[Federal Register Volume 67, Number 1 (Wednesday, January 2, 2002)]
[Rules and Regulations]
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  Federal Register / Vol. 67, No. 1 / Wednesday, January 2, 2002 / 
Rules and Regulations  

[[Page 1]]



DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2000-NE-47-AD; Amendment 39-12564; AD 2001-25-11]
RIN 2120-AA64


Airworthiness Directives; Pratt and Whitney PW4000 Series 
Turbofan Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

-----------------------------------------------------------------------

SUMMARY: This amendment supersedes two airworthiness directives (AD's), 
AD 99-17-16 and AD 2001-15-12. Those AD's both apply to Pratt and 
Whitney (PW) model PW4000 series turbofan engines. AD 99-17-16 
generally requires that operators limit the number of PW4000 engines 
with potentially reduced stability margin to no more than one engine on 
each airplane, and requires initial and repetitive on-wing and test 
cell engine stability tests. It also establishes reporting requirements 
for stability testing data. AD 2001-15-12 also limits the number of 
PW4000 engines with potentially reduced stability on each airplane by 
applying rules based on airplane and engine configuration. In addition, 
AD 2001-15-12 also requires that engines that exceed high pressure 
compressor (HPC) cyclic limits based on cycles-since-overhaul (CSO) are 
removed from service, limits the number of engines with the HPC cutback 
stator (CBS) configuration to one on each airplane, and establishes a 
minimum rebuild standard for engines that are returned to service. 
These AD's were prompted by reports of surges during takeoff on 
airplanes equipped with PW4000 series turbofan engines.
    This amendment continues the limitation on the number of PW4000 
engines with potentially reduced stability on each airplane to no more 
than one, and introduces a new cool engine fuel spike test to allow 
engines to be returned to service after having exceeded cyclic limits 
or undergone work in the shop. This AD also continues the limitation on 
the number of engines with HPC CBS configuration to one on each 
airplane, places a cyclic limit on how long a CBS engine may remain in 
service, and establishes a minimum rebuild standard for engines that 
are returned to service. This amendment is prompted by further analyses 
of compressor surges in PW4000 engines, and continuing reports of 
surges in the PW4000 fleet. The actions specified by this AD are 
intended to prevent engine power losses due to HPC surge.

DATES: Effective January 17, 2002. The incorporation by reference of 
certain publications listed in the rule is approved by the Director of 
the Federal Register as of January 17, 2002.
    Comments for inclusion in the Rules Docket must be received on or 
before March 4, 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-47-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: [email protected]. 
Comments sent via the Internet must contain the docket number in the 
subject line. The service information referenced in this AD may be 
obtained from Pratt & Whitney, 400 Main St., East Hartford, CT 06108, 
(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; or at the 
Office of the Federal Register, 800 North Capitol Street, NW., suite 
700, Washington, DC.

FOR FURTHER INFORMATION CONTACT: Peter White, Aerospace Engineer, 
Engine Certification Office, FAA, Engine and Propeller Directorate, 12 
New England Executive Park, Burlington, MA 01803-5299; telephone (781) 
238-7128; fax (781) 238-7199.

SUPPLEMENTARY INFORMATION: Since 1999, the FAA has noted a growing 
number of takeoff (T/O) surge events in Pratt and Whitney PW4000 series 
turbofan engines. These surges typically occur within 20 to 60 seconds 
after throttle advance to T/O power, a critical phase of flight. These 
events have resulted in numerous aborted T/O's, in-flight engine 
shutdowns, and diverted flights. To date, two events have occurred 
where two engines have surged at once, the latest in March 2001 
involving a twin-engine airplane on takeoff.
    The investigation into these surges revealed that these events are 
due to low stability resulting from open clearances in the aft stages 
of the high pressure compressor (HPC). The most open clearance 
condition in the aft stages of the HPC due to temperature differences 
between the compressor rotor and the compressor stator occurs about 20-
60 seconds after the throttle is advanced for T/O. A binding of the 
compressor flowpath and stator segments within the outer case may add 
to this normal thermal mismatch condition, resulting in uneven wear 
patterns and areas of increased locally open clearances. Further 
investigation revealed common factors that can increase the likelihood 
for a single or multiple-engine surge event. These ``common factors'' 
have been identified as Engine Pressure Ratio (EPR), and ambient 
temperature and pressure. Pratt and Whitney (PW) has used this 
information to better understand the occurrence of the two dual surge 
events experienced to date in the PW4000 series fleet.
    Since 1999, the FAA has issued five AD's that apply to the PW4000 
series engines to address this surge condition. On August 12, 1999, the 
FAA issued AD 99-17-16 (64 FR 45426, dated August 20, 1999) to require 
that operators limit the number of PW4000 engines with potentially 
reduced stability margin to no more than one engine on each airplane, 
and require initial and repetitive on-wing and test cell engine 
stability tests. AD 99-17-16 also establishes reporting requirements 
for stability testing data.
    On October 19, 2000, the FAA issued AD 2000-22-01 (65 FR 63793, 
dated October 25, 2000), to limit the number of engines to one on each 
airplane with

[[Page 2]]

the HPC in a configuration known as the cut-back stator (CBS) 
configuration. AD 2000-22-01 established cyclic limits for the removal 
of HPC's in the CBS configuration and prohibited operators from using 
engines with HPC modules that incorporated the CBS configuration after 
the effective date of that AD. AD 2000-22-01 was later superseded by AD 
2001-15-12.
    On April 13, 2001, the FAA issued emergency AD 2001-08-52 in 
response to the March 2001, dual-engine surge event. That emergency AD 
restricted the use of and, ultimately, required the removal of certain 
PW4000 engines identified by serial number. Those engines were all 
suspect of reduced stability, and, therefore, at higher risk of surges. 
Emergency AD 2001-08-52 was superseded by AD 2001-09-07.
    On April 20, 2001, the FAA issued AD 2001-09-07 (66 FR 21083, dated 
April 27, 2001), to supersede emergency AD 2001-08-52. AD 2001-09-07 
made changes to the list of serial numbers identifying the affected 
engines, clarified the requirements of the emergency AD, and added 
engines with the HPC CBS configuration to the restrictions contained in 
the emergency AD to limit the number of PW4000 engines to no more than 
one engine with potentially reduced stability on each airplane and 
removal of certain PW4000 engines before exceeding cyclic limits that 
are determined by airplane model and engine configuration. AD 2001-09-
07 was also superseded by AD 2001-15-12.
    Finally, on July 17, 2001, the FAA issued AD 2001-15-12 (66 FR 
38896, dated July 26, 2001) that superseded both AD 2000-22-01 and AD 
2001-09-07. AD 2001-15-12 was issued as an interim measure to maintain 
fleet safety while an improved stability screening test was created, 
which would allow improved discrimination of low-surge margin engines. 
AD 2001-15-12 continued the limitation on the number of engines with 
the HPC CBS configuration and with potentially reduced stability on 
each airplane, but based those limitations on an evaluation by 
configuration, installation, thrust rating and other variables. That 
evaluation was used to create cyclic limits for each airplane and 
engine combination to maintain the risk of a multiple engine surge at 
an acceptable level. AD 2001-15-12 also introduced a minimum build 
standard for engines returned to service. Since AD 2001-15-12 was 
issued, the FAA has received reports of 11 additional takeoff surges in 
the PW4000 fleet. This amendment supersedes AD 2001-15-12 and AD 99-17-
16. The FAA has continued to evaluate the PW4000 fleet surge data and 
improve its understanding of the PW4000 fleet's engine surge behavior, 
and has determined that the requirements of currently effective AD's 
are not sufficient to meet the original safety intent of those AD's. An 
evaluation of the PW4000 fleet by configuration, installation, thrust 
rating and utilizing the ``common factor'' variables was performed to 
determine which subpopulations of engines are most prone to high power 
takeoff surges. As a result of this evaluation, cyclic limits were 
created for each airplane and engine combination to maintain the risk 
of multiple-engine surge risk at an acceptable level. An improved off-
wing (test cell) stability margin verification test was developed to 
allow return to service of engines, which were removed for exceeding 
the cycles-since-overhaul threshold, or that have had flowpath work 
performed while in the shop.
    Although AD 2001-15-12 was adopted without notice, the FAA invited 
comments on the rule. The FAA received one comment from an operator of 
PW4000 engines. The operator notes that the AD contains a requirement 
that engines which exceed the specified cyclic limits be removed from 
service within 50 cycles after the effective date of the AD and 
``thereafter.'' The operator requests that the FAA clarify whether that 
initial grace period of 50 cycles is available to only engines that 
have exceeded the cyclic limits on the effective date of the AD or if 
the 50-cycle grace period is also be available to engines that reach 
the cyclic limits after the effective date of the AD. This AD contains 
similar cyclic limits and a similar initial grace period. The FAA has 
changed the wording of the requirement to make clearer that the initial 
grace period applies only to those engines that would otherwise be 
required to be removed immediately upon the AD becoming effective. The 
FAA has determined that allowing those engines to operate for an 
additional 50 cycles will not result in an unacceptable level of safety 
while mitigating some of the cost of an unscheduled engine removal. As 
engines approach the cyclic limits after the effective date of the AD, 
however, the FAA expects that operators will schedule engine removals 
so that no unscheduled removals will be necessary.

FAA's Determination of an Unsafe Condition and Required Actions

    Since the unsafe condition described is likely to exist or develop 
on other PW4000 series turbofan engines of the same type design, this 
AD is being issued to prevent engine power losses due to HPC surge 
events. This AD requires:
     Limiting the number of engines with the HPC CBS 
configuration to one on each airplane prior to further flight after the 
effective date of this AD, and
     Limiting the number of engines that exceed cyclic limits, 
based upon airplane and engine configuration, within 50, 100 or 200 CIS 
after the effective date of this AD, and
     A minimum rebuild standard for engines that are returned 
to service.
    This AD also allows engines removed from service due to exceeded 
cyclic limit to be returned to service after either an HPC overhaul, or 
successfully completing a cool engine fuel spike stability evaluation.

Interim Action

    The actions specified in this AD are considered interim action and 
further action is anticipated based on the continuing investigation of 
the HPC surges. This AD has been coordinated with the FAA Transport 
Airplanes Directorate.

Immediate Adoption of This AD

    Since a situation exists that requires the immediate adoption of 
this regulation, it is found that notice and opportunity for prior 
public comment hereon are impracticable, and that good cause exists for 
making this amendment effective in less than 30 days.

Comments Invited

    Although this action is in the form of a final rule that involves 
requirements affecting flight safety and, thus, was not preceded by 
notice and an opportunity for public comment, comments are invited on 
this rule. Interested persons are invited to comment on this 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 under the caption ADDRESSES. All 
communications received on or before the closing date for comments will 
be considered, and this rule may be amended in light of the comments 
received. Factual information that supports the commenter's ideas and 
suggestions is extremely helpful in evaluating the effectiveness of the 
AD action and determining whether additional rulemaking action would be 
needed.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the rule that might 
suggest a need to modify the rule. All comments submitted will be 
available, both before

[[Page 3]]

and after the closing date for comments, in the Rules Docket for 
examination by interested persons. A report that summarizes each FAA-
public contact concerned with the substance of this AD 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-47-AD.'' The postcard will be date stamped and 
returned to the commenter.

Regulatory Analysis

    This final 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 final rule.
    The FAA has determined that this regulation is an emergency 
regulation that must be issued immediately to correct an unsafe 
condition in airplanes, and is not a ``significant regulatory action'' 
under Executive Order 12866. It has been determined further that this 
action involves an emergency regulation under DOT Regulatory Policies 
and Procedures (44 FR 11034, February 26, 1979). If it is determined 
that this emergency regulation otherwise would be significant under DOT 
Regulatory Policies and Procedures, a final regulatory evaluation will 
be prepared and placed in the Rules Docket. A copy of it, if filed, 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, Airplanes, 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.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by removing Amendment 39-12346 (66 FR 
38896, dated July 26, 2001) and Amendment 39-11263 (64 FR 11263, dated 
August 20, 1999), and by adding a new airworthiness directive (AD), 
Amendment 39-12564, to read as follows:

2001-25-11  Pratt and Whitney: Amendment 39-12564. Docket No. 2000-
NE-47-AD. Supersedes Amendment 39-12346, and Amendment 39-11263.

    Applicability: This airworthiness directive (AD) is applicable 
to Pratt and Whitney (PW) model PW4050, PW4052, PW4056, PW4060, 
PW4060A, PW4060C, PW4062, PW4152, PW4156, PW4156A, PW4158, PW4160, 
PW4460, PW4462, and PW4650 turbofan engines. These engines are 
installed on, but not limited to, certain models of Airbus Industrie 
A300, Airbus Industrie A310, Boeing 747, Boeing 767, and McDonnell 
Douglas MD-11 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 (o) 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 engine power losses due to high pressure compressor 
(HPC) surge, do the following:
    (a) When complying with this AD, determine the configuration and 
category of each engine on each airplane as follows:
    (1) Use the following table 1 to determine the configuration of 
the engine:

                 Table 1.--Engine Configuration Listing
------------------------------------------------------------------------
                                  Configuration
        Configuration              designator           Description
------------------------------------------------------------------------
(i) Phase 1 without high       A                   Engines that did not
 pressure turbine (HPT) 1st                         incorporate the
 turbine vane cut back                              Phase 3
 (1TVCB).                                           configuration at the
                                                    time they were
                                                    originally
                                                    manufactured, or
                                                    have not been
                                                    converted to Phase 3
                                                    configuration; and
                                                    have not
                                                    incorporated HPT
                                                    1TVCB using any
                                                    revision of SB
                                                    PW4ENG 72-514.
------------------------------------------------------------------------
(ii) Phase 1 with 1TVCB......  B                   Same as configuration
                                                    (1) except that HPT
                                                    1TVCB has been
                                                    incorporated using
                                                    any revision of SB
                                                    PW4ENG 72-514.
------------------------------------------------------------------------
(iii) Phase 3, 2nd Run.......  C                   Engines that
                                                    incorporated the
                                                    Phase 3
                                                    configuration at the
                                                    time they were
                                                    originally
                                                    manufactured, or
                                                    have been converted
                                                    to the Phase 3
                                                    configuration during
                                                    service; and that
                                                    have had at least
                                                    one HPC overhaul
                                                    since new.
------------------------------------------------------------------------
(iv) Phase 3, 1st Run........  D                   Same as configuration
                                                    (3) except that that
                                                    the engine has not
                                                    had an HPC overhaul
                                                    since new.
------------------------------------------------------------------------
(v) HPC Cutback Stator         E                   Engines that
 Configuration Engines.                             currently
                                                    incorporate any
                                                    revision of SB's
                                                    PW4ENG72-706,
                                                    PW4ENG72-704, or
                                                    PW4ENG72-711
------------------------------------------------------------------------
(vi) Engines that have passed  F                   Engines which have
 Testing-21.                                        successfully passed
                                                    Testing-21 performed
                                                    in accordance with
                                                    paragraph (h)(1) of
                                                    this AD. Once an
                                                    engine has passed a
                                                    Testing-21, it will
                                                    remain a
                                                    Configuration F
                                                    engine until the HPC
                                                    is overhauled, or is
                                                    replaced with a new
                                                    or overhauled HPC.
------------------------------------------------------------------------


[[Page 4]]

    (2) Use the following Table 2 to determine the category of 
Airbus engines:

            Table 2.--Airbus Airplane Engine Category Listing
------------------------------------------------------------------------
           Engine model             Category   Engine serial number (SN)
------------------------------------------------------------------------
(i) PW4156, PW4156A, and PW4158             1  717201, 717205, 717702,
 engines.                                       717703, 717710, 717752,
                                                717788, 717798, 717799,
                                                724023, 724026, 724027,
                                                724033, 724034, 724036,
                                                724037, 724040, 724041,
                                                724044, 724045, 724048,
                                                724049, 724050, 724051,
                                                724052, 724055, 724056,
                                                724059, 724061, 724062,
                                                724063, 724065, 724067,
                                                724073, 724074, 724075,
                                                724079, 724088, 724089,
                                                724090, 724091, 724094,
                                                724095, 724551, 724552,
                                                724555, 724556, 724557,
                                                724558, 724561, 724562,
                                                724563, 724564, 724567,
                                                724568, 724569, 724570,
                                                724571, 724572, 724573,
                                                724574, 724575, 724576,
                                                724577, 724578, 724640,
                                                724806, 724807, 724808,
                                                724809, 724811, 724820,
                                                724821, 724827, 724833,
                                                724835, 724836, 724840,
                                                724841, 724848, 724849,
                                                724855, 724857, 724858,
                                                724861, 724862, 724865,
                                                724866, 724868, 724909,
                                                724910, 724913, 724914,
                                                724924, 724925, 724926,
                                                724927, 727912, 728519,
                                                728520, 728521, 728522,
                                                728523, 728524, 728525,
                                                728526, 728527, 728528,
                                                728534, 728535, 728536,
                                                728537, 728538, 728539,
                                                728540, 728541, 728542,
                                                728543, 728544, 728545,
                                                728546, 728547, 728548,
                                                728549, 728550, 728551,
                                                728552, 728553, 728554,
                                                728557, 728558, 728559,
                                                728560, 728561, 728562,
                                                728563, 728564.
------------------------------------------------------------------------
(ii) PW4158 engines..............           2  717704, 724001, 724002,
                                                724004, 724005, 724006,
                                                724007, 724008, 724009,
                                                724010, 724011, 724019,
                                                724020, 724031, 724035,
                                                724038, 724039, 724042,
                                                724043, 724047, 724068,
                                                724069, 724071, 724076,
                                                724077, 724080, 724085,
                                                724086, 724087, 724092,
                                                724093, 724096, 724097,
                                                724801, 724802, 724803,
                                                724804, 724805, 724813,
                                                724814, 724819, 724823,
                                                724824, 724825, 724826,
                                                724828, 724831, 724832,
                                                724843, 724846, 724847,
                                                724851, 724852, 724853,
                                                724854, 724859, 724860,
                                                724863, 724864, 724867,
                                                724869, 724870, 724871,
                                                724872, 724873, 724874,
                                                724875, 724876, 724880,
                                                724881, 724882, 724883,
                                                724884, 724885, 724886,
                                                724887, 724888, 724889,
                                                724890, 724892, 724893,
                                                724894, 724895, 724896,
                                                724897, 724898, 724899,
                                                724900, 724932, 727315,
                                                727436, 728501, 728502,
                                                728503, 728504, 728505,
                                                728506, 728507, 728508,
                                                728509, 728510, 728511,
                                                728515, 728518, 728531,
                                                728532, 728533.
------------------------------------------------------------------------
(iii) PW4156, PW4156A, and                  3  All others not listed by
 PW4158..                                       SN in this Table.
------------------------------------------------------------------------

Engines Used on Boeing Airplanes

    (b) Except as provided in paragraph (g) of this AD, within 50 
airplane cycles after the effective date of this AD, limit the 
number of engines that exceed the engine cycles-since-new (CSN), 
engine cycles-since-overhaul (CSO), or engine cycles since passing 
Testing-21 (CST) limits listed in the following Table 3, to:
    (1) No more than one engine per airplane for dual-engine 
airplanes.
    (2) No more than two engines per airplane for three-engine 
airplanes.
    (3) No more than three engines per airplane for four-engine 
airplanes:

                              Table 3.--Engine Stagger Limits for Boeing Airplanes
----------------------------------------------------------------------------------------------------------------
                                                                                B767-PW4060/
    Configuration        B747-PW4056        B767-PW4052        B767-PW4056    PW4060A/PW4060C/    MD-11 PW4460/
     designator                                                                    PW4062            PW4462
----------------------------------------------------------------------------------------------------------------
A...................  1,400 CSN or CSO.  3,000 CSN or CSO.  1,600 CSN or CSO  900 CSN or CSO..  800 CSN or CSO.
B...................  2,100 CSN or CSO.  4,400 CSN or CSO.  2,800 CSN or CSO  2,000 CSN or CSO  1,200 CSN or
                                                                                                 CSO.
C...................  2,100 CSN or CSO.  4,400 CSN or CSO.  2,800 CSN or CSO  2,000 CSN or CSO  1,300 CSN or
                                                                                                 CSO.
D...................  2,600 CSN or CSO.  4,400 CSN or CSO.  3,000 CSN or CSO  2,200 CSN or CSO  2,000 CSN or
                                                                                                 CSO.
E...................  750 CSN or CSO...  750 CSN or CSO...  750 CSN or CSO..  750 CSN or CSO..  750 CSN or CSO.
F...................  800 CST..........  800 CST..........  800 CST.........  800 CST.........  800 CST.
----------------------------------------------------------------------------------------------------------------

    (c) Except as provided in paragraph (g) of this AD, within 100 
airplane cycles after the effective date of this AD, limit the 
number of engines that exceed the CSN, CSO, or CST limits listed in 
Table 3, to:
    (1) No more than one engine per airplane for three-engine 
airplanes.
    (2) No more than two engines per airplane for four-engine 
airplanes.
    (d) Within 200 airplane cycles after the effective date of this 
AD, limit the number of engines that, exceed the CSN, CSO, or CST 
limits listed in Table 3, to no more than one engine per airplane 
for four-engine airplanes.
    (e) Thereafter, ensure that no more than one engine per airplane 
exceeds the CSN, CSO, or CST limit listed in Table 3.

Engines Used on Airbus Airplanes

    (f) For engines installed on Airbus airplanes, do the following:
    (1) Within 50 airplane cycles after the effective date of this 
AD, limit the number of engines that exceed, the CSN, CSO, or CST 
limits listed in the following Table 4, to no more than one engine 
per airplane:

[[Page 5]]



                              Table 4.--Engine Stagger Limits for Airbus Airplanes
----------------------------------------------------------------------------------------------------------------
                                                               A310 PW4156 and
     Configuration       A310 PW4156 and      A300 PW4158     PW4156A and A300
      designator         PW4156A and A300      Category 2      PW4158 Category     A310 PW4152
                        PW4158 Category 1                             3
------------------------------------------------------------------------------------------------
A.....................  900 CSN or CSO...  1,850 CSN or CSO.  500 CSN or CSO..  1,050 CSN or CSO
B.....................  2,200 CSN or CSO.  4,400 CSN or CSO.  1,600 CSN or CSO  4,000 CSN or CSO
C.....................  2,200 CSN or CSO.  4,400 CSN or CSO.  1,600 CSN or CSO  4,000 CSN or CSO
D.....................  4,400 CSN or CSO.  4,400 CSN or CSO.  4,400 CSN or CSO  4,400 CSN or CSO
E.....................  750 CSN or CSO...  750 CSN or CSO...  750 CSN or CSO..  750 CSN or CSO
F.....................  800 CST..........  800 CST..........  800 CST.........  800 CST
----------------------------------------------------------------------------------------------------------------

    (2) Thereafter, ensure that no more than one engine per 
airplane, that exceeds the CSN, CSO, or CST limit listed in Table 4.

Configuration E Engines

    (g) For all configuration E engines, do the following:
    (1) Before further flight, limit the number of engines with 
configuration E from Table 1 of this AD to one on each airplane.
    (2) Remove all engines with configuration E from service before 
accumulating 1,300 CSN or cycles-since-conversion to configuration 
E, whichever is later.

Stability Testing Requirement

    (h) Engines removed from service in accordance with paragraphs 
(b), (c), (d) or (f) of this AD may be returned to service under the 
following conditions:
    (l) After passing a cool-engine fuel spike stability test 
(Testing-21) that has been done in accordance with one of the 
following PW4000 Engine Manual (EM) Temporary Revisions (TR's) as 
applicable, except for engines configured with Configuration E, or 
engines that have experienced a Group 3 takeoff surge:
    (i) PW4000 PW EM 50A443, Temporary Revision No. 71-0026, dated 
November 14, 2001.
    (ii) PW EM 50A822, Temporary Revision No. 71-0018, dated 
November 14, 2001.
    (iii) PW EM 50A605, Temporary Revision No. 71-0035, dated 
November 14, 2001.
    (iv) Engines tested before the effective date in accordance with 
PW IEN 96KC973D, dated October 12, 2001, meets the requirements of 
Testing-21, or
    (2) The HPC was replaced with an HPC that is new from production 
with no time in service, or
    (3) An engine whose HPC has been overhauled, or replaced with an 
overhauled HPC.

Minimum Build Standard

    (i) For any engine that undergoes an HPC overhaul after the 
effective date of this AD, do the following:
    (1) Inspect the HPC mid-hook and rear-hook of the HPC inner case 
for wear in accordance with PW4000 Clean, Inspect and Repair (CIR) 
Manual PN 51A357, Section 72-35-68 Inspection/Check-04, Indexes 8-
11, revised September 15, 2001. If the HPC rear hook is worn beyond 
serviceable limits, replace the HPC inner case rear hook with an 
improved durability hook in accordance with PW SB PW4ENG72-714, 
issued June 27, 2000. If the HPC inner case mid hook is worn beyond 
serviceable limits, repair the HPC inner case mid hook in accordance 
with any revision of PW4000 CIR PN 51A357 Section 72-35-68, Repair-
16, issued June 15, 1996.
    (2) After the effective date of this AD, any engine that 
undergoes an HPC overhaul may not be returned to service unless it 
meets the build standard of the following PW SB's: PW4ENG 72-484, 
PW4ENG 72-486, PW4ENG 72-514, and PW4ENG 72-575. Engines that 
incorporate the Phase 3 configuration already meet the build 
standard defined by PW SB PW4ENG 72-514.
    (j) After the effective date of this AD, any engine that 
undergoes separation of the HPC and HPT modules must not be 
installed on an airplane unless it meets the build standard of PW SB 
PW4ENG 72-514. Engines that incorporate the Phase 3 configuration 
already meet the build standard defined by PW SB PW4ENG 72-514.
    (k) After the effective date of this AD, Testing-21 must be 
performed in accordance with paragraph (h) of this AD, before an 
engine can be returned to service after having undergone maintenance 
in the shop, except under any of the following conditions;
    (1) The HPC was overhauled, or replaced with an overhauled HPC, 
or
    (2) The HPC was replaced with an HPC that is new from production 
with no time in service, or
    (3) The shop visit did not result in the separation of a major 
engine flange, with the exception of the ``A'' flange or ``T'' 
flange.
    (l) When a thrust rating change has been made by using the 
Electronic Engine Control (EEC) programming plug, or an installation 
change has been made, during an HPC overhaul period, use the lowest 
cyclic limit associated with any configuration used during that 
overhaul period.
    (m) For engines that experience a surge, do the following:
    (1) For engines that experience a Group 3 takeoff surge, remove 
the engine from service and perform an HPC overhaul.
    (2) For engines that experience a surge at Engine Pressure 
Ratios (EPR's) greater than 1.25, remove the engine from service 
within 25 cycles and perform Testing-21.

Definitions

    (n) For the purposes of this AD, the following definitions 
apply:
    (1) An HPC overhaul is defined as restoration of the HPC stages 
5 through 15 blade tip clearances to the limits specified in the 
applicable fits and clearances section of the engine manual.
    (2) A Phase 3 engine is identified by a (-3) suffix after the 
engine model number on the data plate if incorporated at original 
manufacture, or a ``CN'' suffix after the engine serial number if 
the engine was converted using PW SB's PW4ENG 72-490, PW4ENG 72-504, 
or PW4ENG 72-572 after original manufacture.
    (3) A Group 3 takeoff surge is defined as the occurrence of any 
of the following engine symptoms during takeoff operation (either at 
reduced, derated or full rated takeoff power setting) after takeoff 
power set, which can be attributed to no specific and correctable 
fault condition after following aircraft level surge-during-forward-
thrust troubleshooting procedures:
    (i) Engine noises, including rumblings and loud ``bang(s).''
    (ii) Unstable engine parameters (EPR, N1, N2, and fuel flow) at 
a fixed thrust setting.
    (iii) Exhaust gas temperature (EGT) increase.
    (iv) Flames from the inlet, the exhaust, or both.

Alternative Methods of Compliance

    (o) 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 requests 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

    (p) Special flight permits may be issued in accordance with 
Secs. 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 done.

Testing-21 Reports

    (q) Report the results of the cool engine fuel spike stability 
assessment tests (Testing-21) to the ANE-142 Branch Manager, Engine 
Certification Office, 12 New England Executive Park, Burlington, MA 
01803-5299, or by electronic mail to [email protected]. The following data must be reported:
    (1) Engine serial number.
    (2) Engine configuration designation per Table 1.
    (3) Date of the cool engine fuel spike stability test.

[[Page 6]]

    (4) HPC Serial Number, and HPC time and cycles since new and 
since compressor overhaul at the time of the test.
    (5) Results of the test (Pass/Fail).

Documents That Have Been Incorporated by Reference

    (r) The inspection shall be done in accordance with the 
following Pratt & Whitney service bulletin (SB), Internal 
Engineering Notice (IEN), Temporary Revisions (TR's), Clean, 
Inspection, and Repair Manual (CIR) repair procedures:

----------------------------------------------------------------------------------------------------------------
           Document No.                    Pages                Revision                      Date
----------------------------------------------------------------------------------------------------------------
PW SB PW4ENG72-714...............  1-2..................  1...................  November 8, 2001.
                                   3....................  Original............  June 27, 2000.
                                   4....................  1...................  November 8, 2001
                                   5-12.................  Original............  June 27, 2000.
    Total pages: 12.
PW IEN 96KC973D..................  All..................  Original............  October 12, 2001.
    Total pages: 19.
PW TR 71-0026....................  All..................  Original............  November 14, 2001.
    Total pages: 24.
PW TR 71-0018....................  All..................  Original............  November 14, 2001.
    Total pages: 24.
PW TR 71-0035....................  All..................  Original............  November 14, 2001.
    Total pages: 24.
PW CIR 51A357, Section 72-35-68,   All..................  Original............  September 15, 2001.
 Inspection/Check-04, Indexes 8-
 11.
    Total pages: 5.
PW CIR 51A357, Section 72-35-68,   All..................  Original............  June 15, 1996.
 Repair 16.
    Total pages: 1.
----------------------------------------------------------------------------------------------------------------

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 St., East 
Hartford, CT 06108, (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 the Federal Register, 800 North Capitol Street, NW, suite 
700, Washington, DC.

Effective Date

    (s) This amendment becomes effective on January 17, 2002.

    Issued in Burlington, Massachusetts, on December 12, 2001.
Robert G. Mann,
Acting Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
[FR Doc. 01-31296 Filed 12-31-01; 8:45 am]
BILLING CODE 4910-13-P