E7-3561. Airworthiness Directives; Pratt & Whitney JT9D-7R4 Turbofan Engines

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: [phone].
• 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 [phone], fax [phone].

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 [phone]) 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.

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
5001341-023	5001341-022	JW2313
5001341-024	5001341-022	JW2498
5001341-025	5001341-022	JW2541
5001341-026	5001341-022	JW2560
5001341-027	5001341-022	JW2589
5001341-028	5001341-022	JW2639
5001341-029	5001341-022	JW2760
5001341-030	5001341-022	JW2792
5001341-031	5001341-022	MO579
5001341-032	5001341-022	MG2825
5001341-033	5001341-022	MG5477
5001341-034	5001341-022	ND5917

The added part SNs are as follows:

PNs	Added SNs
5001341-022	JW4713
5001341-022	MG6743
5001341-022	ND6924
831021-003	ND9177
831021-003	ND9496
831021-003	NS7894
831021-003	NS8559
831021-003	NS9072
804121	PX3805
804121	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.

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

[Amended]

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	SNs
5001341-022	JW2804
5001341-022	JW0354
5001341-022	ND5746
5001341-022	ND5770
5001341-022	JW3992
5001341-022	ND8615
5001341-022	JW0442
5001341-022	JW2317
5001341-022	ND8631
5001341-022	ND8635
5001341-022	JW4624
5001341-022	NE0394
5001341-022	NE0153
5001341-022	NN8054
5001341-022	JW4693
5001341-022	ND7304
5001341-022	MG6108
5001341-022	MG5862
5001341-022	MG5619
5001341-022	NE0308
5001341-022	NE0200
5001341-022	MG6797
5001341-022	JW0230
5001341-022	ND5652
5001341-022	ND5775
5001341-022	JW0251
5001341-022	ND5719
5001341-022	JW0248
5001341-022	ND5785
5001341-022	ND5676
5001341-022	ND5661
5001341-022	JW0265
5001341-022	ND5699
5001341-022	ND5767
5001341-022	JW0259
5001341-022	ND5680
5001341-022	ND5749
5001341-022	JW0235
5001341-022	ND5776
5001341-022	ND8580
5001341-022	MG6039
5001341-022	ND9127
5001341-022	JW4287
5001341-022	JW0262
5001341-022	JW0445
5001341-022	JW4665
5001341-022	MG5901
5001341-022	NE0303
5001341-022	ND8703
5001341-022	JW4574
5001341-022	JW4286
5001341-022	JW4491
5001341-022	JW4630
5001341-022	JW4391
5001341-022	MG6550
5001341-022	MG6776
5001341-022	JW4586
5001341-022	JW0352
5001341-022	JW4261
5001341-022	MG6135
5001341-022	JW4685
5001341-022	MG6772
5001341-022	MG6793
5001341-022	MG7111
5001341-022	ND8618
5001341-022	JW0644
5001341-022	JW4631
5001341-022	JW4651
5001341-022	JW0234
5001341-022	JW4646
804121	NN9016
804121	VJ3393
804121	PX3694
804121	RK9168
804121	PX5023
804121	VJ3324
804121	VJ3504
804121	NN9115
804121	NN8936
804121	PX3816
804121	VJ3412
804121	RK9163
804121	VJ3447
804121	RK9230
804121	RK9109
804121	PX4627
804121	RK8990
804121	SP9459
804121	RK8656
804121	NN8933
804121	VJ3444
804121	ND5864
804121	NN9020
804121	RK8905
804121	SR1733
804121	NN9047
804121	PX3692
804121	PX3786
804121	NN9025
804121	NN9007
804121	RK9100
804121	VJ3399
804121	PX4970
804121	PX5013
804121	RK8904
804121	NN8986
804121	NN8829
804121	VJ3459
804121	RK9143
804121	VJ3414
804121	NN9028
804121	SP1557
804121	PX5003
804121	PX5042
804121	VJ3475
804121	ND7330
804121	PX3714
831021-003	NS8913
831021-003	ND6512
831021-003	ND6941
831021-003	ND9576
831021-003	NS7555
831021-003	NS8286
831021-003	NS7447
831021-003	ND6488
831021-003	ND8296
831021-003	ND6956
831021-003	ND7879
831021-003	ND6509
831021-003	ND9814
831021-003	NN7331
831021-003	ND6991
831021-003	ND6894
831021-003	NS6413
831021-003	ND7344
831021-003	ND6947
831021-003	NN8732
