Federal Aviation Administration (FAA), Department of Transportation (DOT).
Notice of proposed rulemaking (NPRM).
The FAA proposes to supersede an existing airworthiness directive (AD) for Pratt & Whitney (PW) JT9D-7R4 turbofan engines. That AD currently requires inspection of the blade root thickness of 1st stage fan blades identified by part number (P/N) and serial number (SN) in the AD. This proposed AD would require the same actions but would correct 12 P/Ns, add 10 part SNs, and add the definition of next fan blade exposure to the compliance section. This proposed AD results from the discovery of inaccurate part quantity, part numbers, and serial numbers used in AD 2005-26-09. We are proposing this AD to prevent 1st stage fan blade fracture and uncontained engine failure, resulting in possible damage to the airplane.
We must receive any comments on this proposed AD by April 30, 2007.
Use one of the following addresses to comment on this proposed AD.
- DOT Docket Web site: Go to http://dms.dot.gov and follow the instructions for sending your comments electronically.
- Government-wide rulemaking Web site: Go to http://www.regulations.gov and follow the instructions for sending your comments electronically.
- Mail: Docket Management Facility; U.S. Department of Transportation, 400 Seventh Street, SW., Nassif Building, Room PL-401, Washington, DC 20590-0001.
- Fax: (202) 493-2251.
- Hand Delivery: Room PL-401 on the plaza level of the Nassif Building, 400 Seventh Street, SW., Washington, DC, between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.
FOR FURTHER INFORMATION CONTACT:
Kevin Donovan, Aerospace Engineer, Engine Certification Office, FAA, Engine and Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803-5299; telephone (781) 238-7743, fax (781) 238-7199.End Further Info End Preamble Start Supplemental Information
We invite you to send any written relevant data, views, or arguments regarding this proposal. Send your comments to an address listed under ADDRESSES. Include “Docket No. FAA-2005-23072; Directorate Identifier 2005-NE-38-AD” in the subject line of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of the proposed AD. We will consider all comments received by the closing date and may amend the proposed 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 proposed AD. Using the search function of the DMS Web site, anyone can find and read the comments in any of our dockets, including the name of the individual who sent the comment (or signed the comment on behalf of an association, business, labor union, etc.). 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.
Examining the AD Docket
You may examine the docket that contains the proposal, any comments received and any final disposition in person at the Docket Management Facility 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.
On December 16, 2005, the FAA issued AD 2005-26-09, Amendment 39-14430 (70 FR 76381, December 27, 2005). That AD requires inspection of the blade root thickness of 1st stage fan blades identified by P/N and SN. That AD was the result of a report of a repair station that created an unapproved repair on 1st stage fan blades. That condition, if not corrected, could result in 1st stage fan blade fracture and uncontained engine failure, resulting in possible damage to the airplane.
Actions Since AD 2005-26-09 Was Issued
Since AD 2005-26-09 was issued, we received comments on the AD requesting clarification. We considered those requests and have changed the compliance section in this proposed AD for clarification. We also found and corrected 12 incorrect P/Ns, and added 10 part SNs of affected 1st stage fan blades to Table 1 of this proposed AD. The comments and affected P/Ns and SNs are also discussed below. Start Printed Page 9277
Request To Clarify “At the Next 1st Stage Fan Blade Exposure”
Two air carriers request that we clarify “at the next 1st stage fan blade exposure,” to prevent any in-service disruptions or delays. The commenter further states that the 1st stage fan blades can be exposed when:
- Some 1st stage fan blades are replaced due to in-service foreign object damage;
- A 1st stage fan hub is replaced and the same 1st stage fan blades are reused; and
- At shop visit when 1st stage fan blades are removed from the fan hub for cause or work scope.
We agree with adding a paragraph to the proposed AD which defines next 1st stage fan blade exposure. We have defined it as when any 1st stage fan blade is removed from the engine; or when the 1st stage fan hub is removed from the engine.
