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

ACTION: Final rule.

SUMMARY: We are adopting a new airworthiness directive (AD) for the products listed above. This 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:

It has been found the occurrence of corrosion on the Auxiliary Power Unit (APU) mounting rods that could cause the APU rod to break, affecting the APU support structure integrity.

APU support structure failure could result in loss of power of the APU and possible loss of control of the airplane. We are issuing this AD to require actions to correct the unsafe condition on these products.

DATES: This AD becomes effective September 9, 2010. The Director of the Federal Register approved the incorporation by reference of certain publications listed in this AD as of September 9, 2010.

ADDRESSES: You may examine the AD docket on the Internet at http:// www.regulations.gov or in person at the U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue, SE., Washington, DC.

FOR FURTHER INFORMATION CONTACT: Todd Thompson, Aerospace Engineer, International Branch, ANM-116, Transport Airplane Directorate, FAA, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone (425) 227-1175; fax (425) 227-1149.

SUPPLEMENTARY INFORMATION:

Discussion

We issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 to include an AD that would apply to the specified products. That NPRM was published in the Federal Register on August 19, 2009 (74 FR 41807). That NPRM proposed to correct an unsafe condition for the specified products. The MCAI states:

It has been found the occurrence of corrosion on the Auxiliary Power Unit (APU) mounting rods that could cause the APU rod to break, affecting the APU support structure integrity.

APU support structure failure could result in loss of power of the APU and possible loss of control of the airplane. The required action is doing an external detailed inspection for corrosion of the APU auxiliary and center mounting rods and rod ends, and corrective actions if necessary. Corrective actions include removing corrosion, applying anticorrosive treatment, and replacing mounting rods. You may obtain further information by examining the MCAI in the AD docket.

Comments

We gave the public the opportunity to participate in developing this AD. We considered the comments received.

Request for Bridging Requirements for Previously Accomplished Actions

American Eagle Airlines (AEA) requests that we revise the NPRM to include "bridging requirements.'' AEA states that it agrees with the repetitive inspections in the NPRM; however, AEA asserts that there are no bridging requirements to reach the repetitive inspections for airplanes that have already accomplished EMBRAER Service Bulletin 145- 49-0034, Revision 01, dated September 8, 2008. AEA states that bridging requirements are necessary for initializing a repetitive inspection with the initial compliance time of 500 flight hours or 2 months after the effective date of this AD.
We agree with AEA that bridging requirements would be necessary given the proposed compliance times. However, since the NPRM was issued, we have received sufficient technical information to support an extension of the proposed compliance time. We have determined that changing the initial compliance time from 500 flight hours or 2 months after the effective date of this AD to 1,500 flight hours or 180 days after the effective date of this AD, will provide an acceptable level of safety. The new compliance time correlates with Brazilian Airworthiness Directive 2008-10-02, effective October 21, 2008. With the extended compliance times, there should not be a need for bridging requirements. If however, AEA believes that such requirements are still necessary, it may apply for an alternative method of compliance (AMOC) in accordance with the provisions specified in paragraph (g)(1) of this AD.

Request To Revise the Unsafe Condition Specified in Paragraph (e) of the NPRM

EMBRAER states that the undetectable fire condition described in the NPRM is not verifiable since two events must happen for APU rod breakage to occur.
EMBRAER states that the first event is a fire, because the rod breakage by itself is not enough to promote sparks or overheating of any kind. EMBRAER also states that the rod breakage has not been shown to cause leakage of APU oil in the gearbox, or leakage of the fuel lines in the compartment. EMBRAER states both ignition sources and flammable fluids would be required to ignite a fire.
EMBRAER states that for the second event to occur, a fire must start due to the unforeseeable scenario described previously, at which time damage to the fire detector, located in the vicinity of the combustion chamber and accessory gearbox, could occur. EMBRAER states that in-service experience demonstrates that the fire detector must be punctured or extensively crushed for it to lose its capability to detect a fire. Even if that happens, EMBRAER states that the integrity monitoring circuitry of the fire detector is capable of warning the flightcrew if the detector becomes inoperative. EMBRAER also states that in the event of fire detection failure, annunciated on the engine indication crew alert system associated with the APU event, the flight crew is required to carry out instructions in the airplane flight manual section "Abnormal Procedures'' to shut down the APU and discharge the fire extinguishing agent to put out the fire.
From these statements we infer that EMBRAER requests that we revise paragraph (e) of the NPRM to clarify the unsafe condition. We agree with the scenarios EMBRAER has described previously in regards to an undetected fire occurring in the tail cone of the airplane. Therefore, we have changed the Summary section and paragraph (e) of this AD to state, "APU support structure failure could result in loss of power of the APU and possible loss of control of the airplane.''

Request To Extend the Proposed Initial Compliance Time

EMBRAER states that the European Aviation Safety Agency (EASA) and the Ag[ecirc]ncia Nacional de Avia[ccedil][atilde]o Civil (ANAC) fleets have accomplished the respective ADs. This resulted in an approximately 2.5 percent removal rate of the rods, including many unnecessary removals that had no moderate or heavy corrosion at the rod, but mostly corrosion on the rod terminal. EMBRAER states that, in total, only eight rods were conclusively removed due to the meaning of this inspection out of more than 2,200 rods inspected, leading to a rate of 0.35 percentage findings. EMBRAER also states that there were instances of more than one rod removed from the same airplane, conclusively demonstrating that the removal criterion was over-estimated. EMBRAER states that one heavily corroded rod was found on one airplane, and further corrosion could not be found on any other similarly installed rods.
EMBRAER states that with the considerations stated previously, meaning lack of real fire in the compartment, and lack of evidence or reports of corrosion spreading in the current Model EMB 145 fleet, the initial compliance time of 500 flight hours or 2 months after the effective date of the AD is too conservative of an approach. EMBRAER states that this leads to extensive burden and labor costs on operators, and does not lead to a real increased margin of safety levels related to this issue. EMBRAER states that, according to Brazilian Airworthiness Directive 2008-10-02, effective October 21, 2008; and EMBRAER Service Bulletin 145-49-0034, Revision 01, dated September 8, 2008; an adequate approach could be taken within 1,500 flight hours or 6 months from the effective date of the AD, whichever occurs first. EMBRAER states that the same is true for the Legacy fleet in regards to EMBRAER Service Bulletin 145LEG-49-0008, Revision 02, dated September 8, 2008.
We infer that EMBRAER requests that we extend the proposed compliance time specified in the NPRM. We agree that the proposed compliance times are conservative. As we explained previously, since the NPRM has been published, we have determined that the compliance times proposed in the NPRM are no longer necessary as the inspection reports received provided sufficient technical information to extend the compliance time. We are changing the initial compliance time from 500 flight hours or 2 months after the effective date of this AD to 1,500 flight hours or 180 days after the effective date of this AD. The new compliance time correlates with Brazilian Airworthiness Directive 2008-10-02, effective October 21, 2008. No additional changes to the AD are necessary in this regard.

Request To Eliminate Repetitive Detailed Inspections in the AD

EMBRAER states that the repetitive inspection interval currently required by the maintenance review board (MRB) report for C-Check (5,000 flight cycles) states:

Zonal Inspection Task 53-Z313-214-001-A00 Internal General Visual Inspection of the Tail Cone Fairing at C-Check (5,000 FH). Examine the fuselage zone for loose rivets, nicks, cracks, dents, erosion, corrosion, deteriorated protective treatment, foreign objects, and deformation.

EMBRAER states that inspections accomplished in accordance with EMBRAER Service Bulletin 145-49-0034, Revision 01, dated September 8, 2008; and EMBRAER Service Bulletin 145LEG-49-0008, Revision 02, dated September 8, 2008; revealed rods with moderate to heavy corrosion on airplanes between 9,482 total flight hours and 21,506 total flight hours. EMBRAER states that these findings demonstrate that the inspection interval in the MRB is adequate to fully address the issue, or any other operational mishap that might occur at APU removal/installation. EMBRAER also states that a few APU rods are reportedly replaced over time, apart from this AD, demonstrating the MRB task is effective for the repetitive inspections. EMBRAER states that the repetitive detailed inspection in the NPRM is more restrictive than the general visual inspection specified in the MRB.
From these statements, we infer that EMBRAER requests that we eliminate the repetitive detailed inspections specified in the NPRM. We agree with EMBRAER that the repetitive detailed inspection proposed in the NPRM is more conservative than the inspection in the MRB. Since the NPRM was published, we have determined that the repetitive inspections proposed in the NPRM are no longer necessary as the inspection reports received provided sufficient technical information to remove the proposed requirement. The proposed repetitive inspections have been removed from this AD.

