81 FR 67098 - Airworthiness Directives; General Electric Company Turbofan Engines

DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration

Federal Register Volume 81, Issue 190 (September 30, 2016)

We are adopting a new airworthiness directive (AD) for all General Electric Company (GE) GE90-76B, GE90-77B, GE90-85B, GE90-90B, and GE90-94B turbofan engines with high-pressure compressor (HPC) stage 8-10 spool, part numbers (P/Ns) 1694M80G04, 1844M90G01, or 1844M90G02, installed. This AD was prompted by reports of cracks found on the seal teeth of the HPC stage 8-10 spool. This AD requires eddy current inspections (ECIs) or fluorescent penetrant inspections (FPIs) of the HPC stage 8-10 spool seal teeth and removing from service those parts that fail inspection. We are issuing this AD to prevent failure of the HPC stage 8-10 spool, uncontained rotor release, damage to the engine, and damage to the airplane.

[Federal Register Volume 81, Number 190 (Friday, September 30, 2016)]
[Rules and Regulations]
[Pages 67098-67100]
From the Federal Register Online  [www.thefederalregister.org]
[FR Doc No: 2016-23740]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2016-5307; Directorate Identifier 2016-NE-08-AD; 
Amendment 39-18658; AD 2016-19-09]
RIN 2120-AA64


Airworthiness Directives; General Electric Company 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 all 
General Electric Company (GE) GE90-76B, GE90-77B, GE90-85B, GE90-90B, 
and GE90-94B turbofan engines with high-pressure compressor (HPC) stage 
8-10 spool, part numbers (P/Ns) 1694M80G04, 1844M90G01, or

[[Page 67099]]

1844M90G02, installed. This AD was prompted by reports of cracks found 
on the seal teeth of the HPC stage 8-10 spool. This AD requires eddy 
current inspections (ECIs) or fluorescent penetrant inspections (FPIs) 
of the HPC stage 8-10 spool seal teeth and removing from service those 
parts that fail inspection. We are issuing this AD to prevent failure 
of the HPC stage 8-10 spool, uncontained rotor release, damage to the 
engine, and damage to the airplane.

DATES: This AD is effective November 4, 2016.

ADDRESSES: For service information identified in this final rule, 
contact General Electric Company, GE-Aviation, Room 285, 1 Neumann Way, 
Cincinnati, OH 45215, phone: 513-552-3272; email: 
[email protected]. 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-2016-5307.

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-
5307; 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: John Frost, Aerospace Engineer, Engine 
Certification Office, FAA, 1200 District Avenue, Burlington, MA 01803; 
phone: 781-238-7756; fax: 781-238-7199; email: [email protected].

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 all GE GE90-76B, GE90-77B, 
GE90-85B, GE90-90B, and GE90-94B turbofan engines with HPC stage 8-10 
spool, P/Ns 1694M80G04, 1844M90G01, or 1844M90G02, installed. The NPRM 
published in the Federal Register on April 11, 2016 (81 FR 21286). The 
NPRM was prompted by reports of cracks found on the seal teeth of the 
HPC stage 8-10 spool during shop visits. The cracks initiated due to 
higher than intended temperatures at the seal teeth and damage to seal 
teeth coating from heavy rubs into the honeycomb. GE is developing a 
modification to address the unsafe condition.
    The NPRM proposed to require ECIs or FPIs of the HPC stage 8-10 
spool seal teeth and removing from service those parts that fail 
inspection. We are issuing this AD to prevent failure of the HPC stage 
8-10 spool, uncontained rotor release, damage to the engine, and damage 
to 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.

Support of the NPRM as Written

    Boeing and United Airlines support the NPRM as written.

Request To Clarify Performance of ECI and FPI

    Nao Seto requested that the FAA clarify with which service 
information the ECI and FPI will be performed.
    We agree. We added a statement to compliance paragraph (e) in this 
AD indicating the GE service documents in which guidance can be found 
for performing the ECI and the FPI.

Request To Clarify Supplementary Information

    General Electric Aviation requested that the Discussion paragraph 
be changed to read as follows: ``Based on recent testing, change the 
root cause of crack initiation from that of degraded surface properties 
caused by an alloy depletion zone (ADZ) to cracks initiated due to 
higher than intended temperatures at the seal teeth and damage to seal 
teeth coating from heavy rubs into the honeycomb.'' Recent testing and 
analysis have shown that the temperatures in the seal teeth are higher 
than design intent. This elevated temperature increases the stress in 
the region of the seal teeth, aligning with the cracking observed. GE 
also completed testing to determine the impact of alloy depletion zone 
on material capability. Testing showed material capability was not 
impacted.
    We agree. We oversaw the recent testing and analysis which supports 
the requested change. We changed the Discussion paragraph of this AD 
accordingly.

Request To Add Ultrasonic Inspection (USI) to the Compliance

    GE requested that USI be added to the Compliance section as an 
alternate inspection method. Additionally, GE requested that we revise 
the Related Information paragraph (h)(2) of this AD by updating the 
service information to revision 1 based on the qualifying USI 
procedure.
    We disagree. USI procedures are not an acceptable alternative to 
the existing ECI and FPI procedures specified in this AD. A USI is not 
a viable procedure for compliance at this time, therefore, we are not 
updating the service information in paragraph (h)(2) to Revision 1. We 
may consider an AMOC after sufficient substantiated data is presented 
to the FAA. We did not change this AD.

Conclusion

    We reviewed the relevant data, considered the comments received, 
and determined that air safety and the public interest require adopting 
this AD as proposed.

Related Service Information

    We reviewed GE Service Bulletins SB 72-1141 R00, dated December 2, 
2015; and SB 72-1142 R00, dated November 30, 2015. The service 
information describes procedures for inspecting the HPC stage 8-10 
spool seal teeth.

Costs of Compliance

    We estimate that this AD affects 54 engines installed on airplanes 
of U.S. registry. We also estimate that it will take about 1 hour per 
engine to comply with this AD. The average labor rate is $85 per hour. 
We estimate 14 parts will fail inspection at a pro-rated cost of 
$400,000 per part. Based on these figures, we estimate the total cost 
of this AD to U.S. operators to be $5,604,590.

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

[[Page 67100]]

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 to the extent 
that it justifies making a regulatory distinction, 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

0
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]

0
2. The FAA amends Sec.  39.13 by adding the following new airworthiness 
directive (AD):

2016-19-09 General Electric Company: Amendment 39-18658; Docket No. 
FAA-2016-5307; Directorate Identifier 2016-NE-08-AD.

(a) Effective Date

    This AD is effective November 4, 2016.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to General Electric Company (GE) GE90-76B, GE90-
77B, GE90-85B, GE90-90B, and GE90-94B turbofan engines with a high-
pressure compressor (HPC) stage 8-10 spool, part numbers 1694M80G04, 
1844M90G01, or 1844M90G02, installed.

(d) Unsafe Condition

    This AD was prompted by reports of cracks found on the seal 
teeth of the HPC stage 8-10 spool. We are issuing this AD to prevent 
failure of the HPC stage 8-10 spool, uncontained rotor release, 
damage to the engine, and damage to the airplane.

(e) Compliance

    Comply with this AD within the compliance times specified, 
unless already done.
    (1) Perform an eddy current inspection (ECI) or fluorescent 
penetrant inspection (FPI) of the seal teeth of the HPC stage 8-10 
spool as follows:
    (i) For HPC stage 8-10 spools with fewer than 11,000 cycles 
since new (CSN) on the effective day of this AD, inspect at the next 
shop visit after reaching 6,000 CSN, not to exceed 12,500 CSN.
    (ii) For HPC stage 8-10 spools with 11,000 CSN or more on the 
effective day of this AD, inspect within the next 1,500 cycles in 
service.
    (iii) Thereafter, inspect the seal teeth of the HPC stage 8-10 
spool at each shop visit.
    (2) Remove from service any HPC stage 8-10 spool that fails the 
ECI or FPI required by paragraph (e)(1) of this AD and replace with 
a part eligible for installation.
    (3) Guidance on performing the ECI and the FPI can be found in 
GE Service Bulletins (SBs) SB 72-1141 R00, dated December 2, 2015 
and SB 72-1142 R00, dated November 30, 2015.

(f) Definition

    For the purpose of this AD, an engine shop visit is the 
induction of an engine into the shop for maintenance during which 
the compressor discharge pressure seal face is exposed.

(g) Alternative Methods of Compliance (AMOCs)

    The Manager, Engine Certification Office, FAA, may approve AMOCs 
for this AD. Use the procedures found in 14 CFR 39.19 to make your 
request. You may email your request to: [email protected].

(h) Related Information

    (1) For more information about this AD, contact John Frost, 
Aerospace Engineer, Engine Certification Office, FAA, 1200 District 
Avenue, Burlington, MA 01803; phone: 781-238-7756; fax: 781-238-
7199; email: [email protected].
    (2) GE SB 72-1141, R00, dated December 2, 2015 and GE SB 72-
1142, R00, dated November 30, 2015, which are not incorporated by 
reference in this AD, can be obtained from GE, using the contact 
information in paragraph (h)(3) of this AD.
    (3) For service information identified in this AD, contact 
General Electric Company, GE-Aviation, Room 285, 1 Neumann Way, 
Cincinnati, OH 45215, phone: 513-552-3272; email: 
[email protected].
    (4) 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.

(i) Material Incorporated by Reference

    None.

    Issued in Burlington, Massachusetts, on September 26, 2016.
Colleen M. D'Alessandro,
Manager, Engine & Propeller Directorate, Aircraft Certification 
Service.
[FR Doc. 2016-23740 Filed 9-29-16; 8:45 am]
BILLING CODE 4910-13-P