[Federal Register Volume 71, Number 148 (Wednesday, August 2, 2006)]
[Proposed Rules]
[Pages 43674-43676]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 06-6633]


 ========================================================================
 Proposed Rules
                                                 Federal Register
 ________________________________________________________________________
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 This section of the FEDERAL REGISTER contains notices to the public of 
 the proposed issuance of rules and regulations. The purpose of these 
 notices is to give interested persons an opportunity to participate in 
 the rule making prior to the adoption of the final rules.
 
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 

  Federal Register / Vol. 71, No. 148 / Wednesday, August 2, 2006 / 
Proposed Rules  

[[Page 43674]]



DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 35

[Docket No. NE128; Notice No. 35-06-01-SC]


Special Conditions: McCauley Propeller Systems, Model 3D15C1401/
C80MWX-X Propeller

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed special conditions.

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SUMMARY: This action proposes special conditions for McCauley Propeller 
Systems. This 3D15C1401/C80MWX-X model propeller will have a novel or 
unusual design features(s) associated with composite blades. The 
applicable airworthiness regulations do not contain adequate or 
appropriate safety standards for this design feature. These proposed 
special conditions contain the added safety standards that the 
Administrator considers necessary to establish a level of safety 
equivalent to that established by the existing airworthiness standards.

DATES: We must receive your comments by September 1, 2006.

ADDRESSES: You must mail two copies of your comments to: Federal 
Aviation Administration, Engine and Propeller Directorate, Attn: Jay 
Turnberg, Rules Docket (ANE-110), Docket No. NE128, 12 New England 
Executive Park, Burlington, Massachusetts 01803-5299. You may deliver 
two copies to the Engine and Propeller Directorate at the above 
address. You must mark your comments: Docket No. NE128 You can inspect 
comments in the Rules Docket weekdays, except Federal holidays, between 
7:30 a.m. and 4 p.m.

FOR FURTHER INFORMATION CONTACT: Jay Turnberg, ANE-110, Engine and 
Propeller Directorate, Aircraft Certification Service, 12 New England 
Executive Park, Burlington, Massachusetts 01803-5299; telephone (781) 
238-7116; fascimile (781) 238-7199; e-mail [email protected].

SUPPLEMENTARY INFORMATION: 

Comments Invited

    We invite interested people to take part in this rulemaking by 
sending written comments, data, or views. The most helpful comments 
reference a specific portion of the special conditions, explain the 
reason for any recommended change, and include supporting data. We ask 
that you send us two copies of written comments.
    We will file in the docket all comments we receive, as well as a 
report summarizing each substantive public contact with FAA personnel 
about these special conditions. You can inspect the docket before and 
after the comment closing date. If you wish to review the docket in 
person, go to the address in the ADDRESSES section of this preamble 
between 9 a.m. and 5 p.m., Monday through Friday, except Federal 
holidays.
    We will consider all comments we receive by the closing date for 
comments. We will consider comments filed late if it is possible to do 
so without incurring expense or delay. We may change these special 
conditions based on the comments we receive.
    If you want us to let you know we received your comments on this 
proposal, send us a pre-addressed, stamped postcard on which the docket 
number appears. We will stamp the date on the postcard and mail it back 
to you.

Background

    On November 29, 2004, McCauley Propeller applied for type 
certification for a new model 3D15C1401/C80MWX-X propeller. This 
propeller uses blades that are constructed of composite material. The 
blade has a carbon fiber spar, a shell composed of braided carbon fiber 
and fiberglass, and metallic leading edge erosion protection to give 
the material strength properties and durability. The material 
properties depend on the carbon fiber and fiberglass lay-up and the 
resin matrix material that bind the blade together. Composite materials 
introduce fatigue characteristics and failure modes that differ from 
metallic materials.
    The requirements of part 35 were established to address the 
airworthiness considerations associated with propellers with metallic 
hubs and blades. Propeller blades constructed using composite material 
may be subject to damage due to the high impact forces associated with 
a bird strike.
    In addition, part 35 does not require a demonstration of propeller 
integrity following a lightning strike. Composite blades may not safely 
conduct or dissipate the electrical current from a lightning strike. 
Severe damage can result if the propellers are not properly protected. 
Therefore, composite blades must demonstrate propeller integrity 
following a lightning strike.
    Lastly, the current certification requirements address structural 
and fatigue evaluation only of metal propeller blades or hubs and metal 
components of non-metallic blade assemblies. Allowable design stress 
limits for composite blades must consider the deteriorating effects of 
the environment and in-service use, particularly those effects from 
temperature, moisture, erosion and chemical attack. Composite blades 
also present new and different considerations for retention of the 
blades in the propeller hub.

Type Certification Basis

    Under the provisions of 14 CFR 21.17, McCauley Propeller Systems 
must show that the Model 3D15C1401/C80MWX-X propeller meets the 
applicable provisions of Sec.  21.21 and part 35.
    If the Administrator finds that the applicable airworthiness 
regulations (i.e., part 35) do not contain adequate or appropriate 
safety standards for the McCauley Propeller Systems Model 3D15C1401/
C80MWX-X propeller, because of a novel or unusual design feature, 
special conditions are prescribed under the provisions of Sec.  21.16.
    The FAA issues special conditions, as defined by 14 CFR 11.19, in 
accordance with 14 CFR 11.38, which become part of the type 
certification basis in accordance with Sec.  21.17(a)(2).
    Special conditions are initially applicable to the model for which 
they are issued. Should the type certificate for that model be amended 
later to include any other model that incorporates the same or similar 
novel or unusual design feature, or should any other model already 
included on the same type certificate be modified to incorporate the 
same or similar novel or unusual design feature, the special

[[Page 43675]]

conditions would also apply to the other model under Sec.  21.101(d).

Novel or Unusual Design Features

    The McCauley Propeller Systems Model 3D15C1401/C80MWX-X will 
incorporate the following novel or unusual design features: Blades 
constructed of composite materials. Special conditions for centrifugal 
load tests, fatigue limits and evaluation, bird impact, and lightning 
strike are proposed to address the novel and unusual design features. 
The special conditions are discussed below.

Discussion

Centrifugal Load Tests

    Section 35.35 currently requires that the hub and blade retention 
arrangement of propellers with detachable blades be tested to a 
centrifugal load of twice the maximum centrifugal force to which the 
propeller would be subjected during operation. This requirement is 
limited to the blade and hub retention capacity and does not address 
composite materials and composite construction of the propeller 
assembly or changes in materials due to service degradation and 
environmental factors.

Fatigue Limits and Evaluation

    The current requirement does not adequately address composite 
materials and is limited to metallic hubs and blades and primary load-
carrying metal components of non-metallic blades. The proposed special 
conditions will expand the requirements to include all materials and 
components whose failure would cause a hazardous propeller effect and 
take into account material degradation expected in service, material 
property variations, manufacturing variations, and environmental 
effects. The proposed special conditions will clarify that the fatigue 
limits may be determined by tests or analysis based on tests. The 
components whose failure may cause a hazardous propeller effect include 
control system components, when applicable.
    The proposed special conditions will require the applicant to 
conduct fatigue evaluation on a typical aircraft or on an aircraft used 
during aircraft certification to conduct the vibration tests and 
evaluation required by either Sec. Sec.  23.907 or 25.907. The typical 
aircraft may be one used to develop design criteria for the propeller 
or another appropriate aircraft.

Bird Impact

    Currently part 35 has no bird impact requirements. The existing 
requirements only address the airworthiness considerations associated 
with propellers that use wood and metal blades. Propeller blades of 
this type have demonstrated good service experience following a bird 
strike. Propeller blade and spinner construction now use composite 
materials that have a higher potential for damage from bird impact.
    The need for bird impact requirements was recognized when composite 
blades were introduced in the 1970's; the safety issue has been 
addressed by special test and special conditions for composite blade 
certifications. These special conditions were unique for each propeller 
and effectively stated that the propeller will withstand a four-pound 
bird impact without contributing to a hazardous propeller effect. These 
special tests and special conditions have been effective for over fifty 
million flight hours. There have not been any accidents attributed to 
bird impact on composite propellers. The selection of a four-pound bird 
has been substantiated by the extensive service history of blades that 
have been designed using the four-pound bird criteria.

Lightning Strike

    Currently part 35 has no lightning strike requirements. The need 
for lightning strike requirements was recognized when composite blades 
were first introduced in the 1970's; the safety issue has been 
addressed by special tests and special condition for each design using 
composite blades. The special tests and special condition, which were 
unique for each propeller, effectively stated that the propeller must 
be able to withstand a lightning strike without contributing to a 
hazardous propeller effect. These special tests and special conditions 
have been effective for over fifty million flight hours. There have not 
been any accidents attributed to a lightning strike on composite 
propellers.

Applicability

    As discussed above, these special conditions are applicable to 
McCauley propeller systems Model 3D15C1401/C80MWX-X. If McCauley 
Propeller systems applies later for a change to the type certificate to 
include another model incorporating the same novel or unusual design 
feature, these special conditions would apply to that model as well.

Conclusion

    This action affects only certain novel or unusual design features 
on one model of propellers. It is not a rule of general applicability, 
and it affects only the applicants who applied to the FAA for approval 
of these features on the propeller.

List of Subjects in 14 CFR Part 35

    Air transportation, Aircraft, Aviation safety, Safety.

    The authority citation for these special conditions is as follows:

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

The Proposed Special Conditions

    Accordingly, the Federal Aviation Administration (FAA) proposes the 
following special conditions as part of the type certification basis 
for McCauley Propeller Systems Model 3D15C1401/C80MWX-X propellers.
    1. Definitions. Unless otherwise approved by the Administrator and 
documented in the appropriate manuals and certification documents, for 
compliance with these special conditions the following definitions 
apply to the propeller:
    (a) Propeller--the propeller is defined by the components listed in 
the type design.
    (b) Propeller system--the propeller system consists of the 
propeller plus all the components necessary for its functioning, but 
not necessarily included in the propeller type design.
    (c) Hazardous propeller effect--a hazardous propeller effect is:
    (1) A significant overspeed of the propeller.
    (2) The development of excessive drag.
    (3) A significant thrust in the opposite direction to that 
commanded by the pilot.
    (4) The release of the propeller or any major portion of the 
propeller.
    (5) A failure that results in excessive unbalance.
    (6) The unintended movement of the propeller blades below the 
established minimum in-flight low pitch position.
    (d) Major propeller effect--A major propeller effect is:
    (1) An inability to feather for feathering propellers.
    (2) An inability to command a change in propeller pitch.
    (3) A significant uncommanded change in pitch.
    (4) A significant uncontrollable torque or speed fluctuation.
    2. Centrifugal Load Tests. McCauley must demonstrate that the 
propeller, accounting for environmental degradation expected in 
service, complies with paragraphs (a), (b) and (c) of this section 
without evidence of failure, malfunction, or permanent

[[Page 43676]]

deformation that would result in a hazardous propeller effect. 
Environmental degradation may be accounted for by adjustment of the 
loads during the tests.
    (a) The hub, blade retention system, and counterweights must be 
tested for a period of one hour to a load equivalent to twice the 
maximum centrifugal load to which the propeller would be subjected 
during operation at the maximum declared rotational speed.
    (b) If appropriate, blade features associated with transitions to 
the retention system (for example a composite blade bonded to a 
metallic retention), must be tested either during the test of paragraph 
(a) of this section or in a separate component test.
    (c) Components used with or attached to the propeller (for example 
spinners, de-icing equipment, and blade shields) must be subjected to a 
load equivalent to 159 percent of the maximum centrifugal load to which 
the component would be subjected during operation within the 
limitations established for the propeller. This must be performed by 
either:
    (1) Testing at the load for a period of 30 minutes, or
    (2) Analysis based on test.
    3. Fatigue Limits and Evaluation.
    (a) Fatigue limits.
    (1) Fatigue limits must be established by tests, or analysis based 
on tests, or propeller
    (i) Hubs.
    (ii) Blades.
    (iii) Blade retention components.
    (2) The fatigue limits must take into account:
    (i) All known and reasonably foreseeable vibration and cyclic load 
patterns that are expected in service, and
    (ii) Expected service deterioration, variations in material 
properties, manufacturing variations, and environmental effects.
    (b) A fatigue evaluation of the propeller must be conducted to show 
that hazardous propeller effects due to fatigue will be avoided 
throughout the intended operational life of the propeller on either:
    (1) The intended aircraft by complying with Sec. Sec.  23.907 or 
25.907 as applicable, or
    (2) A typical aircraft.
    4. Bird Impact Substantiation. McCauley must demonstrate, by tests 
or analysis based on tests or experience on similar designs, that the 
propeller is capable of withstanding the impact of a four-pound bird at 
the critical location(s) and critical flight condition(s) of the 
intended aircraft without causing a major or hazardous propeller 
effect.
    5. Lightning Strike Substantiation. McCauley must demonstrate, by 
test or analysis based on tests or experience on similar designs, that 
the propeller is capable of withstanding a lightning strike without 
causing a major or hazardous propeller effect.

    Dated: Issued in Burlington, Massachusetts, on July 24, 2006.
Francis A. Favara,
Manager, Engine and Propeller Directorate, Aircraft Certification 
Service.
[FR Doc. 06-6633 Filed 8-1-06; 8:45 am]
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