AD 2001-04-11

This amendment adopts a new airworthiness directive (AD) that is applicable to certain Pratt & Whitney (PW) JT9D series turbofan engines. This amendment requires initial and repetitive detailed eddy current inspections for cracks in 1st stage high pressure turbine (HPT) disks, and, if necessary, replacement with serviceable parts. This amendment is prompted by the discovery of a crack in the web of one cooling air hole on a 1st stage HPT disk. The actions specified by this AD are intended to prevent 1st stage HPT disk cracking, which could result in an uncontained engine failure and damage to the aircraft.

Final rule

2001-04-11 Pratt & Whitney: Amendment 39-12130. Docket No. 99-NE-56-AD.

Applicability: Pratt & Whitney (PW) JT9D-7R4D, -7R4D1, -7R4E, -7R4E1 (AI-500), -7, -7A, -7AH, -7H, -7F, and -20 series turbofan engines, installed on but not limited to Boeing 747 and 767 series, McDonnell Douglas DC-10 series, and Airbus Industrie A310 series aircraft.

Note 1: This airworthiness directive (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 (c) 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 1st stage high pressure turbine (HPT) disk cracking, which could result in an uncontained engine failure and damage to the aircraft, accomplish the following:

JT9D Series
(a) For PW JT9D-7, -7A, -7AH, -7H, -7F, and -20 series turbofan engines, with 1st stage HPT disks, part numbers (P/Ns) 761401, 811401, 823401, 825601, 826001, and 826301:

Initial Inspection
(1) Perform the initial detailed eddy current inspection (ECI) for cracks in accordance with the Accomplishment Instructions of PW Alert Service Bulletin (ASB) No. JT9D A6367, dated July 28, 1999.

(2) Inspect at the following compliance times, depending on whether parts have had prior fluorescent penetrant inspections (FPI) or not.

Initial Compliance Times
No Prior FPI
(3) The following are the initialcompliance times for parts that have had no prior FPI:

(i) For disks with more than 8,000 total part cycles-since-new (CSN) on the effective date of this AD, inspect within 250 cycles-in-service (CIS) after the effective date of this AD.

(ii) For disks with at least 6,000 CSN though no more than 8,000 total part CSN on the effective date of this AD, inspect within 1,000 CIS after the effective date of this AD.

(iii) For disks with at least 4,000 CSN though no more than 5,999 total part CSN on the effective date of this AD, inspect within 2,000 CIS after the effective date of this AD.

(iv) For disks with less than 4,000 total part CSN on the effective date of this AD, inspect prior to accumulating 6,000 total part CSN.

Prior FPI Accomplished
(4) The following are the initial compliance times for parts that have had a previous FPI:

(i) For disks with more than 8,000 CIS since last FPI on the effective date of this AD, inspect within 250 CIS after the effective date of this AD.

(ii) For disks with at least 6,000 CIS though no more than 8,000 CIS since last FPI on the effective date of this AD, inspect within 1,000 CIS after the effective date of this AD.

(iii) For disks with at least 4,000 CIS though no more than 5,999 CIS since last FPI on the effective date of this AD, inspect within 2,000 CIS after the effective date of this AD.

(iv) For disks with less than 4,000 CIS since last FPI on the effective date of this AD, inspect prior to accumulating 6,000 CIS since last FPI on the effective date of this AD.

Repetitive Inspections
(5) Thereafter, perform detailed ECI for cracks:

(i) At intervals not to exceed 6,000 CIS since last ECI.

(ii) Inspect in accordance with the Accomplishment Instructions of PW ASB No. JT9D A6367, dated July 28, 1999.

Cracked Disks
(6) Prior to further flight, replace cracked disks with serviceable parts.

JT9D-7R4 Series
(b) For PW JT9D-7R4D, -7R4D1, -7R4E, and -7R4E1 (AI-500) series turbofan engines, with 1st stage HPT disks, P/N 825601:

Initial Inspection
(1) Perform the initial detailed ECI for cracks in accordance with the Accomplishment Instructions of PW ASB No. JT9D-7R4-A72-563, dated July 28, 1999.

(2) Inspect at the following compliance times, depending on whether parts have had prior FPI or not.

Initial Compliance Times
No Prior FPI
(3) The following are the initial compliance times for parts that have had no prior FPI:

(i) For disks with more than 10,000 total part CSN on the effective date of this AD, inspect within 250 CIS after the effective date of this AD.

(ii) For disks with at least 8,000 CSN though no more than 10,000 total part CSN on the effective date of this AD, inspect within 1,000 CIS after the effective date of this AD.

(iii) For disks with at least 6,000 CSN though no more than 7,999 total part CSN on the effective date of this AD, inspect within 2,000 CISafter the effective date of this AD.

(iv) For disks with less than 6,000 total part CSN on the effective date of this AD, inspect prior to accumulating 8,000 total part CSN.

Prior FPI Accomplished
(4) The following are the initial compliance times for parts that have had a previous FPI:

(i) For disks with more than 10,000 CIS since last FPI on the effective date of this AD, inspect within 250 CIS after the effective date of this AD.

(ii) For disks with at least 8,000 CIS though no more than 10,000 CIS since last FPI on the effective date of this AD, inspect within 1,000 CIS after the effective date of this AD.

(iii) For disks with at least 6,000 CIS though no more than 7,999 CIS since last FPI on the effective date of this AD, inspect within 2,000 CIS after the effective date of this AD.

(iv) For disks with less than 6,000 CIS since last FPI on the effective date of this AD, inspect prior to accumulating 8,000 CIS since last FPI on the effective date of this AD.

Repetitive Inspections
(5) Thereafter, perform detailed ECI for cracks:

(i) At intervals not to exceed 8,000 CIS since last ECI.

(ii) Inspect in accordance with the Accomplishment Instructions of PW ASB No. JT9D-7R4-A72-563, dated July 28, 1999.

Cracked Disks
(6) Prior to further flight, replace cracked disks with serviceable parts.

Alternative Methods of Compliance
(c) 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 shall 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.

Ferry Flights
(d) Special flight permits maybe issued in accordance with sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the aircraft to a location where the inspection requirements of this AD can be accomplished.

Incorporation by Reference
(e) The actions required by this AD must be done in accordance with the following Pratt & Whitney Alert Service Bulletins:

Document No.
Pages
Revision
Date
JT9D A6367
1-12
Original
July 28, 1999
Total pages:12

JT9D-7R4-A72-563
1-37
Original
July 28, 1999
Total pages: 37

This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from Pratt & Whitney, 400 Main Street, East Hartford, CT 06108; telephone: 860 565-6600, fax: 860 565-4503. Copies may be inspected at the FAA, New England Region, Office of the Regional Counsel, 12 New England Executive Park, Burlington, MA; or at the Office of theFederal Register, 800 North Capitol Street, NW, suite 700, Washington, DC.

Effective Date
(f) This amendment becomes effective on May 7, 2001.

A proposal to amend part 39 of the Federal Aviation Regulations (14CFR part 39) to include an AD that is applicable to certain PW JT9D series turbofan engines was published in the Federal Register on March 7, 2000 (65 FR 11940). That action proposed to require initial and repetitive detailed eddy current inspections for cracks in 1st stage HPT disks, and, if necessary, replacement with serviceable parts.

Comments Received
Interested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the comments received.

Support for the Rule as Proposed
Two commenters state their support of the notice of proposed rulemaking (NPRM) as written.

Economic Analysis Question
One commenter states that the cost incurred due to premature engine removal is not captured in the NPRM economic analysis. This cost would adversely impact operators when an engine must be removed prematurely in order to perform disk inspections. The cost would specifically impact this operator when an engine that is not under its maintenance program is acquired and is inducted into its system.

The FAA does not agree. The NPRM cost analysis is based on the costs of parts and labor to U.S. operators needed to perform the required initial inspections, and is not specific to any particular maintenance system. However, the economic analysis is corrected to clarify that the cost totals are for initial inspection only.

Two Types of Compliance Times
Two commenters state that the NPRM's proposed compliance times are inconsistent with the compliance times referenced in PW Alert Service Bulletins (ASB's) JT9D A6376, dated July 28, 1999 and JT9D-7R4-A72-563, dated July 28, 1999. Specifically, for disks that have had a prior fluorescent penetrant inspection, the NPRM proposed reinspections based on cycles-since-new (CSN) intervals. The ASB's, however, require reinspections based on cycles-in-service (CIS) intervals.

The FAA agrees. The compliance is corrected as follows:

In the JT9D series engines section, in paragraph (a)(4)(ii) and (a)(4)(iii), the compliance time type is changed from CSN to CIS.

In the JT9D-7R4 series engines section, in paragraph (b)(4)(ii) and (b)(4)(iii), the compliance time type is changed from CSN to CIS.

Incorrect Aircraft Model Applicability
One commenter states that under the Applicability section in the NPRM, the reference to Airbus Industrie A300 series aircraft is incorrect, and should read Airbus Industrie A310 series aircraft.

The FAA agrees. The Applicability section is corrected in this amendment.

After careful review of the available data, including the comments noted above, the FAA has determined that air safety and the public interest require the adoption of the rule with the changes described previously. The FAA has determined that these changes will neither increase the economic burden on any operator norincrease the scope of the AD.

Economic Analysis
There are approximately 330 engines of the affected design in the worldwide fleet. The FAA estimates that 220 engines installed on aircraft of U.S. registry would be affected by this proposed AD, that it would take approximately 4.5 work hours per engine to accomplish the initial inspection, and that the average labor rate is $60 per work hour. Required parts would cost approximately $165,000 per engine. Based on these figures, the total initial inspection cost impact of the proposed AD on U.S. operators is estimated to be $36,359,400.

Regulatory Impact
This 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 rule.

For the reasons discussed above, I certify that this action (1) is not a "significant regulatory action" under Executive Order 12866; (2) is not a "significant rule" under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (3) 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 final evaluation has been prepared for this action and it is contained in the Rules Docket. A copy of it may be obtained from the Rules Docket at the location provided under the caption "ADDRESSES."

List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.

Adoption of the Amendment
Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration amends 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 adding the following new airworthiness directive: 2001-04-11,