831021-003	ND8536
831021-003	ND6946
831021-003	ND6723
831021-003	ND9294
831021-003	ND9290
831021-003	ND6013
831021-003	ND8937
831021-003	NS7160
831021-003	NS6435
831021-003	NS6591
831021-003	ND9558
831021-003	NS8479
831021-003	NS9382
831021-003	ND8965
831021-003	ND9837
831021-003	ND5959
831021-003	NS6491
831021-003	NS9072
831021-003	ND9625
831021-003	ND6714
831021-003	ND6820
831021-003	ND8972
831021-003	NE0286
831021-003	NE0347
831021-003	ND8010
831021-003	ND8956
831021-003	ND9535
831021-003	ND9831
831021-003	NE0227
831021-003	ND8283
831021-003	ND9730
831021-003	NN7656
831021-003	NS7775
831021-003	ND9815
831021-003	ND6135
831021-003	NS8491
831021-003	NS6395
831021-003	NS8584
831021-003	NN7272
831021-003	MG7159
831021-003	NS6592
831021-003	ND7862
831021-003	ND6684
831021-003	NN7744
831021-003	ND7480
831021-003	ND7873
831021-003	ND6827
831021-003	ND6576
831021-003	ND9261
831021-003	NS8686
831021-003	ND9052
831021-003	ND6897
831021-003	ND6565
831021-003	NN8966
831021-003	PX3707
831021-003	NS7031
831021-003	ND6584
831021-003	ND9883
831021-003	NS6535
831021-003	ND7852
831021-003	ND9662
831021-003	ND7871
831021-003	JW0106
831021-003	ND8305
831021-003	NS6409
831021-003	NE0442
831021-003	ND9095
831021-003	ND9302
831021-003	ND9023
831021-003	ND8009
831021-003	ND8477
831021-003	ND7492
831021-003	ND8776
831021-003	ND6524
831021-003	ND6704
831021-003	ND8911
831021-003	ND8789
831021-003	ND8798
831021-003	ND6407
831021-003	ND7668
831021-003	ND9179
831021-003	NE0421
831021-003	ND6513
831021-003	ND6744
831021-003	ND7654
831021-003	ND7870
831021-003	ND9759
831021-003	ND6561
831021-003	ND5826
831021-003	ND6031
831021-003	ND8714
831021-003	ND8872
831021-003	ND6678
831021-003	ND6629
831021-003	ND8995
831021-003	NE0302
831021-003	ND6405
831021-003	NS8300
831021-003	NS8769
831021-003	NS7147
831021-003	ND6649
831021-003	ND7766
831021-003	NS7864
831021-003	NS8734
831021-003	ND6677
831021-003	NS7911
831021-003	ND8205
831021-003	ND8804
831021-003	ND6639
831021-003	ND8994
831021-003	ND7275
831021-003	ND9195
831021-003	ND6178
831021-003	ND8639
831021-003	ND9760
831021-003	ND9108X
831021-003	ND6427
831021-003	ND6590
831021-003	NS6551
831021-003	JW1158
831021-003	ND6412
831021-003	ND7922
831021-003	NS8678
831021-003	ND8930
831021-003	ND6596
831021-003	ND9570
831021-003	NN9027
831021-003	ND6446
831021-003	NE0275
831021-003	ND9917
831021-003	NS7919
831021-003	NS7907
831021-003	ND6583
831021-003	NN7420
831021-003	ND7746
831021-003	ND8187
831021-003	NN8999
831021-003	ND6043
831021-003	ND7880
831021-003	NN7175
831021-003	ND9816
831021-003	ND8174
831021-003	ND6045
831021-003	NS7562
831021-003	JW0075
831021-003	ND6848
831021-003	ND8531
831021-003	ND6311
831021-003	ND8144
831021-003	ND5798
831021-003	ND8113
831021-003	ND9642
831021-003	ND7436
831021-003	ND9054
831021-003	ND9683
831021-003	ND5991
831021-003	ND6026
831021-003	ND6616
831021-003	ND6530
831021-003	NE0374
831021-003	ND6364
831021-003	ND7718
831021-003	ND6473
831021-003	ND6436
831021-003	ND6887
831021-003	ND6518
831021-003	ND6479
831021-003	NS6330
831021-003	ND7264
831021-003	ND8151
831021-003	ND6562
831021-003	NS8776
831021-003	ND6519
831021-003	ND7659
831021-003	NS9049
831021-003	NS6861
831021-003	ND9571
831021-003	ND9346
831021-003	ND6501
831021-003	NS8505
831021-003	ND9338
831021-003	ND9775
831021-003	ND6485
831021-003	ND7165
831021-003	ND9371
831021-003	ND9537
831021-003	NS7889
831021-003	ND7877
831021-003	ND8670
831021-003	ND9032
831021-003	ND8781
831021-003	ND8604
831021-003	ND9329
831021-003	ND9110
831021-003	ND5997
831021-003	ND6027
831021-003	ND9589
831021-003	ND6575
831021-003	ND6592
831021-003	ND6463
831021-003	NS8583
831021-003	NS8590
831021-003	NS8567
831021-003	NS6795
831021-003	NS7110
831021-003	NS6587
831021-003	NS6404
831021-003	ND6486
5001341-022	JW0942
5001341-022	ND9231
5001341-022	JW4812
5001341-022	ND6555
5001341-022	M1375
5001341-022	MG6627
5001341-022	MG6794
5001341-022	ND9399
5001341-022	NE0084
5001341-022	MG6252
5001341-022	ND7422
5001341-022	ND7043
5001341-022	MG5722
5001341-022	MG5918
5001341-022	ND6984
5001341-022	M0839
5001341-022	M0922
5001341-022	M0938
5001341-022	M1117
5001341-022	M0307
5001341-022	JW3871
5001341-022	M1125
5001341-022	M1149
5001341-022	JW2681
5001341-022	M0270
5001341-022	M1120
5001341-022	M0205
5001341-022	AE9352
5001341-022	JW3492
5001341-022	ND6148
5001341-022	ND8907
5001341-022	M1235
5001341-022	MG5585
5001341-022	ND8436
5001341-022	MG5696
5001341-022	ND8704
5001341-022	JW2284
5001341-022	JW2313
5001341-022	JW2498
5001341-022	JW2541
5001341-022	JW2560
5001341-022	JW2589
5001341-022	JW2639
5001341-022	JW2760
5001341-022	JW2792
5001341-022	M0579
5001341-022	MG2825
5001341-022	MG5477
5001341-022	ND5917
5001341-022	JW1976
5001341-022	JW2653
5001341-022	JW2608
5001341-022	JW2727
5001341-022	JW2764
5001341-022	JW2265
5001341-022	JW2474
5001341-022	JW2396
5001341-022	JW3554
5001341-022	JW2667
5001341-022	MG2302
5001341-022	MG3972
5001341-022	JW3930
5001341-022	ND6749
5001341-022	M1172
5001341-022	JW2104
5001341-022	JW2519
5001341-022	JW2640
5001341-022	JW2517
5001341-022	JW2663
5001341-022	JW2823
5001341-022	M0536
5001341-022	JW2725
5001341-022	MG5917
5001341-022	JW0681
5001341-022	JW0711
5001341-022	JW0740
5001341-022	JW0807
5001341-022	JW1089
5001341-022	JW1362
5001341-022	JW2065
5001341-022	MG2434
5001341-022	MG2846
5001341-022	JW0806
804121	NN9854
804121	NN9024
804121	NN9032
804121	PX5029
804121	NN9050
804121	NS8242
804121	NS8260
804121	PX4273
804121	PX4378
804121	RL0857
804121	RX8763
804121	NS8331
804121	NN9824
804121	MG6979
804121	MG7023
804121	MG7055
804121	RK8914
804121	RL0023
804121	PX4328
804121	RK9008
804121	TG1506
804121	KK8226
804121	MG2604
804121	NS6691
804121	RK8968
804121	NN9917
804121	RK7824
804121	M1343
804121	NS6559
804121	NS7767
804121	NE0363
804121	PX3771
804121	NN9972
804121	RL0460
804121	RK8310
804121	SR2115
804121	TG2826
804121	PX5018
804121	PX5002
831021-003	ND7627
831021-003	ND6890
831021-003	ND7461
831021-003	ND9616
831021-003	NE0413
831021-003	NS8825
831021-003	NS6350
831021-003	NS7168
831021-003	NS7705
831021-003	NS7848
831021-003	ND9128
831021-003	ND9541
831021-003	ND9671
831021-003	ND9684
831021-003	NE0277
831021-003	NE0384
831021-003	NE0396
831021-003	ND6421
831021-003	ND6599
831021-003	ND6614
831021-003	ND7847
831021-003	ND8346
831021-003	ND8853
831021-003	ND8915
831021-003	NS8719
831021-003	NS8838
831021-003	NT0169
831021-003	NS9584
831021-003	ND6445
831021-003	ND6834
831021-003	ND7467
831021-003	ND8887
831021-003	ND6520
831021-003	NS8611
831021-003	NS7640
831021-003	NN7037
831021-003	NN7590
831021-003	NN8120
831021-003	NN8573
831021-003	NN9719
831021-003	NS8784
831021-003	TB6B367
831021-003	NN9557
831021-003	NN9710
831021-003	NS8374
831021-003	NS8770
831021-003	NS9022
831021-003	NS8416
831021-003	NS6474
831021-003	ND8912
831021-003	NT0108
831021-003	NS8836
831021-003	NN8310
831021-003	NS8559
5001341-022	JW4713
5001341-022	MG6743
5001341-022	ND6924
831021-003	ND9177
831021-003	ND9496
831021-003	NS7894
831021-003	NS8559
831021-003	NS9072
804121	PX3805
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.