[Federal Register Volume 66, Number 192 (Wednesday, October 3, 2001)]
[Rules and Regulations]
[Pages 50302-50304]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 01-24429]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 35

[Docket No. NE124; Special Conditions No. 35-002-SC]


Special Conditions: Hartzell Propeller Incorporated, Model HC-
E5A-2/E8991 Propeller

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final special conditions; request for comments.

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SUMMARY: The FAA is issuing special conditions for the Hartzell 
Propeller Incorporated model HC-E5A-2/E8991 constant speed propeller. 
This five-bladed propeller has blades constructed of composite 
materials. This design feature is novel and unusual. The applicable 
airworthiness regulations do not contain adequate or appropriate safety 
standards for this design feature. These special conditions contain the 
additional safety standards for propeller blades constructed of 
composite materials that the Administrator considers necessary to 
establish a level of safety equivalent to that established by the 
existing airworthiness standards.

DATES: The effective date of these special conditions is December 1, 
2001. Comments must be received on or before November 19, 2001.

ADDRESSES: Comments on these special conditions may be mailed in 
duplicate to: Federal Aviation Administration, Office of the Regional 
Counsel, Attn: Rules Docket No. NE124, 12 New England Executive Park, 
Burlington, Massachusetts, 01803-5299. Comments must be marked: Docket 
No. NE124. Comments may be inspected in the Rules Docket between 8 a.m. 
and 4:30 p.m., Monday through Friday, except Federal holidays.

FOR FURTHER INFORMATION CONTACT: Jay Turnberg, FAA, Engine and 
Propeller Standards Staff, Engine and Propeller Directorate, Aircraft 
Certification Service, ANE-110, 12 New England Executive Park, 
Burlington, Massachusetts, 01803-5229; telephone: (781) 238-7116; fax: 
(781) 238-7199; e-mail: [email protected].

SUPPLEMENTARY INFORMATION:   

Comments Invited

    The FAA has determined that good cause exists for making these 
special conditions effective December 1, 2001; however, the FAA invites 
interested parties to submit comments on the special conditions. 
Comments should identify the Rules Docket and special conditions number 
and be submitted in duplicate to the address specified above. The FAA 
will consider all comments received by the closing date. These special 
conditions may be changed in light of the comments received. All 
comments submitted will be available in the Rules Docket for 
examination by interested persons, both before and after the closing 
date for comments. A report summarizing each substantive public contact 
with FAA personnel concerning this proposal will be filed in the 
docket. Commenters wishing the FAA to acknowledge receipt of their 
comments submitted in response to this notice must include a self-
addressed, stamped postcard on which the following statement is made: 
``Comments to Docket No. NE124.'' The postcard will be date-stamped and 
returned to the commenter.

Background

    On May 3, 2000, Hartzell Propeller Incorporated applied for an 
amendment to type certificate (TC) number P20NE to add a new model HC-
E5A-2/E8991 propeller. The HC-E5A-2/E8991 propeller, which is a 
derivative of the HC-E5 propeller currently approved under TC P20NE, 
has blades constructed of composite material. These special conditions 
address the following airworthiness issues for the Hartzell Propeller 
Incorporated model HC-E5A-2/E8991 propeller:


[[Page 50303]]


1. Centrifugal load tests;
2. Fatigue limits and evaluation;
3. Bird impact; and
4. Lightning strike.

    The Hartzell Propeller Incorporated model HC-E5A-2/E8991 propeller 
incorporates blades constructed of composite material. This material 
has fibers that are woven or aligned in specific directions to give the 
material directional strength properties. These properties depend on 
the type of fiber, the orientation and concentration of fiber, and the 
resin matrix material that binds the fibers together. Composite 
materials introduce fatigue characteristics and failure modes that 
differ from metallic materials.

Type Certification Basis

    Under the provisions of 14 CFR 21.101, Hartzell Propeller 
Incorporated must show that the model HC-E5A-2/E8991 propeller meets 
the applicable provisions of the regulations incorporated by reference 
in TC P20NE or the applicable regulations in effect on the date of 
application for the change. The regulations incorporated by reference 
in the TC are commonly referred to as the ``original type certification 
basis.'' The original type certification basis for the HC-E5 series 
propeller is 14 CFR part 35, effective October 14, 1980, as amended by 
Amendments 35-1 through 35-5. Effective August 18, 1990, the HC-E5B-5 
propeller was added to the type certificate, using Amendments 35-1 
through 35-6 as the certification basis.
    Section 21.16 authorizes the FAA to issue special conditions, using 
the procedure prescribed in 14 CFR part 11, when the applicable 
airworthiness regulations do not contain adequate or appropriate safety 
standards. 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 
novel or unusual design feature, or should any other model already 
included on the same type certificate be modified to incorporate the 
same novel or unusual design feature, the special conditions would also 
apply to the other model under the provisions of Sec. 21.101(a)(1). 
Special conditions become part of the type certification basis for that 
product in accordance with Sec. 21.17(a)(2).

Novel or Unusual Design Features

    The FAA finds that the HC-E5A-2/E8991 propeller incorporates blades 
constructed of composite materials, a novel and unusual design feature 
for which the airworthiness regulations in part 35 do not contain 
adequate or appropriate safety standards. Special conditions for 
centrifugal load tests, fatigue limits and evaluation, bird impact, and 
lightning strike address this novel and unusual design feature.

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 hardware 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, as it is limited to metallic hubs and blades and primary 
load-carrying metal components of non-metallic blades. The special 
conditions expand the requirements to include all materials and to 
account for material degradation expected in service, material property 
variations, manufacturing variations, and environmental effects. The 
special conditions clarify that the fatigue limits may be determined by 
tests or analysis based on tests.
    The special conditions 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 Secs. 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 there are no bird impact requirements in part 35. The 
existing requirements only address the airworthiness considerations 
associated with propellers that use wood or metal blades. Propeller 
blades of this type have demonstrated good service experience following 
a bird strike. Propeller blade and spinner construction now uses 
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 1970s; the safety issue has been 
addressed by special tests and special conditions for composite blade 
certifications. These special conditions were unique for each propeller 
and effectively stated that the propeller must be able to withstand a 
four pound bird impact without contributing to a hazardous propeller 
effect. These special tests and special conditions have been effective 
for over forty 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 there are no lightning strike requirements in part 35. 
The need for lightning strike requirements was recognized when 
composite blades were first introduced in the 1970s; the safety issue 
has been addressed by special tests and special conditions for each 
design using composite blades. The special tests and special 
conditions, 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 forty million flight 
hours. There have not been any accidents attributed to a lightning 
strike on composite propellers.

Applicability

    These special conditions are applicable to the Hartzell Propeller 
Incorporated model HC-E5A-2/E8991 propeller. Should Hartzell Propeller 
Incorporated apply at a later date for a change to the type certificate 
to include another model incorporating the same novel or unusual design 
features, the special conditions would apply to that model as well 
under the provisions of Sec. 21.101(a)(1).

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 applicant who applied to the FAA for approval 
of these features on the propeller.
    The substance of these special conditions has been subjected to the 
notice and comment period in several prior instances and has been 
derived without substantive change from those previously issued. The 
FAA has determined that prior public notice and comment are unnecessary 
and that good cause exists for adopting these special conditions 
immediately. Therefore, these special conditions are being made 
effective December 1, 2001. The FAA is, however, requesting comments to 
allow

[[Page 50304]]

interested parties to submit views that may not have been submitted in 
response to the prior opportunities for comment described above.

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 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 the Hartzell Propeller Incorporated 
model HC-E5A-2/E8991 propeller.
    In addition to the requirements of part 35, the following 
requirements apply to the propeller:
    (a) Definitions. Unless otherwise approved by the Administrator and 
documented in the appropriate manuals and certification documents, for 
the purpose of these special conditions the following definitions apply 
to the propeller:
    (1) Hazardous propeller effects. The following are regarded as 
hazardous propeller effects:
    (i) Significant overspeed of the propeller.
    (ii) Development of excessive drag.
    (iii) Thrust in the direction opposite to that commanded by the 
pilot.
    (iv) Release of the propeller or any major portion of the 
propeller.
    (v) Failure that results in excessive unbalance.
    (vi) Unintended movement of the propeller blades below the 
established minimum in-flight low pitch position.
    (2) Major propeller effects. The following are regarded as major 
propeller effects:
    (i) Inability to feather the propeller (for feathering propellers).
    (ii) Inability to command a change in propeller pitch.
    (iii) Significant uncommanded change in pitch.
    (iv) Significant uncontrollable torque or speed fluctuation.
    (b) Centrifugal load tests. It must be demonstrated that a 
propeller, accounting for environmental degradation expected in 
service, complies with paragraphs (b)(1), (b)(2) and (b)(3) of these 
special conditions without evidence of failure, malfunction, or 
permanent deformation that would result in a major or hazardous 
propeller effect. Environmental degradation may be accounted for by 
adjustment of the loads during the tests.
    (1) 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 rated rotational speed.
    (2) If appropriate, blade features associated with transitions to 
the retention system (e.g., a composite blade bonded to a metallic 
retention) may be tested either during the test required by paragraph 
(b)(1) or in a separate component test.
    (3) Components used with or attached to the propeller (e.g., 
spinners, de-icing equipment, and blade erosion 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 at the maximum rated rotational speed. This must be performed 
by either:
    (i) Testing at the required load for a period of 30 minutes; or
    (ii) Analysis based on test.
    (c) Fatigue limits and evaluation.
    (1) Fatigue limits must be established by tests or analysis based 
on tests, for propeller:
    (i) Hubs;
    (ii) Blades; and
    (iii) Blade retention components.
    (2) The fatigue limits must take the following 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.
    (3) 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:
    (i) The intended aircraft, by complying with Secs. 23.907 or 25.907 
as applicable; or
    (ii) A typical aircraft.
    (d) Bird impact. It must be demonstrated, 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.
    (e) Lightning strike. It must be demonstrated, by tests 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.

    Issued in Burlington, Massachusetts on September 17, 2001.
Jay J. Pardee,
Manager, Engine and Propeller Directorate, Aircraft Certification 
Service.
[FR Doc. 01-24429 Filed 10-2-01; 8:45 am]
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