On February 13, 2004, the FAA issued AD 2004-04-04, Amendment 39-13485 (69 FR 8098, February 23, 2004). That AD requires initial and repetitive reviews of the airplane computer systems for master VG actuator fault messages of certain SN master VG actuators. That AD also requires replacement of actuators reported faulty by the FADEC. The background for that AD is as follows:
In September of 2002, GE, the manufacturer of CF34-8E series turbofan engines, replaced its supplier of dual-channel linear variable differential transformers (LVDTs), installed on the master VG actuator, part number 4120T02P02. Since that changing of suppliers, four master VG actuators, installed on CF34-8E engines, with LVDTs produced by the new supplier have been reported with single-channel electrical signal faults. The CF34-8E engines use the same part number VG master actuator as the CF34-8C series engines, which have experienced 54 LVDT faults in service, to date. One of thesemaster VG actuators also experienced a failure of the second LVDT channel, seventeen days after the first single-channel fault report, resulting in the FADEC commanding the engine power to idle. The manufacturer's investigation revealed LVDT coil wire deformation and breakage, caused by thermal expansion of potting material. That condition, if not corrected, could result in dual channel electrical signal faults in the master VG actuator, which will cause an uncommanded reduction of thrust to idle with a subsequent loss of the ability to advance thrust above idle, and result in multiengine loss of thrust if dual-channel faults occur on more than one engine simultaneously, and possible loss of the airplane.
Actions Since AD 2004-04-04 Was Issued
Since AD 2004-04-04 was issued, we learned that PMA holder, Arkwin Industries, Inc., has master VG actuators in service with affected LVDTs installed. The same unsafe condition described previously for master VG actuators, SN APM238AE, and SNs APM242AE and up, is likely to exist or develop on these PMA master VG actuators. The PMA actuators are identified by P/N 1211508-002, SN 238AE, and SNs 241AE and up. These actuators also have GE P/N 4120T02P02 marked on them.
Relevant Service Information
We have reviewed and approved the technical contents of GE Alert Service Bulletin (ASB) No. CF34-8E-AL S/B 75-A0001, Revision 3, dated February 14, 2005, that describes procedures for initial and repetitive reviews of the airplane computer systems for fault messages, and replacement of actuators reported faulty by the FADEC.
FAA's Determination and Requirements of This AD
The unsafe condition described previously is likely to exist or develop on other CF34-8E series turbofan engines of the same type design. We are issuing this AD to prevent dual-channel electrical signal faults in the master VG actuator, which will cause an uncommanded reduction of thrust to idle with a subsequent loss of the ability to advancethrust above idle, and will result in a multiengine loss of thrust if dual-channel faults occur on more than one engine simultaneously.
This AD prohibits installation of any master VG actuator specified in this AD, onto any CF34-8E series turbofan engine after the effective date of the AD. This AD also requires an initial review within 10 days after the effective date of the AD, of the airplane computer systems for fault messages, and replacement of actuators reported faulty by the FADEC. Actuator hardware troubleshooting may be required to identify faulty actuators. Also, this AD requires the same repetitive reviews, at intervals not to exceed 10 days. Replacement of actuators reported faulty by the FADEC is required either before further flight or within 10 days of the first fault occurrence, based on requirements defined in the service information described previously, for the actual fault reported. You must use the service information described previously to perform the actions required by this AD.
FAA's Determination of the Effective Date
Since an unsafe condition exists that requires the immediate adoption of this AD, we have found that notice and opportunity for public comment before issuing this AD are impracticable, and that good cause exists for making this amendment effective in less than 30 days.
Comments Invited
This AD is a final rule that involves requirements affecting flight safety and was not preceded by notice and an opportunity for public comment; however, we invite you to submit any written relevant data, views, or arguments regarding this AD. Send your comments to an address listed under ADDRESSES. Include "AD Docket No. 2004-NE-06-AD" in the subject line of your comments. If you want us to acknowledge receipt of your mailed comments, send us a self-addressed, stamped postcard with the docket number written on it; we will date-stamp your postcard and mail it back to you. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of the rule that might suggest a need to modify it. If a person contacts us verbally, and that contact relates to a substantive part of this AD, we will summarize the contact and place the summary in the docket. We will consider all comments received by the closing date and may amend the AD in light of those comments.
Examining the AD Docket
You may examine the AD Docket (including any comments and service information), by appointment, between 8 a.m. and 4:30 p.m., Monday through Friday, except Federal holidays. See ADDRESSES for the location.
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 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 that the 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); 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 summary of the costs to comply with this AD and placed it in the AD Docket. You may get a copy of this summary by sending a request to us at the address listed under ADDRESSES. Include "AD Docket No. 2004-NE-06-AD" in your request.
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 Federal Aviation Administration amends part 39 of the Federal Aviation Regulations (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 removing Amendment 39-13485 (69 FR 8098, February 23, 2004), and by adding a new airworthiness directive, Amendment 39-14033, to read as follows: