[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]



 ========================================================================
 Rules and Regulations
                                                 Federal Register
 ________________________________________________________________________
 
 This section of the FEDERAL REGISTER contains regulatory documents 
 having general applicability and legal effect, most of which are keyed 
 to and codified in the Code of Federal Regulations, which is published 
 under 50 titles pursuant to 44 U.S.C. 1510.
 
 The Code of Federal Regulations is sold by the Superintendent of Documents. 
 Prices of new books are listed in the first FEDERAL REGISTER issue of each 
 week.
 
 ========================================================================
 

  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.

-----------------------------------------------------------------------

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]
BILLING CODE 4910-13-P