AD 96-11-14

This amendment adopts a new airworthiness directive (AD) that is applicable to certain Saab Model SAAB 2000 series airplanes. This action requires inspections to detect cracking of the lower rib of the rudder, and repair, if necessary. This action also provides for an optional terminating action, which, if accomplished, terminates the repetitive inspection requirement. This amendment is prompted by reports of fatigue cracking of the lower rib of the rudder. The actions specified in this AD are intended to prevent such fatigue cracking and subsequent failure of the primary structure of the rudder, which could result in reduced controllability of the airplane.

Final rule; request for comments

96-11-14 SAAB AIRCRAFT AB: Amendment 39-9639. Docket 96-NM-102-AD.
Applicability: Model SAAB 2000 series airplanes; having serial numbers 004 through 039, inclusive; certificated in any category.

NOTE 1: This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been otherwise modified, altered, or repaired in the area subject to the requirements of this AD. For airplanes that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (f) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.

Compliance: Required as indicated, unless accomplished previously.

To prevent fatigue cracking of the lower rib of the rudder and subsequent reduced controllability of the airplane, accomplish the following:

(a) Within 20 days after the effective date of this AD: Perform a visual inspection to detect cracking of the lower rib of the rudder, in accordance with Saab Service Bulletin 2000-55-005, dated February 2, 1996.

(b) If no cracking is detected: Thereafter, repeat the inspection required by paragraph (a) of this AD at intervals not to exceed 400 hours time-in-service, in accordance with Saab Service Bulletin 2000-55-005, dated February 2, 1996.

(c) If any cracking is detected that is 25 mm in length or less: Prior to further flight, perform a temporary repair in accordance with paragraph 2.C. of the Accomplishment Instructions of Saab Service Bulletin 2000-55-005, dated February 2, 1996. Thereafter, repeat the inspections required by paragraph (a) of this AD at intervals not to exceed 7 days.(d) If any cracking is detected that is more than 25 mm in length: Prior to further flight, repair it in accordance with a method approved by the Manager, Standardization Branch, ANM- 113, FAA, Transport Airplane Directorate.

(e) Modification of the lower rib of the rudder (Modification No. 5736), in accordance with Saab Service Bulletin 2000-55-006, dated April 23, 1996, constitutes terminating action for the repetitive inspection requirements of this AD.

(f) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, Standardization Branch, ANM-113. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Standardization Branch, ANM-113.

NOTE 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Standardization Branch, ANM-113.

(g) Special flight permits may be issued in accordance with sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the airplane to a location where the requirements of this AD can be accomplished.

(h) The inspections and temporary repair shall be done in accordance with Saab Service Bulletin 2000-55-005, dated February 2, 1996. This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from SAAB Aircraft AB, SAAB Aircraft Product Support, S-581.88, Link ping, Sweden. Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

(i) This amendment becomes effective on June 17, 1996.

The Luftfartsverket (LFV), which is the airworthiness authority for Sweden, recently notified the FAA that an unsafe condition may exist on certain Saab Model 2000 series airplanes. The LFV advises that it has received reports indicating that cracking of the bottom rib of the elevator has been detected on two Model SAAB 2000 series airplanes. Investigation revealed that, loose pieces of the web were found inside the rudder on one airplane. The cause of the cracking has been attributed to fatigue. Fatigue cracking and subsequent failure of the rudder, if not detected and corrected in a timely manner, could result in reduced controllability of the airplane.

Explanation of Relevant Service Information
Saab has issued Service Bulletin SAAB 2000-55-005, dated February 2, 1996, which describes procedures for repetitive visual inspections to detect cracking of the lower rib of the rudder. The service bulletin also describes procedures for a temporary repair of cracking that is within certain specified limits. The LFV classified this service bulletin as mandatory and issued Swedish airworthiness directive SAD No. 1-088-R1 in order to assure the continued airworthiness of these airplanes in Sweden.

Additionally, Saab has issued Service Bulletin 2000-55-006, dated April 23, 1996, which describes procedures to modify the elevator by reinforcing the lower rib. This modification (Modification No. 5736) will prevent failure of the rudder due to fatigue cracking of the lower rib. Accomplishment of the modification eliminates the need for the repetitive visual inspections. The LFV has approved the technical content of this service bulletin.

FAA's Conclusions
This airplane model is manufactured in Sweden and is 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 bilateralairworthiness agreement, the LFV has kept the FAA informed of the situation described above. The FAA has examined the findings of the LFV, reviewed all available information, and determined that AD action is necessary for products of this type design that are certificated for operation in the United States.

Explanation of Requirements of Rule
Since an unsafe condition has been identified that is likely to exist or develop on other airplanes of the same type design registered in the United States, this AD is being issued to prevent fatigue cracking of the lower rib of the rudder and subsequent failure of the primary structure of the rudder. Such failure could result in reduced controllability of the airplane. This AD requires repetitive visual inspections to detect cracking of the lower rib of the rudder, and repair, if necessary. The inspections and certain repairs are required to be accomplished in accordance with Saab Service Bulletin 2000-55-005, described previously. Repair of any cracking detected that is beyond the limits specified in that service bulletin is required to be accomplished in accordance with a method approved by the FAA.

This AD also provides for optional modification of the rudder, which, if accomplished, constitutes terminating action for the repetitive inspection requirements of this AD. If accomplished, the modification is required to be accomplished in accordance with SAAB Service Bulletin 2000-55-006.

This is considered to be interim action. The FAA is currently considering requiring the installation of the rudder modification that will constitute terminating action for the repetitive inspections required by this AD. However, the planned compliance time for the installation of the modification is sufficiently long so that notice and public comment will be practicable.

Determination of Rule's Effective Date
Since a situation exists that requires the immediate adoption of this regulation, it is found that noticeand opportunity for prior public comment hereon are impracticable, and that good cause exists for making this amendment effective in less than 30 days.

Comments Invited
Although this action is in the form of a final rule that involves requirements affecting flight safety and, thus, was not preceded by notice and an opportunity for public comment, comments are invited on this rule. Interested persons are invited to comment on this rule by submitting such written data, views, or arguments as they may desire. Communications shall identify the Rules Docket number and be submitted in triplicate to the address specified under the caption "ADDRESSES." All communications received on or before the closing date for comments will be considered, and this rule may be amended in light of the comments received. Factual information that supports the commenter's ideas and suggestions is extremely helpful in evaluating the effectiveness of the AD action and determining whether additional rulemaking action would be needed.

Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the rule that might suggest a need to modify the rule. All comments submitted will be available, both before and after the closing date for comments, in the Rules Docket for examination by interested persons. A report that summarizes each FAA-public contact concerned with the substance of this AD will be filed in the Rules Docket.

Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this rule must submit a self-addressed, stamped postcard on which the following statement is made: "Comments to Docket Number 96-NM-102-AD." The postcard will be date stamped and returned to the commenter.

Regulatory Impact
The regulations adopted herein will not have substantial direct effects 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. Therefore, in accordance with Executive Order 12612, it is determined that this final rule does not have sufficient federalism implications to warrant the preparation of a Federalism Assessment.

The FAA has determined that this regulation is an emergency regulation that must be issued immediately to correct an unsafe condition in aircraft, and that it is not a "significant regulatory action" under Executive Order 12866. It has been determined further that this action involves an emergency regulation under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979). If it is determined that this emergency regulation otherwise would be significant under DOT Regulatory Policies and Procedures, a final regulatory evaluation will be prepared and placed in the Rules Docket. A copy of it, if filed, may be obtained from the Rules Docket at the location provided under the caption "ADDRESSES."

List of Subjects in 14CFR Part 39
Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.

Adoption of the Amendment
Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration amends part 39 of the Federal Aviation Regulations (14 CFR part 39) as follows:

PART 39 - AIRWORTHINESS DIRECTIVES
1. The authority citation for part 39 continues to read as follows:
Authority: 49 USC 106(g), 40113, 44701.

39.13 - [Amended]
2. Section 39.13 is amended by adding the following new airworthiness directive: