SUPPLEMENTARY INFORMATION:

Comments Invited

We invite you to send any written relevant data, views, or arguments about this proposed AD. Send your comments to an address listed under the ADDRESSES section. Include “Docket No. ( printed page 65998) FAA-2009-0994; Directorate Identifier 2009-NE-39-AD” at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of this proposed AD. We will consider all comments received by the closing date and may amend this proposed AD because of those comments.

We will post all comments we receive, without change, to http://www.regulations.gov, including any personal information you provide. We will also post a report summarizing each substantive verbal contact we receive about this proposed AD.

Discussion

On May 20, 2011, we issued AD 2011-11-08, Amendment 39-16707 (76 FR 30529, May 26, 2011), for all RR RB211-535E4-37, -535E4-B-37, -535E4-B-75, and -535E4-C-37 turbofan engines. That AD requires performing an initial FPI on the LP turbine stage 1, 2, and 3 discs at the next engine shop inspection after the effective date of that AD. That AD also requires repetitive inspections at each engine shop visit after accumulating 1,500 cycles since last inspection of the LP turbine stage 1, 2, and 3 discs. That AD resulted from several findings of cracking at the firtrees of LP turbine discs. We issued that AD to detect cracks in the LP turbine stage 1, 2, and 3 discs, which could result in an uncontained release of LP turbine blades and damage to the airplane.

Actions Since Existing AD Was Issued

Since we issued AD 2011-11-08, Amendment 39-16707 (76 FR 30529, May 26, 2011), we found that the definition of “shop visit” in the AD is too restrictive, in that it would require operators to inspect more often than required to ensure safety.

Costs of Compliance

We estimate that this proposed AD would affect about 588 RB211-535 series turbofan engines installed on airplanes of U.S. registry. We also estimate that it would take about 30 work-hours per product to comply with this proposed AD. The average labor rate is $85 per work-hour. No parts are required. Based on these figures, we estimate the cost of this proposed AD on U.S. operators to be $1,499,400.

FAA's Determination

We are proposing this AD because we evaluated all the relevant information and determined that the definition of shop visit is too restrictive, and to correct the unsafe condition described previously. This condition is likely to exist or develop in other products of the same type design.

Proposed AD Requirements

This AD requires accomplishing the same requirements as AD 2011-11-08 (76 FR 30529, May 26, 2011), except the definition of shop visit has been redefined.

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 have determined that this proposed AD would not have federalism implications under Executive Order 13132. This proposed AD 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.

For the reasons discussed above, I certify that the 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),

(3) Will not affect intrastate aviation in Alaska, and

(4) 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.

The Proposed Amendment

Accordingly, under the authority delegated to me by the Administrator, the FAA proposes to amend 14 CFR part 39 as follows: