E7-24382. Airworthiness Directives; ATR Model ATR42 and ATR72 Airplanes

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

We propose to adopt a new airworthiness directive (AD) for the products listed above. This proposed AD results from mandatory continuing airworthiness information (MCAI) originated by an aviation authority of another country to identify and correct an unsafe condition on an aviation product. The MCAI describes the unsafe condition as:

[T]he FAA has published a set of new rules related to the fuel tank safety, including the Special Federal Aviation Regulation 88 (SFAR 88).

The JAA (Joint Aviation Authority) has issued an Interim Policy JAA INT/POL 25/12, to recommend the application of a similar requirement to the National Aviation Authorities (NAA) [of Europe].

* * * * *

* * * ATR carried out a safety review on the fuel tank systems and zones adjacent to the fuel tanks on all ATR models * * *.

* * * * *

The unsafe condition is 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 proposed AD would require actions that are intended to address the unsafe condition described in the MCAI.

DATES:

We must receive comments on this proposed AD by January 16, 2008.

ADDRESSES:

You may send comments by any of the following methods:

• Federal eRulemaking Portal: Go to http://www.regulations.gov. Follow the instructions for submitting comments.
• Fax: [phone].
• Mail: U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue, SE., Washington, DC 20590.
• Hand Delivery: U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-40, 1200 New Jersey Avenue, SE., Washington, DC, between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.

Examining the AD Docket

You may examine the AD docket on the Internet at http://www.regulations.gov; or in person at the Docket Operations office between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The AD docket contains this proposed AD, the regulatory evaluation, any comments received, and other information. The street address for the Docket Operations office (telephone [phone]) is in the ADDRESSES section. Comments will be available in the AD docket shortly after receipt.

FOR FURTHER INFORMATION CONTACT:

Tom Rodriguez, Aerospace Engineer, International Branch, ANM-116, Transport Airplane Directorate, FAA, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone [phone]; fax [phone].

SUPPLEMENTARY INFORMATION:

Comments Invited

We invite you to send any written relevant data, views, or arguments about this proposed AD. Send your comments to an address listed under the ADDRESSES section. Include “Docket No. FAA-2007-0334; Directorate Identifier 2007-NM-206-AD” at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of this proposed AD. We will consider all comments received by the closing date and may amend this proposed AD based on those comments.

We will post all comments we receive, without change, to http://www.regulations.gov, including any personal information you provide. We will also post a report summarizing each substantive verbal contact we receive about this proposed AD.

Discussion

The European Aviation Safety Agency (EASA), which is the Technical Agent for the Member States of the European Community, has issued EASA Airworthiness Directive 2007-0226, dated August 24, 2006 (referred to after this as “the MCAI”), to correct an unsafe condition for the specified products. The MCAI states:

[T]he FAA has published a set of new rules related to the fuel tank safety, including the Special Federal Aviation Regulation 88 (SFAR 88).

The JAA (Joint Aviation Authority) has issued an Interim Policy JAA INT/POL 25/12, to recommend the application of a similar requirement to the National Aviation Authorities (NAA) [of Europe].

This recommendation was followed by French DGAC, which rendered the compliance to JAA INT/POL 25/12 mandatory for all ATR Aircraft.

Under this regulation, all holders of type certificates are required to conduct a design review of their fuel tank systems against explosion risk. It also requires the development and implementation of maintenance and inspection instructions to maintain the safety of the fuel tank system. To answer JAA INT/POL 25/12, and in accordance with SFAR 88 requirements and guideline, ATR carried out a safety review on the fuel tank systems and zones adjacent to the fuel tanks on all ATR models using relevant safety assessment methods of JAR 35.1309.

As a result of this safety review, ATR developed for ATR 42 the modification 05355 (SB (service bulletin) ATR42-28-0039), and for ATR 72 the modification 05356 (SB ATR72-28-1019). Those modifications consist in the installation of fuses adapters on wiring entering the fuel tanks and current limitation devices. For ATR 72 aircraft, the modification also requires replacement of the high level sensors with new sensors having shorter harness.

The modification also includes related investigative and corrective actions, which include inspecting the electrical harness for correct installation and adjusting the harness as necessary, and, for Model ATR42 airplanes, inspecting the bonding strap for correct installation and adjusting the bonding strap. You may obtain further information by examining the MCAI in the AD docket.

The FAA has examined the underlying safety issues involved in 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” (66 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 a 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.

Relevant Service Information

ATR has issued Service Bulletins ATR42-28-0039, Revision 04, dated June 12, 2007; and ATR72-28-1019, Revision 05, dated June 12, 2007. The actions described in this service information are intended to correct the unsafe condition identified in the MCAI.

FAA's Determination and Requirements of This Proposed AD

This product has been approved by the aviation authority of another country, and is approved for operation in the United States. Pursuant to our bilateral agreement with the State of Design Authority, we have been notified of the unsafe condition described in the MCAI and service information referenced above. We are proposing this AD because we evaluated all pertinent information and determined an unsafe condition exists and is likely to exist or develop on other products of the same type design.

Differences Between This AD and the MCAI or Service Information

We have reviewed the MCAI and related service information and, in general, agree with their substance. But we might have found it necessary to use different words from those in the MCAI to ensure the AD is clear for U.S. operators and is enforceable. In making these changes, we do not intend to differ substantively from the information provided in the MCAI and related service information.

We might also have proposed different actions in this AD from those in the MCAI in order to follow FAA policies. Any such differences are highlighted in a NOTE within the proposed AD.

Costs of Compliance

Based on the service information, we estimate that this proposed AD would affect about 55 products of U.S. registry. We also estimate that it would take about 150 work-hours per product to comply with the basic requirements of this proposed AD. The average labor rate is $80 per work-hour. Required parts would cost about $23,000 per product. Where the service information lists required parts costs that are covered under warranty, we have assumed that there will be no charge for these costs. As we do not control warranty coverage for affected parties, some parties may incur costs higher than estimated here. Based on these figures, we estimate the cost of the proposed AD on U.S. operators to be $1,925,000, or $35,000 per product.

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 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 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. 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.

List of Subjects in 14 CFR Part 39

• Air transportation
• Aircraft
• Aviation safety
• Safety

The Proposed Amendment

Accordingly, under the authority delegated to me by the Administrator, the FAA proposes to amend 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. The FAA amends § 39.13 by adding the following new AD:

ATR-GIE Avions De Transport Régional (Formerly Aerospatiale): Docket No. FAA-2007-0334; Directorate Identifier 2007-NM-206-AD.

Comments Due Date

(a) We must receive comments by January 16, 2008.

Affected ADs

(b) None.

Applicability

(c) This AD applies to the airplanes specified in paragraphs (c)(1) and (c)(2) of this AD.

(1) ATR Model ATR42-200, -300, -320, and -500 airplanes, certificated in any category, serial numbers 1 through 642.

(2) ATR Model ATR72-101, -201, -102, -202, -211, -212, and -212A airplanes, certificated in any category, serial numbers 1 through 724.

Subject

(d) Air Transport Association (ATA) of America Code 28: Fuel.

Reason

(e) The mandatory continuing airworthiness information (MCAI) states:

[T]he FAA has published a set of new rules related to the fuel tank safety, including the Special Federal Aviation Regulation 88 (SFAR 88).

The JAA (Joint Aviation Authority) has issued an Interim Policy JAA INT/POL 25/12, to recommend the application of a similar requirement to the National Aviation Authorities (NAA) [of Europe].

This recommendation was followed by French DGAC, which rendered the compliance to JAA INT/POL 25/12 mandatory for all ATR Aircraft.

Under this regulation, all holders of type certificates are required to conduct a design review of their fuel tank systems against explosion risk. It also requires the development and implementation of maintenance and inspection instructions to maintain the safety of the fuel tank system. To answer JAA INT/POL 25/12, and in accordance with SFAR 88 requirements and guidelines, ATR carried out a safety review on the fuel tank systems and zones adjacent to the fuel tanks on all ATR models using relevant safety assessment methods of JAR 35.1309.

As a result of this safety review, ATR developed for ATR 42 the modification 05355 (SB (service bulletin) ATR42-28-0039), and for ATR 72 the modification 05356 (SB ATR72-28-1019). Those modifications consist in the installation of fuses adapters on wiring entering the fuel tanks and current limitation devices. For ATR 72 aircraft, the modification also requires replacement of the high level sensors with new sensors having shorter harness.

The modification also includes related investigative and corrective actions, which include inspecting the electrical harness for correct installation and adjusting the harness as necessary, and, for Model ATR42 airplanes, inspecting the bonding strap for correct installation and adjusting the bonding strap. The unsafe condition is 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.

Actions and Compliance

(f) Within 41 months after the effective date of this AD, unless already done, modify the fuel system and do all applicable related investigative and corrective actions according to the instructions given by the applicable service bulletin listed in Table 1 of this AD. Do all applicable related investigative and corrective actions before further flight. Actions accomplished before the effective date of this AD in accordance with Avions de Transport Regional Service Bulletin ATR42-28-0039, Revision 03, dated November 15, 2006, are considered acceptable for compliance with the corresponding action specified in this AD.

Table 1.—Service Information

Avions de Transport Regional Service Bulletin	Revision level	Date
ATR42-28-0039 (for Model ATR42 Airplanes)	04	June 12, 2007.
ATR72-28-1019 (for Model ATR72 Airplanes)	05	June 12, 2007.

FAA AD Differences

Note:

This AD differs from the MCAI and/or service information as follows: The additional actions specified in the MCAI for operators that have done actions in accordance with previous issues of the service bulletins are not complete. Therefore, this AD only refers to ATR Service Bulletin ATR42-28-0039, Revision 03, dated November 15, 2006; Revision 04, dated June 12, 2007; and ATR72-28-1019, Revision 05, dated June 12, 2007; as appropriate sources of service information for accomplishing the required actions. Operators that have done actions in accordance with previous issues of the service bulletins may request an approval for an alternative method of compliance (AMOC) according to paragraph (g) of this AD, provided that the AMOC provides an acceptable level of safety.

Other FAA AD Provisions

(g) The following provisions also apply to this AD:

(1) Alternative Methods of Compliance (AMOCs): The Manager, ANM-116, International Branch, Transport Airplane Directorate, FAA, has the authority to approve AMOCs for this AD, if requested using the procedures found in 14 CFR 39.19. Send information to ATTN: Tom Rodriguez, Aerospace Engineer, International Branch, ANM-116, Transport Airplane Directorate, FAA, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone [phone]; fax [phone]. Before using any approved AMOC on any airplane to which the AMOC applies, notify your appropriate principal inspector (PI) in the FAA Flight Standards District Office (FSDO), or lacking a PI, your local FSDO.

(2) Airworthy Product: For any requirement in this AD to obtain corrective actions from a manufacturer or other source, use these actions if they are FAA-approved. Corrective actions are considered FAA-approved if they are approved by the State of Design Authority (or their delegated agent). You are required to assure the product is airworthy before it is returned to service.

(3) Reporting Requirements: For any reporting requirement in this AD, under the provisions of the Paperwork Reduction Act, the Office of Management and Budget (OMB) has approved the information collection requirements and has assigned OMB Control Number 2120-0056.

Related Information

(h) Refer to MCAI EASA Airworthiness Directive 2007-0226, dated August 24, 2007, and the service information listed in Table 2 of this AD, for related information.

Table 2.—Related Service Information

Avions de Transport Regional Service Bulletin	Revision level	Date
ATR42-28-0039	04	June 12, 2007.
ATR72-28-1019	05	June 12, 2007.

Issued in Renton, Washington, on December 10, 2007.

Ali Bahrami,

Manager, Transport Airplane Directorate, Aircraft Certification Service.