Discussion
On August 21, 2009, we issued a proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an AD that would apply to certain Twin Commander Aircraft LLC Models 690, 690A, and 690B airplanes. This proposal was published in the Federal Register as a notice of proposed rulemaking (NPRM) on August 28, 2009 (74 FR 44308). The NPRM proposed to require you to inspect between the surface of the LH and RH upper wing skins and the engine mount beam support straps for any signs of corrosion, replace the upper steel straps with parts of improved design, and modify both wings.
Comments
We provided the public the opportunity to participate in developing this AD. The following presents the comments received on the proposal and FAA's response to each comment:
Comment Issue: Extend Compliance Time
Michael Curtis Pidek, William I. Smith, and Tom Bayer all state that with 275 airplanes affected by this AD andonly 15 service centers available to do the actions required in this AD, there is not enough time to comply with the AD.
All three commenters request an extension of the compliance time to allow enough time for the service centers to schedule the work without grounding airplanes until the work can be done.
We do not agree with the commenters. Over 65 airplanes are already in compliance with this AD. We have consulted with Twin Commander Aircraft LLC and they have covered this issue with the service centers. The service centers know how much work is required since they have already done the work on over 65 of the affected airplanes. The service centers plan on using multiple teams to work on several airplanes at the same time. They have confirmed they can perform the actions required in this AD in the compliance time as proposed.
Part of the alternative method of compliance (AMOC) provisions of 14 CFR 39.19 is an extension of the compliance time provided a level of safety acceptable to the FAA is met. The FAA will review any AMOCs of this nature on a case-by-case basis. If we determine the proposal presents an acceptable level of safety, we will approve it as an AMOC to the AD.
We are not changing the final rule AD action based on these comments.
Conclusion
We have carefully reviewed the available data and determined that air safety and the public interest require adopting the AD as proposed except for minor editorial corrections. We have determined that these minor corrections:
Are consistent with the intent that was proposed in the NPRM for correcting the unsafe condition; and
Do not add any additional burden upon the public than was already proposed in the NPRM.
Costs of Compliance
We estimate that this AD will affect 275 airplanes in the U.S. registry.
We estimate the following costs to do the inspection:
Labor Cost
Parts Cost
Total Cost Per Airplane
Total Cost on U.S. Operators
80 work-hours X $80 per hour = $6,400
Not applicable
$6,400
$1,760,000
We estimate the following costs to do any necessary repairs/ replacements that will be required based on the results of the inspection. We have no way of determining the number of airplanes that may need this repair/replacement:
Short Modification--Option A *
Labor Cost
Parts Cost
Total Cost Per Airplane Per Side
250 work-hours X $80 per hour = $20,000 per side
$9,170 per kit per side
$29,170
Middle Modification--Option B *
Labor Cost
Parts Cost
Total Cost Per Airplane Per Side
280 work-hours X $80 per hour = $22,400 per side
$9,170 per kit per side
$31,570
Long Modification--Option C *
Labor Cost
Parts Cost
Total Cost Per Airplane Per Side
320 work-hours X $80 per hour = $25,600 per side
$9,170 per kit per side
$34,770
Note: * Depending on airplane configuration, airplanes with rectangular plates will need the Plate and Hardware Kit (SB237-4) at $2,090 per side. Labor to install this kit is included in Options A, B, and C.
Strap Only Replacement--Option D
Labor Cost
Parts Cost
Total Cost Per Airplane Per Side
75 work-hours X $80 per hour = $6,000 per side
$6,190 per strap per side
$12,190
We estimate the following costs to do the installation of access holes:
Labor Cost
Parts Cost
Total Cost Per Airplane
Total Cost on U.S. Operators
30 work-hours X $80 per hour = $2,400
$1,293
$3,693
$1,015,575
We estimate the following costs to do the wing fastener modification:
Labor Cost
Parts Cost
Total Cost Per Airplane
Total Cost on U.S. Operators
8.5 work-hours X $80 per hour = $680
$250
$930
$255,750
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 AD.
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 this AD:
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 other information as included in the Regulatory Evaluation) 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 "Docket No. FAA-2009-0778; Directorate Identifier 2009-CE-040-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:
PART39--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. FAA amends Sec. 39.13 by adding a new AD to read as follows: