[Federal Register Volume 73, Number 119 (Thursday, June 19, 2008)]
[Rules and Regulations]
[Pages 34843-34844]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E8-13830]
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Rules and Regulations
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Federal Register / Vol. 73, No. 119 / Thursday, June 19, 2008 / Rules
and Regulations
[[Page 34843]]
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 23
[Docket No. CE280; Special Conditions No. 23-220-SC]
Special Conditions: Embraer S.A., Model EMB-500; High Fuel
Temperature
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Final special conditions.
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SUMMARY: These special conditions are issued for the Embraer S.A.,
Model EMB-500 airplane. This airplane will have a novel or unusual
design feature(s) associated with high fuel temperature. 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: June 10, 2008.
FOR FURTHER INFORMATION CONTACT: Peter L. Rouse, Federal Aviation
Administration, Aircraft Certification Service, Small Airplane
Directorate, ACE-111, 901 Locust, Kansas City, Missouri, 816-329-4135,
fax 816-329-4090.
SUPPLEMENTARY INFORMATION:
Background
On October 5, 2005, Embraer S.A. applied for a type certificate for
their new Model EMB-500. The Model EMB-500 is a normal category, low-
winged monoplane with ``T'' tailed vertical and horizontal stabilizers,
retractable tricycle type landing gear and twin turbofan engines
mounted on the aircraft fuselage. Its design characteristics include a
predominance of metallic construction. The maximum takeoff weight is
9,965 pounds, the VMO/MMO is 275 KIAS/M 0.70 and
maximum altitude is 41,000 feet.
Fuel temperatures on the Embraer EMB 500 are higher than envisioned
by 14 CFR part 23. The rule governing fuel system hot weather operation
is 14 CFR part 23, Sec. 23.961, and the rule requires the following:
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, 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.
During other airplane certification projects, the fuel system
temperatures associated with the PW600 series turbofan engines were
much higher than those previously encountered on other engines. The
engine oil/fuel heat fuel system includes an exchanger that cools the
oil and heats the fuel. Consequently, the motive flow fuel that is
returned to the airplane from the engine is hot and heats the airplane
wing fuel and tank. As a result, on the PW615F, the engine inlet
maximum fuel temperature was increased from a development value of 126
[deg]F (52 [deg]C) to an initial (Transport Canada) certification value
of 172 [deg]F (78 [deg]C) for kerosene type fuels.
Initial concerns regarding the safe operation of the airplane with
fuel temperatures significantly greater than 110 [deg]F are identified
as:
Fuel degradation with resultant byproducts at high
temperatures
Operation with the higher vapor liquid ratios
Fuel system component qualification at the higher
temperatures
Solubility of water in fuel
Microbial growth
Fuel tank material/surrounding structure compatibility
with the elevated temperatures
Service and maintenance personnel susceptibility to burns
An initial review of FAA experience regarding airplane fuel
temperatures identifies that for large part 25 aircraft, fuel
temperature upper limits are characterized by Sec. 25.961 values, i.e.
110-120 [deg]F. Operationally, the buildup of vapor pockets within fuel
lines has been an issue from this perspective for large transport
category airplanes. A summary of the maximum engine inlet fuel
temperatures for engines used in part 23 and part 25 business jet
airplanes that are FAA certified follows:
------------------------------------------------------------------------
Sea level maximum inlet fuel
Engine Model temperature
------------------------------------------------------------------------
PWC615F................................... 126 F (52 C) draft IM
PWC615F................................... 172 F (78 C) Transport
Canada
PWC615F................................... 190 F (88 C)
530A, 535A................................ 135 F (57 C)
545A...................................... 135 F (57 C)
305A...................................... 135 F (57 C)
308....................................... 135 F (57 C)
JT15D-4, -4B, -4D......................... 135 F (57 C)
FJ44-3A................................... 200 F (93 C)
FJ44-2A................................... 135 F (57 C)
FJ44-1B................................... 135 F (57 C)
TFE731-2/-3............................... 135 F (57 C)
TFE731-20................................. 135 F (57 C)
------------------------------------------------------------------------
CAR part 3, as amended to May 15, 1956, defined the maximum
anticipated summer air temperatures in Sec. 3.583; ``The maximum
anticipated summer air temperature shall be considered to be 100 [deg]F
at sea level and to decrease from this value at the rate of 3.6 [deg]F
per thousand feet above sea level.'' Concurrently, Sec. 3.438 required
that ``* * * fuel system features conducive to vapor formation shall be
demonstrated to be free from vapor lock when using fuel at a
temperature of 110 [deg]F under critical operating conditions.''
Building from CAR part 3, 14 CFR part 23 envisioned maximum fuel
temperatures at or near 110 [deg]F as set forth in 14 CFR part 23,
Sec. 23.961. The turbine fuel temperature requirement for hot weather
operation is 110 -0, +5 [deg]F, or the maximum outside air temperature
for which approval is requested, whichever is more critical. Engine
heat rejection such that the airplane fuel temperature is characterized
by engine heat rejection rather than ambient air temperature is a new
and novel design that was not envisioned by 14 CFR part 23.
14 CFR part 23 certification experience to date has shown that hot
weather certification testing with 110 [deg]F fuel temperatures is
adequate for fuel system operations for fuel tank fuel temperatures
characterized by ambient air temperatures including cooling as a result
of the atmospheric temperature lapse rate. Heating that increases the
airplane fuel system operational temperatures introduces several fuel
[[Page 34844]]
system concerns. Each must be shown to be acceptable. Compliance by
design (i.e. lack of ability to shutoff the engine motive flow) may be
utilized although associated type certificate data sheet information
may also be necessary to assure future system changes are compliant.
A special condition for the higher fuel system temperatures of the
Embraer EMB 500 airplane was proposed. The special condition requires
the compliance to 14 CFR part 23, Sec. 23.961, fuel system hot weather
operation test temperature to be commensurate with the highest fuel
temperature expected at the maximum outside air temperature for which
approval is requested.
Type Certification Basis
Under 14 CFR part 21, Sec. 21.17, Embraer S.A. must show that the
Model EMB-500 meets the applicable provisions of 14 CFR part 23, as
amended by Amendments 23-1 through 23-55, thereto.
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 EMB-500 because of a novel
or unusual design feature, special conditions are prescribed under
Sec. 21.16.
In addition to the applicable airworthiness regulations and special
conditions, the Model EMB-500 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, and the FAA must issue a
finding of regulatory adequacy under Sec. 611 of Public Law 92-574,
the ``Noise Control Act of 1972.''
Special conditions, as appropriate, as defined in Sec. 11.19, are
issued under Sec. 11.38, and become part of the type certification
basis under Sec. 21.17(a).
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, the special conditions would also apply to the
other model under Sec. 21.101(a).
Novel or Unusual Design Features
The Model EMB-500 will incorporate the following novel or unusual
design features: High Fuel Temperatures.
Discussion of Comments
Notice of proposed special conditions No. 23-07-05-SC for the
Embraer S.A., Model EMB-500 airplanes was published on January 23, 2008
(73 FR 3881). No comments were received, and the special conditions are
adopted as proposed.
Applicability
As discussed above, these special conditions are applicable to the
Model EMB-500. Should Embraer S.A. apply later 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 Sec. 21.101(a).
Conclusion
This action affects only certain novel or unusual design features
on one model, Model EMB-500, 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.
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 the Embraer S.A. Model EMB-500
airplanes.
1. SC Sec. 23.961
Instead of compliance with Sec. 23.961, the following apply:
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, the
initial temperature must be the highest fuel temperature expected at
the maximum outside air temperature for which approval is requested.
Issued in Kansas City, Missouri on June 10, 2008.
Kim Smith,
Manager, Small Airplane Directorate, Aircraft Certification Service.
[FR Doc. E8-13830 Filed 6-18-08; 8:45 am]
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