03-9984. Airworthiness Directives; Pratt & Whitney JT9D-7R4 Series Turbofan Engines

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

The Federal Aviation Administration (FAA) proposes to supersede an existing airworthiness directive (AD) that is applicable to Pratt & Whitney (PW) JT9D-7R4 series turbofan engines. That AD currently requires modifications of the fan case assembly by installing a thicker one-piece fan case shield, and modifications of the outer front fan exit case assembly by installing ring segments. This proposal would require on JT9D-7R4 series turbofan engines with steel fan cases, replacement of the existing one-piece fan case shield with a thicker four-piece fan case shield and would add four fan case shield supports. This proposal is prompted by two uncontained full fan blade fracture events that resulted in penetration of the steel fan case and fan case shield. The actions specified by the proposed AD are intended to prevent uncontained fan blade failures, resulting in damage to the airplane.

DATES:

Comments must be received by June 23, 2003.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), New England Region, Office of the Regional Counsel, Attention: Rules Docket No. 2003-NE-01-AD, 12 New England Executive Park, Burlington, MA 01803-5299. Comments may be inspected at this location, by appointment, between 8 a.m. and 4:30 p.m., Monday through Friday, except Federal holidays. Comments may also be sent via the Internet using the following address: [e-mail]. Comments sent via the Internet must contain the docket number in the subject line.

FOR FURTHER INFORMATION CONTACT:

Keith Lardie, 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

Interested persons are invited to participate in the making of the proposed rule by submitting such written data, views, or arguments as they may desire. Communications should identify the Rules Docket number and be submitted in triplicate to the address specified above. All communications received on or before the closing date for comments, specified above, will be considered before taking action on the proposed rule. The proposals contained in this action may be changed in light of the comments received.

Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the proposed rule. All comments submitted will be available, both before and after the closing date for comments, in the Rules Docket for examination by interested persons. A report summarizing each FAA-public contact concerned with the substance of this proposal will be filed in the Rules Docket.

Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this action must submit a self-addressed, stamped postcard on which the following statement is made: “Comments to Docket Number 2003-NE-01-AD.” The postcard will be date stamped and returned to the commenter.

Availability of NPRM's

Any person may obtain a copy of this NPRM by submitting a request to the FAA, New England Region, Office of the Regional Counsel, Attention: Rules Docket No. 2003-NE-01-AD, 12 New England Executive Park, Burlington, MA 01803-5299.

Discussion

On August 3, 1989, the FAA issued airworthiness directive (AD) 87-23-05R1, Amendment 39-6296 (55 FR 5594, February 16, 1990), to mandate the incorporation of a thicker fan case shield for all JT9D-7R4 series turbofan engine fan cases, before December 31, 1990. That action was prompted by reports of failed fan blades that penetrated the fan case shield after penetrating the fan case. Engines with fan cases made of titanium do not require thicker fan case shields because the titanium fan case and existing shield contains failed blades, and therefore are not affected by this proposal.

Since that AD was issued, two reports of uncontained fan blade failures that penetrated fan case shields were received, in November 1991 and June 2000. Subsequent ground inspections revealed that in each event a fan blade fractured in the root of the blade airfoil, and exited the engine through the fan case shield. These two uncontained engine failures have shown that the thicker fan case shield mandated by AD 87-23-05R1 is insufficient for containing failed fan blades on engines with steel fan cases. This condition, if not corrected, could result in uncontained fan blade failures, resulting in damage to the airplane.

FAA's Determination of an Unsafe Condition and Proposed Actions

Since an unsafe condition has been identified that is likely to exist or develop on other PW JT9D-7R4 series turbofan engines of the same type design, the proposed AD would supersede AD 87-23-05R1 to require on engines with steel fan cases, replacing existing fan case shields with thicker four-piece fan case shields, and adding fan case shield supports.

Economic Analysis

There are approximately 309 JT9D-7R4 series turbofan engines with steel fan cases, of the affected design in the worldwide fleet. The FAA estimates that 155 engines installed on PW JT9D-7R4 series turbofan engines of U.S. registry would be affected by this proposed AD. The FAA also estimates that it would take approximately 16.6 work hours per engine to perform the proposed actions, and that the average labor rate is $60 per work hour. Required parts would cost approximately $3,675 per engine. Based on these figures, the total cost of the proposed AD to U.S. operators is estimated to be $724,005.

Regulatory Analysis

This proposed rule does not have federalism implications, as defined in Executive Order 13132, because it 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. Accordingly, the FAA has not consulted with state authorities prior to publication of this proposed rule.

For the reasons discussed above, I certify that this proposed regulation (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) if promulgated, 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. A copy of the draft regulatory evaluation prepared for this action is contained in the Rules Docket. A copy of it may be obtained by contacting the Rules Docket at the location provided under the caption ADDRESSES.

List of Subjects in 14 CFR Part 39

• Air transportation
• Aircraft
• Aviation safety
• Safety

The Proposed Amendment

Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration proposes to amend part 39 of the Federal Aviation Regulations (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. Section 39.13 is amended by removing Amendment 39-6296, (55 FR 5594, February 16, 1990), and by adding a new airworthiness directive:

Pratt & Whitney: Docket No. 2003-NE-01-AD.

Applicability: This airworthiness directive (AD) is applicable to Pratt & Whitney (PW) JT9D-7R4D, -7R4D1, -7R4E, -7R4E1, -7R4E4, -7R4G2, and -7R4H1 turbofan engines with steel fan cases. These engines are installed on, but not limited to Airbus Industrie A300 and A310, and Boeing 747 and 767 airplanes.

Note 1:

This AD applies to each engine identified in the preceding applicability provision, regardless of whether it has been modified, altered, or repaired in the area subject to the requirements of this AD. For engines that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (d) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.

Compliance: Compliance with this AD is required at the next engine overhaul where access to the fan case aft containment area is available, but no later than December 31, 2012, unless already done.

To prevent uncontained fan blade failures, resulting in damage to the airplane, do the following:

(a) For PW JT9D-7R4D, -7R4D1, -7R4E, -7R4E1, -7R4E4, and -7R4H1 turbofan engines with steel fan cases that have PW service bulletin (SB) 72-312 incorporated, replace fan case shield part number (P/N) 802095 with the four-piece fan case shield and install four fan case shield supports. Information on replacing fan case shields and installing fan case shield supports can be found PW SB JT9D-7R4-72-583, dated December 12, 2002.

(b) For PW JT9D-7R4G2 turbofan engines with steel fan cases that have PW SB 72-88 and PW SB 72-311 incorporated, replace fan case shield P/N 802094 with the four-piece fan case shield and install four fan case shield supports. Information on replacing fan case shields and installing fan case shield supports can be found in Part A of PW SB JT9D-7R4-72-584, dated December 12, 2002.

(c) For PW JT9D-7R4G2 turbofan engines with steel fan cases that do not have PW SB 72-88 incorporated, but have PW SB 72-311 incorporated, replace fan case shield P/N 802094 with the four-piece fan case shield and install four fan case shield supports. Information on replacing fan case shields and installing fan case shield supports can be found in Part B of PW SB JT9D-7R4-72-584, dated December 12, 2002.

Alternative Methods of Compliance

(d) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, Engine Certification Office (ECO). Operators must submit their request through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, ECO.

Note 2:

Information concerning the existence of approved alternative methods of compliance with this airworthiness directive, if any, may be obtained from the ECO.

Special Flight Permits

(e) Special flight permits may be issued in accordance with §§ 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the airplane to a location where the requirements of this AD can be done.

Issued in Burlington, Massachusetts, on April 17, 2003.

Francis A. Favara,

Acting Manager, Engine and Propeller Directorate, Aircraft Certification Service.