DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2016-9405; Directorate Identifier 2016-NE-22-AD;
Amendment 39-18918; AD 2017-12-03]
RIN 2120-AA64

Airworthiness Directives; Pratt & Whitney Division Turbofan
Engines

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: We are adopting a new airworthiness directive (AD) for certain
Pratt & Whitney Division (PW) PW2037, PW2037M, and PW2040 turbofan
engines. This AD was prompted by an unrecoverable engine in-flight
shutdown (IFSD) after an ice crystal icing event. This AD requires
installing a software standard eligible for installation and precludes
the use of electronic engine control (EEC) software standards earlier
than SCN 5B/I. We are issuing this AD to correct the unsafe condition
on these products.

DATES: This AD is effective July 20, 2017.

ADDRESSES: For service information identified in this final rule,
contact Pratt & Whitney Division, 400 Main St., East Hartford, CT
06118; phone: 800-565-0140; fax: 860-565-5442. You may view this
service information at the FAA, Engine & Propeller Directorate, 1200
District Avenue, Burlington, MA. For information on the availability of
this material at the FAA, call 781-238-7125. It is also available on
the internet at http://www.regulations.gov by searching for and
locating Docket No. FAA-2016-9405.

Examining the AD Docket

You may examine the AD docket on the Internet at http://www.regulations.gov
by searching for and locating Docket No. FAA-2016-
9405; or in person at the Docket Management Facility between 9 a.m. and
5 p.m., Monday through Friday, except Federal holidays. The AD docket
contains this AD, the regulatory evaluation, any comments received, and
other information. The address for the Docket Office (phone: 800-647-
5527) is Document Management Facility, U.S. Department of
Transportation, Docket Operations, M-30, West Building Ground Floor,
Room W12-140, 1200 New Jersey Avenue SE., Washington, DC 20590.

FOR FURTHER INFORMATION CONTACT: Kevin Clark, Aerospace Engineer,
Engine Certification Office, FAA, Engine & Propeller Directorate, 1200
District Avenue, Burlington, MA 01803; phone: 781-238-7088; fax: 781-
238-7199; email: kevin.m.clark@faa.gov.

SUPPLEMENTARY INFORMATION:

Discussion

We issued a notice of proposed rulemaking (NPRM) to amend 14 CFR
part 39 by adding an AD that would apply to certain PW PW2037, PW2037M,
and PW2040 turbofan engines. The NPRM published in the Federal Register
on January 5, 2017 (82 FR 1265). The NPRM was prompted by an
unrecoverable engine IFSD after an ice crystal icing event. An attempt
to rapidly restart the engine was made while the EEC had the Active
Clearance Control (ACC) turned on, which caused contraction of the
high-pressure turbine (HPT) case and reduced clearances in the HPT,
with subsequent HPT damage and rotor seizure. A change to the EEC
software can force the ACC to activate at a higher rotor speed to
prevent active ACC during engine restart. The NPRM proposed to preclude
the use of EEC software standards earlier than SCN 5B/I. We are issuing
this AD to prevent failure of the HPT, rotor seizure, failure of one or
more engines, loss of thrust control, and loss of the airplane.

Comments

We gave the public the opportunity to participate in developing
this AD. The following presents the comments received on the NPRM and
the FAA's response to each comment. The Airline Pilots Association and
United Airlines support the NPRM.

Request To Change Compliance

The Boeing Company, PW, Delta Air Lines, Inc., FedEx, and Rudy
Pueschel requested removing the engine serial number requirement for
earlier compliance time and use the Asia Pacific regional requirement
for earlier compliance time. The change would properly capture the risk
of icing events in the Asia Pacific region. This change would also
match the referenced alert service bulletin (ASB).

We disagree. There are difficulties in compliance and enforcement
for regulations based on regions. Using engines serial numbers (S/Ns)
that are currently known to operate in the area was our approach to
best capture the higher risk engines while easing compliance. The
unsafe condition is addressed by upgrading at least one engine per
airplane on all known engines currently operating in the Asia Pacific
region within the shorter compliance period. Finally, this AD requires
all engines with EEC model numbers EEC104-40 and EEC104-60 to upgrade
software earlier than software standard SCN 5B/I by 2024. We did not
change this AD.

