Discussion
We issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 to include an AD that would apply to the specified products. That NPRM was published in the Federal Register on May 7, 2008 (73 FR 25612). That NPRM proposed to correct an unsafe condition for the specified products. The MCAI states:
Following in-flight test deployments, several Air-Driven generators (ADGs) failed to come on-line. Investigation revealed that, as a result of a wiring anomaly that had not been detected during ADG manufacture, a short circuit was possible between certain internal wires and their metallic over-braided shields, which could result in the ADG not providing power when deployed. This directive mandates checking of the ADG and modification of the ADG internal wiring, if required. It also prohibits future installation of unmodified ADGs.
The unsafe condition is that failure of the ADG could lead to loss of several functions essential for safe flight. You may obtain further information by examining the MCAI in the AD docket.
Comments
We gave the public the opportunity to participate in developing this AD. We considered the comments received.
Request To Extend Compliance Time for Inspecting the Identification Plate
Comair requests that we change the compliance time specified in paragraph (f)(1)(ii) of the NPRM to remove the "before further flight'' phrase. Comair states that it has already reviewed its maintenance records and found that affected ADGs are installed on its fleet. Since the review was performed before the effective date of the AD, it is not clear when Comair would be required to inspect the ADG identification plate. Comair suggests a compliance time of 12 months after the effective date of the AD.
We agree to change the compliance time. The intent of the AD is to inspect and modify the ADG wiring within 12 months after the effective date of the AD. We have revised the compliance timeof paragraph (f)(1)(ii) of this AD accordingly.
Request To Shorten Compliance Time and Restrict Dispatch Conditions
Air Line Pilots Association, International (ALPA), requests that the compliance time be shortened from 12 months to 3 months. ALPA states that although its review did not reveal any incidents of full electrical failures in Bombardier airplanes, the ADG is the only remaining source of electrical power sustaining the batteries and flight critical electrical systems if all other generators fail or are unavailable. In addition, ALPA states there are procedures for deferring an engine-driven or APU generator under certain circumstances, but the ADG is a non-deferrable item. ALPA recommends that, given the potential consequences of a full electrical system failure, particularly in low visibility weather conditions in which these airplanes routinely operate, we shorten the compliance time to 3 months. ALPA also recommends that no flights be allowed with a non- operatingengine-driven or APU generator unless this AD has been complied with.
We do not agree to shorten the compliance time. We have considered the risks (probability of dual engine shutdown due to a common cause and total loss of electrical power, including the emergency battery power) and have determined that a 12-month compliance time is appropriate. The issue of not allowing flights to be dispatched without an operational engine-driven or APU generator would be better addressed in the applicable Master Minimum Equipment List (MMEL). We are considering a revision to the MMEL for that issue. No change to the AD was made in this regard.
Request To Revise Applicability
Air Wisconsin Airlines requests that the applicability section of the AD be revised to apply to the part and serial numbers of the ADG instead of the serial numbers of the airplanes. Air Wisconsin points out that the ADG is a rotable, serialized component which can be installed on any applicable airplane.
We donot agree to revise the applicability. The serial number range for the airplane addresses airplanes on which the ADG was delivered and airplanes on which the ADG could be installed. Paragraph (f)(1) of this AD addresses airplanes that were delivered with ADGs installed, while paragraph (f)(2) of this AD addresses airplanes that ADGs could be installed on. We have not revised the AD in this regard.
Request To Revise Installation Criteria for Identification Plate
Air Wisconsin requests that we revise a phrase in paragraph (f)(2) of this AD from "* * * no ADG * * * may be installed * * * unless the identification plate of the ADG is identified with the symbol `24-2' '' to "* * * no ADG * * * may be installed * * * unless the ADG has been modified in accordance with [Bombardier] SB 601R-24-113.'' Air Wisconsin considers that what is important is not that the data plate has been marked "24-2'', but that the modification in the service bulletin is done. Part 121 operators have approved methods for showing compliance with ADs.
We do not agree to revise the phrase in paragraph (f)(2) of this AD. Not all affected ADGs are installed on airplanes operated by Part 121 operators. Bombardier Service Bulletin 601R-24-113, Revision A, dated August 11, 2005, refers to Hamilton Sundstrand Service Bulletin ERPS10AG-24-2, dated February 19, 2004, as a source of information for accomplishing the Bombardier service bulletin. The Hamilton Sundstrand service bulletin specifies that ADGs modified in accordance with that service bulletin should have "24-2'' marked on the identification plates. We have not changed the AD in this regard.
Clarification
We have revised paragraphs (f)(1)(i) and (f)(1)(ii)(A) of this AD from "* * * by this AD.'' to "* * * by this paragraph.'' to clarify that if the criteria in those paragraphs are met, no further actions are required by those paragraphs. The requirements of paragraph (f)(2) of this AD would still be in effect.
We have removed reference to Hamilton Sundstrand Service Bulletin ERPS10AG-24-2, dated February 19, 2004, from paragraph (f)(2) of this AD. Instead, we have added Note 1 of this AD to include this information.
Conclusion
We reviewed the available data, including the comments received, and determined that air safety and the public interest require adopting the AD with the changes described previously. We determined that these changes will not increase the economic burden on any operator or increase the scope of the AD.
Differences Between This AD and the MCAI or Service Information
We have reviewed the MCAI and related service information and, in general, agree with their substance. But we might have found it necessary to use different words from those in the MCAI to ensure the AD is clear for U.S. operators and is enforceable. In making these changes, we do not intend to differ substantively from the information provided in the MCAI and related service information.
We might also have required different actions in this AD from those in the MCAI in order to follow our FAA policies. Any such differences are highlighted in a Note within the AD.
Costs of Compliance
We estimate that this AD will affect 686 products of U.S. registry. We also estimate that it will take about 5 work-hours per product to comply with the basic requirements of this AD. The average labor rate is $80 per work-hour. Required parts will cost about $0 per product. Where the service information lists required parts costs that are covered under warranty, we have assumed that there will be no charge for these parts. As we do not control warranty coverage for affected parties, some parties may incur costs higher than estimated here. Based on these figures, we estimate the cost of this AD to the U.S. operators to be $274,400 or $400 per product.
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 determined that this AD will not have federalism implications under Executive Order 13132. This AD will 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 this AD:
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. 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.
We prepared a regulatory evaluation of the estimated costs to comply with this AD and placed it in the AD docket.
Examining the AD Docket
You may examine the AD docket on the Internet at http:// www.regulations.gov; or in person at the Docket Operations office between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The AD docket contains the NPRM, the regulatory evaluation, any comments received, and other information. The street address for the Docket Operations office (telephone (800) 647-5527) is in the ADDRESSES section. Comments will be available in the AD docket shortly after receipt.
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.
Adoption of the Amendment
Accordingly, under the authority delegated to me by the Administrator, the FAA amends 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.
Sec. 39.13 [Amended]
2. The FAA amends Sec. 39.13 by adding the following new AD: