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Proposed Rule

Airworthiness Directives; Short Brothers Model SD3 Airplanes

Document Details

Information about this document as published in the Federal Register.

Published Document

This document has been published in the Federal Register. Use the PDF linked in the document sidebar for the official electronic format.

Start Preamble

AGENCY:

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

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

The FAA proposes to adopt a new airworthiness directive (AD) for all Short Brothers Model SD3 airplanes. This proposed AD would require installing additional fuel tank bonding jumpers, performing an in-place resistance check of the float switches, inspecting certain internal components of the fuel tanks, and performing related corrective actions if necessary. This proposed AD would also require revisions to the airworthiness limitations section of the Instructions for Continued Airworthiness, and to the airplane flight manual procedures for operation during icing conditions and fuel system failures. This proposed AD results from fuel system reviews conducted by the manufacturer. We are proposing this AD to prevent ignition sources inside the fuel tanks, which could lead to fire or explosion.

DATES:

We must receive comments on this proposed AD by January 4, 2006.

ADDRESSES:

Use one of the following addresses to submit comments on this proposed AD.

  • DOT Docket Web site: Go to http://dms.dot.gov and follow the instructions for sending your comments electronically.
  • Government-wide rulemaking Web site: Go to http://www.regulations.gov and follow the instructions for sending your comments electronically.
  • Mail: Docket Management Facility, U.S. Department of Transportation, 400 Seventh Street, SW., Nassif Building, room PL-401, Washington, DC 20590.
  • Fax: (202) 493-2251.
  • Hand Delivery: Room PL-401 on the plaza level of the Nassif Building, 400 Seventh Street, SW., Washington, DC, between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.

Contact Short Brothers, Airworthiness & Engineering Quality, P.O. Box 241, Airport Road, Belfast BT3 9DZ, Northern Ireland, for service information identified in this proposed AD.

Start Further Info

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 (425) 227-2125; fax (425) 227-1149.

End Further Info End Preamble Start Supplemental Information

SUPPLEMENTARY INFORMATION:

Comments Invited

We invite you to submit any relevant written data, views, or arguments regarding this proposed AD. Send your comments to an address listed in the ADDRESSES section. Include the docket number “FAA-2005-23173; Directorate Identifier 2005-NM-190-AD” at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of the proposed AD. We will consider all comments received by the closing date and may amend the proposed AD in light of those comments.

We will post all comments we receive, without change, to http://dms.dot.gov, including any personal information you provide. We will also post a report summarizing each substantive verbal contact with FAA personnel concerning this proposed AD. Using the search function of that Web site, anyone can find and read the comments in any of our dockets, including the name of the individual who sent the comment (or signed the comment on behalf of an association, business, labor union, etc.). You may review the DOT's complete Privacy Act Statement in the Federal Register published on April 11, 2000 (65 FR 19477-78), or you may visit http://dms.dot.gov. Start Printed Page 72407

Examining the Docket

You may 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 (800) 647-5227) is located on the plaza level of the Nassif Building at the DOT street address stated in the ADDRESSES section. Comments will be available in the AD docket shortly after the Docket Management System receives them.

Discussion

The FAA has examined the underlying safety issues involved in recent fuel tank explosions on several large transport airplanes, including the adequacy of existing regulations, the service history of airplanes subject to those regulations, and existing maintenance practices for fuel tank systems. As a result of those findings, we issued a regulation titled “Transport Airplane Fuel Tank System Design Review, Flammability Reduction and Maintenance and Inspection Requirements” (67 FR 23086, May 7, 2001). In addition to new airworthiness standards for transport airplanes and new maintenance requirements, this rule included Special Federal Aviation Regulation No. 88 (“SFAR 88,” Amendment 21-78, and subsequent Amendments 21-82 and 21-83).

Among other actions, SFAR 88 requires certain type design (i.e., type certificate (TC) and supplemental type certificate (STC)) holders to substantiate that their fuel tank systems can prevent ignition sources in the fuel tanks. This requirement applies to type design holders for large turbine-powered transport airplanes and for subsequent modifications to those airplanes. It requires them to perform design reviews and to develop design changes and maintenance procedures if their designs do not meet the new fuel tank safety standards. As explained in the preamble to the rule, we intended to adopt airworthiness directives to mandate any changes found necessary to address unsafe conditions identified as a result of these reviews.

In evaluating these design reviews, we have established four criteria intended to define the unsafe conditions associated with fuel tank systems that require corrective actions. The percentage of operating time during which fuel tanks are exposed to flammable conditions is one of these criteria. The other three criteria address the failure types under evaluation: single failures, single failures in combination with another latent condition(s), and in-service failure experience. For all four criteria, the evaluations included consideration of previous actions taken that may mitigate the need for further action.

The Joint Aviation Authorities (JAA) has issued a regulation that is similar to SFAR 88. (The JAA is an associated body of the European Civil Aviation Conference (ECAC) representing the civil aviation regulatory authorities of a number of European States who have agreed to co-operate in developing and implementing common safety regulatory standards and procedures.) Under this regulation, the JAA stated that all members of the ECAC that hold type certificates for transport category airplanes are required to conduct a design review against explosion risks.

We have determined that the actions identified in this AD are necessary to reduce the potential of ignition sources inside fuel tanks, which, in combination with flammable fuel vapors, could result in fuel tank explosions and consequent loss of the airplane.

The Civil Aviation Authority (CAA), which is the airworthiness authority for the United Kingdom, notified us that an unsafe condition may exist on all Short Brothers Model SD3 airplanes. The CAA advises that ignition sources may develop inside fuel tanks due to insufficient grounding. This condition, if not corrected, could result in ignition sources occurring inside the fuel tanks, which could lead to fire or explosion.

Relevant Service Information

Short Brothers has issued Service Bulletins SD3 SHERPA-28-2, SD360 SHERPA-28-3, SD330-28-37, and SD360-28-23; all dated June 2004. The service bulletins describe procedures for installing additional bonding jumpers between the vent pipes of both fuel tanks and the airplane structure; for performing an in-place resistance check of the fuel tank float switches; for inspecting the condition of certain sensor cables and cable supports inside the fuel tanks; for inspecting the integrity of the existing bonding of certain vent pipes inside the forward fuel tank; and for performing applicable corrective actions. Corrective actions include replacing defective float switches with new, reconditioned, or serviceable float switches, and repairing damaged sensor cables, cable supports, and existing vent pipe bonding.

Short Brothers has issued Advance Amendment Bulletin 1/2004, dated July 13, 2004, applicable to Shorts airplane flight manuals having Doc. Nos. SB.4.3, SB.4.6, SB.4.8, SB.5.2, SB.6.2, SBH.3.2, SBH.3.3, SBH.3.6, SBH.3.7, SBH.3.8, and SBH.3.9. The advance amendment bulletin describes revisions needed to meet the requirements of FAA SFAR 88 and/or CAA Airworthiness Notice AN55; the revisions affect sections of the flight manuals applicable to operation during icing conditions and fuel system failures.

Short Brothers has issued temporary revisions (TR) to the airworthiness limitations section of the aircraft maintenance manuals (AMM) of the affected airplanes, as shown in the following table. The TRs address airworthiness limitations to certain components of the fuel tank system installations.

AMM Temporary Revisions

Airplane modelTemporary revisionDatedTo AMM
SD3-30TR330-AMM-14June 21, 2004SD3-30 AMM.
SD3-60TR360-AMM-33July 27, 2004SD3-60 AMM.
SD3-60 SHERPATRSD360S-AMM-14July 29, 2004SD3-60 SHERPA AMM.
SD3-SHERPATRSD3S-AMM-15July 28, 2004SD3-SHERPA AMM.

Accomplishing the actions specified in the service information is intended to adequately address the unsafe condition. The CAA mandated the service information and issued British airworthiness directive G-2004-0021, dated August 25, 2004, to ensure the continued airworthiness of these airplanes in the United Kingdom.

FAA's Determination and Requirements of the Proposed AD

This airplane model is manufactured in the United Kingdom and are type certificated for operation in the United States under the provisions of section Start Printed Page 7240821.29 of the Federal Aviation Regulations (14 CFR 21.29) and the applicable bilateral airworthiness agreement. Pursuant to this bilateral airworthiness agreement, the FCAA has kept the FAA informed of the situation described above. We have examined the CAA's findings, evaluated all pertinent information, and determined that we need to issue an AD for airplanes of this type design that are certificated for operation in the United States.

Therefore, we are proposing this AD, which would require accomplishing the actions specified in the service information described previously, except as discussed under “Difference Between the Proposed AD and Service Information.”

Difference Between Proposed AD and Service Information

The service bulletins specify to contact the manufacturer for instructions on how to repair certain conditions, but this proposed AD would require repairing those conditions using a method that we or the CAA (or its delegated agent) approve. In light of the type of repair that would be required to address the unsafe condition, and consistent with existing bilateral airworthiness agreements, we have determined that, for this proposed AD, a repair we or the CAA approve would be acceptable for compliance with this proposed AD.

Clarification of Inspection Terminology

In this proposed AD, the “visual inspection” specified in the Shorts service bulletins is referred to as a “general visual inspection.” We have included the definition for a general visual inspection in a note in the proposed AD.

Costs of Compliance

This proposed AD would affect about 54 airplanes of U.S. registry. The average labor rate is estimated to be $65 per work hour.

The proposed revisions to the AFM and AMM would take about 1 work hour per airplane. Based on these figures, the estimated cost of the proposed revisions for U.S. operators is $3,510, or $65 per airplane.

The proposed resistance check, inspections, and jumper installations, would take about 40 work hours per airplane. Required parts would cost about $10 per airplane. Based on these figures, the estimated cost of these proposed actions for U.S. operators is $140,940, or $2,610 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 proposed AD would not have federalism implications under Executive Order 13132. This proposed AD 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.

For the reasons discussed above, I certify that the 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. 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 proposed AD and placed it in the AD docket. See the ADDRESSES section for a location to examine the regulatory evaluation.

Start List of Subjects

List of Subjects in 14 CFR Part 39

End List of Subjects

The Proposed Amendment

Accordingly, under the authority delegated to me by the Administrator, the FAA proposes to amend 14 CFR part 39 as follows:

Start Part

PART 39—AIRWORTHINESS DIRECTIVES

1. The authority citation for part 39 continues to read as follows:

Start Authority

Authority: 49 U.S.C. 106(g), 40113, 44701.

End Authority
[Amended]

2. The Federal Aviation Administration (FAA) amends § 39.13 by adding the following new airworthiness directive (AD):

Short Brothers PLC: FAA-2005-23173; Directorate Identifier 2005-NM-190-AD.

Comments Due Date

(a) The FAA must receive comments on this AD action by January 4, 2006.

Affected ADs

(b) None.

Applicability

(c) This AD applies to all Shorts Model SD3-60 SHERPA, SD3-SHERPA, SD3-30, and SD3-60 airplanes, certificated in any category.

Note 1:

This AD requires revisions to certain operator maintenance documents to include new inspections. Compliance with these inspections is required by 14 CFR 91.403(c). For airplanes that have been previously modified, altered, or repaired in the areas addressed by these inspections, the operator may not be able to accomplish the inspections described in the revisions. In this situation, to comply with 14 CFR 91.403(c), the operator must request approval for an alternative method of compliance according to paragraph (i) of this AD. The request should include a description of changes to the required inspections that will ensure the continued damage tolerance of the affected structure. The FAA has provided guidance for this determination in Advisory Circular (AC) 25-1529.

Unsafe Condition

(d) This AD results from fuel system reviews conducted by the manufacturer. We are issuing this AD to prevent ignition sources inside the fuel tanks, which could lead to fire or explosion.

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.

