[Federal Register Volume 68, Number 16 (Friday, January 24, 2003)]
[Proposed Rules]
[Pages 3475-3477]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 03-1543]


 ========================================================================
 Proposed Rules
                                                 Federal Register
 ________________________________________________________________________
 
 This section of the FEDERAL REGISTER contains notices to the public of 
 the proposed issuance of rules and regulations. The purpose of these 
 notices is to give interested persons an opportunity to participate in 
 the rule making prior to the adoption of the final rules.
 
 ========================================================================
 

  Federal Register / Vol. 68, No. 16 / Friday, January 24, 2003 / 
Proposed Rules  

[[Page 3475]]



DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97-ANE-05-AD]
RIN 2120-AA64


Airworthiness Directives; Pratt & Whitney JT8D Series Turbofan 
Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: The Federal Aviation Administration (FAA) proposes to 
supersede an existing airworthiness directive (AD), that is applicable 
to Pratt & Whitney JT8D-1, -1A, -1B, -7, -7A, -7B, -9, -9A, -11, -15, -
15A, -17, -17A, -17R, and -17AR turbofan engines. That AD currently 
requires a determination of the utilization rate and protective coating 
type of the 7th, 8th, 9th, 10th, 11th, and 12th stage high pressure 
compressor (HPC) disks, and removal, inspection for corrosion, and 
recoating of those HPC disks based on utilization rate. This proposal 
would require removal and replacement of protective coating of 7th, 
8th, 9th, 10th, 11th, and 12th stage HPC disks, initial and repetitive 
inspections for corrosion pits and cracks, and removal from service as 
required. This proposal is prompted by operator reports of cracks found 
on several JT8D steel HPC disks since the existing AD was published. 
The actions specified in the proposed AD are intended to prevent 
fracture of the HPC disks, which can result in uncontained release of 
engine fragments, inflight engine shutdown, and airframe damage.

DATES: Comments must be received by March 25, 2003.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), New England Region, Office of the Regional 
Counsel, Attention: Rules Docket No. 97-ANE-05-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: ``[email protected]''. 
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 St., East Hartford, CT 06108; 
telephone (860) 565-6600, fax (860) 565-4503. 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: Christopher Spinney, Aerospace 
Engineer, Engine Certification Office, FAA, Engine and Propeller 
Directorate, 12 New England Executive Park, Burlington, MA 01803-5299; 
telephone (781) 238-7175; fax (781) 238-7199.

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 97-ANE-05-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. 97-ANE-05-AD, 12 New England Executive 
Park, Burlington, MA 01803-5299.

Discussion

    On May 29, 1998, the FAA issued AD 98-12-07, Amendment 39-10563 (63 
FR 31340, June 9, 1998), to supersede AD 94-20-01, Amendment 39-9020 
(59 FR 49175, September 27, 1994). AD 98-12-07 requires a determination 
of the utilization rate and protective coating type of the 7th, 8th, 
9th, 10th, 11th, and 12th stage HPC disks, and removal, inspection for 
corrosion, and recoating of those HPC disks based on utilization rate, 
and shortens the inspection interval for certain low utilization disks. 
That action was prompted by a report of an additional uncontained 9th 
stage HPC disk failure due to corrosion pitting. That condition, if not 
corrected, could result in uncontained release of engine fragments, 
inflight engine shutdown, and airframe damage.
    Since that AD was issued, operators have found cracks on various 
JT8D steel HPC disks. Some of these cracks originate in the tierod hole 
area of the disk. The inspection intervals in AD 98-12-07 do not 
account for risk of fractures originating from tierod hole areas. This 
proposal is a result of a complete re-assessment of the risks 
associated with a disk fracture due to a corrosion pit. Since the 
tierod hole corrosion does not correlate well with the utilization rate 
of the disks, that calculation has been eliminated from the proposal. 
Also, because the thin-webbed 9th stage disk represents a higher risk 
of fracture than other part numbers, a tighter inspection interval has 
been assigned to those parts.

Manufacturer's Service Information

    The FAA has reviewed and approved the technical contents of Pratt & 
Whitney Alert Service Bulletin (ASB) No. A6431, dated November 27, 
2002, that describes procedures for initial and repetitive inspections 
to detect corrosion on HPC disks, and removal

[[Page 3476]]

from service of HPC disks corroded beyond serviceable limits. This ASB 
supersedes ASB No. 6038, referenced in AD 98-12-07.

Differences Between This Proposal and the Manufacturer's Service 
Information

    Although PW ASB No. A6431 dated November 27, 2002, refers to the 
ASB issuance date for computing compliance intervals, this proposal 
calls for computing compliance intervals based on the effective date of 
the AD.

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 JT8D-1, -1A, -1B, -7, -7A, -
7B, -9, -9A, -11, -15, -15A, -17, -17A, -17R, and -17AR turbofan 
engines of this same type design, the proposed AD would supersede AD 
98-12-07 to require removal and replacement of coating of 7th, 8th, 
9th, 10th, 11th, and 12th stage HPC disks, initial and repetitive 
inspections for corrosion pits and cracks, and removal from service as 
required. The actions are required to be done in accordance with the 
alert service bulletin described previously.

Economic Analysis

    At the time of publication of AD 98-12-07, there were approximately 
11,119 engines of the affected design in the worldwide fleet. The FAA 
estimated that 6,815 engines installed on aircraft of U.S. registry 
were affected by AD 94-20-01, and 2 work hours would be necessary to 
determine the utilization rate and type of surface treatment. Based on 
domestic fleetwide data, the FAA estimated that approximately 8.7% or 
593 engines were considered to have low utilization rates. 
Approximately 8.6 work hours would be required to remove these engines 
from the aircraft, 500 work hours to tear down, deblade, and to 
reassemble the engine, and 8.6 work hours to reinstall the reassembled 
engines. The FAA estimated 69% of the removed engines would require 
scrapping the disks. The FAA assumed that 3 disks per engine may 
require replacement, and the cost of a new disk would be approximately 
$7,000. The average labor rate is $60 per work hour. Based on these 
figures, the total cost of AD 94-20-01 on U.S. operators was estimated 
to be $ 14,279,542. The cost increase between AD 94-20-01 and the 
superseding AD, AD 98-12-07 was based on the increased inspections of 
some low utilization disks. The FAA estimated 31% of the low 
utilization disks required an additional inspection. The cost of these 
additional inspections was estimated to be $4,426,658. The cost 
increase between AD 98-12-07 and this proposal is based on the 
increased domestic fleet size that will be effected by this proposal. 
The FAA currently estimates the domestic fleet of engines affected by 
this AD to be 1,800 engines. This is an increase of 1,023 engines or 
1.32 times the total number of engines effected by the two previous 
AD's. The total cost of the previous two AD's was $18,706,200, 
therefore, the total cost of this AD is $24,692,184, and the cost 
increase associated with this proposal is $5,985,985.

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.


Sec.  39.13  [Amended]

    2. Section 39.13 is amended by removing Amendment 39-10563, (63 FR 
31340 June 9, 1998), and by adding a new airworthiness directive:

Pratt & Whitney: Docket No. 97-ANE-05-AD. Supersedes AD 98-12-07, 
Amendment 39-10563.

    Applicability: This airworthiness directive (AD) is applicable 
to Pratt & Whitney (PW) JT8D-1, -1A, -1B, -7, -7A, -7B, -9, -9A, -
11, -15, -15A, -17, -17A, -17R, and -17AR turbofan engines. These 
engines are installed on, but not limited to Boeing 737 and 727 
series, and McDonnell Douglas DC-9 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: Compliance with this AD is required as indicated, 
unless already done.
    To prevent fracture of the 7th, 8th, 9th, 10th, 11th, and 12th 
stage high pressure compressor (HPC) disks, which can result in 
uncontained release of engine fragments, inflight engine shutdown, 
and airframe damage, do the following:
    (a) Perform initial and repetitive inspections of HPC disks for 
corrosion pits and cracks after stripping the protective coating in 
accordance with the intervals and procedures specified in the 
compliance section and accomplishment instructions of PW Alert 
Service Bulletin (ASB) No. 6431, dated November 27, 2002.
    (b) Before further flight, replace HPC disks found with 
corrosion pits or cracks beyond serviceable limits as defined by PW 
ASB No. 6431, dated November 27, 2002.
    (c) For the purposes of this AD, use the effective date of this 
AD for computing compliance intervals whenever PW ASB No. A6431, 
dated November 27, 2002, refers to the issuance date of the ASB.

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 
Sec. Sec.  21.197 and 21.199 of the Federal Aviation Regulations (14 
CFR 21.197

[[Page 3477]]

and 21.199) to operate the airplanes to a location where the 
requirements of this AD can be done.

    Issued in Burlington, Massachusetts, on January 16, 2003.
Francis A. Favara,
Acting Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
[FR Doc. 03-1543 Filed 1-23-03; 8:45 am]
BILLING CODE 4910-13-P