On April 27, 2007, the FAA issued Emergency AD 2007-09-51 (EAD) for the specified MDHI model helicopters. The EAD requires, before further flight, removing each affected tail rotor blade assembly and, using a bright light, inspecting the bore of the tail rotor blade root fitting. If the blade assembly does not have a smooth radius, the AD requires replacing it. The AD also requires identifying each airworthy tail rotor blade assembly with the applicable model of helicopter. That action was prompted by a report of an accident after the loss of a tail rotor blade. This condition, if not corrected, could result in the failure of a tail rotor blade and subsequent loss of control of the helicopter.
MDHI has issued Service Bulletin No. SB369H-247, SB369D-204, SB369E-099, and SB369F-084, dated April 26, 2007 (SB), which describes procedures for inspecting the tail rotor blade assembly. The SB states that reports from the field have shown that there are tail rotor blades in operation with a machining defect. The SB further states that these blades have a sharp transition in the tapered end of the root fitting bore that can cause the tail rotor blade root fitting to fail.
Since the unsafe condition described is likely to exist or develop on other MDHI model helicopters of these same type designs, the FAA issued EAD 2007-09-51 to prevent the failure of a tail rotor blade and subsequent loss of control of the helicopter. This AD requires the following, before further flight:
Remove each affected tail rotor blade assembly. Using a bright light, inspect the bore of the tail rotor blade root fitting.
Replace each blade assembly that does not have a smooth radius.
Identify the airworthy tail rotor blade assembly with the applicable model of helicopter.
The actions must be done by following specified portions of the ASB described previously. The 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 each affected blade assembly, inspecting the bore of the tail rotor blade root fitting, and replacing each blade assembly that does not have a smooth radius are required before further flight, and this AD must be issued immediately.
Since it was found that immediate corrective action was required, notice and opportunity for prior public comment thereon were impracticable and contrary to the public interest. Good cause existed to make the AD effective immediately by individual letters issued on April 27, 2007, to all known U.S. owners and operators of MD Helicopters, Inc., Model 369 (Army YOH-6A), 369A (Army OH-6A), 369H, 369HM, 369HS, 369HE, 369D, 369E, 369F, and 369FF helicopters. These conditions still exist, and the AD is hereby published in the Federal Register as an amendment to 14 CFR 39.13 to make it effective to all persons.
The FAA estimates that this AD will affect 980 helicopters of U.S. registry and will require about:
0.1 work hour to identify a blade,
2 work hours to remove, inspect, install and balance the tail rotor blade assemblies on each helicopter,
$80 per work hour labor rate, and
$8,862 for each replacement blade plus hardware.
Based on these figures, we estimate the total cost impact of the AD on U.S. operators to be $1,901,592, assuming 1 out of 10 blades are found defective for an estimated 196 blades that need replacing.
Comments Invited
This 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-2007-28449; Directorate Identifier 2007-SW-18-AD'' at the beginning of your comments. We specifically invite comments on the overallregulatory, 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.
We 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.
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 theStates, 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 an economic evaluation of the estimated costs to comply with this AD. See the DMS to examine the economic evaluation.
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 areissuing 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.
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.
Adoption of the Amendment
Accordingly, 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:
PART 39--AIRWORTHINESS DIRECTIVES
1. The authority citation for part 39 continues to read asfollows:
Authority: 49 U.S.C. 106(g), 40113, 44701.
Sec. 39.13 [Amended]
2. Section 39.13 is amended by adding a new airworthiness directive to read as follows: