04-4929. Airworthiness Directives; Empresa Brasileira de Aeronautica S.A. (EMBRAER) Model EMB-135BJ and EMB-145XR 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 certain EMBRAER Model EMB-135BJ and EMB-145XR series airplanes. This proposal would require repetitive inspections for cracking in the firewall of the auxiliary power unit (APU), and repair of the firewall if necessary. This proposal would also provide an optional terminating action for the repetitive inspections. This action is necessary to detect and correct cracking in the APU firewall, which could result in reduced structural integrity of the firewall, and a consequent uncontained APU fire that could spread to the airplane structure. This action is intended to address the identified unsafe condition.

DATES:

Comments must be received by April 5, 2004.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2003-NM-218-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 [phone]. Comments may also be sent via the Internet using the following address: [e-mail]. Comments sent via fax or the Internet must contain “Docket No. 2003-NM-218-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 Empresa Brasileira de Aeronautica S.A. (EMBRAER), PO Box 343—CEP 12.225, Sao Jose dos Campos—SP, Brazil. 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 [phone]; fax [phone].

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-218-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-318-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

Discussion

The Departmento de Aviacao Civil (DAC), which is the airworthiness authority for Brazil, notified the FAA that an unsafe condition may exist on certain EMBRAER EMB-135BJ and EMB-145XR series airplanes. The DAC advises that it has received reports of cracking in the firewall of the auxiliary power unit (APU). The cracking was caused by differential pressure between the inside and outside of the APU compartment. Such cracking, if not detected and corrected, could result in reduced structural integrity of the firewall and a consequent uncontained APU fire that could spread to the airplane structure.

Explanation of Relevant Service Information

EMBRAER has issued Service Bulletins 145-53-0037 (for Model EMB-145XR series airplanes), dated April 30, 2003; and 145LEG-53-0010 (for Model EMB-135BJ series airplanes), dated June 5, 2003. These service bulletins describe procedures for repetitively inspecting the APU firewall for cracking, and repairing the APU firewall if necessary.

The service bulletins specify that if any crack is found it should be repaired per the applicable structural repair manual (SRM). If any crack is found that exceeds the limits specified in the applicable SRM, a new APU firewall should be installed per Part II of the service bulletin. Replacement of the APU firewall with a new part would eliminate the need for the repetitive inspections. The service bulletins also describe procedures for doing an operational test each time an APU firewall is replaced. Accomplishment of the actions specified in the service bulletins is intended to adequately address the identified unsafe condition. The DAC classified these service bulletins as mandatory and issued Brazilian airworthiness directive 2003-07-02, dated August 18, 2003, to ensure the continued airworthiness of these airplanes in Brazil.

FAA's Conclusions

These airplane models are manufactured in Brazil and are type certificated for operation in the United States under the provisions of section 21.29 of the Federal Aviation Regulations (14 CFR 21.29) and the applicable bilateral airworthiness agreement. Pursuant to this bilateral airworthiness agreement, the DAC has kept us informed of the situation described above. We have examined the findings of the DAC, 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 AD

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.

Consistent with the findings of the DAC, the proposed AD would allow repetitive inspections to continue in lieu of the terminating action. In making this determination, we considered that long-term continued operational safety in this case will be adequately ensured by repetitive inspections to detect cracking in the APU firewall before it represents a hazard to the airplane.

Clarification of Repair Information

If any cracking exceeds the limits specified in the service bulletin, the APU firewall must be replaced with a new APU firewall per the Accomplishment Instructions of the applicable service bulletin.

Cost Impact

We estimate that 40 airplanes of U.S. registry would be affected by this proposed AD.

It would take approximately 1 work hour per airplane to accomplish the proposed repetitive inspections, at an average labor rate of $65 per work hour. Based on these figures, the cost impact of the proposed repetitive inspections on U.S. operators is estimated to be $2,600, or $65 per airplane, per inspection cycle.

The cost impact figure discussed above is 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.

If an operator chooses to do the optional terminating action, rather than continue the repetitive inspections, it would take about 60 work hours per airplane to accomplish the replacement of the APU firewall, at an average labor rate of $65 per work hour. Required parts would cost about $7,784 per airplane. Based on these figures, we estimate the cost of this optional terminating action to be $11,684 per airplane.

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.

§ 39.13

[Amended]

2. Section 39.13 is amended by adding the following new airworthiness directive:

Empresa Brasileira De Aeronautica S.A. (EMBRAER): Docket 2003-NM-218-AD.

Applicability: Model EMB-135BJ series airplanes as listed in EMBRAER Service Bulletin 145LEG-53-0010, dated June 5, 2003; and Model EMB-145XR series airplanes as listed in EMBRAER Service Bulletin 145-53-0037, dated April 30, 2003; certificated in any category.

Compliance: Required as indicated, unless accomplished previously.

To detect and correct cracking in the firewall of the auxiliary power unit (APU), which could result in reduced structural integrity of the firewall, and a consequent uncontained APU fire that could spread to the airplane structure, accomplish the following:

Initial Inspection

(a) Within 200 flight hours or 90 days after the effective date of this AD, whichever is first: Do a detailed inspection of the APU firewall for cracking, per Part I of the Accomplishment Instructions of EMBRAER Service Bulletin 145-53-0037 (for Model EMB-145XR series airplanes), dated April 30, 2003; or Service Bulletin 145LEG-53-0010 (for Model EMB-135BJ series airplanes), dated June 5, 2003; as applicable.

Note 1:

For the purposes of this AD, a detailed inspection is defined as: “An intensive visual examination of a specific structural area, system, installation, or assembly to detect damage, failure, or irregularity. Available lighting is normally supplemented with a direct source of good lighting at intensity deemed appropriate by the inspector. Inspection aids such as mirror, magnifying lenses, etc., may be used. Surface cleaning and elaborate access procedures may be required.”

Repetitive Inspections/Repair

(b) If no cracking is found during any inspection required by paragraph (a) of this AD: Repeat the inspection required by paragraph (a) of this AD thereafter at intervals not to exceed 200 flight hours or 90 days, whichever is first. Accomplishment of the replacement specified in paragraph (d) of this AD terminates the repetitive inspections required by this paragraph.

(c) If any cracking is found during any inspection required by paragraph (a) of this AD: Before further flight, determine if the cracking can be repaired per Part I of the Accomplishment Instructions of EMBRAER Service Bulletin 145-53-0037, dated April 30, 2003; or Service Bulletin 145LEG-53-0010, dated June 5, 2003; as applicable.

(1) If the cracking can be repaired: Before further flight, repair the cracking per Part I of the Accomplishment Instructions of the applicable service bulletin. Repeat the inspection required by paragraph (a) of this AD thereafter at intervals not to exceed 200 flight hours or 90 days, whichever is first.

(2) If the cracking cannot be repaired: Before further flight, replace the APU firewall with a new firewall by accomplishing all of the actions per Part II of the Accomplishment Instructions of the applicable service bulletin. Accomplishment of the replacement terminates the repetitive inspections required by paragraphs (b) and (c)(1) of this AD.

Optional Terminating Action

(d) Replacement of the APU firewall with a new firewall by accomplishing all of the actions per Part II of the Accomplishment Instructions of EMBRAER Service Bulletin 145-53-0037, dated April 30, 2003; or 145LEG-53-0010, dated June 5, 2003; as applicable; constitutes terminating action for the repetitive inspections required by paragraphs (b) and (c)(1) of this AD.

Alternative Methods of Compliance

(e) In accordance with 14 CFR 39.19, the Manager, International Branch, ANM-116, Transport Airplane Directorate, FAA, is authorized to approve alternative methods of compliance for this AD.

Note 2:

The subject of this AD is addressed in Brazilian airworthiness directive 2003-07-02, dated August 18, 2003.

Issued in Renton, Washington, on February 20, 2004.

Kalene C. Yanamura,

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.