[Federal Register Volume 68, Number 221 (Monday, November 17, 2003)]
[Rules and Regulations]
[Pages 64799-64802]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 03-28676]



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  Federal Register / Vol. 68, No. 221 / Monday, November 17, 2003 / 
Rules and Regulations  

[[Page 64799]]



DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 35

[Docket No. NE125; Special Conditions No. 35-003-SC


Special Conditions: Hamilton Sundstrand, Model 54H60-77E 
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 Hamilton 
Sundstrand model 54H60-77E constant speed propeller. This four-bladed 
propeller will have a dual acting digital electro-hydraulic propeller 
control system, which is a novel or unusual design feature. 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: The effective date of these special conditions is December 1, 
2003. The FAA must receive comments on or before January 30, 2004.

ADDRESSES: Mail or deliver comments on these special conditions to: 
Federal Aviation Administration, Office of the Assistant Chief Counsel, 
Attention: Rules Docket NE125, 12 New England Executive Park, 
Burlington, Massachusetts, 01803-5299. You must identify the docket 
number NE125 at the beginning of your comments, and you should submit 
two copies of your comments. You may review the public docket 
containing comments to these special conditions in person at the Office 
of the Regional Counsel 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: 
    The FAA has determined that notice and opportunity for prior public 
comment hereon are impracticable because these procedures would 
significantly delay issuance of the approval design and thus delivery 
of the affected aircraft. In addition, the substance of these special 
conditions has previously been subject to the public comment process 
with no substantive comments received. The FAA therefore finds that 
good cause exists for making these special conditions effective on 
December 1, 2003.

Comments Invited

    The FAA has determined that good cause exists for making these 
special conditions effective December 1, 2003; however; the FAA invites 
interested parties to submit comments on the special conditions. You 
must identify the docket number NE125 at the beginning of your 
comments, and you should submit two copies of your comments. The FAA 
will consider all comments received by the closing date. The FAA may 
change these special conditions 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. The docket will contain a report summarizing each 
substantive public contact with FAA personnel concerning this proposal. 
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. NE125.'' The postcard will be dated-stamped and returned 
to the commenter.

Background

    On February 24, 2003, Hamilton Sundstrand applied for an amendment 
to Type Certificate No. P906 to include the new 54H60-77E propeller. 
The model 54H60-77E, which is a derivative of the model 54H currently 
approved under Type Certificate P906, uses a dual acting digital 
electro-hydraulic propeller control system (EPCS).
    Digital electronic control introduces potential failures associated 
with electrical power, software commands, data, and environmental 
effects that can result in hazardous propeller effects. The applicable 
airworthiness regulations do not contain adequate or appropriate safety 
standards for these design features. These special conditions address 
the following airworthiness issues for the Hamilton Sundstrand 54H60-
77E propeller:
    1. Safety assessment.
    2. Propeller control system.
    These special conditions contain the additional safety standards 
necessary to establish a level of safety equivalent to that established 
by the existing airworthiness standards.

Type Certification Basis

    Under the provisions of 14 CFR 21.101, Hamilton Sundstrand must 
show that the 54H60-77E meets the applicable provisions of the 
regulations incorporated by reference in Type Certificate No. P906 or 
the applicable regulations in effect on the date of application for the 
change to the model 54H. The regulations incorporated by reference in 
the type certificate are commonly referred to as the ``original type 
certification basis.'' The regulations incorporated by reference in 
P906 are Civil Air Regulation (CAR) part 14, as amended in December 15, 
1959.
    In addition, if the regulations incorporated by reference do not 
provide adequate standards with respect to the change, the applicant 
must comply with certain regulations in effect on the date of 
application for the change. Hamilton Sundstrand has elected to show 
compliance with part 35, as amended through Amendment 7, dated December 
28, 1995, for the 54H60-77E.
    If the Administrator finds that the applicable airworthiness 
regulations (i.e., 14 CFR part 35) do not contain adequate or 
appropriate safety standards for the 54H60-77E because of a novel or 
unusual design feature, special conditions are prescribed under the 
provisions of 14 CFR 21.16.

[[Page 64800]]

    As appropriate, special conditions, as defined in Sec.  11.19, are 
issued in accordance with Sec.  11.38 and become part of the type 
certification basis in accordance with 14 CFR 21.101(b)(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 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 14 CFR 21.101(a)(1).

Novel or Unusual Design Features

    The 54H60-77E will incorporate the following novel or unusual 
design features: dual acting digital electro-hydraulic propeller 
control system. Digital electronic control introduces potential 
failures associated with electrical power, software commands, data, and 
environmental effects that can result in hazardous propeller effects. 
The applicable airworthiness regulations do not contain adequate or 
appropriate safety standards for these design features. These special 
conditions address the following airworthiness issues for the Hamilton 
Sundstrand 54H60-77E propeller:
    1. Safety assessment.
    2. Propeller control system.
    These special conditions contain the additional safety standards 
necessary to establish a level of safety equivalent to that established 
by the existing airworthiness standards.
    The existing type certified Hamilton Sundstrand 54H model propeller 
as described in FAA Type Certification Data Sheet P906, amendment 7, 
uses a mechanical governor in the propeller control system. This 
mechanical control system senses propeller speed and adjusts the pitch 
by directing hydraulic oil to the propeller actuator to increase or 
decrease pitch to maintain the propeller at the correct RPM and to 
absorb the engine power.
    The Hamilton Sundstrand EPCS replaces the current mechanical 
control system with a digital electronic governor in the propeller 
control. The digital electronic governor is designed to operate a 
hydro-mechanical interface to direct hydraulic oil to the propeller 
actuator to increase or decrease pitch. The digital electronic control 
logic commands speed governing, synchrophasing, and failure monitoring 
and provides beta scheduling. Digital electronic control introduces 
potential failures associated with electrical power, software commands, 
data, and environmental effects that can result in hazardous propeller 
effects.

Safety Assessment

    The special conditions require the applicant to conduct a safety 
assessment of the propeller in conjunction with the requirements for 
evaluating the digital electro-hydraulic control system. A safety 
assessment is necessary due to the increased complexity of these 
propeller designs and related control systems. The ultimate objective 
of the safety assessment requirement is to ensure that the collective 
risk from all propeller failure conditions is acceptably low. The basis 
is the concept that an acceptable total propeller design risk is 
achievable by managing the individual risks to acceptable levels. This 
concept emphasizes reducing the risk of an event proportionally with 
the severity of the hazard it represents.
    The special conditions are written at the propeller level for a 
typical aircraft. The typical aircraft may be the aircraft intended for 
installation of the propeller. It is advised that the propeller 
applicant have an understanding of the intended aircraft, not to show 
compliance with this requirement, but to design a propeller that will 
be acceptable for the intended aircraft. For example, a part 25 
aircraft may require different failure effects and probability of 
failure than a part 23 aircraft. Showing compliance with the 
requirement without consideration of the intended aircraft may result 
in a propeller that cannot be installed on the intended aircraft.

Propeller Control System

    Currently, part 35 does not adequately address propellers with 
combined mechanical, hydraulic, digital, and electronic control 
systems. Propeller mechanical control systems certified under the 
existing requirements incorporate a mechanical governor that senses 
propeller speed and adjusts the pitch to absorb the engine power to 
maintain the propeller at the selected rotational speed. Propellers 
with digital electronic control components perform the same basic 
function but use software, electronic circuitry, and electro-hydraulic 
actuators. The electronic control systems may also incorporate 
additional functions such as failure monitoring, synchrophasing, and 
beta scheduling. This addition of electronics to the control system may 
introduce new failure modes that can result in hazardous propeller 
effects.

Applicability

    As discussed above, these special conditions apply to the model 
54H60-77E propeller. Should Hamilton Sundstrand apply at a later date 
for a change to the type certificate to include another model 
incorporating the same novel or unusual design feature, the special 
conditions would apply to that model as well under the provisions of 14 
CFR 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 previously been 
subjected to the notice and comment period 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, 2003. The FAA is, however, requesting comments to allow interested 
parties to submit views that may not have been submitted in response to 
the prior opportunity 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 Hamilton Sundstrand model 54H60-
77E 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) Propeller. The propeller is defined by the components listed in 
the type design.
    (2) Propeller system. The propeller system consists of the 
propeller plus all

[[Page 64801]]

the components necessary for its functioning, but not necessarily 
included in the propeller type design.
    (3) Hazardous propeller effects. The following are regarded as 
hazardous propeller effects:
    (i) A significant overspeed of the propeller.
    (ii) The development of excessive drag.
    (iii) Thrust in the opposite direction to that commanded by the 
pilot.
    (iv) A release of the propeller or any major portion of the 
propeller.
    (v) A failure that results in excessive unbalance.
    (vi) The unintended movement of the propeller blades below the 
established minimum in-flight low pitch position.
    (4) Major propeller effects. The following are regarded as major 
propeller effects.
    (i) An inability to feather.
    (ii) An inability to command a change in propeller pitch.
    (iii) A significant uncommanded change in pitch.
    (iv) A significant uncontrollable torque or speed fluctuation.
    (b) Safety analysis.
    (1)(i) Perform an analysis of the propeller system to assess the 
likely consequence of all failures that can reasonably be expected to 
occur. This analysis must consider the following:
    (A) The propeller system in a typical installation. When the 
analysis depends on representative components, assumed interfaces, or 
assumed installed conditions, the analysis must state the assumptions.
    (B) Consequential secondary failures and latent failures.
    (C) Multiple failures referred to in paragraph (b)(4) of these 
special conditions or that result in hazardous propeller effects.
    (ii) Summarize those failures that could result in major propeller 
effects or hazardous propeller effects, together with an estimate of 
the probability of occurrence of those effects.
    (iii) Show that hazardous propeller effects are not predicted to 
occur at a rate in excess of that defined as extremely remote 
(probability of 10-\7\ or less per propeller flight hour). 
As the estimated probability for individual failures may be 
insufficiently precise to enable the applicant to assess the total rate 
for hazardous propeller effects, compliance may be shown by 
demonstrating that the probability of a hazardous propeller effect 
arising from any individual failure can be predicted to be not greater 
than 10-\8\ per propeller flight hour. Probabilities of this 
low order of magnitude may be demonstrated through reliance on 
engineering judgment and previous experience combined with sound design 
and test philosophies.
    (2) The Administrator may, if significant doubt exists, require 
testing to verify any assumption as to the effects of failures or 
likely combination of failures.
    (3) If the primary failure of certain single elements (for example, 
blades) cannot be sensibly estimated in numerical terms, and if the 
failure of such elements is likely to result in hazardous propeller 
effects, then compliance may be shown by meeting the prescribed 
integrity requirements of part 35 and these special conditions. The 
safety analysis must state these instances.
    (4) If reliance is placed on a system or device, such as safety 
devices, feathering and overspeed systems, instrumentation, early 
warning devices, maintenance checks, and similar equipment or 
procedures, to prevent a failure from progressing to hazardous 
propeller effects, the analysis must include the possibility of a 
safety system failure in combination with a basic propeller failure. If 
items of a safety system are outside the control of the propeller 
manufacturer, the safety analysis must state assumptions with respect 
to the reliability of these parts, and the installation and operation 
instructions required under Sec.  35.3 must identify these assumptions.
    (5) If the safety analysis depends on one or more of the following 
items, the analysis must state and appropriately substantiate those 
items.
    (i) Performance of mandatory maintenance actions at stated 
intervals required for certification and other maintenance actions. 
This includes verifying the serviceability of items that could fail in 
a latent manner. These maintenance intervals must be published in the 
appropriate propeller manuals. Additionally, if errors in maintenance 
of the propeller system could lead to hazardous propeller effects, the 
appropriate procedures must be published in the appropriate propeller 
manuals.
    (ii) Verification of the satisfactory functioning of safety or 
other devices at pre-flight or other stated periods. The details of 
this satisfactory functioning must be published in the appropriate 
propeller manuals.
    (iii) The provisions of specific instrumentation not otherwise 
required.
    (iv) A fatigue assessment.
    (6) If applicable, the safety analysis must include the assessment 
of indicating equipment, manual and automatic controls, governors and 
propeller control systems, synchrophasers, synchronizers, and propeller 
thrust reversal systems.
    (c) Propeller control system. The requirements of this section 
apply to any system or component that controls, limits, or monitors 
propeller functions.
    (1) Design, construct, and validate the propeller control system to 
show that:
    (i) The propeller control system, operating in normal and 
alternative operating modes and transition between operating modes, 
performs the intended functions throughout the declared operating 
conditions and flight envelope.
    (ii) The propeller control system functionality is not adversely 
affected by the declared environmental conditions, including 
temperature, electromagnetic interference (EMI), high intensity 
radiated fields (HIRF) and lightning. Document the environmental limits 
to which the system has been satisfactorily validated in the 
appropriate propeller manuals.
    (iii) A method is provided to indicate that an operating mode 
change has occurred if flight crew action is required. In such an 
event, provide operating instructions in the appropriate manuals.
    (2) Design and construct the propeller control system so that, in 
addition to compliance with paragraph (b) of these special conditions, 
Safety analysis:
    (i) A level of integrity consistent with the intended aircraft is 
achieved.
    (ii) A single failure or malfunction of electrical or electronic 
components in the control system does not cause a hazardous propeller 
effect.
    (iii) Failures or malfunctions directly affecting the propeller 
control system in a typical aircraft, such as structural failures of 
attachments to the control, fire, or overheat, do not lead to a 
hazardous propeller effect.
    (iv) The loss of normal propeller pitch control does not cause a 
hazardous propeller effect under the intended operating conditions.
    (v) The failure or corruption of data or signals shared across 
propellers does not cause a major or hazardous propeller effect.
    (3) Design and implement electronic propeller control system 
imbedded software by a method approved by the Administrator that is 
consistent with the criticality of the performed functions and 
minimizes the existence of software errors.
    (4) Design and construct the propeller control system so that the 
failure or corruption of aircraft-supplied does not result in hazardous 
propeller effects.
    (5) Design and construct the propeller control system so that the 
loss, interruption, or abnormal characteristic

[[Page 64802]]

of aircraft-supplied electrical power does not result in hazardous 
propeller effects. Describe the power quality requirements in the 
appropriate manuals.
    (6) Specify the propeller control system description, 
characteristics, and authority, in both normal operation and failure 
conditions, and the range of control of other controlled functions, in 
the appropriate propeller manuals.

    Issued in Burlington, Massachusetts, on November 10, 2003.
Francis A. Favara,
Acting Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
[FR Doc. 03-28676 Filed 11-14-03; 8:45 am]
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