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Proposed Rule

Airworthiness Directives; Saab AB, Saab Aerosystems Model SAAB 340A (SAAB/SF340A) and SAAB 340B Airplanes Modified in Accordance With Supplemental Type Certificate (STC) SA00224WI-D, ST00146WI-D, or SA984GL-D

Document Details

Information about this document as published in the Federal Register.

Published Document

This document has been published in the Federal Register. Use the PDF linked in the document sidebar for the official electronic format.

Start Preamble

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

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

SUMMARY:

We are revising an earlier proposed airworthiness directive (AD) for certain Saab AB, Saab Aerosystems Model SAAB 340A (SAAB/SF340A) and SAAB 340B airplanes. The original NPRM would have required inspecting the fuselage surface for corrosion and cracking behind the external adapter plate of the antennae installation, and repair if necessary. The original NPRM resulted 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. This action revises the original NPRM by correcting an STC number, which would expand the applicability of the original NPRM. We are proposing this supplemental NPRM to detect and correct corrosion and cracking behind the external adapter plate of the antennae of certain damage-tolerant structure, which could result in reduced structural integrity and consequent rapid depressurization of the airplane.

DATES:

We must receive comments on this supplemental NPRM by September 17, 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.

Start Further Info

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.

End Further Info End Preamble Start Supplemental Information

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 issued a notice of proposed rulemaking (NPRM) (the “original NPRM”) to amend 14 CFR part 39 to include an airworthiness directive (AD) that would apply to certain Saab AB, Saab Aerosystems Model SAAB 340A (SAAB/SF340A) and SAAB 340B airplanes. That original NPRM was published in the Federal Register on January 19, 2010 (75 FR 2829). That original NPRM proposed to require inspecting the fuselage surface for corrosion and cracking behind the external adapter plate of the antennae installation, and repair if necessary.

Actions Since Original NPRM Was Issued

Since we issued the original NPRM, we have determined that STC number SA00244WI-D, identified in the applicability of the NPRM, is an incorrect STC number; the correct number is SA00224WI-D. We have corrected this error, which expands the airplanes affected by the original NPRM.

Comments

We gave the public the opportunity to participate in developing this AD. We considered the comments received.

Request To Change the Description of the Unsafe Condition

Saab AB/Aerosystems asks that we change the description of the unsafe condition specified in the NPRM. Saab states that the NPRM indicates that the fuselage skin is classified as “certain safe-life structure.” Saab notes that this does not meet the definition of the airframe/fuselage structure; the fuselage skin is damage tolerant structure according to Section 25.571 of the Federal Aviation Regulations (14 CFR 25.571). Saab adds that this definition is included in the fatigue critical baseline structure (FCBS) list.

We agree with the commenter for the reasons provided. We have changed the description of the unsafe condition in the Summary section and paragraph (e) of this AD accordingly.Start Printed Page 51697

Request To Define Method To Repair Discrepancies

Saab asks that we define the method necessary to repair the discrepancies specified in the NPRM. Saab states that the NPRM does not give any details on how to repair those discrepancies. Saab adds that the method in the NPRM specifies that only approval by the Manager, Wichita Aircraft Certification Office (ACO), will be accepted.

We disagree with the commenter. The discrepancies referred to in this AD are corrosion, and cracking of the fuselage surface as a result of that corrosion. Each airplane may exhibit different extremes of both types of corrosion and cracking, and each repair must be evaluated by the ACO based on the extent of the damage. We have not changed the AD in this regard.

Request to Re-Evaluate the STC Procedures

Saab states that it has reservations about the STC procedures for installation of the TCAS antennae because of the possibility of compromised long-term effects on the airplane. Saab notes that the installation procedures include anchor nuts installed directly in the skin without anchor nut places, acceptance of improper edge distances, compromised surface protection, and no structural reinforcement of the antennae.

We infer that Saab is requesting re-evaluation of the STC procedures; we do not agree. The STC was approved by us in 1991, and there is not enough data at this time to warrant re-evaluation of the STC procedures. Corrosion issues are more than likely the result of the initial installer applying inadequate corrosion protection as indicated by the initial fleet data. Without additional fleet data to confirm otherwise, we cannot concur with any design inadequacies. Therefore, we have not changed the AD in this regard.

Request To Include Replacement Procedure for the Adapter Plate

Saab asks that a replacement procedure for corroded adapter plates be included in Chapter 51-70-60 of the Saab Structural Repair Manual (SRM). Saab states that typical installation of the antennae and associated actions is outlined in the SRM, and the antennae plates are subject to corrosion. Saab adds that a replacement procedure for the adapter plate should be included in the SRM to allow operators to install replacement plates according to design procedures.

We acknowledge and agree with the commenter's concern that the STC holder should have provided appropriate procedures for replacement of corroded adapter plates. Once STC procedures are developed, approved, and available, we might consider additional rulemaking. However, we consider that any further delay in issuing this supplemental NPRM would result in an unacceptable level of risk because doing so would allow the unsafe condition to continue for an indefinite length of time. Therefore, we have not changed the AD in this regard.

FAA's Determination and Proposed Requirements of the Supplemental NPRM

We are proposing this supplemental NPRM because we evaluated all pertinent information and determined an unsafe condition exists and is likely to exist or develop on other products of these same type designs. Certain changes described above expand the scope of the original NPRM. As a result, we have determined that it is necessary to reopen the comment period to provide additional opportunity for the public to comment on this supplemental NPRM.

Explanation of Change to Costs of Compliance

Since issuance of the original NPRM, we have increased the labor rate used in the Costs of Compliance from $80 per work-hour to $85 per work-hour. The Costs of Compliance information, below, reflects this increase in the specified hourly labor rate.

Costs of Compliance

We estimate that this proposed AD would affect 201 airplanes of U.S. registry. The proposed inspection would take about 4 work hours per airplane, at an average labor rate of $85 per work hour. Based on these figures, the estimated cost of the proposed AD for U.S. operators is $68,340, or $340 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 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.

You can find our regulatory evaluation and the estimated costs of compliance in the AD Docket.

Start List of Subjects

List of Subjects in 14 CFR Part 39

End List of Subjects

The Proposed Amendment

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

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PART 39—AIRWORTHINESS DIRECTIVES

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

Start Authority

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

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[Amended]

2. The FAA amends § 39.13 by adding the following new AD:

Saab AB, Saab Aerosystems: Docket No. FAA-2010-0042; Directorate Identifier 2009-NM-010-AD.

Comments Due Date

(a) We must receive comments by September 17, 2010.

Affected ADs

(b) None.

Applicability

(c) This AD applies to the Saab AB, Saab Aerosystems airplanes, certificated in any category, identified in paragraphs (c)(1) and (c)(2) of this AD, that have been modified in Start Printed Page 51698accordance with Supplemental Type Certificate (STC) SA00224WI-D, ST00146WI-D, or SA984GL-D.

(1) Model SAAB 340A (SAAB/SF340A) airplanes, serial numbers 004 through 159 inclusive.

(2) Model SAAB 340B airplanes, serial numbers 160 through 459 inclusive.

Subject

(d) Air Transport Association (ATA) of America Code 53: Fuselage.

Unsafe Condition

(e) This 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. The Federal Aviation Administration is issuing this AD to detect and correct corrosion and cracking behind the external adapter plate of the antennae of certain damage-tolerant structure, which could result in reduced structural integrity and consequent rapid depressurization of the airplane.

Compliance

(f) You are responsible for having the actions required by this AD performed within the compliance times specified.

Inspection/Corrective Actions

(g) Within 600 flight cycles after the effective date of this AD: Remove the external adapter plate of the antennae installation and do a general visual inspection of the fuselage surface for corrosion and cracking behind the external adapter plate of the antennae installation. If any corrosion or cracking is found, repair before further flight. If no corrosion or cracking is found, before further flight, ensure that proper corrosion protection has been applied before reinstalling the adapter plate. Do all the actions required by this paragraph in accordance with a method approved by the Manager, Wichita Aircraft Certification Office (ACO), FAA.

Note 1:

For the purposes of this AD, a general visual inspection is: “A visual examination of an interior or exterior area, installation, or assembly to detect obvious damage, failure, or irregularity. This level of inspection is made from within touching distance unless otherwise specified. A mirror may be necessary to ensure visual access to all surfaces in the inspection area. This level of inspection is made under normally available lighting conditions such as daylight, hangar lighting, flashlight, or droplight and may require removal or opening of access panels or doors. Stands, ladders, or platforms may be required to gain proximity to the area being checked.”

Reporting Requirement

(h) At the applicable time specified in paragraph (h)(1) or (h)(2) of this AD: Submit a report of the positive findings of the inspections required by paragraph (g) of this AD. Send the report to the Manager, Wichita ACO. The report must contain, at a minimum, the inspection results, a description of any discrepancies found, the airplane serial number, and the number of flight cycles and flight hours on the airplane since installation of the STC. 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 contained in this AD and has assigned OMB Control Number 2120-0056.

(1) If the inspection was done on or after the effective date of this AD: Submit the report within 30 days after the inspection.

(2) If the inspection was done before the effective date of this AD: Submit the report within 30 days after the effective date of this AD.

Special Flight Permit

(i) Special flight permits, as described in Section 21.197 and Section 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199), may be issued to operate the airplane to a location where the requirements of this AD can be accomplished, but concurrence by the Manager, Wichita ACO, FAA, is required prior to issuance of the special flight permit.

Alternative Methods of Compliance (AMOCs)

(j)(1) The Manager, Wichita ACO, 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: William Griffith, Aerospace Engineer, Airframe Branch, ACE-118W, FAA, Wichita ACO, 1801 Airport Road, Room 100, Mid-Continent Airport, Wichita, Kansas 67209; telephone (316) 946-4116; fax (316) 946-4107.

(2) To request a different method of compliance or a different compliance time for this AD, follow the procedures in 14 CFR 39.19. Before using any approved AMOC on any airplane to which the AMOC applies, notify your principal maintenance inspector (PMI) or principal avionics inspector (PAI), as appropriate, or lacking a principal inspector, your local Flight Standards District Office. The AMOC approval letter must specifically reference this AD.

Start Signature

Issued in Renton, Washington on August 16, 2010.

Ali Bahrami,

Manager, Transport Airplane Directorate, Aircraft Certification Service.

End Signature End Part End Supplemental Information

[FR Doc. 2010-20852 Filed 8-20-10; 8:45 am]

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