AD 2005-17-16

This AD becomes effective September 30, 2005. The Director of the Federal Register approved the incorporation by reference of certain publications listed in the regulations as of September 30, 2005.

You can get the service information identified in this AD from Pratt & Whitney, 400 Main St., East Hartford, CT 06108; telephone (860) 565-7700; fax (860) 565-1605.

You may examine the AD docket on the Internet at http://dms.dot.gov or in Room PL-401 on the plaza level of the Nassif Building, 400 Seventh Street, SW., Washington, DC.

Keith Lardie, Aerospace Engineer, Engine Certification Office, FAA, Engine and Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803-5299; telephone (781) 238-7189; fax (781) 238-7199.

The FAA proposed to amend 14 CFR part 39 with a proposed airworthiness directive (AD). The proposed AD applies to Pratt & Whitney (PW) JT8D-1, -1A, -1B, -7, -7A, -7B, -9, -9A, -11, -15, -15A, -17, -17A, -17R, -17AR, -209, -217, -217A, -217C, and -219 turbofan engines. We published the proposed AD in the Federal Register on December 30, 2004 (69 FR 78359). That action proposed to require removing affected rotating parts overhauled by a certain repair vendor, and inspecting or replacing the parts as applicable.

You may examine the docket that contains the AD, any comments received, and any final disposition in person at the DMS Docket Offices between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The Docket Office (telephone (800) 647-5227) is located on the plaza level of the Department of Transportation Nassif Building at the street address stated in ADDRESSES. Comments will be available in the AD docket shortly after the DMS receives them.

We provided the public the opportunity to participate in the development of this AD. We have considered the comments received.

One commenter requests that we remove the rear compressor rear hub from the list of affected parts. The commenter states that the part is a nickel alloy similar to the 13th stage disk and there is no cracking or corrosion associated with it. In addition, the rear compressor rear hub is not a life-limited part, and the serial numbers are not readily available. As a result, the commenter feels the proposed AD would force operators to inspect all parts, not just the listed serial number parts.

We agree. We have removed it from this AD.

One commenter asks that this AD include all parts improperly processed by a certain repair vendor, not just the high-pressure compressor.

We do not agree. The proposed AD addresses those parts that pose a safety threat. All other parts either present no known safety threat, or are already addressed through other applicable ADs and field notifications. If we decide that further AD action is necessary to address other parts, we may issue a separate AD at that time.

One commenter asks that we clarify the definition of “shop visit” contained in the AD. The commenter feels that an operator could interpret a shop visit as when an airplane upon which an affected engine is installed, goes into a hangar.

We agree. We included the following definition in the AD: “A shop visit is defined as an engine removal where engine maintenance entails separation of pairs of major engine flanges or the removal of a disk, hub or spool at a maintenance facility, regardless of the scheduled maintenance action or the reason for engine removal.”

One commenter asks that we not place time restrictions on operators to inspect rear compressor front and rear compressor rear hubs and instead inspect them when they are accessible. Because they aren't life-limited parts, the hubs are not tracked by serial numbers. The commenter believes the proposed AD would require operators to inspect every JT8D before March 31, 2008. Those inspections would force early removal of many engines. We partially agree. Table 1 of this AD lists all life-limited rear compressor front hubs, and operators must inspect them by the March 31, 2008, deadline. Table 2 of this AD lists all rear compressor front hubs that are non-life limited. Operators must inspect them at the next accessibility. We removed the rear compressor rear hubs from this AD, based on a previous comment.

One commenter asks us to explain how we determined the March 31, 2008 compliance date. The commenter states that it is unclear how we selected that compliance date since corrosion inspection ADs 2003-16-05 and 2003-12-07, as well as PW ASBs A6431 and A6435, designate July 18, 2011, as a compliance date.

We evaluated the results of a risk analysis based on inspection data obtained from a sample of parts repaired by the repair vendor. That analysis demonstrated a greater risk of failure if the parts were only inspected for corrosion and not for cracking as mandated in ADs 2003-16-05 and 2003-12-07. Based on that risk analysis, we set March 31, 2008, as the date by which operators must complete the inspections.

One commenter recommends inspecting all parts listed in Tables 1 and 2 that have zero cycles-in-service since May 14, 2001, using PW ASB A6442 and made available for use as spare parts.

We do not agree. Parts listed in Table 1 were subjected to shot peening that could mask surface cracks. Parts listed in Table 2 were not. If the parts in Table 1 were cracked and, thereafter, shot peened, the cracks will reopen once operated in an engine, a significant factor in our risk analysis and the resulting compliance schedule in the proposed AD. Since there is no effective inspection to detect these cracks, operators may use only parts that have been in service. This is consistent with the manufacturer's disposition instructions in ASB A6442 that state, “All compressor disks and hubs listed in Table 1 that are not installed in an engine MUST be scrapped.”

One commenter requests that the definition of installed part be included in this AD to prevent “operation of a part physically installed in a module.”

We do not agree. A definition of “installed part” is unnecessary because this proposed AD prohibits all parts with zero cycles-in-service that are listed in Table 1 from entering service, regardless of whether they are installed or not. However, we added a new paragraph (h) to prevent installing any engine that has an affected disk or hub that has zero cycles-in-service after May 14, 2001, and recodified the subsequent paragraphs.

One commenter asks that we explain the cost to operators, suggesting that we evaluate the cost as if every part fails inspection. The commenter states that the current market value for all affected parts is $14,413,020, and the cost to disassemble, inspect and reassemble engines outside of regularly scheduled maintenance is $1,766,440.

We disagree. We still consider our evaluation of cost as noted in the NPRM valid. We do not expect that every part will fail the inspection, although we estimate that the number will be substantial. In addition, we did not include the full cost of every disk in the economic analysis if the disks must be replaced before they reach their certified life, a normal operating expense. Accordingly, we didn't change the Costs to Comply.

One commenter asks that we add a sentence to Paragraph (g) that reads “This includes all parts on the shelf that have not been used.”

We do not agree. This AD is clear as written. We have not added the sentence.

We have carefully reviewed the available data, including the comments received, and determined that air safety and the public interest require adopting the AD with the changes described previously. We have determined that these changes will neither increase the economic burden on any operator nor increase the scope of the AD.

These actions are interim actions and we might take further rulemaking action in the future.

We estimate that this AD will affect about 632 JT8D engines installed on airplanes of U.S. registry. We estimate that 158 engines will require access to the high-pressure compressor outside of regularly scheduled maintenance, and will require 66 work hours per engine. The high pressure compressor section of the remaining 474 engines will be inspected during regularly scheduled maintenance, and will not require additional labor costs to inspect. The average labor rate is $65 per work hour. We estimate that half of the parts presently installed will require replacement, at a cost of approximately $6,730,800. Based on this information, we estimate the total cost of the AD to U.S. operators to be $7,398,620.

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.

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 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 placed it in the AD Docket. You may get a copy of this summary at the address listed under ADDRESSES.

Accordingly, under the authority delegated to me by the Administrator, the Federal Aviation Administration amends 14 CFR part 39 as follows:

1. The authority citation for part 39 continues to read as follows:

2. The FAA amends § 39.13 by adding the following new airworthiness directive: