E9-29053. Special Conditions: Embraer S.A., Model EMB-505; High Fuel Temperature

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Final special conditions; request for comments.

SUMMARY:

These special conditions are issued for the Embraer S.A., Model EMB-505 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:

The effective date of these special conditions is December 1, 2009. We must receive your comments by January 6, 2010.

ADDRESSES:

You must mail two copies of your comments to: Federal Aviation Administration, Regional Counsel, ACE-7, Attention: Rules Docket Clerk, Docket No. CE301, Room 506, 901 Locust, Kansas City, Missouri 64106. Mark comments: Docket No. CE301. 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, Aircraft Certification Service, Small Airplane Directorate, ACE-111, 901 Locust, Kansas City, Missouri, 816-329-4135, fax [phone].

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 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 data, views, or arguments as they may desire. 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 concerning 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 on or before 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 the FAA to acknowledge receipt of the comments on this proposal, include with your comments 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.

Discussion

Background

On October 9, 2006, Embraer S.A. applied for a type certificate for their new Model EMB-505. The Model EMB-505 is a commuter 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 17,967 pounds, the V_MO/M_MO is 320 KCAS/M 0.78 and maximum altitude is 45,000 feet.

Fuel temperatures on the Embraer EMB 505 are higher than envisioned by 14 CFR part 23. The rule governing fuel system hot weather operation is 14 CFR part 23, § 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 °F, −0 °, +5 ° 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 recently designed turbofan engines were much higher than those previously encountered on previous airplane certification projects. 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 PW535E, the engine inlet maximum fuel temperature was determined to reach up to 196.7 °F (91.5 °C) during design development testing.

Initial concerns regarding the safe operation of the airplane with fuel temperatures significantly greater than 110 °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 § 25.961 values, i.e., 110-120 °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:

Engine model	Sea level maximum inlet fuel 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 § 3.583; “The maximum anticipated summer air temperature shall be considered to be 100 °F at sea level and to decrease from this value at the rate of 3.6 °F per thousand feet above sea level.” Concurrently, § 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 °F under critical operating conditions.” Building from CAR part 3, 14 CFR part 23 envisioned maximum fuel temperatures at or near 110 °F as set forth in 14 CFR part 23, § 23.961. The turbine fuel temperature requirement for hot weather operation is 110 −0, +5 °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 °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 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-505 airplane was proposed. The special condition requires the compliance to 14 CFR part 23, § 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 the provisions of 14 CFR part 21, § 21.17, Embraer S.A. must show that the Model EMB-505 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-505 because of a novel or unusual design feature, special conditions are prescribed under § 21.16.

In addition to the applicable airworthiness regulations and special conditions, the Model EMB-505 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 § 611 of Public Law 92-574, the “Noise Control Act of 1972.”

The FAA issues special conditions, as appropriate, as defined in § 11.19, under § 11.38, and they become part of the type certification basis under § 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 or similar novel or unusual design feature, the special conditions would also apply to the other model.

Novel or Unusual Design Features

The Model EMB-505 will incorporate the following novel or unusual design features:

High Fuel Temperatures.

Applicability

As discussed above, these special conditions are applicable to the Model EMB-505. 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.

Conclusion

This action affects only certain novel or unusual design features on one model, Model EMB-505, 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, the Federal Aviation Administration (FAA) issues the following special conditions as part of the type certification basis for the Embraer S.A. Model EMB-505 airplanes.

1. SC § 23.961:

Instead of compliance with § 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 December 1, 2009.

William J. Timberlake,

Acting Manager, Small Airplane Directorate, Aircraft Certification Service.