E6-7015. Airworthiness Directives; Empresa Brasileira de Aeronautica S.A. (EMBRAER) Model EMB-135 and 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 all EMBRAER Model EMB-135 and EMB-145, -145ER, -145MR, -145LR, -145XR, -145MP, and -145EP airplanes. The proposed AD would have required inspecting to determine the part number of the ailerons. For airplanes with affected aileron part numbers, the proposed AD would have required reworking the aileron damper fitting, and for certain airplanes, replacing the rod end of the aileron damper assembly with an improved rod end. Since the proposed AD was issued, we have received new data indicating that there is no unsafe condition associated with structural failure of the rod end of the aileron damper. Accordingly, the proposed AD is withdrawn.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-2006-23673; the directorate identifier for this docket is 2005-NM-233-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 all EMBRAER Model EMB-135 and EMB-145, -145ER, -145MR, -145LR, -145XR, -145MP, and -145EP airplanes. That NPRM was published in the Federal Register on January 25, 2006 (71 FR 4067). The NPRM would have required inspecting to determine the part number of the ailerons. For airplanes with affected aileron part numbers, the NPRM would have required reworking the aileron damper fitting. Also, for certain airplanes, the NPRM would have required replacing the rod end of the aileron damper assembly with an improved rod end. The NPRM resulted from reports of structural failure of the rod end of the aileron damper, which was caused by insufficient clearance between the lugs of the aileron damper fitting and the rod end of the aileron damper. The proposed actions were intended to prevent failure of the aileron damper, which could result in failure of the aileron actuator and consequent reduced controllability of the airplane.

Comments

EMBRAER requests that we withdraw the NPRM. EMBRAER points out that the unsafe condition stated in the NPRM (failure of the aileron damper, which could result in failure of the aileron actuator and consequent reduced controllability of the airplane) is incorrect. While the NPRM was intended to address reports of structural failure of the rod end of the aileron damper, there is no unsafe condition caused by such a failure. The aileron damper was introduced to improve safety by increasing redundancy: the aileron damper prevents vibration of the aileron surface in the event of failure of both rods of the aileron power control actuator (PCA). Failure of the rod end of the aileron damper and subsequent failure of the aileron damper will not cause vibration of the aileron surface.

Further, while failure of the rod ends of the aileron PCA could result in reduced controllability of the airplane, this unsafe condition is already addressed by another action. EMBRAER notes that the FAA has previously issued AD 99-05-04 (64 FR 13894, March 23, 1999). That AD requires inspections to detect and correct cracking or failure of the rod ends of the aileron PCA on all EMBRAER Model EMB-145 series airplanes.

EMBRAER further states that repetitive inspections of the aileron damper rod ends and fitting lugs for integrity and general condition are specified as a Certification Maintenance Requirement (for Model EMB-135 airplanes) and a System Inspection Requirement (for Model EMB-145 airplanes). The failures of the aileron damper rod ends that prompted the NRPM were discovered during inspections performed under these requirements.

We agree with the commenter's request to withdraw the NPRM. EMBRAER Service Bulletin 145-27-0108, Revision 01, dated April 28, 2005, which the NPRM references as the appropriate source of service information for the required actions, was issued to correct insufficient clearance between the lugs of the aileron damper fitting and the rod end of the aileron damper. We have coordinated with EMBRAER and have determined that the actions in that service bulletin are not intended to address an unsafe condition. Doing those actions may provide an economic benefit to operators by preventing the need for an expensive repair in the event that damage is detected during routine inspections. Since there is no unsafe condition, the proposed AD is unnecessary.

FAA's Conclusions

Upon further consideration, we have determined that there is no unsafe condition associated with structural failure of the rod end of the aileron damper. Accordingly, the NPRM is withdrawn.

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-2006-23673, Directorate Identifier 2005-NM-233-AD, which was published in the Federal Register on January 25, 2006 (71 FR 4067).

Issued in Renton, Washington, on April 28, 2006.

Ali Bahrami,

Manager, Transport Airplane Directorate, Aircraft Certification Service.