Airworthiness Directives; Saab AB, Saab Aerosystems Model SAAB 340A (SAAB/SF340A) and SAAB 340B Airplanes Modified in Accordance With Supplemental Type Certificate (STC) SA00244WI-D, ST00146WI-D, or SA984GL-D

AGENCY:

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

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

The FAA proposes to adopt a new airworthiness directive (AD) for certain Saab AB, Saab Aerosystems Model SAAB 340A (SAAB/SF340A) and SAAB 340B airplanes. This proposed AD would require inspecting the fuselage surface for corrosion and cracking behind the external adapter plate of the antennae installation, and repair if necessary. This proposed AD results from a report of a crack found behind the external adapter plate of the antennae during inspection. Similar cracking was found on two additional airplanes, and extensive corrosion was found on one airplane. We are proposing this AD to detect and correct corrosion and cracking behind the external adapter plate of the antennae of certain safe-life structure, which could result in reduced structural integrity and consequent rapid depressurization of the airplane.

DATES:

We must receive comments on this proposed AD by March 5, 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:

William Griffith, Aerospace Engineer, Airframe Branch, ACE-118W, FAA, Wichita Aircraft Certification Office, 1801 Airport Road, Room 100, Mid-Continent Airport, Wichita, Kansas 67209; telephone (316) 946-4116; fax (316) 946-4107.

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-2010-0042; Directorate Identifier 2009-NM-010-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 received a report of a crack found behind the external adapter plate of the antennae during inspection of a Model SAAB 340A airplane, serial number 142. Similar cracking was found on two additional airplanes, and extensive corrosion was found on one airplane. These airplanes had Supplemental Type Certificate (STC) work done by a common installer. Investigation revealed that insufficient corrosion protection was applied during installation. No known data show that other airplanes with work done elsewhere in accordance with STC SA00244WI-D, ST00146WI-D, or SA984GL-D have had common corrosion issues. The STC data provided show sufficient corrosion protection is specified in STCs SA00244WI-D, ST00146WI-D, and SA984GL-D for other airplanes, and the unsafe condition is limited to airplanes on which the identified STC work was done. Corrosion and cracking behind the external adapter plate of the antennae of certain safe-life structure if not detected and corrected, could result in reduced structural integrity and consequent rapid depressurization of the airplane.

The subject area on certain Model SAAB 340B airplanes is almost identical to that on the affected Model SAAB 340A airplanes. Therefore, those Model SAAB 340B airplanes may be subject to the unsafe condition revealed on the Model SAAB 340A airplanes.

FAA's Determination and Requirements of the Proposed AD

These airplane models are manufactured in Sweden and 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.

We are proposing this AD, which would require inspecting the fuselage surface for corrosion or cracking behind the external adapter plate of the Supplemental Type Certificate antennae installation. This proposed AD also would require repair of any corrosion or cracking found. All actions, including any repairs, are required to be done in accordance with a method approved by the Manager, Wichita Aircraft Certification Office (ACO), FAA. For airplanes on which no corrosion or cracking is found, the proposed AD would require ensuring that proper corrosion protection has been applied before reinstalling the adapter plate, in accordance with a method approved by the Manager, Wichita ACO.

This proposed AD does not provide credit for actions that may have already been done to address the identified unsafe condition since no FAA-approved method for accomplishing the required actions exists. However, if any operator already has removed the adapter plate and done a repair, that operator may request approval of an alternative method of compliance (AMOC) under the provisions of paragraph (j) of this proposed AD.

Costs of Compliance

This proposed AD would affect about 201 airplanes of U.S. registry. The proposed inspection would take about 4 work hours per airplane, at an average labor rate of $80 per work hour. Based on these figures, the estimated cost of the proposed AD for U.S. operators is $64,320, or $320 per airplane.

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. See the ADDRESSES section for a location to examine the regulatory evaluation.

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.