Request To Extend the Compliance Time for the Reporting Requirement

EMBRAER states that the EASA and ANAC ADs were issued in advance of this proposed NPRM. EMBRAER also states that the current status of U.S. operators that have proactively started inspecting their fleets is 55 percent of the total fleet, meaning nearly 380 airplanes have already been inspected. EMBRAER states that since the proposed compliance time for the initial inspection specified in the NPRM is 500 flight hours, with the current average of 120 flight hours per month fleet usage, it would take more than 4 months to complete the first inspection. EMBRAER states that, since the results remain unchanged with time, it is recommended that the 30-day reporting requirement be extended to 120 days minimum, reducing unnecessary labor burden and processing for the operators.
From these statements, we infer that EMBRAER requests that we extend the compliance time for submitting the inspection results from 30 days to 120 days. We disagree with extending the compliance time for submitting the inspection results. We also disagree that the report is an undue burden to the operator. A reporting requirement is instrumental in ensuring that we can gather as much information as possible regarding the extent and nature of the problem, especially when findings of corrosion are involved and in cases where that data might not be available through other established means. This information is necessary to ensure that proper corrective action will be taken. We have not changed this AD regarding this issue.

Request To Change Proposed Compliance Time Frame

Trans States Airlines requests a change in the proposed compliance time for the initial inspection from 2 months to 60 days after the effective date of the AD. Trans States Airlines states that 60 days is an exact period where 2 months will vary based on the months involved. Trans States Airlines also requests that the repetitive requirements read "1,500 flight hours, or 180 days after the effective date of this AD,'' instead of "1,500 flight hours, or 6 months after the date of this AD,'' for the same reason.
We agree with Trans States Airlines' request to use number of days instead of months. Trans States Airlines is correct in stating that days are more definitive time than months. We also have determined that changing the initial compliance time from 500 flight hours or 2 months after the effective date of this AD to 1,500 flight hours or 180 days after the effective date of this AD, will provide an acceptable level of safety. We have changed the final rule regarding this issue.
In regards to using days versus months for the repetitive inspections, as we stated previously, we have determined that the repetitive inspections proposed in the NPRM are no longer necessary and have been removed from this AD. No further change to this AD is necessary in this regard.

Request To Allow Additional Part Numbers

Trans States Airlines requests that we revise the NPRM to allow mounting rods with part number -001 or -005 as an acceptable method of compliance for replacement of the rod as allowed in the EMBRAER EMB- 135/-145 Illustrated Parts Catalog.
We disagree with Trans State Airlines' request to use part number - 001 or -005 as an acceptable method of compliance for replacing the mounting rods. The illustrated parts catalog is not regulated by the FAA, and EMBRAER did not provide us with information to ensure that these parts adequately address the unsafe condition. However, operators may apply to use an AMOC for this AD, as specified in paragraph (g)(1) of this AD. Because of the unsafe condition that exists, Brazilian Airworthiness Directive 2008-10-02, effective October 21, 2008; EMBRAER Service Bulletin 145-49-0034, Revision 01, dated September 8, 2008; and EMBRAER Service Bulletin 145LEG-49-0008, Revision 02, dated September 8, 2008; specify that if moderate corrosion is found, the affected mounting rod is to be replaced with a new mounting rod having the same part number. We have not changed this AD regarding this issue.

