05-2832. Airworthiness Directives; Saab Model SAAB SF340A and SAAB 340B Series Airplanes

AGENCY:

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

ACTION:

Final rule.

SUMMARY:

The FAA is adopting a new airworthiness directive (AD) for all Saab Model SAAB SF340A and SAAB 340B series airplanes. This AD requires a one-time inspection to determine the part and serial numbers of certain engine vibration isolators (mounts) and the cure dates of certain molded assemblies incorporated in those engine mounts; and related corrective actions if necessary. This AD is prompted by a report that disbonding of the elastomer from the inner metal core and shim of certain engine vibration 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 issuing this AD to prevent reduced integrity of the fire-shielding capacity of the nacelle structure and a possible fire detector fault.

DATES:

This AD becomes effective March 23, 2005.

The incorporation by reference of a certain publication listed in the AD is approved by the Director of the Federal Register as of March 23, 2005.

ADDRESSES:

For service information identified in this AD, contact Saab Aircraft AB, SAAB Aircraft Product Support, S-581.88, Linkping, Sweden.

You can examine this information at the National Archives and Records Administration (NARA). For information on the availability of this material at NARA, call [phone], or go to: http://www.archives.gov/​federal_​register/​code_​of_​federal_​regulations/​ibr_​locations.html.

Docket: The AD docket contains the proposed AD, comments, and any final disposition. 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 U.S. Department of Transportation, 400 Seventh Street SW., room PL-401, Washington, DC. This docket number is FAA-2004-19447; the directorate identifier for this docket is 2004-NM-97-AD.

FOR FURTHER INFORMATION CONTACT:

Mike Borfitz, Aerospace Engineer, International Branch, ANM-116, FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone [phone]; fax [phone].

SUPPLEMENTARY INFORMATION:

The FAA proposed to amend 14 CFR Part 39 with an AD for all Saab Model SAAB SF340A and SAAB 340B series airplanes. That action, published in the Federal Register on October 27, 2004 (69 FR 62625), proposed to require a one-time inspection to determine the part and serial numbers of certain engine vibration isolators (mounts) and the cure dates of certain molded assemblies incorporated in those engine mounts; and related corrective actions if necessary.

Comments

We provided the public the opportunity to participate in the development of this AD. We have considered the comment that has been submitted on the proposed AD.

Request To Withdraw Proposed AD

The commenter requests that the proposed AD be withdrawn. The commenter states that delamination of a bonded canister (molded assembly) is readily apparent and would have been detected during the scheduled inspections recommended in the Saab maintenance program. The commenter also mentions that the molded assemblies have a life limit of 5,000 flight hours, at which point those assemblies are removed from the airplane. The commenter notes that by the time the proposed AD is issued, almost three years would have passed since the affected molded assemblies were put into service. The commenter remarks that it is unlikely that any affected molded assembly remaining in the field would not have already been identified and removed from service during the regularly scheduled maintenance inspection program. The commenter states that, for the reasons mentioned above, the FAA needs to consider the timing of the proposed AD. The commenter suggests that, at this late date, the unsafe condition regarding the removal of molded assemblies subject to delamination would have resolved itself.

We do not agree with the commenter's request to withdraw this AD. The procedures specified in a service bulletin are not mandatory. Therefore, we must issue an AD to ensure that the identified unsafe condition is properly addressed. Even if the current U.S.-registered fleet is in compliance with the requirements of this AD, the issuance of the rule is still necessary to ensure that any affected airplane that is imported and placed on the U.S. register in the future will be required to be in compliance as well. We also want to ensure that, if the subject molded assemblies are currently in an operator's spare parts inventory, the actions required by this AD are performed. In addition, as provided by paragraph (e) of this AD, operators who have already done all of the actions required by this AD are already in compliance with this AD, and no further action is required by them. Furthermore, the requirements of this AD include a general visual inspection for chafing of the nacelle structure and fire sensor loop. This inspection is necessary because chafing of the nacelle structure and fire sensor loop is part of the unsafe condition addressed by this AD. We must ensure that operators did this inspection and did not just replace the engine mounts. Also, the airworthiness authority for the state of design issued an airworthiness directive mandating the same actions required by this AD. No change has been made to this AD regarding this issue.

Changes to This AD

We have added a new paragraph (g), Parts Installation, in this AD to clarify that, prior to the installation of an engine vibration mount on an airplane, the part and serial number of the engine vibration mount, and the cure date of the molded assembly incorporated in the engine mount must be determined, and any applicable corrective action accomplished before further flight, in accordance with the requirements of paragraph (f) of this AD. Although this was our intent in the proposed AD, the Parts Installation paragraph was inadvertently omitted from the proposed AD. The subsequent paragraphs in this AD have been reidentified accordingly.

Also, for clarification purposes, certain terminology in the proposed AD has been changed in this AD. The phrase “molded assembly engine mounts (isolators)” has been changed to “engine vibration isolators (mounts).” The term “bonded canister assemblies” has been changed to “molded assemblies.”

Conclusion

We have carefully reviewed the available data, including the comment that has been submitted, and determined that air safety and the public interest require adopting the AD with the changes described previously. We have determined that these changes will neither increase the economic burden on any operator nor increase the scope of the AD.

Costs of Compliance

This AD affects about 170 airplanes of U.S. registry. The required actions will 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 AD for U.S. operators is $22,100 or $130 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 AD will not have federalism implications under Executive Order 13132. This AD will 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 this AD:

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

(2) Is not a “significant rule” under 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 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
• Incorporation by reference
• Safety

Adoption of the Amendment

Accordingly, under the authority delegated to me by the Administrator, the FAA amends 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):

2005-04-04 SAAB Aircraft AB: Amendment 39-13976. Docket No. FAA-2004-19447; Directorate Identifier 2004-NM-97-AD.

Effective Date

(a) This AD becomes effective March 23, 2005.

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 engine vibration isolators (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 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 engine vibration mounts, and the cure dates of certain molded 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 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 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.”

Parts Installation

(g) As of the effective date of this AD, no person may install on any airplane an engine vibration mount unless the part and serial number of the engine vibration mount, and the cure date of the molded assembly incorporated in the engine mount, have been determined and any applicable corrective action accomplished before further flight, in accordance with the requirements of paragraph (f) of this AD.

Alternative Methods of Compliance (AMOCs)

(h) 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

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

Material Incorporated by Reference

(j) You must use Saab Service Bulletin 340-71-059, dated May 16, 2003, including Attachment 1, dated April 30, 2003; to perform the actions that are required by this AD, unless the AD specifies otherwise. The Director of the Federal Register approves the incorporation by reference of this document in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. For copies of the service information, contact Saab Aircraft AB, SAAB Aircraft Product Support, S-581.88, Linkoping, Sweden. For information on the availability of this material at the National Archives and Records Administration (NARA), call [phone], or go to http://www.archives.gov/​federal_​register/​code_​of_​federal_​regulations/​ibr_​locations.html.

You may view the AD docket at the Docket Management Facility, U.S. Department of Transportation, 400 Seventh Street, SW., room PL-401, Nassif Building, Washington, DC.

Issued in Renton, Washington, on January 31, 2005.

Kalene C. Yanamura,

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.