[Federal Register Volume 78, Number 160 (Monday, August 19, 2013)]
[Rules and Regulations]
[Pages 50317-50320]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2013-20152]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 23

[Docket No. FAA-2013-0413; Special Conditions No. 23-259-SC]


Special Conditions: Cessna Aircraft Company, Model J182T; Diesel 
Cycle Engine Installation

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final special conditions.

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SUMMARY: These special conditions are issued for the Cessna Aircraft 
Company (Cessna) Model J182T airplane. This airplane will have a novel 
or unusual design feature(s) associated with the installation of an 
aircraft diesel engine (ADE). 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 Date: August 19, 2013.

FOR FURTHER INFORMATION CONTACT: Mr. Peter Rouse, Federal Aviation 
Administration, Small Airplane Directorate, Aircraft Certification 
Service, 901 Locust, Room 301, Kansas City, MO 64106; telephone (816) 
329-4135; facsimile (816) 329-4090.

SUPPLEMENTARY INFORMATION: 

Background

    On April 2, 2012, Cessna applied for an amendment to Type 
Certificate No. 3A13 to include the new Model J182T with the Societe de 
Motorisation Aeronautiques (SMA) Engines, Inc. SR305-230E-C1 which is a 
four-stroke, air cooled, diesel cycle engine that uses turbine (jet) 
fuel. The Model No. J182T, which is a derivative of the T182 currently 
approved under Type Certificate No. 3A13, is an aluminum, four place, 
single engine airplane with a cantilever high wing, with the SMA SR305-
230E-C1 diesel cycle engine and associated systems installed.
    In anticipation of the reintroduction of diesel engine technology 
into the small airplane fleet, the FAA issued Policy Statement PS-
ACE100-2002-004 on May 15, 2004, which identified areas of 
technological concern. Refer to this policy for a detailed summary of 
the FAA's development of diesel engine requirements.
    The general areas of concern involving the application of a diesel 
cycle engine are:
     The power characteristics of the engine,
     the use of turbine fuel in an airplane class that is 
typically powered by gasoline fueled engines,
     the vibration characteristics, both normal and with an 
inoperative cylinder,
     anticipated use of an electronic engine control system,
     the appropriate limitations and indications for a diesel 
cycle engine, and
     the failure modes of a diesel cycle engine.

A historical record review of diesel engine use in aircraft and part 23 
identified these concerns. The review identified specific regulatory 
areas requiring evaluation for applicability to diesel engine 
installations. These concerns are not considered universally applicable 
to all types of possible diesel engines and diesel engine 
installations. However, after reviewing the Cessna installation, the 
SMA engine type, the SMA engine requirements, and Policy Statement PS-
ACE100-2002-004, the FAA proposes engine installation and fuel system 
special conditions. The SMA engine has a Full Authority Digital Engine 
Control (FADEC), which also requires special conditions. The FADEC 
special conditions will be issued in a separate notice.

Type Certification Basis

    Under the provisions of Sec.  21.101, Cessna must show that the 
J182T meets the applicable provisions of the regulations incorporated 
by reference in Type Certificate No. 3A13 or the applicable regulations 
in effect on the date of application for the change to the model T182T. 
The regulations incorporated by reference in the type certificate are 
commonly referred to as the ``original type certification basis.'' In 
addition, the J182T certification basis includes special conditions and 
equivalent levels of safety.
    If the Administrator finds that the applicable airworthiness 
regulations (i.e., 14 CFR part 23) do not contain adequate or 
appropriate safety standards for the J182T because of a novel or 
unusual design feature, special conditions are prescribed under the 
provisions of Sec.  21.16.
    In addition to the applicable airworthiness regulations and special 
conditions, the J182T must comply with the fuel vent and exhaust 
emission requirements of 14 CFR part 34 and the noise certification 
requirements of 14 CFR part 36.
    The FAA issues special conditions, as defined in Sec.  11.19, under 
Sec.  11.38 and they become part of the type certification basis under 
Sec.  21.101.
    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.

Novel or Unusual Design Features

    The J182T will incorporate the following novel or unusual design 
features: The installation of an ADE.

