This amendment adopts a new AD for Enstrom Model F-28, F-28A, F-28C, F-28C-2, F-28C-2R, F-28F, F-28F-R, 280, 280C, 280F, 280FX, TH-28, 480, and 480B helicopters with a retention pin, part number (P/N) 28-14007-3, installed, with a serial number (S/N) that is listed in the following table: \n\n\tRetention Pin S/N \n\n\nRetention Pin S/N \n04098-01 through 04098-56 \n05018-01 through 05018-36 \n05143-01 through 05143-56 \n05341-1 through 05341-8 \n05341-10 through 05341-17 \n05341-19 \n05341-21 through 05341-33 \n05341-35 through 05341-42 \n05341-44 through 05341-59 \n05341-61 \n05341-62 \n05341-64 through 05341-71 \n06214-3 through 06214-14 \n06214-16 through 06214-23 \n06214-25 through 06214-29 \n06214-31 \n06214-33 through 06214-35 \n06214-37 through 06214-57 \n06214-59 through 06214-68 \n\n\nThis action requires, before further flight, visually checking each retention pin to determine if the S/N, which is marked on the head of the retention pin, is listed inthe Applicability section of this AD. If there is no serial number marked on the head of the retention pin (i.e., the retention pin head is blank), the retention pin does not need to be replaced and this visual check constitutes a terminating action for the requirements of this AD for that retention pin. If an affected retention pin is installed, determining the retention pin's number of hours time-in-service (TIS) and removing and replacing it with an airworthy retention pin that has a S/N that is not listed in the Applicability section of this AD is required: \n\n\tWithin the next 5 hours TIS or within 30 days, whichever occurs first, if the retention pin has 545 or more hours TIS, or \n\n\tOn or before reaching 550 hours TIS or within 30 days, whichever occurs first, if the retention pin has less than 545 hours TIS. \n\nThis amendment is prompted by a report from the manufacturer that some retention pins were manufactured from steel that did not meet the specifications cited on the engineering drawing. The actions specified in this AD are intended to prevent failure of a retention pin, separation of a main rotor blade from the helicopter, and subsequent loss of control of the helicopter. \n\n\tWe have reviewed Enstrom Helicopter Corporation Service Directive Bulletin (SDB) No. 0102 and Enstrom Helicopter Corporation SDB No. T- 029, both dated March 20, 2007, which specify visual and magnetic particle inspections for cracks in certain serial-numbered retention pins, and repairing or replacing retention pins in accordance with certain inspection criteria. This AD does not require inspections for cracks but requires that each affected retention pin be replaced. \n\n\tThis unsafe condition is likely to exist or develop on other helicopters of the same type design. Therefore, this AD is being issued to prevent failure of a retention pin, separation of a main rotor blade from the helicopter, and subsequent loss of control of the helicopter. This AD requires removing and replacing certain serial-numbered retention pins. The visual check required by this AD may be performed by an owner/operator (pilot), but must be entered into the aircraft records showing compliance with paragraph (a) of this AD in accordance with 14 CFR 43.11 and 91.417(a)(2)(v). This AD allows a pilot to perform this check because it involves only a visual check of the head of each retention pin to determine the S/N. \n\n\tThe short compliance time involved is required because the previously described critical unsafe condition can adversely affect the controllability and structural integrity of the helicopter. Therefore, removing and replacing each affected retention pin is required within 5 hours TIS or within 30 days, depending on the retention pin's hours TIS, which constitutes a very short time period, and this AD must be issued immediately. \n\n\tSince a situation exists that requires the immediate adoption of this regulation, it is found that notice and opportunity for prior public comment hereon are impracticable, and that good cause exists for making this amendment effective in less than 30 days. \n\n\tWe estimate that this AD will affect 39 helicopters, and \n\n\tDetermining the S/N of all retention pins (3 on each helicopter) will take approximately 0.5 work hour; \n\n\tDetermining the hours TIS of three affected retention pins will take approximately 1 work hour; and \n\n\tRemoving and replacing three retention pins will take approximately 3 work hours at an average labor rate of $80 per work hour. Required parts will cost approximately $680 per helicopter. Based on these figures, we estimate the total cost impact of the AD on U.S. operators to be $1,040 per helicopter or $40,560 if all retention pins get replaced on the entire fleet. \n\nComments Invited \n\n\tThis AD is a final rule that involves requirements that affect flight safety and was not preceded by notice and an opportunity for public comment; however, we invite you to submit any written data, views, or arguments regarding this AD. Send your comments to an address listed under ADDRESSES. Include "Docket No. FAA-2007-28813; Directorate Identifier 2007-SW-09-AD'' at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of the AD. We will consider all comments received by the closing date and may amend the AD in light of those comments. \n\n\tWe will post all comments we receive, without change, to http://dms.dot.gov , including any personal information you provide. We will also post a report summarizing each substantive verbal contact with FAA personnel concerning this AD. Using the search function of our docket Web site, you can find and read the comments to any of our dockets, including the name of the individual who sent the comment. You may review the DOT's complete Privacy Act Statement in the Federal Register published on April 11, 2000 (65 FR 19477-78), or you may visit http://dms.dot.gov . \n\nRegulatory Findings \n\n\tWe 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. \n\n\tFor the reasons discussed above, I certify that the regulation: \n\n\t1. Is not a "significant regulatory action'' under Executive Order 12866; \n\n\t2. Is not a "significant rule'' under the DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and \n\n\t3. 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. \n\n\tWe prepared an economic evaluation of the estimated costs to comply with this AD. See the DMS to examine the economic evaluation. \n\nAuthority for This Rulemaking \n\n\tTitle 49 of the United States Codespecifies 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. \n\n\tWe 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. \n\nList of Subjects in 14 CFR Part 39 \n\n\tAir transportation, Aircraft, Aviation safety, Safety. \n\nAdoption of the Amendment \n\nAccordingly, pursuant to 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: \n\nPART 39--AIRWORTHINESS DIRECTIVES \n\n1. The authority citation for part 39 continues to read as follows: \n\n\tAuthority: 49 U.S.C. 106(g), 40113, 44701. \n\nSec. 39.13 (Amended) \n\n2. Section 39.13 is amended by adding a new airworthiness directive to read as follows: