Airworthiness Directives; Short Brothers Model SD3-60 Series Airplanes

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

This document proposes the adoption of a new airworthiness directive (AD) that is applicable to all Short Brothers Model SD3-60 series airplanes. This proposal would require inspection of the welded joints of the balance weight brackets for the left and right elevator trim tabs for cracking; repetitive inspections, as applicable; and corrective actions including the eventual replacement of all brackets, which would constitute terminating action for the repetitive inspections. This action is necessary to prevent the loss of the balance weight for the elevator trim tab, which could result in incorrect trim during takeoff and landing, and reduced controllability of the airplane. This action is intended to address the identified unsafe condition.

DATES:

Comments must be received by May 24, 2004.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2003-NM-236-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-236-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 Short Brothers, Airworthiness & Engineering Quality, P.O. Box 241, Airport Road, Belfast BT3 9DZ, Northern Ireland. This information may be examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington.

FOR FURTHER INFORMATION CONTACT:

Todd Thompson, Aerospace Engineer, International Branch, ANM-116, FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 227-1175; 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-236-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-236-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

Discussion

The Civil Aviation Authority (CAA), which is the airworthiness authority for the United Kingdom, notified the FAA that an unsafe condition may exist on all Short Brothers Model SD3-60 series airplanes. The CAA advises that, on one affected airplane, the balance weight assembly for an elevator trim tab detached during landing. Subsequent investigation showed that the failure was caused by fatigue cracking emanating from the weld of the balance weight bracket. This condition, if not corrected, could result in the loss of the balance weight for the elevator trim tab, which could cause incorrect trim during takeoff and landing, and reduced controllability of the airplane.

Explanation of Relevant Service Information

Shorts has issued Short Brothers Service Bulletin SD360-55-20, dated June 26, 2003, which describes procedures for performing a dye penetrant inspection for cracking in the welded joints of the balance weight brackets for the left and right elevator trim tabs. Depending on the results of the dye penetrant inspection, the total number of flight hours accumulated on the airplane and/or the brackets, and the length of any crack, the service bulletin describes procedures for further investigative and corrective actions. These investigative and corrective actions include refitting the balance weights, performing repetitive inspections, repairing the bracket (including a further dye penetrant inspection), and/or replacing the bracket with a new or serviceable bracket, as applicable. The service bulletin gives compliance times for eventual replacement of all brackets when they reach their life limits. This service bulletin permits further flight with brackets having a cracked welded joint, within certain limits.

Accomplishment of the actions specified in the service bulletin is intended to adequately address the identified unsafe condition. The CAA classified this service bulletin as mandatory and issued British airworthiness directive 009-06-2003 to ensure the continued airworthiness of these airplanes in the United Kingdom.

FAA's Conclusions

This airplane model is manufactured in the United Kingdom and is type certificated for operation in the United States under the provisions of § 21.29 of the Federal Aviation Regulations (14 CFR 21.29) and the applicable bilateral airworthiness agreement. Pursuant to this bilateral airworthiness agreement, the CAA has kept the FAA informed of the situation described above. The FAA has examined the findings of the CAA, 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 require accomplishment of the actions specified in the service bulletin described previously, except as discussed below.

Differences Between the Proposed AD and the Service Bulletin

Unlike the procedures described in Short Brothers Service Bulletin SD360-55-20, dated June 26, 2003, this proposed AD would not permit further flight if cracks of any length are detected in the welded joints of the balance weight brackets. We have determined that, because of the safety implications and consequences associated with such cracking, any bracket with a cracked welded joint must be repaired or replaced before further flight.

The service bulletin specifies that operators may contact the manufacturer for disposition of certain conditions when refitting balance weights; in those conditions; however, this proposed AD would require operators to obtain further disposition instructions from the FAA or the CAA (or its delegated agent).

Cost Impact

The FAA estimates that 42 airplanes of U.S. registry would be affected by this proposed AD, that it would take approximately 12 work hours per airplane to accomplish the proposed inspections, and that the average labor rate is $65 per work hour. Based on these figures, the cost impact of this proposed action on U.S. operators is estimated to be $32,760, or $780 per airplane, per inspection cycle.

It would take approximately 8 hours per airplane to accomplish the proposed replacement of the brackets. Required parts would cost approximately $632 per airplane. Based on these figures, the cost impact of this proposed action on U.S. operators is estimated to be $48,384, or $1,152 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.