Airworthiness Directives; Saab Model SAAB-Fairchild SF340A (SAAB/SF340A) and SAAB 340B Airplanes

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Supplemental notice of proposed rulemaking; reopening of comment period.

SUMMARY:

This document revises an earlier proposed airworthiness directive (AD), applicable to certain Saab Model SAAB-Fairchild SF340A (SAAB/SF340A) and SAAB 340B airplanes, that would have required modification of the hot detection system of the tail pipe harness of the engine nacelles. This new action revises the original NPRM by reducing the compliance time for the modification and adding repetitive inspections. The actions specified by this new proposed AD are intended to prevent false warning indications to the flightcrew from the hot detection system due to discrepancies of the harness, which could result in unnecessary aborted takeoffs on the ground or an in-flight engine shutdown. This action is intended to address the identified unsafe condition.

DATES:

Comments must be received by July 21, 2006.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2003-NM-114-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 (425) 227-1232. Comments may also be sent via the Internet using the following address: 9-anm-nprmcomment@faa.gov. Comments sent via fax or the Internet must contain “Docket No. 2003-NM-114-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, Linkping, Sweden. This information may be examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington.

FOR FURTHER INFORMATION CONTACT:

Mike Borfitz, Aerospace Engineer, International Branch, ANM-116, Transport Airplane Directorate, FAA, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 227-2677; fax (425) 227-1149.

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 2003-NM-114-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. 2003-NM-114-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

Discussion

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to add an airworthiness directive (AD), applicable to certain Saab Model SAAB SF340A and SAAB 340B series airplanes, was published as a notice of proposed rulemaking (NPRM) in the Federal Register on April 1, 2004 (69 FR 17101). That NPRM would have required modification of the hot detection system of the tail pipe harness of the engine nacelles. That NPRM was prompted by reports of false warning indications to the flightcrew from the hot detection system of the tail pipe harness of the engine nacelles. That condition, if not corrected, could result in unnecessary aborted takeoffs on the ground or an in-flight engine shutdown.

Actions Since Issuance of Original NPRM

Since the issuance of the original NPRM, we have been receiving reports from operators indicating new incidents of false warning indications to the flightcrew from the hot detection system of the tail pipe harness of the engine nacelles. We have determined that, the unsafe condition is severe enough to justify adding repetitive general visual inspections after accomplishing the modification, in order to maintain an appropriate level of safety. The one-time inspection specified in the original NPRM was determined to be appropriate in consideration of the safety implications at that time. However, in light of the additional reports, we have added repetitive inspections at intervals not to exceed 12 months to paragraph (a) of this supplemental NPRM.

This supplemental NPRM also requires that operators report the results of all hot tail pipe events to the Swedish Civil Aviation Authority (Luftfartsstyrelsen). Because the cause of the events is not known, these required reports will help determine the extent of the problem in the affected fleet. Based on the results of these reports, we may determine that further corrective action is warranted.

New Relevant Service Information

We have received Saab Service Bulletin 340-26-030, Revision 01, dated November 14, 2003. (The original NPRM refers to Service Bulletin 340-26-030, dated October 28, 2002, as the appropriate source of service information for accomplishing the proposed actions.) Revision 01 of the service bulletin adds no significant changes to the original issue and has been added to the supplemental NPRM as the appropriate source of service information for accomplishing the actions.

Comments

Due consideration has been given to the comments received in response to the original NPRM.

Request To Add Certain Repetitive Inspection Requirements

Mesaba Airlines states that initially it had problems with false warning indications from the hot detection system, and after several attempts, came up with a process to seal the tail pipe hot detectors with thixotropic sealant. The commenter notes that the work instructions it developed were added to Saab Service Bulletin 340-26-029, and adds that it has had success with this new process and has had a low number of false warning indications. The commenter states that the inspection and application of sealant specified in its Maintenance Review Board (MRB) Item 26-12-01 (Bench Check of Exhaust Duct Overtemp Spot Detectors) are done every 6,000 flight hours; the replacement of the spot detectors is done at the same time. (The inspection is referenced as Task #0600-454-01E and Task #0600-464-01E, and the application of sealant is referenced as Chapter 26-12-05, in the SAAB 340 Airplane Maintenance Manual.) The commenter asks that this visual inspection of the harness and associated terminal ends, and application of thixotropic sealant to the detector/terminal end areas every 6,000 flight hours be added to the original NPRM. The commenter adds that these actions would be done in conjunction with the replacement of the spot detectors.

We partially agree with the commenter. We agree that additional general visual inspections, as identified by the commenter, are necessary. We do not agree that those inspections can be done at intervals of 6,000 flight hours, as specified in the referenced maintenance manual. In light of the additional incidents that have occurred, a repetitive interval of 6,000 flight hours would not address the unsafe condition in a timely manner. We have revised paragraph (a) of this supplemental NPRM to specify accomplishing a general visual inspection for discrepancies of the heat shrink sleeve, thixotropic sealant, and connectors for damage and/or corrosion, and doing all applicable repairs. We find that repetitive inspections and maintenance done every 12 months will result in a decrease in incidents of false warning indications to the flightcrew from the hot detection system. Additionally, we do not agree to add replacement of the spot detectors in conjunction with the actions because such replacement is an on-condition action.

Request To Add Parts Cost

Saab Aircraft states that in the “Cost Impact” section of the original NPRM we have specified that required parts would be free of charge. The commenter notes that Paragraph 1.G. (Material—Cost and Availability) of the referenced service bulletin specifies, “Price and availability for Modification Kit No. SAAB 340-26—3-01/02 will be furnished on request.” The commenter provided the parts cost for the kits and asked that the cost be added to the original NPRM. We agree, and we have changed the cost impact section of this supplemental NPRM to reflect the parts cost.

Explanation of Change to Applicability

We have revised the applicability of the original NPRM to identify model designations as published in the most recent type certificate data sheet for the affected models.

Explanation of Change to Costs of Compliance

After the original NPRM was issued, we 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 $65 per work hour to $80 per work hour. The cost impact information, below, reflects this increase in the specified hourly labor rate.

Conclusion

Since certain changes expand the scope of the original NPRM, we have determined that it is necessary to reopen the comment period to provide additional opportunity for public comment.

Cost Impact

We estimate that 280 airplanes of U.S. registry would be affected by this supplemental NPRM.

It would take about 10 work hours per airplane to accomplish the proposed modification, at an average labor rate of $80 per work hour. Required parts cost would be between $218 and $2,253. Based on these figures, the cost impact of the proposed modification on U.S. operators is estimated to be between $1,018 and $3,053 per airplane.

It would take about 1 work hour per airplane to accomplish the proposed inspection and application of sealant, at an average labor rate of $80 per work hour. Based on these figures, the cost impact of this proposed action on U.S. operators is estimated to be $22,400, or $80 per airplane, per inspection cycle.

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.

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 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.