2012-15097. Airworthiness Directives; Dassault Aviation 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 Dassault Aviation Model FALCON 7X airplanes. The proposed AD would have required revising the maintenance program to incorporate a limitation that reduced time between overhauls, and required an initial overhaul, of the direct current (DC) generator (bearings). Since the proposed AD was issued, we have received new data that confirm the identified unsafe condition is not sufficient to warrant issuance of an AD. Accordingly, the proposed AD is withdrawn.

ADDRESSES:

You may examine the AD docket on the Internet at http://www.regulations.gov;​; or in person at the Docket Management Facility between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The AD docket contains this AD action, the regulatory evaluation, any comments received, and other information. The address for the Docket Office (telephone [phone]) is the Document Management Facility, U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue SE., Washington, DC 20590.

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:

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 Dassault Aviation Model FALCON 7X airplanes. That NPRM was published in the Federal Register on March 15, 2011 (76 FR 13924). That NPRM would have required revising the maintenance program to incorporate a limitation that reduced time between overhauls, and required an initial overhaul, of the DC generator (bearings). That NPRM resulted 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 described the unsafe condition as:

Time between overhaul (TBO) of DC [direct current] generator bearings is set at 1,000 flight hours (FH) in the airworthiness limitations section of the Falcon 7X Aircraft Maintenance Manual Chapter 5.40.

In service report has shown that the bearing current design cannot sustain the current TBO. * * *

* * * * *

Failure to comply with those revised maintenance tasks could constitute an unsafe condition.

The proposed actions were intended to prevent failure of the DC generator bearings, which could lead to loss of the generator and potential loss of electrical power to the fly-by-wire system and subsequent loss of control of the airplane.

Actions Since NPRM (76 FR 13924, March 15, 2011) Was Issued

Since we issued the NPRM (76 FR 13924, March 15, 2011), the airplane manufacturer provided further information on the redundancy of the electrical system that supplies power to the fly-by-wire system. There are three DC generators that can supply electrical power to the fly-by-wire system. Electrical power can also be supplied by two independent permanent magnet alternator converters that are dedicated to that system. Failure of all three DC generators to supply electrical power automatically triggers a command to deploy the ram air turbine, which will supply the airplane systems (including fly-by-wire) with sufficient electrical power for continued safe flight and landing.

FAA's Conclusions

Upon further consideration, we have determined that, based on the airplane design, and the multiple electrical power generation sources, the potential loss of one DC generator due to an un-reduced maintenance interval would not result in loss of electrical power to the airplane. Therefore, the potential loss of one DC generator does not constitute an unsafe condition. Accordingly, the NPRM (76 FR 13924, March 15, 2011) is withdrawn.

Withdrawal of the NPRM (76 FR 13924, March 15, 2011) 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 (76 FR 13924, March 15, 2011), 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
• Incorporation by reference
• Safety

The Withdrawal

Accordingly, we withdraw the NPRM, Docket No. FAA-2011-0222, Directorate Identifier 2010-NM-056-AD, which was published in the Federal Register on March 15, 2011 (76 FR 13924).

Issued in Renton, Washington, on June 12, 2012.

Kalene C. Yanamura,

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.