[Federal Register Volume 65, Number 58 (Friday, March 24, 2000)]
[Proposed Rules]
[Pages 15878-15880]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-7225]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97-ANE-44]
RIN 2120-AA64


Airworthiness Directives; Pratt & Whitney PW4164, PW4168, and 
PW4168A 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 PW4164, 
PW4168, and PW4168A series turbofan engines. AD 98-04-14 currently 
requires initial and repetitive torque checks for loose or broken front 
pylon mount bolts, replacement, if necessary, with new bolts, and 
establishment of a new cyclic life limit. This action would add initial 
and repetitive torque checks of new material MP159 front pylon mount 
bolts. In addition, this action would add initial and repetitive visual 
inspections of the primary mount thrust load path. This proposal is 
prompted by the introduction into service of the new MP159 front pylon 
mount bolts and the determination through fatigue testing that the 
forward engine mount bearing housings have insufficient fatigue life 
expectancy. The actions specified by the proposed AD are intended to 
prevent front pylon mount bolt and primary mount thrust load path 
failure, which could result in engine separation from the aircraft.

DATES: Comments must be received by April 24, 2000.

ADDRESSES: Submit comments to the Federal Aviation Administration 
(FAA), New England Region, Office of the Regional Counsel, Attention: 
Rules Docket No. 97-ANE-44, 12 New England Executive Park, Burlington, 
MA 01803-5299. 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. 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 St., East Hartford, CT 06108; 
telephone (860) 565-8860, fax (860) 565-4503. This information may be 
examined 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 (781) 
238-7130, 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 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 97-ANE-44.'' 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 Regional Counsel, 
Attention: Rules Docket No. 97-ANE-44, 12 New England Executive Park, 
Burlington, MA 01803-5299.

Discussion

    On February 6, 1998, the Federal Aviation Administration (FAA) 
issued airworthiness directive AD 98-04-14, Amendment 39-10326 (63 FR 
9730, February 26, 1998), applicable to Pratt & Whitney (PW) PW4164, 
PW4168, and PW4168A series turbofan engines. That AD requires initial 
and repetitive inspections for loose or broken front pylon mount bolts, 
replacement, if necessary, with new bolts, and establishment of a new 
cyclic life limit of 11,000 cycles in service (CIS) for INCO 718 
material bolts. That action was prompted by flight testing that 
revealed higher than predicted loads for front pylon mount bolts, 
resulting in decreased service life. That condition, if not corrected, 
could result in front pylon mount bolt failure, which could result in 
engine separation from the aircraft.

Events Since the Issuance of the AD

    Since the issuance of that AD, PW introduced a new material bolt to 
address the fatigue life shortfall of the original INCO 718 material 
bolts, part number (P/N) 54T670. MP159 material bolts, P/N 51U615, do 
not require a life limit. However, in a bolt-out configuration, fatigue 
testing indicated that there was insufficient margin to meet the 8,000 
cycles-in-service (CIS)

[[Page 15879]]

minimum inspection requirement for the aircraft. Therefore, the FAA 
determined a repetitive torque check interval of 1,000 CIS, plus or 
minus 250 CIS, to be consistent with the torque check interval required 
for the INCO 718 material bolts, P/N 54T670.
    In addition, fatigue testing of the secondary thrust load path 
using the measured flight loads demonstrated that with a primary thrust 
load path failure, there is insufficient fatigue life expectancy of the 
forward engine mount bearing housing. Therefore, a repetitive visual 
inspection of the primary mount thrust load path at a 1,000 CIS, plus 
or minus 250 CIS, interval is required

Service Information

    The FAA has reviewed and approved the technical contents of the 
following PW Service Bulletins (SBs):
     No. PW4G-100-A71-20, dated December 9, 1999, that 
describes procedures for torque checking MP159 material bolts, P/N 
51U615.
 No. PW4G-100-A71-18, dated September 15, 1999, that describes 
procedures for visually inspecting the primary mount thrust load path.

Proposed Actions

    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 98-04-14 to maintain the inspections of 
the INCO 718 material bolts, P/N 54T670, and replacement, if necessary, 
with serviceable parts. This superseding AD would also maintain the 
life limit of 11,000 CSN for the INCO 718 material bolts, P/N 54T670. 
However, based on a comment received to AD 98-04-14, the initial torque 
check would now be required for bolts with 1,000 or fewer CSN before 
accumulating 1,250 CSN, or 250 CIS after the effective date of this AD, 
whichever occurs first.

New Actions

    This AD would also require initial and repetitive torque checks of 
MP159 material bolts, P/N 51U615, and the primary mount thrust load 
path. If any of the bolts are found loose or broken, all four bolts 
must be replaced with serviceable bolts.
    Also, this AD would require initial and repetitive visual 
inspections of the primary mount thrust load path. If any components of 
the primary mount thrust load path are found cracked, then this AD 
would require replacement with serviceable parts.

Economic Analysis

    There are approximately 75 engines of the affected design in the 
worldwide fleet. The FAA estimates that 10 engines installed on 
aircraft of US registry would be affected by this proposed AD, that it 
would take approximately 3 work hours per engine to accomplish the 
proposed actions, and that the average labor rate is $60 per work hour. 
Required parts would cost approximately $18,832 per engine. Based on 
these figures, the total cost impact of the proposed AD on U.S. 
operators is estimated to be $190,120.

Agency Findings

    This proposal 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 proposal.
    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 39-10326, (63 FR 
9730, February 26, 1998), and by adding a new airworthiness directive 
to read as follows:

Pratt & Whitney: Docket No. 97-ANE-44. Supersedes AD 98-04-14, 
Amendment 39-10326.
    Applicability: Pratt & Whitney (PW) PW4164, PW4168, and PW4168A 
series turbofan engines, with front pylon mount bolts, part numbers 
(P/Ns) 54T670 or 51U615, installed. These engines are installed on 
but not limited to Airbus Industrie A330 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 (e) 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 front pylon mount bolt and primary mount thrust load 
path failure, which could result in engine separation from the 
aircraft, accomplish the following:

INCO 718 Material Bolts Torque Checks

    (a) Perform initial and repetitive torque checks of INCO 718 
material front pylon mount bolts, P/N 54T670, and replace, if 
necessary, with new bolts, in accordance with the Accomplishment 
Instructions of Pratt & Whitney Service Bulletin (SB) No. PW4G-100-
A71-9, Revision 1, dated November 24, 1997, as follows:
    (1) For front pylon mount bolts, P/N 54T670, with 1,000 or fewer 
cycles-since-new (CSN) on the effective date of this AD, perform 
torque checks in accordance with Part (A) of the Accomplishment 
Instructions of the SB at the earliest of:
    (i) Before accumulating 1,250 CSN, or
    (ii) Within 250 cycles-in-service (CIS) after the effective date 
of this AD, or
    (iii) The next engine removal for any cause.
    (2) Thereafter, perform torque checks at intervals not less than 
750 or greater than 1,250 CIS since last torque check, not to exceed 
11,000 CSN, in accordance with Part (A) of the Accomplishment 
Instructions of the SB.
    (3) For front pylon mount bolts, P/N 54T670, with more than 
1,000 CSN but less than 5,750 CSN on the effective date of this AD, 
accomplish the following:
    (i) Perform an initial torque check within 250 CIS after the 
effective date of this AD, or at the next engine removal for any 
cause, whichever occurs first, in accordance with Part (A) of the 
Accomplishment Instructions of the SB.
    (ii) Thereafter, perform torque checks at intervals not less 
than 750 or greater than 1,250 CIS since last torque check, not to 
exceed 11,000 CSN.
    (4) For front pylon mount bolts, P/N 54T670, with 5,750 or more 
CSN but less

[[Page 15880]]

than 8,000 CSN on the effective date of this AD, accomplish the 
following in accordance with Part (B) of the Accomplishment 
Instructions of the SB:
    (i) Perform an initial torque check within 250 CIS after the 
effective date of this AD, or prior to the next engine removal for 
any cause, whichever occurs first.
    (ii) Thereafter, perform torque checks at intervals not less 
than 750 or greater than 1,250 CIS since last torque check, not to 
exceed 11,000 CSN.
    (5) For front pylon mount bolts, P/N 54T670, with 8,000 or more 
CSN but less than 11,000 CSN on the effective date of this AD, 
perform an inspection in accordance with the schedule and procedures 
of the Appendix to the SB.
    (6) Prior to further flight, replace all four bolts in 
accordance with Part (A), Paragraph 1(D) of the Accomplishment 
Instructions of the SB, if any are found loose or broken.

INCO 718 Material Bolts Life Limit

    (b) This AD establishes a new life limit of 11,000 CSN for front 
pylon mount bolts, P/N 54T670. Except as provided in paragraph (e) 
of this AD, no front pylon mount bolts, P/N 54T670, may exceed this 
new life limit after the effective date of this AD.

MP159 Material Bolts Inspections

    (c) Perform initial and repetitive torque checks of front pylon 
mount bolts, P/N 51U615, in accordance with the Accomplishment 
Instructions of PW SB PW4G-100-A71-20, dated December 9, 1999, as 
follows:
    (1) Perform the initial torque check at the earliest of the 
following:
    (i) Before accumulating 1,250 CSN, or
    (ii) Within 250 CIS after the effective date of this AD, or
    (iii) The next engine removal for any cause.
    (2) Thereafter, perform torque inspections at intervals not less 
than 750 or greater than 1,250 CIS since last torque inspection.
    (3) Prior to further flight, replace all four bolts, if any are 
found loose or broken.

Primary Mount Thrust Load Path Inspections

    (d) Perform initial and repetitive visual inspections of the 
primary mount thrust load path, in accordance with the 
Accomplishment Instructions of PW4G-100-A71-18, dated September 15, 
1999, as follows:
    (1) Perform the initial visual inspection at the earliest of the 
following:
    (i) Before accumulating 1,250 CSN, or
    (ii) Within 250 CIS after the effective date of this AD, or
    (iii) The next engine removal for any cause.
    (2) Thereafter, perform visual inspections at intervals not less 
than 750 or greater than 1,250 CIS since last visual inspection.
    (3) Prior to further flight, replace all cracked parts with 
serviceable parts.

Alternative Methods of Compliance

    (e) 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. 
Operators shall submit their requests through an appropriate FAA 
Principal Maintenance Inspector, who may add comments and then send 
it to the Manager, Engine Certification Office.

    Note 2: Information concerning the existence of approved 
alternative methods of compliance with this airworthiness directive, 
if any, may be obtained from the Engine Certification Office.

Ferry Flights

    (f) Special flight permits may be 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 airplane to a location where 
the inspection requirements of this AD can be accomplished.

    Issued in Burlington, Massachusetts, on March 17, 2000.
Mark C. Fulmer,
Assistant Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
[FR Doc. 00-7225 Filed 3-23-00; 8:45 am]
BILLING CODE 4910-13-U