[Federal Register Volume 76, Number 69 (Monday, April 11, 2011)]
[Rules and Regulations]
[Pages 19903-19907]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2011-8547]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 23

[Docket No. CE310; Special Conditions No. 23-250-SC


Special Conditions: Diamond Aircraft Industry Model DA-40NG; 
Diesel Cycle Engine

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final special conditions; request for comments.

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SUMMARY: These special conditions are issued for the Diamond Aircraft 
Industry (DAI) GmbH model DA-40NG the Austro Engine GmbH model E4 
aircraft diesel engine (ADE) using turbine (jet) fuel. This airplane 
will have a novel or unusual design feature(s) associated with the 
installation of a diesel cycle engine utilizing turbine (jet) fuel. 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 April 1, 2011.
    We must receive your comments by May 11, 2011.

ADDRESSES: Mail two copies of your comments to: Federal Aviation 
Administration, Regional Counsel, ACE-7, Attn: Rules Docket No. CE310, 
901 Locust, Kansas City, MO 64106. You may deliver two copies to the 
Regional Counsel at the above address. Mark your comments: Docket No. 
CE310. You may inspect comments in the Rules Docket weekdays, except 
Federal holidays, between 7:30 a.m. and 4 p.m.

FOR FURTHER INFORMATION CONTACT: Peter L. Rouse, Federal Aviation 
Administration, Small Airplane Directorate, Aircraft Certification 
Service, ACE-111, 901 Locust, Kansas City, Missouri, 816-329-4135, fax 
816-329-4090.

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 design 
approval and thus delivery of the affected aircraft. In addition, the 
substance of these special conditions has been subject to the public 
comment process in several prior instances with no substantive comments 
received. The FAA therefore finds that good cause exists for making 
these special conditions effective upon issuance.

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 7:30 a.m. and 4 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 these 
special conditions, 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 May 11, 2010 Diamond Aircraft Industry GmbH applied for an 
amendment to Type Certificate No. A47CE to include the new Model DA-
40NG with the Austro Engine GmbH Model E4 ADE. The Model DA-40NG, which 
is a derivative of the model DA-40 currently approved under Type 
Certificate No. A47CE, is a fully composite, four place, single-engine 
airplane with a cantilever low wing, T-tail airplane with the Austro 
Engine GmbH Model E4 diesel engine and an increased maximum takeoff 
gross weight from 1150 kilograms (kg) to 1280 kg (2535 pounds (lbs) to 
2816 lbs).
    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 involve the power characteristics of 
the diesel engines, the use of turbine fuel in an airplane class that 
is typically powered by gasoline fueled engines and the vibration 
characteristics and failure modes of diesel engines. A review of the 
historical record 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

[[Page 19904]]

types of possible diesel engines and diesel engine installations. 
However, after reviewing the DAI installation, the Austro engine type, 
the Austro Control GmbH (ACG) requirements, and Policy Statement PS-
ACE100-2002-004, the FAA issues these fuel system and engine related 
special conditions. The Austro 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, DAI must show that the model 
DA-40NG meets the applicable provisions of the regulations incorporated 
by reference in Type Certificate No. A47CE or the applicable 
regulations in effect on the date of application for the change to the 
model DA-40. The regulations incorporated by reference in the type 
certificate are commonly referred to as the ``original type 
certification basis.'' In addition, the certification basis includes 
special conditions and equivalent levels of safety for the following:
    Special Conditions:
     Engine torque (Provisions similar to Sec.  23.361, 
paragraphs (b)(1) and (c)(3)).
     Flutter (Compliance with Sec.  23.629, paragraphs (e)(1) 
and (2)).
     Powerplant--Installation (Provisions similar to Sec.  
23.901(d)(1) for turbine engines).
     Powerplant--Fuel System--Fuel system with water saturated 
fuel (Compliance with Sec.  23.951 requirements).
     Powerplant--Fuel System--Fuel system hot weather operation 
(Compliance with Sec.  23.961 requirements).
     Powerplant--Fuel system--Fuel tank filler connection 
(Compliance with Sec.  23.973(f) requirements).
     Powerplant--Fuel system--Fuel tank outlet (Compliance with 
Sec.  23.977 requirements).
     Equipment--General--Powerplant Instruments (Compliance 
with Sec.  23.1305 requirements).
     Operating Limitations and Information--Powerplant 
limitations--Fuel grade or designation (Compliance with Sec.  
23.1521(d) requirements).
     Markings And Placards--Miscellaneous markings and 
placards--Fuel, oil, and coolant filler openings (Compliance with Sec.  
23.1557(c)(1) requirements).
     Powerplant--Fuel system--Fuel-Freezing.
     Powerplant Installation--Vibration levels.
     Powerplant Installation--One cylinder inoperative.
     Powerplant Installation--High Energy Engine Fragments.
    Equivalent level of safety for:
     Cockpit controls--23.777(d)
     Motion and effect of cockpit controls--23.779(b)
     Liquid Cooling--Installation--23.1061
     Ignition switches--23.1145
    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 model DA-40NG 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 model DA-40NG 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 become part of the type certification basis in 
accordance with 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 model DA-40NG will incorporate the following novel or unusual 
design features: Installation of the Austro Engine GmbH Model E4 ADE 
diesel engine utilizing turbine (jet) fuel.

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 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 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).
    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 23-8B, 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.

[[Page 19905]]

Limitations and Indications

    Section 23.1305(a) and Sec.  23.1305(b)(2) will apply, except that 
propeller revolutions per minute (RPM) will be displayed. Sections 
23.1305(b)(4), 23.1305(b)(5), and 23.1305(b)(7) are deleted. Additional 
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, will 
apply.

Applicability

    As discussed above, these special conditions are applicable to the 
model DA-40NG. Should DAI 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 airplanes. 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 airplane.
    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. It is 
unlikely that prior public comment would result in a significant change 
from the substance contained herein. Therefore, because a delay would 
significantly affect the certification of the airplane, which is 
imminent, the FAA has determined that prior public notice and comment 
are unnecessary and impracticable, and good cause exists for adopting 
these special conditions upon issuance. The FAA is requesting comments 
to allow interested persons 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 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 
21.17; 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 Diamond Aircraft Industry GmbH Model 
DA-40NG with the installation of the Austro Engine GmbH Model E4 
aircraft diesel engine.
    1. Engine torque (Provisions similar to Sec.  23.361, paragraphs 
(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.
    (a) 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 14 
CFR 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:
    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 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[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 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 [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 23-8B, Flight Test Guide 
for Certification of Part 23 Airplanes.

[[Page 19906]]

    6. Powerplant--Fuel system--Fuel tank filler connection (Compliance 
with Sec.  23.973(f) requirements):
    In place of compliance with Sec.  23.973(e) and (f), 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.
    7. Powerplant--Fuel system--Fuel tank outlet (Compliance with Sec.  
23.977 requirements):
    In place of compliance with Sec.  23.977(a)(1) and (a)(2), 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.
    8. Equipment--General--Powerplant Instruments (Compliance with 
Sec.  23.1305 and 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) A tachometer indicating propeller speed.
    (e) A coolant temperature indicator.
    (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, in percentage.
    (h) Fuel temperature.
    (i) Fuel flow (engine fuel consumption).
    In place of compliance to Sec.  91.205, comply 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.
    9. Operating Limitations and Information--Powerplant limitations-- 
Fuel grade or designation (Compliance with Sec.  23.1521(d) 
requirements):
    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 
engines within the limitations in paragraphs (b) and (c) of Sec.  
23.1521.
    10. Markings and Placards--Miscellaneous markings and placards-- 
Fuel, oil, and coolant filler openings (Compliance with Sec.  
23.1557(c)(1) requirements):
    Instead of compliance with Sec.  23.1557(c)(1), 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.
    11. 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).
    12. 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.
    13. 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.
    14. 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.


[[Page 19907]]


    Issued in Kansas City, Missouri, on April 1, 2011.
John Colomy,
Acting Manager, Small Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 2011-8547 Filed 4-8-11; 8:45 am]
BILLING CODE 4910-13-P