80 FR 32440 - Special Conditions: CFM International, LEAP-1A and -1C Engine Models; Incorporation of Woven Composite Fan Blades

DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration

Federal Register Volume 80, Issue 110 (June 9, 2015)

These special conditions are issued for the CFM International (CFM), LEAP-1A and -1C engine models. These engine models will have a novel or unusual design feature associated with the engine fan blades-- new woven composite fan blades. The applicable airworthiness regulations do not contain adequate or appropriate safety standards for this design feature. These special conditions contain the additional safety standards that the Administrator considers necessary to establish a level of safety equivalent to that established by the existing airworthiness standards.

[Federal Register Volume 80, Number 110 (Tuesday, June 9, 2015)]
[Rules and Regulations]
[Pages 32440-32441]
From the Federal Register Online  [www.thefederalregister.org]
[FR Doc No: 2015-14084]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 33

[Docket No. FAA-2014-0637; Special Conditions No. 33-015-SC]


Special Conditions: CFM International, LEAP-1A and -1C Engine 
Models; Incorporation of Woven Composite Fan Blades

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final special conditions.

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SUMMARY: These special conditions are issued for the CFM International 
(CFM), LEAP-1A and -1C engine models. These engine models will have a 
novel or unusual design feature associated with the engine fan blades--
new woven composite fan blades. The applicable airworthiness 
regulations do not contain adequate or appropriate safety standards for 
this design feature. These special conditions contain the additional 
safety standards that the Administrator considers necessary to 
establish a level of safety equivalent to that established by the 
existing airworthiness standards.

DATES: Effective July 9, 2015.

FOR FURTHER INFORMATION CONTACT: For technical questions concerning 
this action, contact Alan Strom, ANE-111, Engine and Propeller 
Directorate, Aircraft Certification Service, 12 New England Executive 
Park, Burlington, Massachusetts 01803; telephone (781) 238-7143; 
facsimile (781) 238-7199; email [email protected].
    For legal questions concerning this action, contact Vincent 
Bennett, ANE-7, Engine and Propeller Directorate, Aircraft 
Certification Service, 12 New England Executive Park, Burlington, 
Massachusetts 01803; telephone (781) 238-7044; facsimile (781) 238-
7055; email [email protected].

SUPPLEMENTARY INFORMATION: 

Background

    On June 27, 2012, CFM International (CFM) applied for a type 
certificate for their new LEAP-1A and -1C engine models. The LEAP 
engine models are high-bypass-ratio engines that incorporate a novel 
and unusual design feature--new woven composite fan blades. The woven 
composite fan blades will have significant differences in material 
property characteristics when compared to conventionally designed fan 
blades using non-composite metallic materials.
    Special conditions are required to ensure that the LEAP-1A and -1C 
woven composite design fan blades account for the differences in 
material properties and failure modes relative to conventional single-
load path metallic blades. In addition, different containment 
requirements may be applied provided CFM shows that the blade design 
below the inner annulus flow path line provides multiple load paths and 
crack arresting features that prevent delamination or crack propagation 
to blade failure during the life of the blade.
    These special conditions are necessary because the applicable 
airworthiness regulations do not contain adequate or appropriate safety 
standards for the new woven composite design fan blades.

Type Certification Basis

    Under the provisions of Title 14, Code of Federal Regulations (14 
CFR) 21.17, CFM must show that the LEAP-1A and -1C engine models meet 
the applicable provisions of the applicable regulations in effect on 
the date of application, except as detailed in paragraphs 21.101(b) and 
(c). The FAA has determined the following certification basis for the 
LEAP-1A and -1C engine models:
    1. 14 CFR part 33, ``Airworthiness Standards: Aircraft Engines,'' 
dated February 1, 1965, with Amendments 33-1 through 33-32, dated 
September 20, 2012.
    If the FAA finds that the regulations in effect on the date of the 
application for the change do not provide adequate or appropriate 
safety standards for the LEAP-1A and -1C engine models because of a 
novel or unusual design feature, special conditions are prescribed 
under the provisions of Sec.  21.16.
    Special conditions are initially applicable to the engine model for 
which they are issued. Should the type certificate for that engine 
model be amended later to include any other engine model that 
incorporates the same novel or unusual design feature, the special 
conditions would also apply to the other engine model under Sec.  
21.101.
    In addition to complying with the applicable product airworthiness 
regulations and special conditions, the LEAP-1A and -1C engine models 
must comply with the fuel venting and exhaust emission requirements of 
14 CFR part 34.
    The FAA issues special conditions, as defined in 14 CFR 11.19, in 
accordance with Sec.  11.38, and they become part of the type-
certification basis under Sec.  21.17(a)(2).

Novel or Unusual Design Features

    The LEAP-1A and -1C engine models will incorporate the following 
novel or unusual design feature:
    The LEAP-1A and -1C engine models will incorporate woven composite 
fan blades. The woven composite fan blades will have significant 
differences in material property characteristics when compared to 
conventionally designed fan blades using non-composite metallic 
materials. Composite material design provides the capability to 
incorporate multiple load paths and crack arresting features that 
prevent delamination or crack propagation to blade failure during the 
life of the blade.

[[Page 32441]]

    The woven composite fan blades are a novel and unusual design 
feature that requires additional airworthiness standards for type 
certification of the LEAP-1A and -1C engine models.

Discussion of Comments

    A notice of proposed special conditions, No. 33-14-02-SC, for the 
CFM LEAP-1A and--1C engine models was published in the Federal Register 
on Friday, November 14, 2014 (79 FR 68137). No comments were received 
and the special conditions are adopted as proposed.

Applicability

    As discussed above, these special conditions are applicable to the 
LEAP -1A and -1C engine models. Should CFM apply at a later date for a 
change to the type certificate to include another model on the same 
type certificate incorporating the same novel or unusual design 
feature, the special conditions would apply to that model as well.

Conclusion

    This action affects only certain novel or unusual design features 
on LEAP-1A and -1C engine models. It is not a rule of general 
applicability and applies only to CFM, who requested FAA approval of 
this engine feature.

List of Subjects in 14 CFR Part 33

    Aircraft, Engines, Aviation Safety, Reporting and recordkeeping 
requirements.

    The authority citation for these special conditions is as follows:

    Authority:  49 U.S.C. 106(g), 40113, 44701, 44702, 44704.

The Special Conditions

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the following special conditions are issued as part of 
the type certification basis for CFM LEAP-1A and -1C engine models.

1. Part 33, Requirements

    In addition to the airworthiness standards in 14 CFR part 33, 
effective February 1, 1965, with Amendments 33-1 through 33-32 
applicable to the LEAP-1A and -1C engine models, CFM will:
    (a) Conduct an engine fan blade containment test with the fan blade 
failing at the inner annulus flow path line instead of at the outermost 
retention groove.
    (b) Substantiate by test and analysis, or other methods acceptable 
to the FAA, that a fan disk and fan blade retention system with minimum 
material properties can withstand, without failure, a centrifugal load 
equal to two times the maximum load the retention system could 
experience within approved engine operating limitations. The fan blade 
retention system includes the portion of the fan blade from the inner 
annulus flow path line inward to the blade dovetail, the blade 
retention components, and the fan disk and fan blade attachment 
features.
    (c) Using a procedure approved by the FAA, establish an operating 
limitation that specifies the maximum allowable number of start-stop 
stress cycles for the fan blade retention system. The life evaluation 
must include the combined effects of high-cycle and low-cycle fatigue. 
If the operating limitation is less than 100,000 cycles, that 
limitation must be specified in Chapter 5 of the Engine Manual 
Airworthiness Limitations Section. The procedure used to establish the 
maximum allowable number of start-stop stress cycles for the fan blade 
retention system will incorporate the integrity requirements in 
paragraphs (c)(1), (c)(2), and (c)(3) of these special conditions for 
the fan blade retention system.
    (1) An engineering plan, which establishes and maintains that the 
combinations of loads, material properties, environmental influences, 
and operating conditions, including the effects of parts influencing 
these parameters, are well known or predictable through validated 
analysis, test, or service experience.
    (2) A manufacturing plan that identifies the specific manufacturing 
constraints necessary to consistently produce the fan blade retention 
system with the attributes required by the engineering plan.
    (3) A service management plan that defines in-service processes for 
maintenance and repair of the fan blade retention system, which will 
maintain attributes consistent with those required by the engineering 
plan.
    (d) Substantiate by test and analysis, or other methods acceptable 
to the FAA, that the blade design below the inner annulus flow path 
line provides multiple load paths and crack arresting features that 
prevent delamination or crack propagation to blade failure during the 
life of the blade.
    (e) Substantiate that during the service life of the engine, the 
total probability of an individual blade retention system failure 
resulting from all possible causes, as defined in Sec.  33.75, will be 
extremely improbable with a cumulative calculated probability of 
failure of less than 10-9 per engine flight hour.
    (f) Substantiate by test or analysis that not only will the engine 
continue to meet the requirements of Sec.  33.75 following a lightning 
strike on the composite fan blade structure, but that the lightning 
strike will not cause damage to the fan blades that would prevent 
continued safe operation of the affected engine.
    (g) Account for the effects of in-service deterioration, 
manufacturing variations, minimum material properties, and 
environmental effects during the tests and analyses required by 
paragraphs (a), (b), (c), (d), (e), and (f) of these special 
conditions.
    (h) Propose fleet leader monitoring and field sampling programs 
that will monitor the effects of engine fan blade usage and fan blade 
retention system integrity.
    (i) Mark each fan blade legibly and permanently with a part number 
and a serial number.

    Issued in Burlington, Massachusetts, on June 1, 2015.
Ann C. Mollica,
Acting Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
[FR Doc. 2015-14084 Filed 6-8-15; 8:45 am]
 BILLING CODE 4910-13-P