On August 14, 2008, we issued Emergency AD 2008-17-51 for the specified MDHI model helicopters. The Emergency AD requires fluorescent magnetic particle inspecting the aft threads of the control cable for a crack and replacing the control cable with an airworthy part if you find a crack. If you do not find a crack, the Emergency AD requires that you demagnetize the cable threads until you reach a certain gauss level. The Emergency AD also requires visually inspecting the aft cable attach bracket for a crack and for interference with movement of the control cable or for deformation of the aft cable attach bracket. If a crack or interference with movement of the control cable or deformation of the aft cable attach bracket exists, the Emergency AD requires replacing the bracket with an airworthy part. The Emergency AD also requires modifying the control cable conduit and the rotating cone control rod and identifying the rotating cone control rod with part number``900C2010582-105.'' The Emergency AD was prompted by three reports of in-flight failure of the control cable and loss of yaw control resulting in emergency landings and subsequent damage to the helicopter. This condition, if not corrected, could result in loss of yaw control and subsequent loss of control of the helicopter.
MDHI has issued Service Bulletin SB900-108R1, dated August 13, 2008, which describes procedures for magnetic particle inspecting and modifying the control cable and rotating cone control rod installation.
Since the unsafe condition described is likely to exist or develop on other MDHI model helicopters of the same type design, we issued Emergency AD 2008-17-51 to prevent loss of yaw control and subsequent loss of control of the helicopter. The Emergency AD requires the following, before further flight:
Remove the rotating cone, the thruster extension, and the rotating cone control rod, and NAS1193K4CP lock device (2 parts).
Do a fluorescent magnetic particle inspection for a crack in the aft threads of the control cable. If you find a crack, replace the control cable with an airworthy part. If you do not find a crack, demagnetize the cable threads until you reach a gauss level of +/-3.
Visually inspect the aft cable attach bracket for a crack. Inspect for interference with the movement of the control cable or for deformation of the aft cable attach bracket. If a crack or interference with the movement of the control cable or deformation of the aft cable attach bracket exists, replace the bracket with an airworthy part.
Cut and modify the aft end of the control cable conduit.
Modify the rotating cone control rod by drilling lock wire holes. Using permanent ink, identify the rotating cone control rod with part number 900C2010582-105.
Inspect the control cable for proper adjustment.
Install the rotating cone control rod.
Install the thruster extension.
Install the rotating cone. If you adjust the control cable at the attach brackets, inspect for interference with the movement of the control cable or for deformation of the aft cable attach bracket. If interference with the movement of the control cable or deformation of the aft cable attach bracket exists, replace the bracket with an airworthy part.
Rerig the antitorque directional control system.
The actions must be done by following specified portions of the service bulletin described previously. The short compliance time involved is required because the previously described critical unsafe condition can adversely affect the controllability of the helicopter. Therefore, the actions described previously 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, and good cause existed to make the AD effective immediately by individual letters issued on August 14, 2008, to all known U.S. owners and operators of MDHI Model MD900 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 33 helicopters of U.S. registry. It will take about 5.5 work hours to remove, modify, visually inspect, and install parts, and 2 work hours to fluorescent magnetic particle inspect the aft threads in the control cable per helicopter at an average labor rate of $80 per work hour. The kits required to modify the control cable cost about $8,603 for the entire fleet. Based on these figures, we estimate the total cost impact of the AD on U.S. operators to be $28,403.
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-2008- 1250; Directorate Identifier 2008-SW-49-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.
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 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).
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 an economic evaluation of the estimated costs to comply with this AD. See the AD docket 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 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.
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 FederalAviation 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. Section 39.13 is amended by adding a new airworthiness directive to read as follows: