Source: https://www.federalregister.gov/documents/2009/09/01/E9-21057/special-conditions-cessna-aircraft-company-model-525c-high-fuel-temperature
Timestamp: 2018-04-23 02:52:13
Document Index: 91256906

Matched Legal Cases: ['§\u200923', 'art 23', '§\u200923', '§\u200923', '§\u200923', '§\u200923', '§\u200923', '§\u200923', '§\u200923', '§\u200921']

45133-45135 (3 pages)
Notice No. 23-09-03-SC
https://www.federalregister.gov/d/E9-21057 https://www.federalregister.gov/d/E9-21057
This notice proposes special conditions for the Cessna Aircraft Company, Model 525C 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 proposed 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.
Comments on this proposal may be mailed in duplicate to: Federal Aviation Administration, Regional Counsel, ACE-7, Attention: Rules Docket, Docket No. CE299, 901 Locust, Room 506, Kansas City, Missouri 64106, or delivered in duplicate to the Regional Counsel at the above address. Comments must be marked: CE299. Comments may be inspected in the Rules Docket weekdays, except Federal holidays, between 7:30 a.m. and 4 p.m.
Interested persons are invited to participate in the making of these proposed special conditions by submitting such written data, views, or arguments as they may desire. Communications should identify the regulatory docket or notice number and be submitted in duplicate to the address specified above. All communications received on or before the closing date for comments will be considered by the Administrator. The proposals described in this notice may be changed in light of the comments received. All comments received will be available in the Rules Docket for examination by interested persons, both before and after the closing date for comments. A report summarizing each substantive public contact with FAA personnel concerning this rulemaking will be filed in the docket. Persons wishing the FAA to acknowledge receipt of their comments submitted in response to this notice must include with those comments a self-addressed, stamped postcard on which the following statement is made: “Comments to CE299.” The postcard will be date stamped and returned to the commenter.
On August 9, 2006, Cessna Aircraft Company applied for an amendment to Type Certificate Number A1WI to include the new model 525C (CJ4). The model 525C (CJ4), which is a derivative of the model 525B (CJ3) currently approved under Type Certificate Number A1WI, 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. The maximum takeoff weight is 16,950 pounds, the VMO/MMO is 305 KIAS/M 0.77 and maximum altitude is 45,000 feet.
The Cessna Model 525C (CJ4) fuel tank system is similar to other Cessna Model 525 designs which use the Williams FJ44 series of engine. The fuel tank system is configured to reject engine heat through the airplane fuel tank system by using an engine oil/fuel heat exchanger. Certified as part of the engine, the engine oil/fuel heat exchanger cools the oil and heats the fuel. Over time the engine manufacturers have optimized the design, size, placement, and space management of the oil/fuel heat exchanger such that today's engines now reject more heat back into the airplane fuel tank system than has existed in the past. As can be seen by the chart below we are now exposing the fuel tank system and airplane to temperatures above the critical temperature test requirements of §§ 23.961 and 23.965(d), which has been the FAA standard for fuel system hot weather operations and fuel tank test and evaluation since 1951.
Start Printed Page 45134
IM max. fuel pump inlet temp. (sea level) (°F)
525, CJ1+ FJ44-1AP 205 115 165 255
525A, CJ2 FJ44-2C 230 140 188 200
525B, CJ3 FJ44-3A 202 117 155 200
14 CFR part 23 certification experience to date has shown that fuel system hot weather certification testing with 110 °F fuel temperatures is adequate for fuel system operations for fuel tank temperatures characterized by ambient air temperatures including cooling as a result of the atmospheric temperature lapse rate. Heating of the fuel that increases the airplane fuel tank system operational temperatures introduces a number of fuel tank system and airplane 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. The following are those concerns:
Evaluation of engine, fuel tank system and airplane performance and engine compatibility with elevated fuel tank system temperatures. [§§ 23.901(e)(1) and (e)(2), 23.939(a), and 23.951(a)]
Evaluation of fuel tank system and airplane performance due to fuel degradation and resultant byproducts at elevated fuel tank system temperatures. [§§ 23.961, 23.939(a), 23.993(e), 23.1301, and 23.1529)]
Evaluation of fuel tank system and airplane performance and engine compatibility due to the higher vapor/liquid ratios with elevated fuel tank system temperatures. [§§ 23.903(f), 23.951(a), 23.955(a) and (f), 23.961, and 23.1301]
Evaluation of fuel tank system and airplane performance and engine compatibility due to the solubility of water and potential for greater microbial growth with elevated fuel tank system temperatures. [§§ 23.951(c) and 23.971]
Evaluation of fuel tank system and airplane performance due to elevated fuel tank system material temperatures and surrounding structure compatibility. [§§ 23.613(c), 23.963(a), 23.965(d), and 23.993(e)]
Evaluation of fuel tank system component qualification as a result of elevated fuel tank system temperatures. [§§ 23.1301 and 23.1309]
Evaluation of service/maintenance instructions, activities and personnel due to elevated fuel tank system temperatures. [§ 23.1529]
As discussed above, these special conditions are applicable to the Model 525C. Should Cessna Aircraft Company 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 under the provisions of § 21.101.
This action affects only certain novel or unusual design features on one model, model 525C, 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.
Accordingly, the Federal Aviation Administration (FAA) proposes the following special conditions as part of the type certification basis for the Cessna Aircraft Company, model 525C airplanes.
Issued in Kansas City, Missouri on August 20, 2009.
[FR Doc. E9-21057 Filed 8-31-09; 8:45 am]