Revision of Airplane Flight Manual (AFM)

(f) Within 30 days after the effective date of this AD, revise the Limitations and Normal Procedures sections of the AFMs as specified in Table 1 of this AD to include the information in Shorts Advance Amendment Bulletin 1/2004, “Introduction of Changes to Meet the Requirements of FAA SFAR 88 and/or UK CAA Airworthiness Notice AN55,” dated July 13, 2004, as specified in the advance amendment bulletin. This advance amendment bulletin addresses operation during icing conditions and fuel system failures. Operate the airplane according to the limitations and procedures in the advance amendment bulletin.

Note 2:

The requirements of paragraph (f) of this AD may be done by inserting a copy of the advance amendment bulletin into the AFM. When this advance amendment Start Printed Page 72409bulletin has been included in general revisions of the AFM, the general revisions may be inserted into the AFM and the advance amendment bulletin may be removed, provided the relevant information in the general revision is identical to that in the advance amendment bulletin.

Table 1.—AFM Revisions

Airplane modelAFM documents to be revised
SD3-30SBH.3.2, SBH.3.3, SBH.3.6, SBH.3.7, SBH.3.8, and SBH.3.9.
SD3-60SB.4.3, SB.4.6, and SB.4.8.
SD3-60 SHERPASB.5.2.
SD3-SHERPASB.6.2.

Revision of Airworthiness Limitation (AWL) Section

(g) Within 180 days after the effective date of this AD: Revise the AWL section of the Instructions for Continued Airworthiness by incorporating airplane maintenance manual sections 5-20-01 and 5-20-02 as introduced by the Shorts temporary revisions (TR) specified in Table 1 of this AD into the AWL section of the AMMs for the airplane models specified in Table 1. Thereafter, except as provided by paragraph (i) of this AD, no alternative structural inspection intervals may be approved for the longitudinal skin joints in the fuselage pressure shell.

Note 3:

The requirements of paragraph (g) of this AD may be done by inserting a copy of the applicable TR into the applicable AMM. When the TR has been included in general revisions of the AMM, the general revisions may be inserted in the AMM and the TR may be removed, provided the relevant information in the general revision is identical to that in the TR.

Table 2.—AMM Temporary Revisions

Airplane modelTemporary revisionDatedTo AMM
SD3-30TR330-AMM-14June 21, 2004SD3-30 AMM.
SD3-60TR360-AMM-33July 27, 2004SD3-60 AMM.
SD3-60 SHERPATRSD360S-AMM-14July 29, 2004SD3-60 SHERPA AMM.
SD3-SHERPATRSD3S-AMM-15July 28, 2004SD3-SHERPA AMM.

Resistance Check, Inspection, and Jumper Installation

(h) Within 180 days after the effective date of this AD: Perform the insulation resistance check, general visual inspections, and bonding jumper wire installations; in accordance with Shorts Service Bulletin SD330-28-37, SD360-28-23, SD360 SHERPA-28-3, or SD3 SHERPA-28-2; all dated June 2004; as applicable. If any defects or damage are discovered during any inspection or check required by this AD, before further flight, repair the defects or damage using a method approved by either the Manager, International Branch, ANM-116, Transport Airplane Directorate, FAA; or the Civil Aviation Authority (CAA) (or its delegated agent).

Note 4:

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 normally 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.”

Alternative Methods of Compliance (AMOCs)

(i)(1) 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.

(2) Before using any AMOC approved in accordance with § 39.19 on any airplane to which the AMOC applies, notify the appropriate principal inspector in the FAA Flight Standards Certificate Holding District Office.

Related Information

(j) British airworthiness directive G-2004-0021, dated August 25, 2004, also addresses the subject of this AD.

Start Signature

Issued in Renton, Washington, on November 25, 2005.

Ali Bahrami,

Manager, Transport Airplane Directorate, Aircraft Certification Service.

End Signature End Part End Supplemental Information

[FR Doc. 05-23600 Filed 12-2-05; 8:45 am]

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