Request To Change Method To Identify Engines Affected by Earlier
Compliance Time

Delta Air Lines, Inc. and FedEx requested removing the engine
serial number requirement for earlier compliance time and use extended
range twin-engine operations (ETOPs) or Aircraft Tail Number
requirements for earlier compliance time. The change was requested to
ease with compliance and help properly capture the safety risk of
operating in the Asia Pacific region.

We disagree. Operators may have ETOPs flights that do not operate
in the Asia Pacific region and would then be mandated to the earlier
compliance time unnecessarily. Typically the EEC remains with the
engine instead of the aircraft so tracking engines would be more
appropriate than aircraft. However, we will review any Alternative
Methods of Compliance (AMOCs) submitted to cover the regional risk to
any operator's specific fleet instead of tracking through engine S/Ns.
We did not change this AD.

Request To Change Compliance Time

Delta Air Lines, Inc. and FedEx requested using EEC S/Ns instead of
engine S/Ns to track the earlier compliance times because, as the
software is removed and upgraded on the EEC that the EEC should be
tracked to properly follow the software upgrades.

We partially agree. We agree that tracking EEC serial numbers would
assist in tracking software because EECs are removed or replaced more
often than engines. We disagree with this approach because our
available Asia Pacific region information only includes engine S/Ns. We
did not change this AD.

Request To Clarify Engine S/Ns

Rudy Pueschel and PW requested clarification that the affected
engine S/Ns are those engines currently operating in the Asia Pacific
region, to assist operators in knowing why specific engines require
earlier compliance.

We agree. Knowing the engines with certain S/Ns are currently
operating in the Asia Pacific region will help operators understand the
risk and unsafe condition. We revised the Differences Between this
Proposed AD and the Service Information section.

Request To Change Compliance Time

FedEx and PW requested changing the engine shop visit definition to
when the EEC is accessible at a maintenance facility. The EEC is a line
replaceable unit (LRU) which may be replaced outside of a major flange
separation shop visit definition. This would also align with the ASB.

We disagree. Our decision to use the separation of pairs of major
mating engine flanges for the definition of an "engine shop visit" is
based on the average time between shop visits and allows a period of
time to operate with an adequate level of safety without unduly
burdening operators not flying in the Asia Pacific Region. This is to
avoid grounding aircraft that may be at a facility capable of replacing
the EEC, but, not having the required parts or equipment to do so at
the time. We did not change this AD.

Request To Change Compliance Time

Delta Air Lines, Inc. requested removing the engine shop visit
requirement because the EEC is an LRU and may not line up with a major
flange separation engine shop visit definition.

We disagree. The risk requires complying at the next engine shop
visit. Our decision to use the separation of pairs of major mating
engine flanges for the definition of an "engine shop visit" is based
on the average time between shop visits and allows a period of time to
operate with an adequate level of safety without unduly burdening
operators not flying in the Asia Pacific Region. This is to avoid
grounding aircraft that may be at a facility capable of replacing the
EEC, but, not having the required parts or equipment to do so at the
time. We did not change this AD.

Request To Change Service Information

Delta Air Lines, Inc., FedEx, and PW requested changing the
required action from removing software earlier than software standard
SCN 5B/I to install or upgrade to software standard SCN 5B/I, because
there are no instructions for removing software. PW ASB PW2000 A73-170,
dated July 14, 2016 is only for upgrading the software.

We partially agree. We disagree with mandating installation of
software standard SCN 5B/I because that would prohibit the installation
of a newer software standard in the future. We agree that an
alternative to removing EEC software is needed because there are no
instructions for removing software. This AD requires upgrading
software, or installing an EEC that is eligible for installation. We
changed paragraph (g) of this AD from "remove software" to "upgrade
software".

Request To Change Compliance Time

Delta Air Lines, Inc. and PW requested that we specify a date in
the compliance paragraphs of this AD to provide clarity on the deadline
for compliance.

We agree. We changed the compliance paragraphs of this AD to
include specific dates.

Request To Change Applicability

Delta Air Lines, Inc. and PW requested that we specify EEC model
numbers EEC104-40 and EEC104-60 in the Installation Prohibition section
because the Installation Prohibition section applies only to EEC model
numbers EEC104-40 and EEC104-60, not to all EECs.

We agree. We revised paragraph (h) of this AD.