Discussion

    Several major concerns were identified in developing FAA policy. 
These include installing the diesel engine and noting its vibration 
levels under both normal operating conditions and when one cylinder is 
inoperative. The concerns also include accommodating turbine fuels in 
airplane systems that have generally evolved based on gasoline 
requirements, anticipated use of a FADEC to control the engine, and 
appropriate limitations and indications for a diesel engine powered 
airplane. The general concerns associated with the aircraft diesel 
engine installation are as follows:

Installation and Vibration Requirements
Fuel and Fuel System Related Requirements
Limitations and Indications

    Installation and Vibration Requirements: These special conditions 
include requirements similar to the

[[Page 50318]]

requirements of Sec.  23.901(d)(1) for turbine engines. In addition to 
the requirements of Sec.  23.901 applied to reciprocating engines, the 
applicant will be required to construct and arrange each diesel engine 
installation to result in vibration characteristics that do not exceed 
those established during the type certification of the engine. These 
vibration levels must not exceed vibration characteristics that a 
previously certificated airframe structure has been approved for, 
unless such vibration characteristics are shown to have no effect on 
safety or continued airworthiness. The engine installation must be 
shown to be free of whirl mode flutter and also any one cylinder 
inoperative flutter effects. The engine limit torque design 
requirements as specified in Sec.  23.361 are also modified.
    An additional requirement to consider vibration levels and/or 
effects of an inoperative cylinder was imposed. Also, a requirement to 
evaluate the engine design for the possibility of, or effect of, 
liberating high-energy engine fragments, in the event of a catastrophic 
engine failure, requirements was added.
    Fuel and Fuel System Related Requirements: Due to the use of 
turbine fuel, this airplane must comply with the requirements in Sec.  
23.951(c). In addition, the fuel flow requirements of Sec.  23.955(c) 
are modified to be reflective of the diesel engine operating 
characteristics.
    Section 23.961 will be complied with using the turbine fuel 
requirements. These requirements will be substantiated by flight-
testing as described in Advisory Circular (AC) 23-8C, Flight Test Guide 
for Certification of Part 23 Airplanes.
    This special condition specifically requires testing to show 
compliance to Sec.  23.961 and adds the possibility of testing non-
aviation diesel fuels.
    To ensure fuel system compatibility and reduce the possibility of 
misfueling, and discounting the first clause of Sec.  23.973(f) 
referring to turbine engines, the applicant will comply with Sec.  
23.973(f).
    Due to the use of turbine fuel, the applicant will comply with 
Sec.  23.977(a)(2), and Sec.  23.977(a)(1) will not apply. ``Turbine 
engines'' will be interpreted to mean ``aircraft diesel engine'' for 
this requirement. An additional requirement to consider the possibility 
of fuel freezing was imposed.
    Due to the use of turbine fuel, the applicant will comply with 
Sec.  23.1305(c)(8).
    Due to the use of turbine fuel, the applicant must comply with 
Sec.  23.1557(c)(1)(ii). Section 23.1557(c)(1)(ii) will not apply. 
``Turbine engine'' is interpreted to mean ``aircraft diesel engine'' 
for this requirement.

Limitations and Indications

    Section 23.1305 will apply, except that the critical engine 
parameters for this installation that will be displayed include:
    (1) Power setting, in percentage, and
    (2) Fuel temperature.
    Due to the use of turbine fuel, the requirements for Sec.  
23.1521(d), as applicable to fuel designation for turbine engines, as 
well as compliance to Sec.  23.1557(c)(1)(ii) will be in lieu of Sec.  
23.1557(c)(1)(i).

Discussion of Comments

    Notice of final special conditions No. 23-259-SC, with request for 
comments, for Cessna Aircraft Company, Model J182T was published in the 
Federal Register on May 16, 2013 (78 FR 28719). One comment was 
received from Cessna Aircraft Company indicating AC-23-8B is referenced 
in the ``Discussion'' section of this special condition; however, AC 
23-8C is used in ``The Special Conditions'' section. It was the FAA's 
intent to reference the current advisory circular, AC 23-8C, throughout 
this document. Compliance with the current AC 23-8, regardless of 
revision version, is required. These final special conditions corrects 
this oversight by changing the reference to AC 23-8B to AC 23-8C in the 
``Discussion'' section above.

