E6-10175. Airworthiness Directives; Empresa Brasileira de Aeronautica S.A. (EMBRAER) Model EMB-145, -145ER, -145MR, -145LR, -145XR, -145MP, and -145EP Airplanes

AGENCY:

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

ACTION:

Proposed rule; withdrawal.

SUMMARY:

The FAA withdraws a notice of proposed rulemaking (NPRM) that proposed a new airworthiness directive (AD) for certain EMBRAER Model EMB-145, -145ER, -145MR, -145LR, -145XR, -145MP, and -145EP airplanes. The proposed AD would have required modifying the routing of wire harness W407 near the fire extinguishing tube in the area of each engine, and installing new supports for related wiring. Since the proposed AD was issued, we have received new data indicating that the identified unsafe condition does not exist. Accordingly, the proposed AD is withdrawn.

ADDRESSES:

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 [phone]) is located on the plaza level of the Nassif Building at the U.S. Department of Transportation, 400 Seventh Street SW., Room PL-401, Washington, DC. This docket number is FAA-2006-23739; the directorate identifier for this docket is 2005-NM-240-AD.

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: 

Discussion

We proposed to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) with a notice of proposed rulemaking (NPRM) for a new AD for certain EMBRAER Model EMB-145, -145ER, -145MR, -145LR, -145XR, -145MP, and -145EP airplanes. That NPRM was published in the Federal Register on February 2, 2006 (71 FR 5626). The NPRM would have required modifying the routing of wire harness W407 near the fire extinguishing tube in the area of each engine, and installing new supports for related wiring. The NPRM resulted from reports of chafing of wire harness W407 against the supports and nacelle structure in the engine area. The proposed actions were intended to prevent such chafing, which could result in an engine shutting down during flight.

Actions Since NPRM Was Issued

Since we issued the NPRM, the airplane manufacturer, EMBRAER, has provided additional information concerning the unsafe condition identified in the NPRM. EMBRAER Service Bulletin 145-71-0008, Change 01, dated July 24, 2001 (which was referenced as the appropriate source of service information for accomplishing the proposed actions), addressed chafing of wire harness W407 on the left- and right-hand engines. However, EMBRAER subsequently indicates that the objective of that service bulletin was not considered to be a means to avoid in-flight shutdown (IFSD) and, in fact, wire harness W407 is not engine control related. The harness is related to the engine lip anti-ice system, starter control valve, engine fire detection system, and engine bleed air extraction systems. None of these systems are possible contributors to an uncommanded IFSD. In addition, reported IFSD events in the EMB-145 fleet related to chafing of a different harness—the engine control harness—are associated with the engine manufacturer-provided harness, which is not the subject of EMBRAER Service Bulletin 145-71-0008.

EMBRAER states that chafing (among other things) of the engine control system harness can cause internal failure of the full authority digital engine control (FADEC), which leads to a fuel shutoff valve closure command. However, in May 2001, EMBRAER introduced FADEC internal modifications for airplanes in production to prevent an inadvertent IFSD. Also, for FADECs manufactured before May 2001, Rolls-Royce, the engine manufacturer, developed an external adapter with the same design objectives as those of EMBRAER's internal modifications. These adapters have already been sent to operators to install in their affected airplanes. EMBRAER adds that the engine inspection tasks from the airplane maintenance program have been revised and improved, as well as the engine harness inspection and installation tasks in the aircraft maintenance manual (AMM).

FAA's Conclusions

Upon further consideration, we have determined that the unsafe condition identified in the NPRM does not exist. Accordingly, the NPRM is withdrawn.

We have coordinated this action with the Departamento de Aviação Civil (DAC), which is the airworthiness authority for Brazil. The DAC indicates it is considering cancelling its related airworthiness directive, 2005-10-05, which was effective November 17, 2005.

Withdrawal of the NPRM does not preclude the FAA from issuing another related action or commit the FAA to any course of action in the future.

Regulatory Impact

Since this action only withdraws an NPRM, it is neither a proposed nor a final rule and therefore is not covered under Executive Order 12866, the Regulatory Flexibility Act, or DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979).

List of Subjects in 14 CFR Part 39

• Air transportation
• Aircraft
• Aviation safety
• Safety

The Withdrawal

Accordingly, we withdraw the NPRM, Docket No. FAA-2006-23739; Directorate Identifier 2005-NM-240-AD, which was published in the Federal Register on February 2, 2006 (71 FR 5626).

Issued in Renton, Washington, on June 21, 2006.

Kalene C. Yanamura,

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.