Comments Invited
This AD is a final rule that involves requirements affecting flight safety, and we did not provide you with notice and an opportunity to provide your comments prior to it becoming effective. However, we invite you to participate in this rulemaking by submitting written comments, data, or views. We also invite comments relating to the economic, environmental, energy, or federalism impacts that resulted from adopting this AD. The most helpful comments reference a specific portion of the AD, explain the reason for any recommended change, and include supporting data. To ensure the docket does not contain duplicate comments, commenters should send only one copy of written comments, or if comments are filed electronically, commenters should submit them only one time. We will file in the docket all comments that we receive, as well as a report summarizing each substantive public contact with FAA personnel concerning this rulemaking duringthe comment period. We will consider all the comments we receive and may conduct additional rulemaking based on those comments.
Discussion
We are adopting a new AD for Columbia Model 234 helicopters. This AD requires visually and tap inspecting each rotor blade for any defect, damage, or disbond. If there is a defect, damage, or a disbond, this AD requires the blade to be repaired or replaced before further flight. Also, this AD requires dye-penetrant inspecting the aft pylon structure for a crack in the area of the station (STA) 534 and 594 tension attachment fittings. If there is a crack, this AD requires repairing or replacing the aft pylon before further flight. This AD is prompted by an accident caused by fatigue failure of the structure surrounding the aft pylon following an aft rotor blade failure. Due to existing blade damage, a portion of an aft rotor blade separated from the aircraft, causing vibration, which accelerated fatigue cracking of the aft pylon surrounding structure and overloaded the structure to failure. This caused the aft pylon to separate from the aircraft. The actions specified in this AD are intended to detect cracks in the aft pylon surrounding structure and defects, damage, or disbonds in the rotor blades and to prevent separation of a portion of the rotor blade, vibration, overload of the aft pylon surrounding structure, departure of the aft pylon, and
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subsequent loss of control of the helicopter.
FAA's Determination
We are issuing this AD because we evaluated all the relevant information and determined the unsafe condition described previously is likely to exist or develop in other helicopters of this same type design.
Related Service Information
Columbia issued Service Bulletin No. 234-54-0004, Revision 0, dated November 22, 2013 (SB 234-54-0004), specifying an initial and recurring dye-penetrant inspection to detect and correct cracking of the aft pylon structure at the STA 534and 594 tension attachment fittings. If a crack is found, SB 234-54-0004 specifies contacting the manufacturer before further flight.
Columbia also issued Service Bulletin No. 234-62-0008, Revision 1, dated December 6, 2013 (SB 234-62-0008), specifying recurring visual inspections of the entire rotor blade for defects, damage and disbonds and recurring tap inspections of the rotor blade trailing edge for disbonding conditions. If any damage or disbond is detected, SB 234-62- 0008 specifies referring to the maintenance manual for serviceability and repair, contacting the manufacturer for repair assistance, or replacing the blade before further flight.
AD Requirements
This AD requires:
Within 50 hours time-in-service (TIS):
[cir] Cleaning, visually inspecting, and tap inspecting each rotor blade for a defect, damage, or disbond.
[cir] Repairing any defect, damage, or disbond if within acceptable limits, and replacing the blade if beyond acceptable limits, before further flight.
Within 50 hours TIS and thereafter at intervals not to exceed 100 hours TIS, inspecting the aft pylon at STA 534 and 594 as follows:
[cir] Dye-penetrant inspecting the aft pylon at the attachment fittings and surrounding structure for a crack.
[cir] If there is a crack, before further flight, repairing or replacing the aft pylon.
This AD prohibits installing an aft pylon or a rotor blade until these inspections are accomplished.
Differences Between This AD and the Service Information
This AD does not require the 500-hour TIS inspection of the rotor blade or the 3,000 hour TIS after initial inspection of the pylon structure as specified in the service information. We plan to publish a notice of proposed rulemaking to give the public an opportunity to comment on those long-term requirements. Also, this AD does not require contacting the manufacturer.
Interim Action
We consider this AD to be an interim action. The design approval holder is currently developing a terminating action that will address the unsafe condition identified in this AD. Once this terminating action is identified, we might consider further rulemaking then.
Costs of Compliance
We estimate that this AD affects 4 helicopters of U.S. Registry. We estimate that operators may incur the following costs to comply with this AD. Labor costs are estimated at $85 per hour. We estimate 1 work hour to visually inspect all blades, 6 work hours to dye-penetrant inspect the pylon, and 4 work hours to do the tap test inspection. Based on these estimates, the total cost is $935 per helicopter and $3,740 for the U.S. fleet. To replace a blade, we estimate 4 work hours and $250,000 for parts, for a total cost of $250,340 per helicopter.
FAA's Justification and Determination of the Effective Date
Providing an opportunity for public comments before adopting these AD requirements would delay implementing the safety actions needed to correctthis known unsafe condition. Therefore, we find that the risk to the flying public justifies waiving notice and comment prior to adopting this rule because of the severity of the failure and high rate of occurrence for repairs in blades and cracks in the pylon on other aircraft. Also, the required corrective actions must be done within 50 hours TIS, a very short time period based on the average flight-hour utilization rate of these helicopters. The repetitive inspections are required at intervals not to exceed 100 hours TIS, which can be reached within as short a time as 2 weeks.
Since an unsafe condition exists that requires the immediate adoption of this AD, we determined that notice an opportunity for public comment before issuing this AD are impracticable and contrary to the public interest and that good cause exists for making this amendment effective in less than 30 days.
Authority for This Rulemaking
Title 49 of the United States Code specifies the FAA's authorityto 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, and 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, I certify that this AD:
1. Is not a ``significant regulatory action'' under Executive Order 12866;
2. Is not a ``significant rule'' under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979);
3. Will not affect intrastate aviation in Alaska to the extent that it justifies making a regulatory distinction; and
4. 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 and placed it in the AD docket.
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.