2011-15543. Airworthiness Directives; Piper Aircraft, Inc. Models PA-24, PA-24-250, and PA-24-260 Airplanes

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

We propose to adopt a new airworthiness directive (AD) for the products listed above. This proposed AD would require either replacement of the stabilator horn assembly or repetitive inspection of the stabilator horn assembly for corrosion or cracks with replacement of the stabilator horn assembly if any corrosion or cracks are found. This proposed AD was prompted by reports of cracks developing in the stabilator horn assembly. We are proposing this AD to detect and correct corrosion or cracks in the stabilator horn assembly. Corrosion or cracks could lead to failure of the stabilator horn. Consequently, failure of the stabilator horn could lead to a loss of pitch control in flight.

DATES:

We must receive comments on this proposed AD by August 8, 2011.

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: [phone].
• 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 Piper Aircraft, Inc., 2926 Piper Drive, Vero Beach, Florida 32960; telephone: [phone]; fax: [phone]; Internet: http://www.newpiper.com/​company/​publications.asp. You may review copies of the referenced service information at the FAA, Small Airplane Directorate, 901 Locust St., Kansas City, Missouri 64106. For information on the availability of this material at the FAA, call [phone].

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: [phone]) is in the ADDRESSES section. Comments will be available in the AD docket shortly after receipt.

FOR FURTHER INFORMATION CONTACT:

Gregory K. Noles, Aerospace Engineer, FAA, Atlanta Aircraft Certification Office, 1701 Columbia Avenue, College Park, Georgia 30337; phone: [phone]; fax: [phone]; e-mail: [e-mail].

SUPPLEMENTARY INFORMATION:

Comments Invited

We invite you to send any written relevant data, views, or arguments about this proposal. Send your comments to an address listed under the ADDRESSES section. Include “Docket No. FAA-2011-0639; Directorate Identifier 2011-CE-016-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

We issued Special Airworthiness Information Bulletin (SAIB) CE-04-88, dated September 15, 2004. This SAIB alerted owners and operators of Piper Aircraft, Inc. (Piper) Models PA-23, PA-24, PA-30, and PA-39 airplanes of potential corrosion of the stabilator torque tube, attach fittings, and attaching fasteners and recommended inspections of these parts. Based on the information available at issuance of this SAIB, the FAA had determined that an unsafe condition did not exist under 14 CFR part 39.

After reviewing service data for corrosion on the stabilator torque tubes, Piper issued Piper Service Bulletin No. 1160, dated December 26, 2005. This service information is for stabilator torque tube assembly inspection. We then received reports of cracks found in the stabilator horn, part number (P/N) 20397-00, during maintenance inspections per SAIB CE-04-88 or Service Bulletin 1160.

With FAA assistance, the National Institute for Aviation Research (NIAR) investigated and concluded the root cause of the stabilator horn cracking was stress corrosion.

We found two service difficulty reports for this safety issue. In parallel, the International Comanche Society (ICS) surveyed operators and provided additional service data. The ICS survey included approximately 80 targeted inspections and found 18 incidences of stabilator horn cracking, with all incidences occurring on Models PA-24 and PA-24-250 airplanes. The same configuration of horn and torque assembly exists on Model PA-24-260 airplanes.

This condition, if not corrected, could result in failure of the stabilator horn. Consequently, failure of the stabilator horn could lead to a loss of pitch control in flight.

Relevant Service Information

We reviewed Piper Aircraft, Inc. Service Bulletin No. 1189, dated April 29, 2010. The service information describes procedures for stabilator horn assembly inspection.

FAA's Determination

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

Proposed AD Requirements

This proposed AD would require either replacement of the stabilator horn assembly or repetitive inspection of the stabilator horn assembly for corrosion or cracks with replacement of the stabilator horn assembly if any corrosion or cracks are found.

Differences Between the Proposed AD and the Service Information

The service information requires an initial inspection of the stabilator horn assembly upon reaching the initial 1,000 hours time-in-service (TIS), with a repetitive inspection every 100 hours TIS thereafter. After installation of a new stabilator horn assembly, the inspection cycle starts over with an initial inspection at 1,000 hours TIS since the new stabilator horn assembly was installed with the 100-hour TIS repetitive inspections thereafter.

This proposed AD requires either one of the following options: (1) An initial inspection of the stabilator horn assembly upon reaching 1,000 hours TIS or within 100 hours TIS after the effective date of the AD, whichever occurs later, with repetitive inspections every 500 hours TIS or 3 years, whichever occurs first; or (2) replacement of the stabilator horn assembly upon reaching 1,000 hours TIS or within the next 100 hours TIS after the effective date of this AD, whichever occurs later. After replacement of the stabilator horn assembly, within 1,000 hours TIS or 10 years, whichever occurs first, the stabilator horn assembly must be replaced or be initially inspected and start the inspection cycle in option 1.

The service information applies to Piper Models PA-24, PA-24-250, PA-24-260, PA-24-400, PA-30, and PA-39 airplanes. We only have service history on Models PA-24 and PA-24-250 airplanes.

While there is no service history of this unsafe condition on Model PA-24-260 airplanes, we are including it in the AD because it is an identical configuration to Models PA-24 and PA-24-250 airplanes for the horn and torque tube.

There is no service history of this unsafe condition on the Models PA-24-400, PA-30, and PA-39 airplanes, including inspections from the ICS operator survey. Also, these models have a thicker torque tube, which reduces clamp-up forces; clamp-up forces are a key factor of the stress corrosion cracking. Therefore, we are not including the Models PA-24-400, PA-30, and PA-39 airplanes in the applicability of this AD.

Costs of Compliance

We estimate that this proposed AD affects 3,100 airplanes of U.S registry.

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

Estimated costs

Action	Labor cost	Parts cost	Cost per product	Cost on U.S. operators
Stabilator horn assembly inspection	12 work-hours × $85 per hour = $1,020	Not applicable	$1,020	$3,162,000

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 might need this replacement:

On-Condition Costs

Action	Labor cost	Parts cost	Cost per product
Stabilator horn assembly replacement	12 work-hours × $85 per hour = $1,020	$572	$1,592

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

Authority for This Rulemaking

Title 49 of the United States Code specifies the FAA's authority to issue rules on aviation safety. Subtitle I, section 106, describes the authority of the FAA Administrator. Subtitle VII: Aviation Programs, describes in more detail the scope of the Agency's authority.

We are issuing this rulemaking under the authority described in Subtitle VII, Part A, Subpart III, Section 44701: “General requirements.” Under that section, Congress charges the FAA with promoting safe flight of civil aircraft in air commerce by prescribing regulations for practices, methods, and procedures the Administrator finds necessary for safety in air commerce. This regulation is within the scope of that authority because it addresses an unsafe condition that is likely to exist or develop on products identified in this rulemaking action.

Regulatory Findings

We determined that this proposed AD would not have federalism implications under Executive Order 13132. This proposed AD would not have a substantial direct effect on the States, on the relationship between the national Government and the States, or on the distribution of power and responsibilities among the various levels of government.

For the reasons discussed above, I certify this proposed regulation:

(1) Is not a “significant regulatory action” under Executive Order 12866,

(2) Is not a “significant rule” under the DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979),

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

(4) Will not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act.

List of Subjects in 14 CFR Part 39

• Air transportation
• Aircraft
• Aviation safety
• Incorporation by reference
• Safety

The Proposed Amendment

Accordingly, under the authority delegated to me by the Administrator, the FAA proposes to amend 14 CFR part 39 as follows:

PART 39—AIRWORTHINESS DIRECTIVES

1. The authority citation for part 39 continues to read as follows:

Authority: 49 U.S.C. 106(g), 40113, 44701.

§ 39.13

[Amended]

2. The FAA amends § 39.13 by adding the following new airworthiness directive (AD):

Piper Aircraft, Inc.: Docket No. FAA-2011-0639, Directorate Identifier 2011-CE-016-AD.

Comments Due Date

(a) We must receive comments by August 8, 2011.

Affected ADs

(b) None.

Applicability

(c) This AD applies to the following Piper Aircraft, Inc. airplanes, certificated in any category:

(1) Model PA-24, serial numbers (SNs) 24-1 through 24-3687;

(2) Model PA-24-250, SNs 24-1, 24-103 through 24-3687; and

(3) Model PA-24-260, SNs 24-3642 and 24-4000 through 24-5034.

Subject

(d) Joint Aircraft System Component (JASC)/Air Transport Association (ATA) of America Code 27: Flight Controls.

Unsafe Condition

(e) This AD was prompted by reports of cracks developing in the stabilator horn assembly. We are issuing this AD to detect and correct corrosion or cracks in the stabilator horn assembly. Corrosion or cracks could lead to failure of the stabilator horn. Consequently, failure of the stabilator horn could lead to a loss of pitch control in flight.

Compliance

(f) Comply with this AD following Piper Aircraft, Inc. Service Bulletin No. 1189, dated April 29, 2010, within the compliance times specified in this AD, unless already done (does not eliminate the repetitive actions of this AD).

Inspection/Replacement

(g) When the stabilator horn assembly reaches a total of 1,000 hours time-in-service (TIS) or within the next 100 hours TIS after the effective date of this AD, whichever occurs later, do either of the following actions:

(1) Initially inspect the stabilator horn assembly for corrosion or cracks. Repetitively thereafter inspect at intervals not to exceed 500 hours TIS or 3 years, whichever occurs first; or

(2) Replace the stabilator horn assembly with a new stabilator horn assembly. Repetitively thereafter replace the stabilator horn assembly with a new stabilator horn assembly within the next 1,000 hours TIS after the last replacement or within the next 10 years after the last replacement, whichever occurs first.

(h) If any corrosion or cracks are found during any of the inspections required in paragraph (g)(1) of this AD, before further flight, you must replace the stabilator horn assembly with a new stabilator horn assembly. After the new stabilator horn assembly reaches a total of 1,000 hours TIS or within the next 10 years after the last replacement, whichever occurs first, you must do either of the actions required in paragraphs (g)(1) or (g)(2) of this AD.

(i) You may at any time replace the stabilator horn assembly with a new stabilator horn assembly, provided no corrosion or cracks were found during an inspection that would require replacement before further flight. After the new stabilator horn assembly reaches a total of 1,000 hours TIS or within the next 10 years after the last replacement, whichever occurs first, you must do either of the actions required in paragraphs (g)(1) or (g)(2) of this AD.

(j) If you replace the stabilator horn assembly as specified in paragraph (g)(2) of this AD, after the new stabilator horn assembly reaches a total of 1,000 hours TIS or within the next 10 years after the last replacement, whichever occurs first, you may begin the inspection requirements of paragraph (g)(1) instead of the repetitive replacement requirements of paragraph (g)(2).

Note:

Piper Aircraft, Inc. Service Bulletin No. 1160, dated December 26, 2005; Special Airworthiness Information Bulletin CE-04-88, dated September 15, 2004; and AD 74-13-03, Amendment 39-2588 (41 FR 17371, April 26, 1976) are related to this AD action. For the attached torque tube, you may consider combining that inspection with the requirements of this AD.

Special Flight Permit

(k) Special flight permits are permitted with the following limitation: flight with known cracks is prohibited.

Alternative Methods of Compliance (AMOCs)

(l)(1) The Manager, Atlanta 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 the Related Information section 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.

Related Information

(m) For more information about this AD, contact Gregory K. Noles, Aerospace Engineer, FAA, Atlanta ACO, 1701 Columbia Avenue, College Park, Georgia 30337; phone: [phone]; fax: [phone]; e-mail: [e-mail].

(n) For service information identified in this AD, contact Piper Aircraft, Inc., 2926 Piper Drive, Vero Beach, Florida 32960; telephone: [phone]; fax: [phone]; Internet: http://www.newpiper.com/​company/​publications.asp. You may review copies of the referenced service information at the FAA, Small Airplane Directorate, 901 Locust St., Kansas City, Missouri 64106. For information on the availability of this material at the FAA, call [phone].

Issued in Kansas City, Missouri on June 16, 2011.

John Colomy,

Acting Manager, Small Airplane Directorate, Aircraft Certification Service.