, dated June 1, 2005.
(3) If corrosion or discrepancies are found during any inspection required in paragraphs (e)(1)(i) and (e)(1)(ii) of this AD, do the following:
(i) replace the defective part with a new part if the corrosion or discrepancy is beyond the repairable limits stated in the service information; or (ii) repair the defective part if the corrosion or discrepancy is within the repairable limits stated in the service information.	Replace or repair the defective part before further flight after the inspection in which corrosion or discrepancies are found. After each replacement or repair, continue with the repetitive inspection requirement in paragraph (e)(1) of this AD	Follow Pilatus PC-6 Service Bulletin No. 53-001, Rev. No. 1, dated June 1, 2005.
(4) Replace the following:
(i) all Fairchild connecting pieces, part number (P/N) 6232.0026.XX, with a Pilatus connecting piece, P/N 6232.0026.XX. The Fairchild part has a rivet in the middle that is not on the Pilatus part; and (ii) all fittings, P/N 116.40.06.033 without an index after the P/N, with an improved part, P/N 116.40.06.033 with an index of “A” or “B” after the P/N or with P/N 116.40.06.112	Within the next 100 hours TIS after the effective date of this AD. After replacement, repetitively inspect thereafter at intervals not-to-exceed 3,500 hours TIS or 7 years, whichever occurs first. If after the inspection required in paragraph (e)(1) of this AD, you determine that you already have a P/N 116.40.06.033 with an index of “A” or “B” or a P/N 116.40.06.112 installed, repetitively inspect thereafter at intervals not-to-exceed 3,500 hours TIS or 7 years, whichever occurs first after the part was installed	Follow Pilatus PC-6 Service Bulletin No. 53-001, Rev. No. 1, dated June 1, 2005.
(5) Do not install any of the following:
(i) Fairchild connecting piece, P/N 6232.0026.XX (it has a rivet in the middle that is not on the Pilatus part); and (ii) fitting, P/N 116.40.06.033, without an index after the part number	As of the effective date of this AD	Follow Pilatus PC-6 Service Bulletin No. 53-001, Rev. No. 1, dated June 1, 2005.

Note 2:

Even though not required in this AD, the FAA recommends that you send all defective parts to Pilatus at the address specified in paragraph (g) of this AD. With the part, include the aircraft serial number, flying hours, and cycles.

May I Request an Alternative Method of Compliance?

(f) You may request a different method of compliance or a different compliance time for this AD by following the procedures in 14 CFR 39.19. Unless FAA authorizes otherwise, send your request to your principal inspector. The principal inspector may add comments and will send your request to the Manager, Standards Office, Small Airplane Directorate, FAA. For information on any already approved alternative methods of compliance, contact Doug Rudolph, Aerospace Engineer, FAA, Small Airplane Directorate, 901 Locust, Room 301, Kansas City, Missouri 64106; telephone: [phone]; facsimile: [phone].

Is There Other Information That Relates to This Subject?

(g) Swiss AD HB-2005-080, effective date March 2, 2005, also addresses the subject of this AD. The Federal Office for Civil Aviation (FOCA), which is the airworthiness authority for Switzerland, classified Pilatus PC-6 Service Bulletin No. 53-001, Rev. No. 1, dated June 1, 2005, as mandatory. The FAA anticipates that the FOCA will issue a new Swiss AD in order to ensure the continued airworthiness of these airplanes in Switzerland.

May I Get Copies of the Documents Referenced in This AD?

(h) You may get copies of the documents referenced in this AD from 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 FAA-2005-20515.

Issued in Kansas City, Missouri, on June 7, 2005.

Kim Smith,

Acting Manager, Small Airplane Directorate, Aircraft Certification Service.