04-24034. Airworthiness Directives; Saab Model SAAB SF340A and SAAB 340B Series Airplanes

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

The FAA proposes to adopt a new airworthiness directive (AD) for all Saab Model SAAB SF340A and SAAB 340B series airplanes. This proposed AD would require a one-time inspection to determine the part and serial numbers of certain molded assembly engine mounts (isolators) and the cure dates of certain bonded canister assemblies incorporated in those engine mounts; and related corrective actions if necessary. This proposed AD is prompted by a report that disbonding of the elastomer from the inner metal core and shim of certain molded assembly engine mounts has occurred within a few hundred hours of operation, causing heavy chafing of the engine support system and chafing of the fire sensor loop. We are proposing this AD to prevent reduced integrity of the fire-shielding capacity of the nacelle structure and a possible fire detector fault.

DATES:

We must receive comments on this proposed AD by November 26, 2004.

ADDRESSES:

Use one of the following addresses 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.
• By 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 Saab Aircraft AB, SAAB Aircraft Product Support, S-581.88, Linköping, Sweden.

You can examine the contents of this AD docket on the Internet at http://dms.dot.gov,, or at the Docket Management Facility, U.S. Department of Transportation, 400 Seventh Street SW., Room PL-401, on the plaza level of the Nassif Building, Washington, DC.

FOR FURTHER INFORMATION CONTACT:

Technical information: Dan Rodina, Aerospace Engineer, International Branch, ANM-116, FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone [phone]; fax [phone].

Plain language information: Marcia Walters, [e-mail].

SUPPLEMENTARY INFORMATION:

Docket Management System (DMS)

The FAA has implemented new procedures for maintaining AD dockets electronically. As of May 17, 2004, new AD actions are posted on DMS and assigned a docket number. We track each action and assign a corresponding directorate identifier. The DMS AD docket number is in the form “Docket No. FAA-2004-99999.” The Transport Airplane Directorate identifier is in the form “Directorate Identifier 2004-NM-999-AD.” Each DMS AD docket also lists the directorate identifier (“Old Docket Number”) as a cross-reference for searching purposes.

Comments Invited

We invite you to submit any relevant written data, views, or arguments regarding this proposed AD. Send your comments to an address listed under ADDRESSES. Include “Docket No. FAA-2004-19447; Directorate Identifier 2004-NM-97-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 submitted 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 with FAA personnel concerning this proposed AD. Using the search function of our docket Web site, anyone can find and read the comments in 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.). You can review the DOT's complete Privacy Act Statement in the Federal Register published on April 11, 2000 (65 FR 19477-78), or you can visit http://dms.dot.gov.

We are reviewing the writing style we currently use in regulatory documents. We are interested in your comments on whether the style of this document is clear, and your suggestions to improve the clarity of our communications that affect you. You can get more information about plain language at http://www.faa.gov/​language and http://www.plainlanguage.gov.

Examining the Docket

You can examine the AD docket on the Internet at http://dms.dot.gov,, or in person at the Docket Management Facility office between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The Docket Management Facility office (telephone [phone]) is located on the plaza level of the Nassif Building at the DOT street address stated in the ADDRESSES section. Comments will be available in the AD docket shortly after the DMS receives them.

Discussion

The Luftfartsverket (LFV), which is the airworthiness authority for Sweden, notified us that an unsafe condition may exist on all Saab Model SAAB SF340A and SAAB 340B series airplanes. The LFV advises that disbonding of the elastomer from the inner metal core and shim of the bonded canister assemblies incorporated in certain molded assembly engine mounts (isolators) has occurred within a few hundred hours of operation. This disbonding could reduce the redundancy and change the stiffness and damping characteristics of the engine support system, cause heavy chafing of the nacelle structure, and cause chafing of the fire sensor loop. This condition, if not corrected, could result in reduced integrity of the fire-shielding capacity of the nacelle structure and a possible fire detector fault.

Relevant Service Information

Saab has issued Saab Service Bulletin 340-71-059, dated May 16, 2003. The service bulletin describes procedures for a one-time inspection to determine the part and serial numbers of certain molded assembly engine mounts (isolators) and the cure dates of certain bonded canister assemblies incorporated in those engine mounts; an inspection for chafing of the nacelle structure of all airplanes and for chafing of the fire sensor loop of certain airplanes; and related corrective actions if necessary. Corrective actions include replacement of the engine mounts and repair or replacement of chafed nacelle structure and fire sensor loop components. Accomplishing the actions specified in the service information is intended to adequately address the unsafe condition. The LFV mandated the service information and issued Swedish airworthiness directive SAD 1-192, dated May 16, 2003, to ensure the continued airworthiness of these airplanes in Sweden.

Service Bulletin 340-71-059 refers to Barry Controls Service Letter 93948-71-05, dated April 30, 2003, as an additional source of service information for determining the part numbers and serial numbers of certain molded assembly engine mounts, and the cure dates of the bonded canister assemblies incorporated in those engine mounts.

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. Pursuant to this bilateral airworthiness agreement, the LFV has kept the FAA informed of the situation described above. We have examined the LFV's findings, evaluated all pertinent information, and determined that we need to issue an AD for products of this type design that are certificated for operation in the United States.

Therefore, we are proposing this AD, which would require a one-time inspection to determine the part and serial numbers of certain molded assembly engine mounts (isolators) and the cure dates of the bonded canister assemblies incorporated in those engine mounts; a general visual inspection for chafing of certain elements adjacent to those engine mounts; and related corrective actions if necessary. The proposed AD would require you to use Saab Service Bulletin 340-71-059 described previously to perform these actions, except as discussed under “Clarification of Inspection Terminology.”

Clarification of Inspection Terminology

Saab Service Bulletin 340-71-059 specifies an inspection for chafing of certain elements adjacent to certain molded assembly engine mounts. To eliminate any confusion about this inspection, this proposed AD would require a general visual inspection of those elements. Note 2 of this proposed AD includes a definition of this type of inspection.

Costs of Compliance

This proposed AD would affect about 170 airplanes of U.S. registry. The proposed actions would take about 2 work hours per airplane, at an average labor rate of $65 per work hour. Based on these figures, the estimated cost of this proposed AD for U.S. operators is $22,100 or $130 per airplane.

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. 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.

§ 39.13

[Amended]

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

SAAB Aircraft AB: Docket No. FAA-2004-19447; Directorate Identifier 2004-NM-97-AD.

Comments Due Date

(a) The Federal Aviation Administration must receive comments on this AD action by November 26, 2004.

Affected ADs

(b) None.

Applicability

(c) This AD applies to all Model SAAB SF340A and SAAB 340B series airplanes, certificated in any category.

Unsafe Condition

(d) This AD was prompted by a report that disbonding of the elastomer from the inner metal core and shim of certain molded assembly engine mounts (isolators) has occurred within a few hundred hours of operation, causing heavy chafing of the engine support system and chafing of the fire sensor loop. We are issuing this AD to prevent reduced integrity of the fire-shielding capacity of the engine nacelle structure and a possible fire detector fault.

Compliance

(e) You are responsible for having the actions required by this AD performed within the compliance times specified, unless the actions have already been done.

Inspection

(f) Within 500 flight hours after the effective date of this AD, perform a one-time inspection to determine the part and serial numbers of certain molded assembly engine mounts (isolators) and the cure dates of certain bonded canister assemblies incorporated in those engine mounts; and a general visual inspection for chafing of the nacelle structure and fire sensor loop; and related corrective actions, as applicable; in accordance with the Accomplishment Instructions of Saab Service Bulletin 340-71-059, dated May 16, 2003. Corrective actions must be accomplished prior to further flight.

Note 1:

Saab Service Bulletin 340-71-059 refers to Barry Controls Service Letter 93948-71-05, dated April 30, 2003, as an additional source of service information.

Note 2:

For the purposes of this AD, a general visual inspection is “a visual examination of a 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 normal 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.”

Alternative Methods of Compliance (AMOCs)

(g) The Manager, International Branch, ANM-116, Transport Airplane Directorate, FAA, has the authority to approve AMOCs for this AD, if requested in accordance with the procedures found in 14 CFR 39.19.

Related Information

(h) Swedish airworthiness directive SAD 1-192, dated May 16, 2003, also addresses the subject of this AD.

Issued in Renton, Washington, on October 18, 2004.

Kalene C. Yanamura,

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.