Applicability

    As discussed above, these special conditions are applicable to the 
Model J182T. Should Cessna 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.

Conclusion

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

List of Subjects in 14 CFR Part 23

    Aircraft, Aviation safety, Signs and symbols.

Citation

    The authority citation for these special conditions is as follows:

    Authority: 49 U.S.C. 106(g), 40113 and 44701; 14 CFR 21.16 and 
21.101; and 14 CFR 11.38 and 11.19.

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 Cessna Model J182T airplanes.

1. Engine Torque (Provisions Similar to Sec.  23.361(b)(1) and (c)(3))

    a. For diesel engine installations, the engine mounts and 
supporting structure must be designed to withstand the following:
    (1) A limit engine torque load imposed by sudden engine stoppage 
due to malfunction or structural failure.
    (2) The effects of sudden engine stoppage may alternatively be 
mitigated to an acceptable level by utilization of isolators, dampers 
clutches, and similar provisions, so unacceptable load levels are not 
imposed on the previously certificated structure.
    b. The limit engine torque to be considered under Sec.  23.361(a) 
must be obtained by multiplying the mean torque by a factor of four for 
diesel cycle engines.
    (1) If a factor of less than four is used, it must be shown that 
the limit torque imposed on the engine mount is consistent with the 
provisions of Sec.  23.361(c). In other words, it must be shown that 
the use of the factors listed in Sec.  23.361(c)(3) will result in 
limit torques on the mount that are equivalent to or less than those 
imposed by a conventional gasoline reciprocating engine.

2. Flutter--(Compliance With Sec.  23.629(e)(1) and (e)(2) 
Requirements)

    The flutter evaluation of the airplane done in accordance with 
Sec.  23.629 must include--
    (a) Whirl mode degree of freedom which takes into account the 
stability of the plane of rotation of the propeller and significant 
elastic, inertial, and aerodynamic forces, and
    (b) Propeller, engine, engine mount and airplane structure 
stiffness and damping variations appropriate to the particular 
configuration, and
    (c) The flutter investigation will include showing the airplane is 
free from flutter with one cylinder inoperative.

3. Powerplant--Installation (Provisions Similar to Sec.  23.901(d)(1) 
for Turbine Engines)

    Considering the vibration characteristics of diesel engines, the 
applicant must comply with the following:

[[Page 50319]]

    a. Each diesel engine installation must be constructed and arranged 
to result in vibration characteristics that--
    (1) Do not exceed those established during the type certification 
of the engine; and
    (2) Do not exceed vibration characteristics that a previously 
certificated airframe structure has been approved for--
    (i) Unless such vibration characteristics are shown to have no 
effect on safety or continued airworthiness, or
    (ii) Unless mitigated to an acceptable level by utilization of 
isolators, dampers clutches, and similar provisions, so that 
unacceptable vibration levels are not imposed on the previously 
certificated structure.

4. Powerplant--Fuel System--Fuel System With Water Saturated Fuel 
(Compliance With Sec.  23.951(c) Requirements)

    Considering the fuel types used by diesel engines, the applicant 
must comply with the following:
    a. Each fuel system for a diesel engine must be capable of 
sustained operation throughout its flow and pressure range with fuel 
initially saturated with water at 80[emsp14][deg]F and having 0.75cc of 
free water per gallon added and cooled to the most critical condition 
for icing likely to be encountered in operation.
    b. Methods of compliance that are acceptable for turbine engine 
fuel systems requirements of Sec.  23.951(c) are also considered 
acceptable for this requirement.

5. Powerplant--Fuel System--Fuel Flow (Compliance With Sec.  23.955 
Requirements)

    In place of Sec.  23.955(c), the engine fuel system must provide at 
least 100 percent of the fuel flow required by the engine, or the fuel 
flow required to prevent engine damage, if that flow is greater than 
100 percent. The fuel flow rate must be available to the engine under 
each intended operating condition and maneuver. The conditions may be 
simulated in a suitable mockup. This flow must be shown in the most 
adverse fuel feed condition with respect to altitudes, attitudes, and 
any other condition that is expected in operation.

6. Powerplant--Fuel System--Fuel System Hot Weather Operation 
(Compliance With Sec.  23.961 Requirements)

    In place of compliance with Sec.  23.961, the applicant must comply 
with the following:
    a. Each fuel system must be free from vapor lock when using fuel at 
its critical temperature, with respect to vapor formation, when 
operating the airplane in all critical operating and environmental 
conditions for which approval is requested. For turbine fuel, or for 
aircraft equipped with diesel cycle engines that use turbine or diesel 
type fuels, the initial temperature must be 110[emsp14][deg]F, -0[deg], 
+5[deg] or the maximum outside air temperature for which approval is 
requested, whichever is more critical.
    b. The fuel system must be in an operational configuration that 
will yield the most adverse, that is, conservative results.
    c. To comply with this requirement, the applicant must use the 
turbine fuel requirements and must substantiate these by flight-
testing, as described in Advisory Circular (AC) 23-8C, Flight Test 
Guide for Certification of Part 23 Airplanes.

7. Powerplant--Fuel System--Fuel Tank Filler Connection (Compliance 
With Sec.  23.973(f) Requirements)

    In place of compliance with Sec.  23.973(e), the applicant must 
comply with the following:
    For airplanes that operate on turbine or diesel type fuels, the 
inside diameter of the fuel filler opening must be no smaller than 2.95 
inches.

8. Powerplant--Fuel System--Fuel Tank Outlet (Compliance With Sec.  
23.977(a)(2) Requirements)

    In place of compliance with Sec.  23.977(a)(1), the applicant will 
comply with the following:
    There must be a fuel strainer for the fuel tank outlet or for the 
booster pump. This strainer must, for diesel engine powered airplanes, 
prevent the passage of any object that could restrict fuel flow or 
damage any fuel system component.

9. Equipment--General--Powerplant Instruments (Compliance With Sec.  
23.1305 and Sec.  91.205 Requirements)

    In place of compliance with Sec.  23.1305, the applicant will 
comply with the following:
    Below are required powerplant instruments:
    (a) A fuel quantity indicator for each fuel tank, installed in 
accordance with Sec.  23.1337(b).
    (b) An oil pressure indicator.
    (c) An oil temperature indicator.
    (d) An oil quantity measuring device for each oil tank which meets 
the requirements of Sec.  23.1337(d).
    (e) A tachometer indicating propeller speed.
    (f) An indicating means for the fuel strainer or filter required by 
Sec.  23.997 to indicate the occurrence of contamination of the 
strainer or filter before it reaches the capacity established in 
accordance with Sec.  23.997(d).
    Alternately, no indicator is required if the engine can operate 
normally for a specified period with the fuel strainer exposed to the 
maximum fuel contamination as specified in MIL-5007D. Additionally, 
provisions for replacing the fuel filter at this specified period (or a 
shorter period) are included in the maintenance schedule for the engine 
installation.
    (g) Power setting either in percentage power, or through the use of 
manifold pressure.
    (h) Fuel temperature indicator.
    (i) Fuel flow indicator (engine fuel consumption) or fuel pressure.
    If percentage power is used in place of manifold pressure, 
compliance to Sec.  91.205 will be accomplished with the following:
    The diesel engine has no manifold pressure gauge as required by 
Sec.  91.205, in its place, the engine instrumentation as installed is 
to be approved as equivalent. The Type Certification Data Sheet (TCDS) 
is to be modified to show power indication will be accepted to be 
equivalent to the manifold pressure indication.

10. Operating Limitations and Information--Powerplant Limitations--Fuel 
Grade or Designation (Compliance With Sec.  23.1521 Requirements)

    All engine parameters that have limits specified by the engine 
manufacturer for takeoff or continuous operation must be investigated 
to ensure they remain within those limits throughout the expected 
flight and ground envelopes (e.g. maximum and minimum fuel 
temperatures, ambient temperatures, as applicable, etc.). This is in 
addition to the existing requirements specified by Sec.  23.1521(b) and 
(c). If any of those limits can be exceeded, there must be continuous 
indication to the flight crew of the status of that parameter with 
appropriate limitation markings.
    Instead of compliance with Sec.  23.1521(d), the applicant must 
comply with the following:
    The minimum fuel designation (for diesel engines) must be 
established so it is not less than required for the operation of the 
engine within the limitations in paragraphs (b) and (c) of Sec.  
23.1521.

[[Page 50320]]

11. Markings and Placards--Miscellaneous Markings and Placards--Fuel, 
and Oil, Filler Openings (Compliance With Sec.  23.1557(c)(1)(ii) 
Requirements)

    Instead of compliance with Sec.  23.1557(c)(1)(i), the applicant 
must comply with the following:
    Fuel filler openings must be marked at or near the filler cover 
with--
    For diesel engine-powered airplanes--
    (a) The words ``Jet Fuel''; and
    (b) The permissible fuel designations, or references to the 
Airplane Flight Manual (AFM) for permissible fuel designations.
    (c) A warning placard or note that states the following or similar:
    ``Warning--this airplane is equipped with an aircraft diesel 
engine; service with approved fuels only.''
    The colors of this warning placard should be black and white.

12. Powerplant--Fuel System--Fuel-Freezing

    If the fuel in the tanks cannot be shown to flow suitably under all 
possible temperature conditions, then fuel temperature limitations are 
required. These limitations will be considered as part of the essential 
operating parameters for the aircraft. Limitations will be determined 
as follows:
    (a) The takeoff temperature limitation must be determined by 
testing or analysis to define the minimum fuel cold-soaked temperature 
that the airplane can operate on.
    (b) The minimum operating temperature limitation must be determined 
by testing to define the minimum acceptable operating temperature after 
takeoff (with minimum takeoff temperature established in (1) above).

13. Powerplant Installation--Vibration Levels

    Vibration levels throughout the engine operating range must be 
evaluated and:
    (a) Vibration levels imposed on the airframe must be less than or 
equivalent to those of the gasoline engine; or
    (b) Any vibration level higher than that imposed on the airframe by 
the replaced gasoline engine must be considered in the modification and 
the effects on the technical areas covered by the following paragraphs 
must be investigated:
    14 CFR part 23, Sec. Sec.  23.251; 23.613; 23.627; 23.629 (or CAR 
3.159, as applicable to various models); 23.572; 23.573; 23.574 and 
23.901.
    Vibration levels imposed on the airframe can be mitigated to an 
acceptable level by utilization of isolators, damper clutches, and 
similar provisions so that unacceptable vibration levels are not 
imposed on the previously certificated structure.

14. Powerplant Installation--One Cylinder Inoperative

    Tests or analysis, or a combination of methods, must show that the 
airframe can withstand the shaking or vibratory forces imposed by the 
engine if a cylinder becomes inoperative. Diesel engines of 
conventional design typically have extremely high levels of vibration 
when a cylinder becomes inoperative. Data must be provided to the 
airframe installer/modifier so either appropriate design considerations 
or operating procedures, or both, can be developed to prevent airframe 
and propeller damage.

15. Powerplant Installation--High Energy Engine Fragments

    It may be possible for diesel engine cylinders (or portions 
thereof) to fail and physically separate from the engine at high 
velocity (due to the high internal pressures). This failure mode will 
be considered possible in engine designs with removable cylinders or 
other non-integral block designs. The following is required:
    (a) It must be shown that the engine construction type (massive or 
integral block with non-removable cylinders) is inherently resistant to 
liberating high energy fragments in the event of a catastrophic engine 
failure; or
    (b) It must be shown by the design of the engine, that engine 
cylinders, other engine components or portions thereof (fragments) 
cannot be shed or blown off of the engine in the event of a 
catastrophic engine failure; or
    (c) It must be shown that all possible liberated engine parts or 
components do not have adequate energy to penetrate engine cowlings; or
    (d) Assuming infinite fragment energy, and analyzing the trajectory 
of the probable fragments and components, any hazard due to liberated 
engine parts or components will be minimized and the possibility of 
crew injury is eliminated. Minimization must be considered during 
initial design and not presented as an analysis after design 
completion.

    Issued in Kansas City, Missouri, on August 12, 2013.
Earl Lawrence,
Manager, Small Airplane Directorate, Aircraft Certification Service.
[FR Doc. 2013-20152 Filed 8-16-13; 8:45 am]
BILLING CODE 4910-13-P