Request for Removal of Reporting Requirement

Trans States Airlines states that the reporting requirement is an undue burden on the operator. Trans States Airlines states that, of the 50 mounting rods removed for corrosion, only two were found to have actually had corrosion. Trans States Airlines states that more than 2,000 rods have already been inspected, and it believes sufficient data already exist to determine the need for further rulemaking.
From these statements, we infer that Trans States Airlines is asking that we remove the proposed reporting requirement from the NPRM. We have obtained further information from EMBRAER regarding the reporting requirement. EMBRAER states that the report is necessary so that more comprehensive data can be aquired. We disagree with Trans States Airlines in removing the reporting requirement and that the report is an undue burden to the operator. A reporting requirement is instrumental in ensuring that we can gather as much information as possible regarding the extent and nature of the problem, especially in cases where that data might not be available through other established means. This information is necessary to ensure that proper corrective action will be taken. We have not changed this AD regarding this issue.

Clarification of the Retention Requirements for the Reporting Requirement

Trans States Airlines requests clarification for the retention requirements for the proposed reporting requirement specified in the NPRM.
We agree to clarify the retention requirements for the reporting requirement specified in paragraph (g)(3) of this AD. We have obtained further information from Trans States Airlines. Trans States Airlines questions how long it must prove that it has complied with the reporting requirement in the AD, since the report is not considered part of the maintenance records.
Only one report is required by this AD. Once the report has been submitted, no further action is required by this AD. We have not changed this AD regarding this issue.

Request To Add an E-Mail Address to the Reporting Address

Trans States Airlines states that including EMBRAER's mailing address and telephone number in paragraph (f)(3) of the NPRM, makes those the only approved methods for reporting, and that e-mail would not be an acceptable method for reporting inspection findings.
From this statement, we infer that Trans States Airlines requests that for the reporting requirement in paragraph (f)(3) of the NPRM, we include an e-mail address in the contact information.
We agree with Trans States Airlines' request to include an e-mail address in the contact information. We have determined that an e-mail is an acceptable method of compliance for reporting inspection findings to EMBRAER. EMBRAER has provided us with an e-mail address and we have added that address to paragraph (f)(3) of this AD.

Request To Exclude Light Corrosion From the Reporting Requirement

Expressjet Airlines requests that the light corrosion findings be removed from the reporting requirement in the NPRM. Expressjet Airlines states that paragraph (f)(3) of the NPRM states to send a report of the positive findings, including level of corrosion, such as light, moderate, or heavy, to EMBRAER. Expressjet Airlines also states that EMBRAER Service Bulletin 145-49-0034, Revision 01, dated September 8, 2008, requires only that moderate or heavy corrosion be reported.
We agree with Expressjet Airlines that reporting of light corrosion is not necessary. Since the NPRM was issued, we have received sufficient technical information to remove the reporting requirement for light corrosion. We have revised paragraph (f)(3) of this AD to remove light corrosion from the reporting requirement of this AD.

Conclusion

We reviewed the available data, including the comments received, and determined that air safety and the public interest require adopting the AD with the changes described previously. We determined that these changes will not increase the economic burden on any operator or increase the scope of the AD.

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 required different actions in this AD from those in the MCAI in order to follow our FAA policies. Any such differences are highlighted in a NOTE within the AD.

Explanation of Changes to Costs of Compliance

Since issuance of the NPRM, we have increased the labor rate used in the Costs of Compliance from $80 per work-hour to $85 per work-hour. The Costs of Compliance information, below, reflects this increase in the specified hourly labor rate.

Costs of Compliance

We estimate that this AD will affect 761 products of U.S. registry. We also estimate that it will take about 8 work-hours per product to comply with the basic requirements of this AD. The average labor rate is $85 per work-hour. Based on these figures, we estimate the cost of this AD to the U.S. operators to be $517,480, or $680 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 AD will not have federalism implications under Executive Order 13132. This AD will 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 AD:
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 AD and placed it in the AD docket.

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 the NPRM, the regulatory evaluation, any comments received, and other information. The street address for the Docket Operations office (telephone (800) 647-5527) is in the ADDRESSES section. Comments will be available in the AD docket shortly after receipt.

List of Subjects in 14 CFR Part 39

Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.

Adoption of the Amendment

Accordingly, under the authority delegated to me by the Administrator, the FAA amends 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.

Sec. 39.13 [Amended]

2. The FAA amends Sec. 39.13 by adding the following new AD: