02-905. Airworthiness Directives; Pratt & Whitney PW4000 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 PW4000 series turbofan engines. That AD currently requires operators to perform initial and repetitive inspections for cracking of high pressure compressor (HPC) front drum rotors based on cycle usage. That AD also requires the removal from service of any cracked HPC front drum rotors. This proposal clarifies inspection requirements for cracking of high pressure compressor (HPC) front drum rotors that have fewer than 1,000 cycles-since-new (CSN). This proposal is prompted by comments from operators seeking more clarity about the inspection requirements of paragraph (a)(1) of the current AD. The actions specified in the proposed AD are intended to prevent HPC drum rotor failure from cracks that could result in an uncontained engine failure and damage to the airplane.

DATES:

Comments must be received by February 14, 2002.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), New England Region, Office of the Regional Counsel, Attention: Rules Docket No. 2000-NE-49-AD, 12 New England Executive Park, Burlington, MA 01803-5299. Comments may be inspected at this location, by appointment, between 8:00 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.

The service information referenced in the proposed rule may be obtained from Pratt & Whitney, 400 Main Street, East Hartford, CT 06108. This information may be examined, by appointment, at the FAA, New England Region, Office of the Regional Counsel, 12 New England Executive Park, Burlington, MA.

FOR FURTHER INFORMATION CONTACT:

Tara Goodman, 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 2000-NE-49-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. 2000-NE-49-AD, 12 New England Executive Park, Burlington, MA 01803-5299.

Discussion

On October 12, 2001, the FAA issued AD 2001-20-13, Amendment 39-12461 (66 FR 52023, October 12, 2001), to require operators to perform initial and repetitive inspections for cracking of HPC front drum rotors based on cycle usage. That amendment also requires the removal from service of any cracked HPC front drum rotors. That action was prompted by reports that 11 HPC front drum rotors have been found cracked on the spacer surface between the sixth and seventh stage disks. That condition, if not corrected, could result in HPC front drum rotor failure that could result in an uncontained engine failure and damage to the airplane.

Since that AD was issued, the FAA received three comments from operators stating that the inspection requirements stated in paragraph (a)(1) are inconsistent with the alert service bulletin. The FAA agreed with these comments and paragraph (a)(1) has been changed to clarify inspection requirements for cracking of HPC front drum rotors that have fewer than 1,000 CSN.

Manufacturer's Service Information

The FAA has reviewed and approved the technical contents of Pratt & Whitney Alert Service Bulletin (ASB) PW4ENG A72-722, dated September 29, 2000 and (ASB) PW4ENG A72-722, Revision 1, dated June 7, 2001 that describe procedures for initial and repetitive inspections for cracking of HPC front drum rotors based on cycle usage and the removal from service of any cracked HPC front drum rotors.

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 Pratt & Whitney PW4000 series turbofan engines, products of this same type design, the proposed AD would supersede AD 2001-20-13 to clarify inspection requirements for front drum rotors that have fewer than 1,000 cycles-since-new. The actions are required to be done in accordance with the service bulletins described previously.

Economic Analysis

The FAA estimates that there will be no additional costs attributable to this proposed supersedure.

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 39-12461, (66 FR 52023, October 12, 2001), and by adding a new airworthiness directive:

Pratt & Whitney: Docket No. 2000-NE-49-AD. Supersedes AD 2001-20-13, Amendment 39-12461.

Applicability

This airworthiness directive (AD) applies to Pratt & Whitney (PW) models PW4052, PW4056, PW4060, PW4062, PW4152, PW4156A, PW4158, PW4460, and PW4462 turbofan engines. These engines are installed on but not limited to Boeing 747, 767, McDonnell Douglas MD-11, Airbus Industrie A300, and A310 series 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

Required as indicated, unless accomplished previously.

To prevent failure of the high pressure compressor (HPC) front drum rotor from cracks, that could result in an uncontained engine failure and damage to the airplane, do the following:

Initial Inspection

(a) Perform an initial borescope inspection for cracks in accordance with the Accomplishment Instructions, On-Wing paragraphs 1 through 13, of Pratt & Whitney (PW) Alert Service Bulletin (ASB) No. PW4ENG A72-722, dated September 29, 2000 or Revision 1, dated June 7, 2001, as follows:

(1) For HPC front drum rotors with fewer than 1,000 cycles-since-new (CSN) on the effective date of this AD, perform an initial inspection within 500 cycles-in-service (CIS) after accumulating 1,000 CSN.

(2) For HPC front drum rotors with 1,000 CSN or more after the effective date of this AD, perform an initial inspection within 500 CIS after the effective date of this AD.

(3) If the presence of a crack needs to be confirmed, perform an eddy current inspection (ECI) within five flight cycles of the on-wing borescope inspection.

(4) If the presence of a crack needs to be confirmed and the suspect crack indication extends from the knife edges to the disk radius directly adjacent to the spacer wall of the sixth or seventh stage as shown in Figures 2 and 3 of PW ASB No. PW4ENG A72-722, dated September 29, 2000, or Revision 1, dated June 7, 2001, the ECI inspection must be done before further flight.

(5) If the presence of a crack is confirmed, remove and replace the HPC front drum rotor with a serviceable part before further flight.

(6) HPC front drum rotors fluorescent penetrant inspected at the last shop visit, as cited in the compliance section of the ASB, within 500 cycles of the effective date of this AD, satisfy the initial inspection requirement.

Repetitive Inspections

(b) Thereafter, perform borescope inspections within 2,200 cycles-since-last-inspection, in accordance with the Accomplishment Instructions, On-Wing paragraphs 1 through 13, of PW ASB No. PW4ENG A72-722, dated September 29, 2000, or Revision 1, dated June 7, 2001.

(1) If the presence of a crack needs to be confirmed, perform an ECI within five flight cycles.

(2) If the presence of a crack needs to be confirmed and the suspect crack indication extends from the knife edges to the disk radius directly adjacent to the spacer wall of the sixth or seventh stage as shown in Figures 2 and 3 of PW ASB No. PW4ENG A72-722, dated September 29, 2000, or Revision 1, dated June 7, 2001, the ECI inspection must be done before further flight.

(3) If the presence of a crack is confirmed, remove and replace with a serviceable HPC front drum rotor before further flight.

Definition of Suspect Crack Indication

(c) For the purposes of this AD, a suspect crack indication is defined as a response from the visual borescope inspection procedure that denotes the possible presence of a material discontinuity and requires interpretation to determine its significance.

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 Federal Aviation Administration (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 accomplished.

Issued in Burlington, Massachusetts, on January 7, 2002.

Jay J. Pardee,

Manager, Engine and Propeller Directorate, Aircraft Certification Service.