Suggestion To Report When Finding Affected 1st Stage Fan Blades
Air Canada suggests that operators finding any affected 1st stage fan blades should report back to the FAA. The commenter states that by requiring this reporting, all 520 of the blades can then be accounted for, and the FAA can close the AD. The commenter is also concerned that if some blades cannot be accounted for, such as blades already scrapped, misplaced, or shelved, then the AD will never be closed, and operators will be forced to verify the AD indefinitely at every 1st stage fan blade installation.
We do not agree. This proposed AD requires a onetime inspection for a specific population of 1st stage fan blades. If an operator has inspected and verified a certain set of 1st stage fan blades in accordance with the proposed AD, then at the next 1st stage fan blade exposure, only replacement blades that are listed in Table 1 of the proposed AD will require inspection and verification.
Request To Clarify or Remove Paragraph (e)
Air Canada states that compliance paragraph (e) mentions that the AD must be performed within the compliance times specified, but there are no times specified. The commenter requests this instruction be removed or clarified.
We partially agree. We revised the compliance times for clarification in the proposed AD.
Comment That “At Exposure” Limit Is Not a Practical Limit
ABX AIR claims that the “at exposure” limit in the AD is not practical. They said that “at exposure” will require the operators to set up a special inspection schedule to accomplish this onetime inspection which is not suitable for fleet operators.
We partially agree. Inspecting the affected parts at the next 1st stage fan blade exposure is sufficient. It is not necessary for operators to set up a special inspection schedule since this inspection does not impact the FAA-approved maintenance program procedures. However, for clarification, we added a definition for “next first stage fan blade exposure” to the proposed AD.
Request To Clarify “Before Installing the 1st Stage Fan Blades”
ABX AIR requests that we clarify “before installing the 1st stage fan blades” in paragraph (f). ABX believes the AD should contain a concise clarifying statement such as: “After the active date of this AD, no person may install, on any airplane, any blade listed in Table 1 of this AD unless the actions of this AD have already been accomplished.”
We agree. We added a prohibition statement that states that after the effective date of this (proposed) AD, do not install any 1st stage fan blades listed in Table 1 of this AD on any airplane, unless the actions of this AD have been done to the 1st stage fan blades.
P/Ns Corrected, and P/Ns and SNs Added
Since we issued AD 2005-26-09, we found and corrected 12 incorrect P/Ns, and added 10 part SNs of affected 1st stage fan blades in Table 1 of this proposed AD. The corrected numbers are as follows:
|Incorrect P/Ns||Corrected P/Ns||SNs|
The added part SNs are as follows:
We have carefully reviewed the available data, including the comments received, and determined that air safety and the public interest require proposing this 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 proposed AD.
FAA's Determination and Requirements of the Proposed AD
We have evaluated all pertinent information and identified an unsafe condition that is likely to exist or develop on other products of this same type design. For that reason, we are proposing this AD, which would require:
- Checking the 1st stage fan blade for a circled, letter I, on the approved marking area of the outboard side of the blade platform. If the blade has this marking, no further action is required.
- Removing 1st stage fan blades without a circled, letter I, on the approved marking area of the outboard side of the blade platform if installed; and
- Inspecting the 1st stage fan blade root thickness; and
- Returning to service 1st stage fan blades that pass the inspection, after properly marking the blade.
Costs of Compliance
We estimate that this proposed AD would affect 531 1st stage fan blades installed on JT9D-7R4 turbofan engines installed on airplanes of U.S. registry. We also estimate that it would take about 0.5 work-hour per 1st stage fan blade to perform the proposed actions, and that the average labor rate is $80 per work-hour. Based on these figures, we estimate the total cost of the proposed AD to U.S. operators to be $21,240.
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. Start Printed Page 9278
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 proposed AD would not have federalism implications under Executive Order 13132. This proposed AD would 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 proposed 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. Would 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 regulatory evaluation of the estimated costs to comply with this proposed AD. See the ADDRESSES section for a location to examine the regulatory evaluation.Start List of Subjects
List of Subjects in 14 CFR Part 39End List of Subjects
The Proposed Amendment
Under the authority delegated to me by the Administrator, the Federal Aviation Administration proposes to amend 14 CFR part 39 as follows:Start Part
PART 39—AIRWORTHINESS DIRECTIVES
1. The authority citation for part 39 continues to read as follows:
2. The FAA amends § 39.13 by removing Amendment 39-14430 (70 FR 76381, December 27, 2005), and by adding a new airworthiness directive to read as follows:
Pratt & Whitney: Docket No. FAA-2005-23072; Directorate Identifier 2005-NE-38-AD.
Comments Due Date
(a) The Federal Aviation Administration (FAA) must receive comments on this airworthiness directive (AD) action by April 30, 2007.
(b) This AD supersedes AD 2005-26-09.
(c) This AD applies to Pratt & Whitney (PW) JT9D-7R4 turbofan engines. These engines are installed on, but not limited to, Airbus A300 and A310, and Boeing 747 and 767 airplanes.
(d) This AD results from the discovery of inaccurate part quantity, part numbers, and serial numbers used in AD 2005-26-09. We are issuing this AD to prevent 1st stage fan blade fracture and uncontained engine failure, resulting in possible damage to the airplane.
(e) You are responsible for having the actions required by this AD performed within the compliance times specified unless the actions have already been done.
(f) For 1st stage fan blades that are listed by part number (P/N) and serial number (SN) in Table 1 of this AD, do the following:
|Start Printed Page 9279|
|Start Printed Page 9280|
|Start Printed Page 9281|
For Engines Installed on an Airplane
(1) For engines installed on an airplane with affected 1st stage fan blades installed, perform the actions in paragraphs (f)(3) through (f)(6)(ii) of this AD at the next 1st stage fan blade exposure.
For Engines Not Installed on an Airplane, or, for Affected 1st Stage Fan Blades Not Installed in an Engine
(2) For engines not installed on an airplane with affected 1st stage fan blades installed, or, for affected 1st stage fan blades not installed in an engine, paragraph (h) of this AD applies.
1st Stage Fan Blade Check
(3) Check the 1st stage fan blade for a circled, letter I, on the approved marking area of the outboard side of the blade platform. If the blade has this marking, no further action is required.
(4) Remove 1st stage fan blades without a circled, letter I, on the approved marking area of the outboard side of the blade platform, if installed.
(5) Inspect the 1st stage fan blade root thickness. You can find information on inspecting the blade root thickness in PW Engine Manual Section 72-31-02, Inspect-01, and Repair-23.
(6) For 1st stage fan blades that pass the inspection referenced in paragraph (f)(5) of this AD:
(i) Vibropeen the letter I and a circle around that letter, on the approved marking area of the outboard side of the blade platform. You can find information on approved blade marking in the JT9D-7R4 Engine Manual, Section 72-31-02, Typical Repair-13, Mark Repair Codes.
(ii) Return the 1st stage fan blades to service.
(g) For the purposes of paragraph (f)(1) of this AD, next 1st stage fan blade exposure is:
(1) When any 1st stage fan blade is removed from the engine; or
(2) When the 1st stage fan hub is removed from the engine.
(h) After the effective date of this AD, do not install any 1st stage fan blades listed in Table 1 of this AD on any airplane, unless the actions of this AD have been done to the 1st stage fan blades.
Alternative Methods of Compliance
(i) The Manager, Engine Certification Office, has the authority to approve alternative methods of compliance for this AD if requested using the procedures found in 14 CFR 39.19.
Issued in Burlington, Massachusetts, on February 23, 2007.
Peter A. White,
Acting Manager, Engine and Propeller Directorate, Aircraft Certification Service.
[FR Doc. E7-3561 Filed 2-28-07; 8:45 am]
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