04-6685. Airworthiness Directives; Saab Model SAAB 2000 Series Airplanes

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

This document proposes the supersedure of an existing airworthiness directive (AD), applicable to certain Saab Model SAAB 2000 series airplanes, that currently requires repetitive inspections for discrepancies of the upper and lower areas of the backup struts in the left and right nacelles; and corrective actions, if necessary. This action would require repetitive inspections for cracks in the lower areas of the backup struts, and corrective action if necessary. This action would also require the eventual replacement of the backup struts with new, improved struts, which would terminate the repetitive inspections. The actions specified by the proposed AD are intended to prevent failure of the backup struts in the left and right nacelles due to fatigue cracking, which could result in loss of fail-safe redundancy in the design of the nacelle in terms of load capability, and consequent separation of the engine from the airplane and subsequent reduced controllability of the airplane. This action is intended to address the identified unsafe condition.

DATES:

Comments must be received by April 26, 2004.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2001-NM-316-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Comments may be inspected at this location between 9 a.m. and 3 p.m., Monday through Friday, except Federal holidays. Comments may be submitted via fax to [phone]. Comments may also be sent via the Internet using the following address: [e-mail]. Comments sent via fax or the Internet must contain “Docket No. 2001-NM-316-AD” in the subject line and need not be submitted in triplicate. Comments sent via the Internet as attached electronic files must be formatted in Microsoft Word 97 or 2000 or ASCII text.

The service information referenced in the proposed rule may be obtained from Saab Aircraft AB, SAAB Aircraft Product Support, S-581.88, Linköping, Sweden. This information may be examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington.

FOR FURTHER INFORMATION CONTACT:

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

SUPPLEMENTARY INFORMATION:

 

Comments Invited

Interested persons are invited to participate in the making of the proposed 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 above. All communications received on or before the closing date for comments, specified above, will be considered before taking action on the proposed rule. The proposals contained in this action may be changed in light of the comments received.

Submit comments using the following format:

• Organize comments issue-by-issue. For example, discuss a request to change the compliance time and a request to change the service bulletin reference as two separate issues.
• For each issue, state what specific change to the proposed AD is being requested.
• Include justification (e.g., reasons or data) for each request.

Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the proposed 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 summarizing each FAA-public contact concerned with the substance of this proposal will be filed in the Rules Docket.

Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this action must submit a self-addressed, stamped postcard on which the following statement is made: “Comments to Docket Number 2001-NM-316-AD.” The postcard will be date stamped and returned to the commenter.

Availability of NPRMs

Any person may obtain a copy of this NPRM by submitting a request to the FAA, Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2001-NM-316-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

Discussion

On June 28, 2000, the FAA issued AD 2000-13-09, amendment 39-11808 (65 FR 41871, July 7, 2000), applicable to certain Saab Model SAAB 2000 series airplanes, to require repetitive detailed visual and dye penetrant inspections of certain areas of the backup struts in the left and right nacelles to detect discrepancies; and corrective actions, if necessary. That action was prompted by issuance of mandatory continuing airworthiness information by a foreign civil airworthiness authority. The requirements of that AD are intended to prevent failure of the backup struts in the left and right nacelles due to fatigue cracking, which could result in loss of fail-safe redundancy in the design of the nacelle in terms of load capability, and consequent separation of the engine from the airplane and subsequent reduced controllability of the airplane.

Actions Since Issuance of Previous Rule

The preamble to AD 2000-13-09 explains that we were considering further rulemaking for the requirements, which constituted “interim action.” We now have determined that further rulemaking is indeed necessary; this proposed AD follows from that determination. The manufacturer has improved the design and manufacturing of the backup struts, which will improve their fatigue strength.

Further, although previous investigation indicated the possibility of cracking in the upper area of the backup strut, no cracks were found in that area. The manufacturer consequently determined that inspection of the upper strut area is unnecessary.

Explanation of Relevant Service Information

The manufacturer has issued Saab Service Bulletins (SBs) 2000-54-024 and 2000-54-025, both dated September 7, 2001. SB 2000-54-025 describes procedures for repetitive fluorescent dye penetrant inspections for cracks of the lower areas of the backup struts of the left and right nacelles around the welding in the pipe and in the attachment fitting. Corrective actions include incorporating SB 2000-54-024, which describes procedures for replacing—with new, improved parts—the backup struts in the electrical and hydraulic bays in the nacelles. SB 2000-54-025 provides operators the option of contacting Saab for repair instructions. Replacement of all four backup struts eliminates the need for the repetitive inspections. The Luftfartsverket (LFV), which is the airworthiness authority for Sweden, classified these SBs as mandatory and issued Swedish airworthiness directive 1-165, dated September 10, 2001, to ensure the continued airworthiness of these airplanes in Sweden.

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 bilateral airworthiness agreement, the LFV has kept the FAA informed of the situation described above. We have 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 Proposed 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, the proposed AD would supersede AD 2000-13-09 to require repetitive fluorescent dye penetrant inspections for cracks of the lower ends of the nacelle backup struts. The proposed AD would also require immediate corrective action if necessary and eventual replacement of the backup struts with new, improved struts, which would terminate the repetitive inspections. The actions would be required to be accomplished in accordance with the SBs described previously, except as discussed below.

Differences Between the Proposed AD and the SBs/Swedish Airworthiness Directive

SB 2000-54-025 and the Swedish airworthiness directive specify a compliance time for the inspection of 1,650 flight hours after the last inspection. We instead provide varying compliance times intended to ensure that all airplanes—regardless of inspection status or number of flight hours since the last inspection—would be inspected in a timely manner.

Although SB 2000-54-025 specifies that operators may contact the manufacturer for disposition of certain repair (cracking) conditions, this proposed AD would not allow this option but would require operators to replace cracked struts in accordance with SB 2000-54-024.

Although SB 2000-54-025 recommends that operators send Saab a report of the inspection results, this proposed AD would not require a report.

Additional Change to Existing AD

We have reviewed the figures we have used over the past several years to calculate AD costs to operators. To account for various inflationary costs in the airline industry, we find it necessary to increase the labor rate used in these calculations from $60 per work hour to $65 per work hour. The cost impact information, below, reflects this increase in the specified hourly labor rate.

Cost Impact

This proposed AD would affect about 3 airplanes of U.S. registry.

The proposed inspection of the lower ends of the backup struts would take about 4 work hours per airplane, at an average labor rate of $65 per work hour. Based on these figures, the cost impact of this proposed action on U.S. operators is estimated to be $780, or $260 per airplane, per inspection cycle.

Replacing all four backup struts would take about 80 work hours per airplane, at an average labor rate of $65 per work hour. Required parts would cost about $165,416 per airplane. Based on these figures, the cost impact of this proposed action on U.S. operators is estimated to be $511,848, or $170,616 per airplane.

The cost impact figures discussed above are based on assumptions that no operator has yet accomplished any of the proposed requirements of this AD action, and that no operator would accomplish those actions in the future if this AD were not adopted. The cost impact figures discussed in AD rulemaking actions represent only the time necessary to perform the specific actions actually required by the AD. These figures typically do not include incidental costs, such as the time required to gain access and close up, planning time, or time necessitated by other administrative actions.

Regulatory Impact

The regulations proposed herein 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. Therefore, it is determined that this proposal would not have federalism implications under Executive Order 13132.

For the reasons discussed above, I certify that 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) if promulgated, 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. A copy of the draft regulatory evaluation prepared for this action is contained in the Rules Docket. A copy of it may be obtained by contacting the Rules Docket at the location provided under the caption ADDRESSES.

List of Subjects in 14 CFR Part 39

• Air transportation
• Aircraft
• Aviation safety
• Safety

The Proposed Amendment

Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration proposes to amend 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 U.S.C. 106(g), 40113, 44701.

§ 39.13

[Amended]

2. Section 39.13 is amended by removing amendment 39-11808 (65 FR 41871, July 7, 2000), and by adding a new airworthiness directive (AD), to read as follows:

SAAB Aircraft AB: Docket 2001-NM-316-AD. Supersedes AD 2000-13-09, Amendment 39-11808.

Applicability: Model SAAB 2000 series airplanes, certificated in any category, serial numbers -004 through -063 inclusive.

Compliance: Required as indicated, unless accomplished previously.

To prevent failure of the backup struts in the left and right nacelles due to fatigue cracking, which could result in loss of fail-safe redundancy in the design of the nacelle in terms of load capability, and consequent separation of the engine from the airplane and subsequent reduced controllability of the airplane, accomplish the following:

Inspection

(a) At the applicable time specified in Table 1 of this AD: Perform a fluorescent dye penetrant inspection for cracks of the lower ends of the backup struts in the left and right nacelles, in accordance with SAAB Service Bulletin 2000-54-025, dated September 7, 2001. Although the service bulletin specifies to submit certain information to the manufacturer, this AD does not require a report.

Table 1.—Fluorescent Dye Penetrant Inspection Compliance Times

If, as of the effective date of this new AD, the inspection required by AD 2000-13-09, amendment 39-11808—	And if the airplane has, as of the effective date of this new AD—	Then do the inspection within—
Has been done	Fewer than 4,500 flight cycles	1,650 flight hours after accomplishment of the most recent inspection done per AD 2000-13-09.
Has been done	4,500 or more flight cycles	900 flight hours after the most recent inspection done per AD 2000-13-09.
Has not been done	Any number of flight cycles	200 flight hours after the effective date of this new AD.

Follow-On/Corrective Actions

(b) If no crack is found during the inspection required by paragraph (a) of this AD: Repeat the inspection at intervals not to exceed 1,650 flight hours, until the actions required by paragraph (d) of this AD have been done.

(c) If any crack is found during any inspection required by paragraph (a) of this AD: Replace the cracked strut with a new, improved strut before further flight in accordance with SAAB Service Bulletin 2000-54-024, dated September 7, 2001. Although the service bulletin provides the option of contacting the manufacturer for repair instructions, this AD requires that any alternative repair be done in accordance with a method approved by either the Manager, International Branch, ANM-116, Transport Airplane Directorate, FAA; or the LFV (or its delegated agent). Replacement of a backup strut terminates the repetitive inspections required by this AD for that strut only.

Strut Replacement

(d) Except as required by paragraph (c) of this AD: Within 36 months after the effective date of this AD, replace all four backup struts in the electrical and hydraulic bays of the nacelles with new, improved struts, in accordance with the Accomplishment Instructions of SAAB Service Bulletin 2000-54-024, dated September 7, 2001. Replacement of all four backup struts terminates the requirements of this AD.

Alternative Methods of Compliance

(e) In accordance with 14 CFR 39.19, the Manager, International Branch, ANM-116, is authorized to approve alternative methods of compliance for this AD.

Note 1:

The subject of this AD is addressed in Swedish airworthiness directive 1-165, dated September 10, 2001.

Issued in Renton, Washington, on March 19, 2004.

Kevin M. Mullin,

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.