Document headings vary by document type but may contain
                    the following: the agency or agencies that issued and signed a document
the number of the CFR title and the number of each part
                      the document amends, proposes to amend, or is directly
                      related to
the agency docket number / agency internal file number
the RIN which identifies each regulatory action listed in
                      the Unified Agenda of Federal Regulatory and Deregulatory
                      Actions See the
                    Document Drafting Handbook
                    for more details.
 Department of Transportation Federal Aviation Administration 14 CFR Part 39
[Docket No. FAA-2005-23072; Directorate Identifier 2005-NE-38-AD]
RIN 2120-AA64
 AGENCY: Federal Aviation Administration (FAA), Department of Transportation (DOT).
 ACTION: Notice of proposed rulemaking (NPRM).
 SUMMARY: 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.
 DATES: We must receive any comments on this proposed AD by April 30, 2007.
 ADDRESSES: 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.


SUPPLEMENTARY INFORMATION: Comments Invited 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. Discussion 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. 
                    ( print 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
SNs5001341-023
5001341-022
JW23135001341-024
5001341-022
JW24985001341-025
5001341-022
JW25415001341-026
5001341-022
JW25605001341-027
5001341-022
JW25895001341-028
5001341-022
JW26395001341-029
5001341-022
JW27605001341-030
5001341-022
JW27925001341-031
5001341-022
MO5795001341-032
5001341-022
MG28255001341-033
5001341-022
MG54775001341-034
5001341-022
ND5917
 The added part SNs are as follows: PNs
Added 
                             SNs5001341-022
JW47135001341-022
MG67435001341-022
ND6924831021-003
ND9177831021-003
ND9496831021-003
NS7894831021-003
NS8559831021-003
NS9072804121
PX3805804121
PX4266
 Conclusion 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. 
                    ( print 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. Regulatory Findings 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. List of Subjects in 14 CFR Part 39 Air transportation
Aircraft
Aviation safety
Safety
 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: 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. § 39.13
  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. Affected ADs (b) This AD supersedes AD 2005-26-09. Applicability (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. Unsafe Condition (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. Compliance (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: Table 1.—Affected 1st Stage Fan Blades
P/Ns
SNs5001341-022
JW28045001341-022
JW03545001341-022
ND57465001341-022
ND57705001341-022
JW39925001341-022
ND86155001341-022
JW04425001341-022
JW23175001341-022
ND86315001341-022
ND86355001341-022
JW46245001341-022
NE03945001341-022
NE01535001341-022
NN80545001341-022
JW46935001341-022
ND73045001341-022
MG61085001341-022
MG58625001341-022
MG56195001341-022
NE03085001341-022
NE02005001341-022
MG67975001341-022
JW02305001341-022
ND56525001341-022
ND57755001341-022
JW02515001341-022
ND57195001341-022
JW02485001341-022
ND57855001341-022
ND56765001341-022
ND56615001341-022
JW02655001341-022
ND56995001341-022
ND57675001341-022
JW02595001341-022
ND56805001341-022
ND57495001341-022
JW02355001341-022
ND57765001341-022
ND85805001341-022
MG60395001341-022
ND91275001341-022
JW42875001341-022
JW02625001341-022
JW04455001341-022
JW46655001341-022
MG59015001341-022
NE03035001341-022
ND87035001341-022
JW45745001341-022
JW42865001341-022
JW44915001341-022
JW46305001341-022
JW43915001341-022
MG65505001341-022
MG67765001341-022
JW45865001341-022
JW03525001341-022
JW42615001341-022
MG61355001341-022
JW46855001341-022
MG67725001341-022
MG67935001341-022
MG71115001341-022
ND86185001341-022
JW06445001341-022
JW46315001341-022
JW46515001341-022
JW02345001341-022
JW4646804121
NN9016804121
VJ3393804121
PX3694804121
RK9168804121
PX5023804121
VJ3324804121
VJ3504804121
NN9115804121
NN8936804121
PX3816804121
VJ3412804121
RK9163804121
VJ3447804121
RK9230804121
RK9109804121
PX4627804121
RK8990804121
SP9459804121
RK8656804121
NN8933804121
VJ3444804121
ND5864804121
NN9020804121
RK8905804121
SR1733804121
NN9047804121
PX3692804121
PX3786804121
NN9025804121
NN9007804121
RK9100804121
VJ3399804121
PX4970804121
PX5013( print page 9279)804121
RK8904804121
NN8986804121
NN8829804121
VJ3459804121
RK9143804121
VJ3414804121
NN9028804121
SP1557804121
PX5003804121
PX5042804121
VJ3475804121
ND7330804121
PX3714831021-003
NS8913831021-003
ND6512831021-003
ND6941831021-003
ND9576831021-003
NS7555831021-003
NS8286831021-003
NS7447831021-003
ND6488831021-003
ND8296831021-003
ND6956831021-003
ND7879831021-003
ND6509831021-003
ND9814831021-003
NN7331831021-003
ND6991831021-003
ND6894831021-003
NS6413831021-003
ND7344831021-003
ND6947831021-003
NN8732831021-003
ND8536831021-003
ND6946831021-003
ND6723831021-003
ND9294831021-003
ND9290831021-003
ND6013831021-003
ND8937831021-003
NS7160831021-003
NS6435831021-003
NS6591831021-003
ND9558831021-003
NS8479831021-003
NS9382831021-003
ND8965831021-003
ND9837831021-003
ND5959831021-003
NS6491831021-003
NS9072831021-003
ND9625831021-003
ND6714831021-003
ND6820831021-003
ND8972831021-003
NE0286831021-003
NE0347831021-003
ND8010831021-003
ND8956831021-003
ND9535831021-003
ND9831831021-003
NE0227831021-003
ND8283831021-003
ND9730831021-003
NN7656831021-003
NS7775831021-003
ND9815831021-003
ND6135831021-003
NS8491831021-003
NS6395831021-003
NS8584831021-003
NN7272831021-003
MG7159831021-003
NS6592831021-003
ND7862831021-003
ND6684831021-003
NN7744831021-003
ND7480831021-003
ND7873831021-003
ND6827831021-003
ND6576831021-003
ND9261831021-003
NS8686831021-003
ND9052831021-003
ND6897831021-003
ND6565831021-003
NN8966831021-003
PX3707831021-003
NS7031831021-003
ND6584831021-003
ND9883831021-003
NS6535831021-003
ND7852831021-003
ND9662831021-003
ND7871831021-003
JW0106831021-003
ND8305831021-003
NS6409831021-003
NE0442831021-003
ND9095831021-003
ND9302831021-003
ND9023831021-003
ND8009831021-003
ND8477831021-003
ND7492831021-003
ND8776831021-003
ND6524831021-003
ND6704831021-003
ND8911831021-003
ND8789831021-003
ND8798831021-003
ND6407831021-003
ND7668831021-003
ND9179831021-003
NE0421831021-003
ND6513831021-003
ND6744831021-003
ND7654831021-003
ND7870831021-003
ND9759831021-003
ND6561831021-003
ND5826831021-003
ND6031831021-003
ND8714831021-003
ND8872831021-003
ND6678831021-003
ND6629831021-003
ND8995831021-003
NE0302831021-003
ND6405831021-003
NS8300831021-003
NS8769831021-003
NS7147831021-003
ND6649831021-003
ND7766831021-003
NS7864831021-003
NS8734831021-003
ND6677831021-003
NS7911831021-003
ND8205831021-003
ND8804831021-003
ND6639831021-003
ND8994831021-003
ND7275831021-003
ND9195831021-003
ND6178831021-003
ND8639831021-003
ND9760831021-003
ND9108X831021-003
ND6427831021-003
ND6590831021-003
NS6551831021-003
JW1158831021-003
ND6412831021-003
ND7922831021-003
NS8678831021-003
ND8930831021-003
ND6596831021-003
ND9570831021-003
NN9027831021-003
ND6446831021-003
NE0275831021-003
ND9917831021-003
NS7919831021-003
NS7907831021-003
ND6583831021-003
NN7420831021-003
ND7746831021-003
ND8187831021-003
NN8999831021-003
ND6043831021-003
ND7880831021-003
NN7175831021-003
ND9816831021-003
ND8174831021-003
ND6045831021-003
NS7562831021-003
JW0075831021-003
ND6848831021-003
ND8531831021-003
ND6311831021-003
ND8144831021-003
ND5798831021-003
ND8113831021-003
ND9642831021-003
ND7436831021-003
ND9054831021-003
ND9683831021-003
ND5991831021-003
ND6026831021-003
ND6616831021-003
ND6530831021-003
NE0374831021-003
ND6364831021-003
ND7718831021-003
ND6473831021-003
ND6436831021-003
ND6887831021-003
ND6518831021-003
ND6479831021-003
NS6330831021-003
ND7264831021-003
ND8151831021-003
ND6562831021-003
NS8776831021-003
ND6519831021-003
ND7659831021-003
NS9049831021-003
NS6861831021-003
ND9571831021-003
ND9346831021-003
ND6501831021-003
NS8505( print page 9280)831021-003
ND9338831021-003
ND9775831021-003
ND6485831021-003
ND7165831021-003
ND9371831021-003
ND9537831021-003
NS7889831021-003
ND7877831021-003
ND8670831021-003
ND9032831021-003
ND8781831021-003
ND8604831021-003
ND9329831021-003
ND9110831021-003
ND5997831021-003
ND6027831021-003
ND9589831021-003
ND6575831021-003
ND6592831021-003
ND6463831021-003
NS8583831021-003
NS8590831021-003
NS8567831021-003
NS6795831021-003
NS7110831021-003
NS6587831021-003
NS6404831021-003
ND64865001341-022
JW09425001341-022
ND92315001341-022
JW48125001341-022
ND65555001341-022
M13755001341-022
MG66275001341-022
MG67945001341-022
ND93995001341-022
NE00845001341-022
MG62525001341-022
ND74225001341-022
ND70435001341-022
MG57225001341-022
MG59185001341-022
ND69845001341-022
M08395001341-022
M09225001341-022
M09385001341-022
M11175001341-022
M03075001341-022
JW38715001341-022
M11255001341-022
M11495001341-022
JW26815001341-022
M02705001341-022
M11205001341-022
M02055001341-022
AE93525001341-022
JW34925001341-022
ND61485001341-022
ND89075001341-022
M12355001341-022
MG55855001341-022
ND84365001341-022
MG56965001341-022
ND87045001341-022
JW22845001341-022
JW23135001341-022
JW24985001341-022
JW25415001341-022
JW25605001341-022
JW25895001341-022
JW26395001341-022
JW27605001341-022
JW27925001341-022
M05795001341-022
MG28255001341-022
MG54775001341-022
ND59175001341-022
JW19765001341-022
JW26535001341-022
JW26085001341-022
JW27275001341-022
JW27645001341-022
JW22655001341-022
JW24745001341-022
JW23965001341-022
JW35545001341-022
JW26675001341-022
MG23025001341-022
MG39725001341-022
JW39305001341-022
ND67495001341-022
M11725001341-022
JW21045001341-022
JW25195001341-022
JW26405001341-022
JW25175001341-022
JW26635001341-022
JW28235001341-022
M05365001341-022
JW27255001341-022
MG59175001341-022
JW06815001341-022
JW07115001341-022
JW07405001341-022
JW08075001341-022
JW10895001341-022
JW13625001341-022
JW20655001341-022
MG24345001341-022
MG28465001341-022
JW0806804121
NN9854804121
NN9024804121
NN9032804121
PX5029804121
NN9050804121
NS8242804121
NS8260804121
PX4273804121
PX4378804121
RL0857804121
RX8763804121
NS8331804121
NN9824804121
MG6979804121
MG7023804121
MG7055804121
RK8914804121
RL0023804121
PX4328804121
RK9008804121
TG1506804121
KK8226804121
MG2604804121
NS6691804121
RK8968804121
NN9917804121
RK7824804121
M1343804121
NS6559804121
NS7767804121
NE0363804121
PX3771804121
NN9972804121
RL0460804121
RK8310804121
SR2115804121
TG2826804121
PX5018804121
PX5002831021-003
ND7627831021-003
ND6890831021-003
ND7461831021-003
ND9616831021-003
NE0413831021-003
NS8825831021-003
NS6350831021-003
NS7168831021-003
NS7705831021-003
NS7848831021-003
ND9128831021-003
ND9541831021-003
ND9671831021-003
ND9684831021-003
NE0277831021-003
NE0384831021-003
NE0396831021-003
ND6421831021-003
ND6599831021-003
ND6614831021-003
ND7847831021-003
ND8346831021-003
ND8853831021-003
ND8915831021-003
NS8719831021-003
NS8838831021-003
NT0169831021-003
NS9584831021-003
ND6445831021-003
ND6834831021-003
ND7467831021-003
ND8887831021-003
ND6520831021-003
NS8611831021-003
NS7640831021-003
NN7037831021-003
NN7590831021-003
NN8120831021-003
NN8573831021-003
NN9719831021-003
NS8784831021-003
TB6B367831021-003
NN9557831021-003
NN9710831021-003
NS8374831021-003
NS8770831021-003
NS9022831021-003
NS8416831021-003
NS6474831021-003
ND8912831021-003
NT0108831021-003
NS8836831021-003
NN8310831021-003
NS85595001341-022
JW47135001341-022
MG67435001341-022
ND6924831021-003
ND9177831021-003
ND9496831021-003
NS7894831021-003
NS8559831021-003
NS9072804121
PX3805( print page 9281)804121
PX4266
 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. Definition (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. Prohibited Installation (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. Related Information (j) None.
 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] BILLING CODE 4910-13-P