Request To Change Costs of Compliance

PW requested that we change the number of affected engines to 303
because only 303 engines have EEC model numbers EEC104-40 or EEC104-60,
installed.

We agree. We changed the Costs of Compliance section.

Request To Change Discussion

Delta Air Lines, Inc. requested that we change the Discussion
section to clarify that for the event engine, the attempted engine
relight with the ACC turned on caused contraction of the HPT case and
reduced clearances in the HPT, with subsequent HPT damage and rotor
seizure. Delta also requested that we clarify that the EEC controls ACC
activation.

We agree. We revised the Discussion section.

Request To Change Difference Between This Proposed AD and the Service
Information Paragraph

Delta Air Lines, Inc. requested clarification in the "Differences
Between this Proposed AD and the Service Information" section that the
AD appears to apply all engines and not just to PW2000 with EEC model
numbers EEC104-40 and EEC104-60. To provide further clarification,
Delta also requests stating to which engines the July 2024 date applies.

We agree. This AD is applicable to PW2000 engines with EEC model
numbers EEC104-40 and EEC104-60. We added the affected EEC model
numbers to the Differences Between this AD and the Service Information section.

Request To Change Compliance

Delta Air Lines, Inc. requested that we remove the ellipses from
Figure 1 to paragraph (g) of this AD. Ellipses should not be in the
list and may suggest missing information.

We agree. We removed the ellipses from Figure 1 to paragraph (g) of this AD.

Request Reopening the Additional Comment Period

Delta Air Lines, Inc. requested reopening the comment period
because of expected significant changes to the language of this AD.

We disagree. In response to the public comments we received on the
NPRM, we made minor changes to the compliance section of this AD for
clarification. However, we did not make any significant changes to this
AD. Also we determined that air safety and the public interest require
adopting this AD without delay.

Conclusion

We reviewed the relevant data, considered the comments received,
and determined that air safety and the public interest require adopting
this AD with the changes described previously.

We also determined that these changes will not increase the
economic burden on any operator or increase the scope of this AD.

Related Service Information

We reviewed PW ASB PW2000 A73-170, dated July 14, 2016. The ASB
describes procedures for modifying or replacing the EEC. This service
information is reasonably available because the interested parties have
access to it through their normal course of business or by the means
identified in the ADDRESSES section.

Differences Between This AD and the Service Information

PW ASB PW2000 A73-170, dated July 14, 2016, specifies compliance
for any PW2000 engine with EEC model numbers EEC104-40 and EEC104-60,
flown, or expected to be flown, in the Asian Pacific latitudes and
longitudes, while this AD lists specific engine S/Ns that are currently
known to operate in the Asia Pacific region. Also, PW ASB PW2000 A73-
170, dated July 14, 2016, provides until 2026 to comply, while this AD
provides until July 2024 for all PW2000 engines with EEC104-40 and
EEC104-60 to comply.

Costs of Compliance

We estimate that this AD affects 303 engines, installed on
airplanes of U.S. registry.

We estimate the following costs to comply with this AD:

Estimated Costs

Authority for This Rulemaking

Title 49 of the United States Code specifies the FAA's authority to
issue rules on aviation safety. Subtitle I, section 106, describes the
authority of the FAA Administrator. Subtitle VII: Aviation Programs,
describes in more detail the scope of the Agency's authority.

We are issuing this rulemaking under the authority described in
Subtitle VII, Part A, Subpart III, Section 44701: "General
requirements." Under that section, Congress charges the FAA with
promoting safe flight of civil aircraft in air commerce by prescribing
regulations for practices, methods, and procedures the Administrator
finds necessary for safety in air commerce. This regulation is within
the scope of that authority because it addresses an unsafe condition
that is likely to exist or develop on products identified in this
rulemaking action.

Regulatory Findings

This AD will not have federalism implications under Executive Order
13132. This AD will 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.

For the reasons discussed above, I certify that this AD:

(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),

(3) Will not affect intrastate aviation in Alaska, and

(4) 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.

List of Subjects in 14 CFR Part 39

Air transportation, Aircraft, Aviation safety, Incorporation by
reference, Safety.

Adoption of the Amendment

Accordingly, under the authority delegated to me by the
Administrator, the FAA amends 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. The FAA amends Sec. 39.13 by adding the following new airworthiness
directive (AD):