[Federal Register Volume 59, Number 50 (Tuesday, March 15, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-5941]


[[Page Unknown]]

[Federal Register: March 15, 1994]


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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 93-ANE-79]

 

Airworthiness Directives; Pratt & Whitney JT8D Series Turbofan 
Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the supersedure of an existing 
airworthiness directive (AD), applicable to Pratt & Whitney JT8D series 
turbofan engines, that currently requires repetitive inspections of the 
combustion chamber outer case (CCOC). This action would reduce the rear 
flange inspection interval for CCOC's when only the aft face of the 
rear flange has been inspected and introduce an improved ultrasonic 
probe assembly. This proposal is prompted by reports of rupture of 
CCOC's that had only the aft face of the rear flange inspected in 
accordance with the current AD. The CCOC's ruptured due to cracks on 
the forward face of the rear flange that were not detected during this 
inspection and had propagated to critical lengths within the inspection 
interval required by the current AD. The actions specified by the 
proposed AD are intended to prevent CCOC flange cracks that could 
result in uncontained engine failure, inflight engine shutdown, engine 
cowl release, and airframe damage.

DATES: Comments must be received by May 16, 1994.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), New England Region, Office of the Assistant Chief 
Counsel, Attention: Rules Docket No. 93-ANE-79, 12 New England 
Executive Park, Burlington, MA 01803-5299. Comments may be inspected at 
this location between 8 a.m. and 4:30 p.m., Monday through Friday, 
except Federal holidays.
    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 at the FAA, New England Region, 
Office of the Assistant Chief Counsel, 12 New England Executive Park, 
Burlington, MA.

FOR FURTHER INFORMATION CONTACT: Mark A. Rumizen, Aerospace Engineer, 
Engine Certification Office, FAA, Engine and Propeller Directorate, 12 
New England Executive Park, Burlington, MA 01803-5299; telephone (617) 
238-7137, fax (617) 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 notice 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 notice must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 93-ANE-79.'' The postcard will be date stamped and 
returned to the commenter.

Availability of NPRMs

    Any person may obtain a copy of this NPRM by submitting a request 
to the FAA, New England Region, Office of the Assistant Chief Counsel, 
Attention: Rules Docket No. 93-ANE-79, 12 New England Executive Park, 
Burlington, MA 01803-5299.

Discussion

    On October 3, 1989, the Federal Aviation Administration (FAA) 
issued airworthiness directive (AD) 87-11-07 R1, Amendment 39-6360 (54 
FR 46045, November 1, 1989), applicable to Pratt & Whitney (PW) JT8D 
series turbofan engines, to require repetitive eddy current, 
fluorescent penetrant, fluorescent magnetic penetrant, or visual 
inspections for cracks in the rear flange, and ultrasonic, fluorescent 
penetrant, or fluorescent magnetic penetrant inspections for cracks in 
the PS4 boss, and drain bosses of the combustion chamber outer case 
(CCOC). That action was prompted by reports of uncontained rupture of 
the CCOC. That condition, if not corrected, could result in CCOC flange 
cracks that if undetected could result in uncontained engine failure, 
inflight engine shutdown, engine cowl release, and airframe damage.
    Since the issuance of that AD, the FAA has received reports of 
rupture of CCOC's that had only the aft face of the rear flange 
inspected in accordance with the current AD. The CCOC's ruptured due to 
cracks on the forward face of the rear flange that were not detected 
during this inspection and propagated to critical lengths within the 
inspection interval required by the current AD. The FAA has determined 
that a reduced inspection interval is required if only the aft face of 
the rear flange is inspected and the forward face is not inspected. The 
proposed AD maintains the rear flange inspection, but specifies this 
reduced interval if only the aft face of the rear flange is inspected.
    The requirement in the current AD to inspect the CCOC at every shop 
visit, in addition to the specified cyclic intervals, is maintained in 
this proposed AD. This inspection requirement is necessary to meet 
safety of flight criteria based on the statistical forecasting models 
utilized to assess this problem. The proposed AD also requires 
reporting of CCOC inspection results to the FAA for the purpose of 
updating these statistical forecasting models.
    The current AD requires more frequent inspection of the PS4 boss 
and drain bosses that have been weld repaired. This requirement is 
maintained in the proposed AD and was based on analytical studies and 
component tests that revealed a greater propensity for these weld 
repaired bosses to develop cracks.
    The FAA has reviewed and approved the technical contents of PW 
Alert Service Bulletin (ASB) No. 5676, Revision 8, dated November 5, 
1993, that describes procedures for initial and repetitive inspections 
of the CCOC for cracks.
    Since an unsafe condition has been identified that is likely to 
exist or develop on other products of this same type design, the 
proposed AD would supersede AD 87-11-07 R1 to reduce the inspection 
interval for CCOC's that have had only the aft face of the rear flange 
inspected and introduce an improved ultrasonic probe assembly.
    The FAA estimates that 6,815 engines installed on aircraft of U.S. 
registry would be affected by this proposed AD, that it would take 
approximately 4 work hours per engine to accomplish the proposed 
actions, and that the average labor rate is $55 per work hour. Based on 
these figures, the total cost impact of the proposed AD on U.S. 
operators is estimated to be $1,499,300.
    The regulations proposed herein would not have substantial direct 
effects 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. Therefore, in 
accordance with Executive Order 12612, it is determined that this 
proposal would not have sufficient federalism implications to warrant 
the preparation of a Federalism Assessment.
    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 14 
CFR part 39 of the Federal Aviation Regulations as follows:

PART 39--AIRWORTHINESS DIRECTIVES

    1. The authority citation for part 39 continues to read as follows:

    Authority: 49 U.S.C. App. 1354(a), 1421 and 1423; 49 U.S.C. 
106(g); and 14 CFR 11.89.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by removing amendment 39-6360 (54 FR 
46045, November 1, 1989) and by adding a new airworthiness directive to 
read as follows:

Pratt & Whitney: Docket No. 93-ANE-79. Supersedes AD 87-11-07 R1, 
Amendment 39-6360 and AD 87-11-07, Amendment 39-5619.

    Applicability: Pratt & Whitney (PW) Models JT8D-1, -1A, -1B, -7, 
-7A, -7B, -9, -9A, -11, -15, -15A, -17, -17A, -17R, and -17AR 
turbofan engines, installed on but not limited to Boeing 727 and 737 
series aircraft, and McDonnell Douglas DC-9 series aircraft.
    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent combustion chamber outer case (CCOC) flange cracks 
that could result in uncontained engine failure, inflight engine 
shutdown, engine cowl release, and airframe damage, accomplish the 
following:
    (a) Ultrasonic, eddy current, fluorescent penetrant, fluorescent 
magnetic penetrant, or visually inspect the CCOC PS4 boss, drain 
boss, and rear flange for cracks at each engine shop visit after the 
effective date of this AD, in accordance with paragraph 2.B.(3) of 
PW Alert Service Bulletin (ASB) No. 5676, Revision 8, dated November 
5, 1993.
    (b) Ultrasonic, fluorescent penetrant, fluorescent magnetic 
penetrant, or visually inspect the CCOC PS4 boss and drain boss, 
which have not been weld repaired, for cracks at the initial and 
repetitive intervals specified in paragraph 1.E.(1) and Table 1 of 
PW ASB No. 5676, Revision 8, dated November 5, 1993, in accordance 
with the Accomplishment Instructions of paragraph 2 and Table 3 of 
PW ASB No. 5676, Revision 8, dated November 5, 1993.
    (c) Eddy current, fluorescent penetrant, fluorescent magnetic 
penetrant, or visually inspect the CCOC rear flange for cracks at 
the initial and repetitive intervals specified in paragraph 1.E.(1) 
and Table 1 of PW ASB No. 5676, Revision 8, dated November 5, 1993, 
in accordance with the Accomplishment Instructions of paragraph 2 
and Table 3 of PW ASB No. 5676, Revision 8, dated November 5, 1993.
    (d) Ultrasonic, fluorescent penetrant, fluorescent magnetic 
penetrant, or visually inspect the CCOC PS4 boss and drain boss, 
which have been weld repaired, for cracks at the interval specified 
in paragraph 1.E.(1) and Table 1 of PW ASB No. 5676, Revision 8, 
dated November 5, 1993, in accordance with the Accomplishment 
Instructions of paragraph 2 and Table 3 of PW ASB No. 5676, Revision 
8, dated November 5, 1993.
    (e) CCOC's inspected in accordance with paragraphs (a), (b), 
(c), and (d) of this AD that are found cracked must be removed from 
service prior to further flight and replaced with a serviceable 
part.
    (f) For the purpose of this AD, a shop visit is defined as an 
engine removal to perform engine maintenance that cannot be 
performed on-wing, that entails separation of pairs of mating engine 
lettered flanges or the removal of a compressor disk, hub, or spool, 
or removal of a turbine disk.
    (g) Report the following information in writing, if a case is 
found cracked, within 30 days of the inspection, to the Manager, 
Engine Certification Office, Engine and Propeller Directorate, 
Aircraft Certification Service, FAA, 12 New England Executive Park, 
Burlington, MA 01803-05299; Telex Number 949301 FAANE BURL; fax 
(617) 238-7199:
    (1) Engine Serial Number
    (2) Inspection date
    (3) Case Part Number and Serial Number
    (4) Case total time in service and cycles in service (if 
estimate, so note)
    (5) Case time in service and cycles in service since last 
inspection
    (6) Method of inspection used
    (7) Crack location and size

The reporting requirements of this proposed AD terminate one year 
from the effective date of the AD.
    (h) Information collection requirements contained in this 
proposed regulation have been approved by the Office of Management 
and Budget under the provisions of the Paperwork Reduction Act of 
1980 (Pub. L. 96-511) and have been assigned OMB control number 
2120-0056.
    (i) 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. The 
request should be forwarded through an appropriate FAA Principal 
Maintenance Inspector, who may add comments and then send it to the 
Manager, Engine Certification Office.

    Note: Information concerning the existence of approved 
alternative methods of compliance with this airworthiness directive, 
if any, may be obtained from the Engine Certification Office.

    (j) Special flight permits may be issued in accordance with FAR 
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 March 8, 1994.
Jay J. Pardee,
Manager, Engine and Propeller Directorate, Aircraft Certification 
Service.
[FR Doc. 94-5941 Filed 3-14-94; 8:45 am]
BILLING CODE 4910-13-P